redone result, op, tests for result, op, graph

gof/_test_graph.py

+
+
+import unittest
+from graph import *
+
+from op import Op
+from result import ResultBase, BrokenLinkError
+
+
+class MyResult(ResultBase):
+
+    def __init__(self, thingy):
+        self.thingy = thingy
+        ResultBase.__init__(self, role = None, data = [self.thingy], constant = False)
+
+    def __eq__(self, other):
+        return isinstance(other, MyResult) and other.thingy == self.thingy
+
+    def __str__(self):
+        return str(self.thingy)
+
+    def __repr__(self):
+        return str(self.thingy)
+
+
+class MyOp(Op):
+
+    def validate_update(self):
+        for input in self.inputs:
+            if not isinstance(input, MyResult):
+                raise Exception("Error 1")
+        self.outputs = [MyResult(sum([input.thingy for input in self.inputs]))]
+
+
+class _test_inputs(unittest.TestCase):
+
+    def test_0(self):
+        r1, r2 = MyResult(1), MyResult(2)
+        op = MyOp(r1, r2)
+        assert inputs(op.outputs) == set([r1, r2])
+
+    def test_1(self):
+        r1, r2, r5 = MyResult(1), MyResult(2), MyResult(5)
+        op = MyOp(r1, r2)
+        op2 = MyOp(op.outputs[0], r5)
+        assert inputs(op2.outputs) == set([r1, r2, r5])
+
+
+class _test_orphans(unittest.TestCase):
+
+    def test_0(self):
+        r1, r2, r5 = MyResult(1), MyResult(2), MyResult(5)
+        op = MyOp(r1, r2)
+        op2 = MyOp(op.outputs[0], r5)
+        assert orphans([r1, r2], op2.outputs) == set([r5])
+    
+
+class _test_as_string(unittest.TestCase):
+
+    leaf_formatter = str
+    node_formatter = lambda op, argstrings: "%s(%s)" % (op.__class__.__name__,
+                                                        ", ".join(argstrings))
+
+    def test_0(self):
+        r1, r2 = MyResult(1), MyResult(2)
+        op = MyOp(r1, r2)
+        assert as_string([r1, r2], op.outputs) == ["MyOp(1, 2)"]
+
+    def test_1(self):
+        r1, r2, r5 = MyResult(1), MyResult(2), MyResult(5)
+        op = MyOp(r1, r2)
+        op2 = MyOp(op.outputs[0], r5)
+        assert as_string([r1, r2, r5], op2.outputs) == ["MyOp(MyOp(1, 2), 5)"]
+
+    def test_2(self):
+        r1, r2, r5 = MyResult(1), MyResult(2), MyResult(5)
+        op = MyOp(r1, r2)
+        op2 = MyOp(op.outputs[0], op.outputs[0])
+        assert as_string([r1, r2, r5], op2.outputs) == ["MyOp(*1 -> MyOp(1, 2), *1)"]
+
+    def test_3(self):
+        r1, r2, r5 = MyResult(1), MyResult(2), MyResult(5)
+        op = MyOp(r1, r2)
+        op2 = MyOp(op.outputs[0], op.outputs[0])
+        assert as_string(op.outputs, op2.outputs) == ["MyOp(3, 3)"]
+        assert as_string(op2.inputs, op2.outputs) == ["MyOp(3, 3)"]
+
+
+class _test_clone(unittest.TestCase):
+
+    def test_0(self):
+        r1, r2 = MyResult(1), MyResult(2)
+        op = MyOp(r1, r2)
+        new = clone([r1, r2], op.outputs)
+        assert as_string([r1, r2], new) == ["MyOp(1, 2)"]
+
+    def test_1(self):
+        r1, r2, r5 = MyResult(1), MyResult(2), MyResult(5)
+        op = MyOp(r1, r2)
+        op2 = MyOp(op.outputs[0], r5)
+        new = clone([r1, r2, r5], op2.outputs)
+        assert op2.outputs[0] == new[0] and op2.outputs[0] is not new[0]
+        assert op2 is not new[0].owner
+        assert new[0].owner.inputs[1] is r5
+        assert new[0].owner.inputs[0] == op.outputs[0] and new[0].owner.inputs[0] is not op.outputs[0]
+
+    def test_2(self):
+        "Checks that manipulating a cloned graph leaves the original unchanged."
+        r1, r2, r5 = MyResult(1), MyResult(2), MyResult(5)
+        op = MyOp(MyOp(r1, r2).outputs[0], r5)
+        new = clone([r1, r2, r5], op.outputs)
+        new_op = new[0].owner
+        new_op.inputs = MyResult(7), MyResult(8)
+
+        assert as_string(inputs(new_op.outputs), new_op.outputs) == ["MyOp(7, 8)"]
+        assert as_string(inputs(op.outputs), op.outputs) == ["MyOp(MyOp(1, 2), 5)"]
+
+
+
+if __name__ == '__main__':
+    unittest.main()
+
+
+

gof/_test_op.py

+
+import unittest
+from copy import copy
+from op import *
+from result import ResultBase, BrokenLinkError
+
+
+class MyResult(ResultBase):
+
+    def __init__(self, thingy):
+        self.thingy = thingy
+        ResultBase.__init__(self, role = None, data = [self.thingy], constant = False)
+
+    def __eq__(self, other):
+        return isinstance(other, MyResult) and other.thingy == self.thingy
+
+    def __str__(self):
+        return str(self.thingy)
+
+    def __repr__(self):
+        return str(self.thingy)
+
+
+class MyOp(Op):
+
+    def validate_update(self):
+        for input in self.inputs:
+            if not isinstance(input, MyResult):
+                raise Exception("Error 1")
+        self.outputs = [MyResult(sum([input.thingy for input in self.inputs]))]
+
+
+class _test_Op(unittest.TestCase):
+
+    # Sanity tests
+    def test_sanity_0(self):
+        r1, r2 = MyResult(1), MyResult(2)
+        op = MyOp(r1, r2)
+        assert op.inputs == [r1, r2] # Are the inputs what I provided?
+        assert op.outputs == [MyResult(3)] # Are the outputs what I expect?
+
+    # validate_update
+    def test_validate_update(self):
+        try:
+            MyOp(ResultBase(), MyResult(1)) # MyOp requires MyResult instances
+        except Exception, e:
+            assert str(e) == "Error 1"
+        else:
+            raise Exception("Expected an exception")
+
+    # Setting inputs and outputs
+    def test_set_inputs(self):
+        r1, r2 = MyResult(1), MyResult(2)
+        op = MyOp(r1, r2)
+        r3 = op.outputs[0]
+        op.inputs = MyResult(4), MyResult(5)
+        assert op.outputs == [MyResult(9)] # check if the output changed to what I expect
+        assert r3.data is op.outputs[0].data # check if the data was properly transferred by set_output
+        
+    def test_set_bad_inputs(self):
+        op = MyOp(MyResult(1), MyResult(2))
+        try:
+            op.inputs = MyResult(4), ResultBase()
+        except Exception, e:
+            assert str(e) == "Error 1"
+        else:
+            raise Exception("Expected an exception")
+
+    def test_set_outputs(self):
+        r1, r2 = MyResult(1), MyResult(2)
+        op = MyOp(r1, r2) # here we only make one output
+        try:
+            op.outputs = MyResult(10), MyResult(11) # setting two outputs should fail
+        except TypeError, e:
+            assert str(e) == "The new outputs must be exactly as many as the previous outputs."
+        else:
+            raise Exception("Expected an exception")
+        
+
+    # Tests about broken links
+    def test_create_broken_link(self):
+        r1, r2 = MyResult(1), MyResult(2)
+        op = MyOp(r1, r2)
+        r3 = op.out
+        op.inputs = MyResult(3), MyResult(4)
+        assert r3 not in op.outputs
+        assert r3.replaced
+        
+    def test_cannot_copy_when_input_is_broken_link(self):
+        r1, r2 = MyResult(1), MyResult(2)
+        op = MyOp(r1, r2)
+        r3 = op.out
+        op2 = MyOp(r3)
+        op.inputs = MyResult(3), MyResult(4)
+        try:
+            copy(op2)
+        except BrokenLinkError:
+            pass
+        else:
+            raise Exception("Expected an exception")
+        
+    def test_get_input_broken_link(self):
+        r1, r2 = MyResult(1), MyResult(2)
+        op = MyOp(r1, r2)
+        r3 = op.out
+        op2 = MyOp(r3)
+        op.inputs = MyResult(3), MyResult(4)
+        try:
+            op2.get_input(0)
+        except BrokenLinkError:
+            pass
+        else:
+            raise Exception("Expected an exception")
+        
+    def test_get_inputs_broken_link(self):
+        r1, r2 = MyResult(1), MyResult(2)
+        op = MyOp(r1, r2)
+        r3 = op.out
+        op2 = MyOp(r3)
+        op.inputs = MyResult(3), MyResult(4)
+        try:
+            op2.get_inputs()
+        except BrokenLinkError:
+            pass
+        else:
+            raise Exception("Expected an exception")
+
+    def test_repair_broken_link(self):
+        r1, r2 = MyResult(1), MyResult(2)
+        op = MyOp(r1, r2)
+        r3 = op.out
+        op2 = MyOp(r3, MyResult(10))
+        op.inputs = MyResult(3), MyResult(4)
+        op2.repair()
+        assert op2.outputs == [MyResult(17)]
+
+    # Tests about string representation
+    def test_create_broken_link(self):
+        r1, r2 = MyResult(1), MyResult(2)
+        op = MyOp(r1, r2)
+        assert str(op) == "MyOp(1, 2)"
+
+
+
+if __name__ == '__main__':
+    unittest.main()

gof/_test_result.py

+
+import unittest
+from result import *
+
+class _test_ResultBase(unittest.TestCase):
+    def test_0(self):
+        r = ResultBase()
+    def test_1(self):
+        r = ResultBase()
+        assert r.state is Empty
+
+        r.data = 0
+        assert r.data == 0
+        assert r.state is Computed
+        
+        r.data = 1
+        assert r.data == 1
+        assert r.state is Computed
+
+        r.data = None
+        assert r.data == None
+        assert r.state is Empty
+
+
+if __name__ == '__main__':
+    unittest.main()

gof/env.py

@@ -6,53 +6,21 @@ from utils import ClsInit
 from err import GofError, GofTypeError, PropagationError
 from op import Op
 from result import is_result
-from features import Listener, Orderings, Constraint, Tool
+from features import Listener, Orderings, Constraint, Tool, uniq_features
 import utils
 
 __all__ = ['InconsistencyError',
            'Env']
 
 
-# class AliasDict(dict):
-#     "Utility class to keep track of what result has been replaced with what result."
-
-#     def group(self, main, *keys):
-#         "Marks all the keys as having been replaced by the result main."
-#         keys = [key for key in keys if key is not main]
-#         if self.has_key(main):
-#             raise Exception("Only group results that have not been grouped before.")
-#         for key in keys:
-#             if self.has_key(key):
-#                 raise Exception("Only group results that have not been grouped before.")
-#             if key is main:
-#                 continue
-#             self.setdefault(key, main)
-
-#     def ungroup(self, main, *keys):
-#         "Undoes group(main, *keys)"
-#         keys = [key for key in keys if key is not main]
-#         for key in keys:
-#             if self[key] is main:
-#                 del self[key]
-
-#     def __call__(self, key):
-#         "Returns the currently active replacement for the given key."
-#         next = self.get(key, None)
-#         while next:
-#             key = next
-#             next = self.get(next, None)
-#         return key
-
-
-
-#TODO: why is this not in err.py? -James
-class InconsistencyError(GofError):
+class InconsistencyError(Exception):
     """
     This exception is raised by Env whenever one of the listeners marks
     the graph as inconsistent.
     """
     pass
 
+
 def require_set(cls):
     """Return the set of objects named in a __env_require__ field in a base class"""
     r = set()
@@ -70,22 +38,22 @@ def require_set(cls):
             r.add(req)
     return r
 
+
 class Env(graph.Graph):
     """
-    An Env represents a subgraph bound by a set of input results and a set of output
-    results. An op is in the subgraph iff it depends on the value of some of the Env's
-    inputs _and_ some of the Env's outputs depend on it. A result is in the subgraph
-    iff it is an input or an output of an op that is in the subgraph.
+    An Env represents a subgraph bound by a set of input results and a
+    set of output results. An op is in the subgraph iff it depends on
+    the value of some of the Env's inputs _and_ some of the Env's
+    outputs depend on it. A result is in the subgraph iff it is an
+    input or an output of an op that is in the subgraph.
 
-    The Env supports the replace operation which allows to replace a result in the
-    subgraph by another, e.g. replace (x + x).out by (2 * x).out. This is the basis
-    for optimization in omega.
+    The Env supports the replace operation which allows to replace a
+    result in the subgraph by another, e.g. replace (x + x).out by (2
+    * x).out. This is the basis for optimization in omega.
 
-    An Env can have listeners, which are instances of EnvListener. Each listener is
-    informed of any op entering or leaving the subgraph (which happens at construction
-    time and whenever there is a replacement). In addition to that, each listener can
-    implement the 'consistent' and 'ordering' methods (see EnvListener) in order to
-    restrict how ops in the subgraph can be related.
+    An Env's functionality can be extended with features, which must
+    be subclasses of L{Listener}, L{Constraint}, L{Orderings} or
+    L{Tool}.
 
     Regarding inputs and orphans:
     In the context of a computation graph, the inputs and orphans are both
@@ -93,7 +61,6 @@ class Env(graph.Graph):
     named as inputs will be assumed to contain fresh.  In other words, the
     backward search from outputs will stop at any node that has been explicitly
     named as an input.
-
     """
 
     ### Special ###
@@ -102,11 +69,6 @@ class Env(graph.Graph):
         """
         Create an Env which operates on the subgraph bound by the inputs and outputs
         sets. If consistency_check is False, an illegal graph will be tolerated.
-
-        Features are class types derived from things in the tools file.  These
-        can be listeners, constraints, orderings, etc.  Features add much
-        (most?) functionality to an Env.
-
         """
 
         self._features = {}
@@ -115,30 +77,12 @@ class Env(graph.Graph):
         self._orderings = {}
         self._tools = {}
 
-#         self._preprocessors = set()
-
-#         for feature in features:
-#             if issubclass(feature, tools.Preprocessor):
-#                 preprocessor = feature()
-#                 self._preprocessors.add(preprocessor)
-#                 inputs, outputs = preprocessor.transform(inputs, outputs)
-
         # The inputs and outputs set bound the subgraph this Env operates on.
         self.inputs = set(inputs)
         self.outputs = set(outputs)
         
-        for feature_class in utils.uniq_features(features):
+        for feature_class in uniq_features(features):
             self.add_feature(feature_class, False)
-#             feature = feature_class(self)
-#             if isinstance(feature, tools.Listener):
-#                 self._listeners.add(feature)
-#             if isinstance(feature, tools.Constraint):
-#                 self._constraints.add(feature)
-#             if isinstance(feature, tools.Orderings):
-#                 self._orderings.add(feature)
-#             if isinstance(feature, tools.Tool):
-#                 self._tools.add(feature)
-#                 feature.publish()
 
         # All ops in the subgraph defined by inputs and outputs are cached in _ops
         self._ops = set()
@@ -234,20 +178,6 @@ class Env(graph.Graph):
             except KeyError:
                 pass
 
-#         for i, feature in enumerate(self._features):
-#             if isinstance(feature, feature_class): # exact class or subclass, nothing to do
-#                 return
-#             elif issubclass(feature_class, feature.__class__): # superclass, we replace it
-#                 new_feature = feature_class(self)
-#                 self._features[i] = new_feature
-#                 break
-#         else:
-#             new_feature = feature_class(self)
-#             self._features.append(new_feature)
-#         if isinstance(new_feature, tools.Listener):
-#             for op in self.io_toposort():
-#                 new_feature.on_import(op)
-
     def get_feature(self, feature_class):
         try:
             return self._features[feature_class]
@@ -325,7 +255,7 @@ class Env(graph.Graph):
             self.outputs.add(new_r)
 
         # The actual replacement operation occurs here. This might raise
-        # a GofTypeError
+        # an error.
         self.__move_clients__(clients, r, new_r)
 
         # This function undoes the replacement.

gof/ext.py

 
-from copy import copy
-from op import Op
-from lib import DummyOp
-from features import Listener, Constraint, Orderings
-from env import InconsistencyError
-from utils import ClsInit
-import graph
+# from copy import copy
+# from op import Op
+# from lib import DummyOp
+# from features import Listener, Constraint, Orderings
+# from env import InconsistencyError
+# from utils import ClsInit
+# import graph
 
 
-#TODO: move mark_outputs_as_destroyed to the place that uses this function
-#TODO: move Return to where it is used.
-__all__ = ['IONames', 'mark_outputs_as_destroyed']
+__all__ = ['Destroyer', 'Viewer']
 
 
-class IONames:
-    """
-    Requires assigning a name to each of this Op's inputs and outputs.
-    """
-
-    __metaclass__ = ClsInit
-
-    input_names = ()
-    output_names = ()
-    
-    @staticmethod
-    def __clsinit__(cls, name, bases, dct):
-        for names in ['input_names', 'output_names']:
-            if names in dct:
-                x = getattr(cls, names)
-                if isinstance(x, str):
-                    x = [x,]
-                    setattr(cls, names, x)
-                if isinstance(x, (list, tuple)):
-                    x = [a for a in x]
-                    setattr(cls, names, x)
-                    for i, varname in enumerate(x):
-                        if not isinstance(varname, str) or hasattr(cls, varname) or varname in ['inputs', 'outputs']:
-                            raise TypeError("In %s: '%s' is not a valid input or output name" % (cls.__name__, varname))
-                        # Set an attribute for the variable so we can do op.x to return the input or output named "x".
-                        setattr(cls, varname,
-                                property(lambda op, type=names.replace('_name', ''), index=i:
-                                         getattr(op, type)[index]))
-                else:
-                    print 'ERROR: Class variable %s::%s is neither list, tuple, or string' % (name, names)
-                    raise TypeError, str(names)
-            else:
-                setattr(cls, names, ())
 
-#     def __init__(self, inputs, outputs, use_self_setters = False):
-#         assert len(inputs) == len(self.input_names)
-#         assert len(outputs) == len(self.output_names)
-#         Op.__init__(self, inputs, outputs, use_self_setters)
 
-    def __validate__(self):
-        assert len(self.inputs) == len(self.input_names)
-        assert len(self.outputs) == len(self.output_names)
 
-    @classmethod
-    def n_inputs(cls):
-        return len(cls.input_names)
-        
-    @classmethod
-    def n_outputs(cls):
-        return len(cls.output_names)
-        
-    def get_by_name(self, name):
-        """
-        Returns the input or output which corresponds to the given name.
-        """
-        if name in self.input_names:
-            return self.input_names[self.input_names.index(name)]
-        elif name in self.output_names:
-            return self.output_names[self.output_names.index(name)]
-        else:
-            raise AttributeError("No such input or output name for %s: %s" % (self.__class__.__name__, name))
 
 
 

gof/features.py

 
-from copy import copy
-from op import Op
-import result
-import graph
+# from copy import copy
+# from op import Op
+# import result
+# import graph
+
 import utils
 
-from random import shuffle
+# from random import shuffle
 
 
 __all__ = ['Feature',
@@ -13,10 +14,11 @@ __all__ = ['Feature',
            'Constraint',
            'Orderings',
            'Tool',
-           'EquivTool',
-           'InstanceFinder',
-           'PrintListener',
-           'ChangeListener',
+           'uniq_features',
+#           'EquivTool',
+#           'InstanceFinder',
+#           'PrintListener',
+#           'ChangeListener',
            ]
 
 
@@ -24,256 +26,236 @@ __all__ = ['Feature',
 class Feature(object):
     
     def __init__(self, env):
+        """
+        Initializes the Feature's env field to the parameter
+        provided.
+        """
         self.env = env
 
 
 class Listener(Feature):
+    """
+    When registered by an env, each listener is informed of any op
+    entering or leaving the subgraph (which happens at construction
+    time and whenever there is a replacement).
+    """
 
     def on_import(self, op):
-        pass
+        """
+        This method is called by the env whenever a new op is
+        added to the graph.
+        """
+        raise utils.AbstractFunctionError()
     
     def on_prune(self, op):
-        pass
+        """
+        This method is called by the env whenever an op is
+        removed from the graph.
+        """
+        raise utils.AbstractFunctionError()
 
     def on_rewire(self, clients, r, new_r):
-        pass
+        """
+        clients -> (op, i) pairs such that op.inputs[i] is new_r
+                   but used to be r
+        r -> the old result that was used by the ops in clients
+        new_r -> the new result that is now used by the ops in clients
+
+        Note that the change from r to new_r is done before this
+        method is called.
+        """
+        raise utils.AbstractFunctionError()
 
 
 class Constraint(Feature):
+    """
+    When registered by an env, a Constraint can restrict the ops that
+    can be in the subgraph or restrict the ways ops interact with each
+    other.
+    """
 
     def validate(self):
-        return True
+        """
+        Raises an L{InconsistencyError} if the env is currently
+        invalid from the perspective of this object.
+        """
+        raise utils.AbstractFunctionError()
 
 
 class Orderings(Feature):
+    """
+    When registered by an env, an Orderings object can provide supplemental
+    ordering constraints to the subgraph's topological sort.
+    """
 
     def orderings(self):
-        return {}
+        """
+        Returns {op: set(ops that must be evaluated before this op), ...}
+        This is called by env.orderings() and used in env.toposort() but
+        not in env.io_toposort().
+        """
+        raise utils.AbstractFunctionError()
 
 
 class Tool(Feature):
+    """
+    A Tool can extend the functionality of an env so that, for example,
+    optimizations can have access to efficient ways to search the graph.
+    """
 
     def publish(self):
-        pass
-
-
-# class Preprocessor(Feature):
-
-#     def transform(self, inputs, outputs):
-#         return inputs, outputs
-
-#     def __call__(self, inputs, outputs):
-#         return self.transform(inputs, outputs)
-
-
-# class Optimization(object):
-
-#     def require(self):
-#         return []
-
-#     def apply(self, env):
-#         pass
-
-#     def __call__(self, env):
-#         return self.apply(env)
-
-
-
-
-# Optimization
-#  * require <tool_class>*
-#  * apply
-
-# Prog
-#  * __init__
-#    * inputs
-#    * outputs
-#    * listeners, constraints, orderings
-#      * dispatched by isinstance Listener, etc.
-#    * {tool_class: preferred_implementation, ...}
-
-
-
-class EquivTool(Listener, Tool, dict):
-
-    def on_rewire(self, clients, r, new_r):
-        repl = self(new_r)
-        if repl is r:
-            self.ungroup(r, new_r)
-        elif repl is not new_r:
-            raise Exception("Improper use of EquivTool!")
-        else:
-            self.group(new_r, r)
-
-    def publish(self):
-        self.env.equiv = self
-
-    def group(self, main, *keys):
-        "Marks all the keys as having been replaced by the Result main."
-        keys = [key for key in keys if key is not main]
-        if self.has_key(main):
-            raise Exception("Only group results that have not been grouped before.")
-        for key in keys:
-            if self.has_key(key):
-                raise Exception("Only group results that have not been grouped before.")
-            if key is main:
-                continue
-            self.setdefault(key, main)
-
-    def ungroup(self, main, *keys):
-        "Undoes group(main, *keys)"
-        keys = [key for key in keys if key is not main]
-        for key in keys:
-            if self[key] is main:
-                del self[key]
-
-    def __call__(self, key):
-        "Returns the currently active replacement for the given key."
-        next = self.get(key, None)
-        while next:
-            key = next
-            next = self.get(next, None)
-        return key
-
-
-
-class InstanceFinder(Listener, Tool, dict):
-
-    def __init__(self, env):
-        self.env = env
-
-    def all_bases(self, cls):
-        return utils.all_bases(cls, lambda cls: issubclass(cls, Op))
-#        return [cls for cls in utils.all_bases(cls) if issubclass(cls, Op)]
-
-    def on_import(self, op):
-        for base in self.all_bases(op.__class__):
-            self.setdefault(base, set()).add(op)
-
-    def on_prune(self, op):
-        for base in self.all_bases(op.__class__):
-            self[base].remove(op)
-            if not self[base]:
-                del self[base]
-
-    def __query__(self, cls):
-        all = [x for x in self.get(cls, [])]
-        shuffle(all) # this helps a lot for debugging because the order of the replacements will vary
-        while all:
-            next = all.pop()
-            if next in self.env.ops():
-                yield next
-
-    def query(self, cls):
-        return self.__query__(cls)
-
-    def publish(self):
-        self.env.get_instances_of = self.query
-
-
-
-class PrintListener(Listener):
-
-    def __init__(self, env, active = True):
-        self.env = env
-        self.active = active
-        if active:
-            print "-- initializing"
-
-    def on_import(self, op):
-        if self.active:
-            print "-- importing: %s" % graph.as_string(self.env.inputs, op.outputs)
-
-    def on_prune(self, op):
-        if self.active:
-            print "-- pruning: %s" % graph.as_string(self.env.inputs, op.outputs)
-
-    def on_rewire(self, clients, r, new_r):
-        if self.active:
-            if r.owner is None:
-                rg = id(r) #r.name
+        """
+        This is only called once by the env, when the Tool is added.
+        Adds methods to env.
+        """
+        raise utils.AbstractFunctionError()
+
+
+
+def uniq_features(_features, *_rest):
+    """Return a list such that no element is a subclass of another"""
+    # used in Env.__init__ to 
+    features = [x for x in _features]
+    for other in _rest:
+        features += [x for x in other]
+    res = []
+    while features:
+        feature = features.pop()
+        for feature2 in features:
+            if issubclass(feature2, feature):
+                break
         else:
-                rg = graph.as_string(self.env.inputs, r.owner.outputs)
-            if new_r.owner is None:
-                new_rg = id(new_r) #new_r.name
-            else:
-                new_rg = graph.as_string(self.env.inputs, new_r.owner.outputs)
-            print "-- moving from %s to %s" % (rg, new_rg)
-
+            res.append(feature)
+    return res
 
 
-class ChangeListener(Listener):
 
-    def __init__(self, env):
-        self.change = False
+# MOVE TO LIB
 
-    def on_import(self, op):
-        self.change = True
+# class EquivTool(Listener, Tool, dict):
 
-    def on_prune(self, op):
-        self.change = True
+#     def on_rewire(self, clients, r, new_r):
+#         repl = self(new_r)
+#         if repl is r:
+#             self.ungroup(r, new_r)
+#         elif repl is not new_r:
+#             raise Exception("Improper use of EquivTool!")
+#         else:
+#             self.group(new_r, r)
 
-    def on_rewire(self, clients, r, new_r):
-        self.change = True
+#     def publish(self):
+#         self.env.equiv = self
+
+#     def group(self, main, *keys):
+#         "Marks all the keys as having been replaced by the Result main."
+#         keys = [key for key in keys if key is not main]
+#         if self.has_key(main):
+#             raise Exception("Only group results that have not been grouped before.")
+#         for key in keys:
+#             if self.has_key(key):
+#                 raise Exception("Only group results that have not been grouped before.")
+#             if key is main:
+#                 continue
+#             self.setdefault(key, main)
+
+#     def ungroup(self, main, *keys):
+#         "Undoes group(main, *keys)"
+#         keys = [key for key in keys if key is not main]
+#         for key in keys:
+#             if self[key] is main:
+#                 del self[key]
+
+#     def __call__(self, key):
+#         "Returns the currently active replacement for the given key."
+#         next = self.get(key, None)
+#         while next:
+#             key = next
+#             next = self.get(next, None)
+#         return key
+
+
+# class InstanceFinder(Listener, Tool, dict):
+
+#     def __init__(self, env):
+#         self.env = env
 
-    def __call__(self, value = "get"):
-        if value == "get":
-            return self.change
-        else:
-            self.change = value
+#     def all_bases(self, cls):
+#         return utils.all_bases(cls, lambda cls: issubclass(cls, Op))
+# #        return [cls for cls in utils.all_bases(cls) if issubclass(cls, Op)]
 
+#     def on_import(self, op):
+#         for base in self.all_bases(op.__class__):
+#             self.setdefault(base, set()).add(op)
 
+#     def on_prune(self, op):
+#         for base in self.all_bases(op.__class__):
+#             self[base].remove(op)
+#             if not self[base]:
+#                 del self[base]
+
+#     def __query__(self, cls):
+#         all = [x for x in self.get(cls, [])]
+#         shuffle(all) # this helps a lot for debugging because the order of the replacements will vary
+#         while all:
+#             next = all.pop()
+#             if next in self.env.ops():
+#                 yield next
 
+#     def query(self, cls):
+#         return self.__query__(cls)
 
+#     def publish(self):
+#         self.env.get_instances_of = self.query
 
 
 
-# class SuperFinder(Listener, Tool, dict):
+# class PrintListener(Listener):
 
-#     def __init__(self, env, props):
+#     def __init__(self, env, active = True):
 #         self.env = env
-#         self.props = props
+#         self.active = active
+#         if active:
+#             print "-- initializing"
 
 #     def on_import(self, op):
-#         for prop, value in self.props(op).items():
-#             self.setdefault(prop, {}).setdefault(value, set()).add(op)
+#         if self.active:
+#             print "-- importing: %s" % graph.as_string(self.env.inputs, op.outputs)
 
 #     def on_prune(self, op):
-#         for prop, value in self.props(op).items():
-#             self[prop][value].remove(op)
-#             if len(self[prop][value]) == 0:
-#                 del self[prop][value]
-#                 if len(self[prop]) == 0:
-#                     del self[prop]
-
-#     def __query__(self, order, template):
-#         all = []
-#         for prop, value in template.items():
-#             all += [x for x in self.get(prop, {}).get(value, set())]
-#         # If not None, the order option requires the order listener to be included in the env under the name 'order'
-#         if order == 'o->i':
-#             all.sort(lambda op1, op2: self.env.order[op1].__cmp__(self.env.order[op2]))
-#         elif order == 'i->o':
-#             all.sort(lambda op1, op2: self.env.order[op2].__cmp__(self.env.order[op1]))
-#         while all:
-#             next = all.pop()
-#             if next in self.env.ops():
-#                 yield next
+#         if self.active:
+#             print "-- pruning: %s" % graph.as_string(self.env.inputs, op.outputs)
 
-#     def query(self, **template):
-#         return self.__query__(None, template)
+#     def on_rewire(self, clients, r, new_r):
+#         if self.active:
+#             if r.owner is None:
+#                 rg = id(r) #r.name
+#             else:
+#                 rg = graph.as_string(self.env.inputs, r.owner.outputs)
+#             if new_r.owner is None:
+#                 new_rg = id(new_r) #new_r.name
+#             else:
+#                 new_rg = graph.as_string(self.env.inputs, new_r.owner.outputs)
+#             print "-- moving from %s to %s" % (rg, new_rg)
 
-#     def query_downstream(self, **template):
-#         return self.__query__('i->o', template)
 
-#     def query_upstream(self, **template):
-#         return self.__query__('o->i', template)
 
-#     def publish(self):
-#         self.env.query = self.query
+# class ChangeListener(Listener):
 
+#     def __init__(self, env):
+#         self.change = False
 
+#     def on_import(self, op):
+#         self.change = True
 
+#     def on_prune(self, op):
+#         self.change = True
 
+#     def on_rewire(self, clients, r, new_r):
+#         self.change = True
 
+#     def __call__(self, value = "get"):
+#         if value == "get":
+#             return self.change
+#         else:
+#             self.change = value
 

gof/graph.py

 
 from copy import copy
 
-from result import BrokenLink, BrokenLinkError
-from op import Op
 import utils
 
 
@@ -11,11 +9,17 @@ __all__ = ['inputs',
            'ops',
            'clone', 'clone_get_equiv',
            'io_toposort',
+           'default_leaf_formatter', 'default_node_formatter',
+           'op_as_string',
            'as_string',
            'Graph']
 
 
-def inputs(o, repair = False):
+is_result = utils.attr_checker('owner', 'index')
+is_op = utils.attr_checker('inputs', 'outputs')
+
+
+def inputs(o):
     """
     o -> list of output Results
 
@@ -24,21 +28,12 @@ def inputs(o, repair = False):
     """
     results = set()
     def seek(r):
-        if isinstance(r, BrokenLink):
-            raise BrokenLinkError
         op = r.owner
         if op is None:
             results.add(r)
         else:
-            for i in range(len(op.inputs)):
-                try:
-                    seek(op.inputs[i])
-                except BrokenLinkError:
-                    if repair:
-                        op.refresh()
-                        seek(op.inputs[i])
-                    else:
-                        raise
+            for input in op.inputs:
+                seek(input)
     for output in o:
         seek(output)
     return results
@@ -60,8 +55,6 @@ def results_and_orphans(i, o):
     incomplete_paths = []
 
     def helper(r, path):
-        if isinstance(r, BrokenLink):
-            raise BrokenLinkError
         if r in i:
             results.update(path)
         elif r.owner is None:
@@ -128,45 +121,56 @@ def orphans(i, o):
     return results_and_orphans(i, o)[1]
 
 
-def clone(i, o):
+def clone(i, o, copy_inputs = False):
     """
     i -> list of input Results
     o -> list of output Results
+    copy_inputs -> if True, the inputs will be copied (defaults to False)
 
     Copies the subgraph contained between i and o and returns the
-    outputs of that copy (corresponding to o). The input Results in
-    the list are _not_ copied and the new graph refers to the
-    originals.
+    outputs of that copy (corresponding to o).
     """
-    new_o, equiv = clone_get_equiv(i, o)
-    return new_o
+    equiv = clone_get_equiv(i, o)
+    return [equiv[output] for output in o]
 
 
 def clone_get_equiv(i, o, copy_inputs = False):
     """
     i -> list of input Results
     o -> list of output Results
+    copy_inputs -> if True, the inputs will be replaced in the cloned
+                   graph by copies available in the equiv dictionary
+                   returned by the function (copy_inputs defaults to False)
 
-    Returns (new_o, equiv) where new_o are the outputs of a copy of
-    the whole subgraph bounded by i and o and equiv is a dictionary
-    that maps the original ops and results found in the subgraph to
-    their copy (akin to deepcopy's memo). See clone for more details.
+    Returns equiv a dictionary mapping each result and op in the
+    graph delimited by i and o to a copy (akin to deepcopy's memo).
     """
 
     d = {}
 
-    for op in ops(i, o):
-        d[op] = copy(op)
+    for input in i:
+        if copy_inputs:
+            d[input] = copy(input)
+        else:
+            d[input] = input
+
+    def clone_helper(result):
+        if result in d:
+            return d[result]
+        op = result.owner
+        if not op:
+            return result
+        else:
+            new_op = op.__class__(*[clone_helper(input) for input in op.inputs])
+            d[op] = new_op
+            for output, new_output in zip(op.outputs, new_op.outputs):
+                d[output] = new_output
+            return d[result]
 
-    for old_op, op in d.items():
-        for old_output, output in zip(old_op.outputs, op.outputs):
-            d[old_output] = output
-        for i, input in enumerate(op.inputs):
-            owner = input.owner
-            if owner in d:
-                op._inputs[i] = d[owner].outputs[input._index]
+    for output in o:
+        clone_helper(output)
 
-    return [[d[output] for output in o], d]
+    return d
 
 
 def io_toposort(i, o, orderings = {}):
@@ -188,17 +192,32 @@ def io_toposort(i, o, orderings = {}):
     all = ops(i, o)
     for op in all:
         prereqs_d.setdefault(op, set()).update(set([input.owner for input in op.inputs if input.owner and input.owner in all]))
-#        prereqs_d[op] = set([input.owner for input in op.inputs if input.owner and input.owner in all])
     return utils.toposort(prereqs_d)
 
 
-def as_string(i, o):
+default_leaf_formatter = str
+default_node_formatter = lambda op, argstrings: "%s(%s)" % (op.__class__.__name__,
+                                                            ", ".join(argstrings))
+
+def op_as_string(i, op,
+                 leaf_formatter = default_leaf_formatter,
+                 node_formatter = default_node_formatter):
+    strs = as_string(i, op.inputs, leaf_formatter, node_formatter)
+    return node_formatter(op, strs)
+
+
+def as_string(i, o,
+              leaf_formatter = default_leaf_formatter,
+              node_formatter = default_node_formatter):
     """
     i -> list of input Results
     o -> list of output Results
+    leaf_formatter -> function that takes a result and returns a string to describe it
+    node_formatter -> function that takes an op and the list of strings corresponding
+                      to its arguments and returns a string to describe it
 
     Returns a string representation of the subgraph between i and o. If the same
-    Op is used by several other ops, the first occurrence will be marked as
+    op is used by several other ops, the first occurrence will be marked as
     '*n -> description' and all subsequent occurrences will be marked as '*n',
     where n is an id number (ids are attributed in an unspecified order and only
     exist for viewing convenience).
@@ -219,50 +238,37 @@ def as_string(i, o):
     done = set()
 
     def multi_index(x):
-        try:
         return multi.index(x) + 1
-        except:
-            return 999
-
-    def describe(x, first = False):
-        if isinstance(x, Result):
-            done.add(x)
-            if x.owner is not None and x not in i:
-                op = x.owner
-                idx = op.outputs.index(x)
-                if idx:
-                    s = describe(op, first) + "." + str(idx)
-                else:
-                    s = describe(op, first)
-                return s
-            else:
-                return str(id(x))
 
-        elif isinstance(x, Op):
-            if x in done:
-                return "*%i" % multi_index(x)
+    def describe(r):
+        if r.owner is not None and r not in i:
+            op = r.owner
+            idx = op.outputs.index(r)
+            if idx == op._default_output_idx:
+                idxs = ""
             else:
-                done.add(x)
-                if not first and hasattr(x, 'name') and x.name is not None:
-                    return x.name
-                s = x.__class__.__name__ + "(" + ", ".join([describe(v) for v in x.inputs]) + ")"
-                if x in multi:
+                idxs = "::%i" % idx
+            if op in done:
+                return "*%i%s" % (multi_index(x), idxs)
+            else:
+                done.add(op)
+                s = node_formatter(op, [describe(input) for input in op.inputs])
+                if op in multi:
                     return "*%i -> %s" % (multi_index(x), s)
                 else:
                     return s
-        
         else:
-            raise TypeError("Cannot print type: %s" % x.__class__)
-
-    return "[" + ", ".join([describe(x, True) for x in o]) + "]"
+            return leaf_formatter(r)
 
+    return [describe(output) for output in o]
 
-# Op.__str__ = lambda self: as_string(inputs(self.outputs), self.outputs)[1:-1]
-# Result.__str__ = lambda self: as_string(inputs([self]), [self])[1:-1]
 
 
 
 class Graph:
+    """
+    Object-oriented wrapper for all the functions in this module.
+    """
 
     def __init__(self, inputs, outputs):
         self.inputs = inputs

gof/op.py

@@ -4,8 +4,9 @@ Contains the Op class, which is the base interface for all operations
 compatible with gof's graph manipulation routines.
 """
 
-from result import BrokenLink
-from utils import ClsInit, all_bases, all_bases_collect
+from result import BrokenLinkError
+from utils import ClsInit, all_bases, all_bases_collect, AbstractFunctionError
+import graph
 
 from copy import copy
 
@@ -29,10 +30,6 @@ class Op(object):
 
     __slots__ = ['_inputs', '_outputs']
 
-    #create inputs and outputs as read-only attributes
-    inputs = property(lambda self: self._inputs, doc = "The list of this Op's input Results.")
-    outputs = property(lambda self: self._outputs, doc = "The list of this Op's output Results.")
-
     _default_output_idx = 0
 
     def default_output(self):
@@ -45,236 +42,465 @@ class Op(object):
     out = property(default_output, 
             doc = "Same as self.outputs[0] if this Op's has_default_output field is True.")
 
-    def __init__(self, inputs, outputs, use_self_setters = False):
-        """
-        Initializes the '_inputs' and '_outputs' slots and sets the
-        owner of all outputs to self.
-
-        If use_self_setters is False, Op::set_input and Op::set_output
-        are used, which do the minimum checks and manipulations. Else,
-        the user defined set_input and set_output functions are
-        called (in any case, all inputs and outputs are initialized
-        to None).
-        """
-        self._inputs = [None] * len(inputs)
-        self._outputs = [None] * len(outputs)
 
-        if use_self_setters:
-            for i, input in enumerate(inputs):
-                self.set_input(i, input, validate = False)
-            for i, output in enumerate(outputs):
-                self.set_output(i, output, validate = False)
-            self.validate()
-        else:
-            for i, input in enumerate(inputs):
-                Op.set_input(self, i, input, validate = False)
-            for i, output in enumerate(outputs):
-                Op.set_output(self, i, output, validate = False)
-            self.validate()
+    def __init__(self, *inputs):
+        self._inputs = None
+        self._outputs = None
+        self.__set_inputs(inputs)
+        self.validate_update()
 
-        self.validate()
 
+    def __get_input(self, i):
+        input = self._inputs[i]
+        if input.replaced:
+            raise BrokenLinkError()
+        return input
+    def __set_input(self, i, new_input):
+        self._inputs[i] = new_input
 
 
+    def __get_inputs(self):
+        for input in self._inputs:
+            if input.replaced:
+                raise BrokenLinkError()
+        return self._inputs
+    def __set_inputs(self, new_inputs):
+        self._inputs = list(new_inputs)
 
-    def set_input(self, i, input, allow_changes = False, validate = True):
-        """
-        Sets the ith input of self.inputs to input. i must be an
-        integer in the range from 0 to len(self.inputs) - 1 and input
-        must be a Result instance. The method may raise a GofTypeError
-        or a GofValueError accordingly to the semantics of the Op, if
-        the new input is of the wrong type or has the wrong
-        properties.
-
-        If i > len(self.inputs), an IndexError must be raised. If i ==
-        len(self.inputs), it is allowed for the Op to extend the list
-        of inputs if it is a vararg Op, else an IndexError should be
-        raised.
-
-        For a vararg Op, it is also allowed to have the input
-        parameter set to None for 0 <= i < len(self.inputs), in which
-        case the rest of the inputs will be shifted left. In any other
-        situation, a ValueError should be raised.
-
-        In some cases, set_input may change some outputs: for example,
-        a change of an input from float to double might require the
-        output's type to also change from float to double. If
-        allow_changes is True, set_input is allowed to perform those
-        changes and must return a list of pairs, each pair containing
-        the old output and the output it was replaced with (they
-        _must_ be different Result instances). See Op::set_output for
-        important information about replacing outputs. If
-        allow_changes is False and some change in the outputs is
-        required for the change in input to be correct, a
-        PropagationError must be raised.
-
-        This default implementation sets the ith input to input and
-        changes no outputs. It returns None.
-        """
-        previous = self.inputs[i]
-        self.inputs[i] = input
-        if validate:
+
+    def __get_output(self, i):
+        return self._outputs[i]
+    def __set_output(self, i, new_output):
+        old_output = self._outputs[i]
+        if old_output != new_output:
+            old_output.replaced = True
             try:
-                self.validate()
+                # We try to reuse the old storage, if there is one
+                new_output.data = old_output.data
             except:
-                # this call gives a subclass the chance to undo the set_outputs 
-                # that it may have triggered...
-                # TODO: test this functionality!
-                self.set_input(i, previous, True, False)
+                pass
+            new_output.role = (self, i)
+            self._outputs[i] = new_output
 
 
-    def set_output(self, i, output, validate = True):
-        """
-        Sets the ith output to output. The previous output, which is
-        being replaced, must be invalidated using Result::invalidate.
-        The new output must not already have an owner, or its owner must
-        be self. It cannot be a broken link, unless it used to be at this
-        spot, in which case it can be reinstated.
-
-        For Ops that have vararg output lists, see the regulations in
-        Op::set_input.
-        """
-        if isinstance(output.owner, BrokenLink) \
-           and output.owner.owner is self \
-           and output.owner.index == i:
-            output.revalidate()
-        else:
-            output.set_owner(self, i) # this checks for an already existing owner
-        previous = self.outputs[i]
-        if previous:
-            previous.invalidate()
-        self.outputs[i] = output
-        if validate:
+    def __get_outputs(self):
+        return self._outputs
+    def __set_outputs(self, new_outputs):
+        if self._outputs is None:
+            for i, output in enumerate(new_outputs):
+                output.role = (self, i)
+            self._outputs = new_outputs
+            return
+        
+        if len(self._outputs) != len(new_outputs):
+            raise TypeError("The new outputs must be exactly as many as the previous outputs.")
+
+        for i, new_output in enumerate(new_outputs):
+            self.__set_output(i, new_output)
+
+
+    def get_input(self, i):
+        return self.__get_input(i)
+    def set_input(self, i, new_input):
+        old_input = self.__get_input(i)
         try:
-                self.validate()
+            self.__set_input(i, new_input)
+            self.validate_update()
         except:
-                self.set_output(i, previous, False)
+            self.__set_input(i, old_input)
+            self.validate_update()
+            raise
+
+
+    def get_inputs(self):
+        return self.__get_inputs()
+    def set_inputs(self, new_inputs):
+        old_inputs = self.__get_inputs()
+        try:
+            self.__set_inputs(new_inputs)
+            self.validate_update()
+        except:
+            self._inputs = old_inputs
+            raise
 
 
-    def _dontuse_repair(self, allow_changes = False):
+    def get_output(self, i):
+        return self.__get_output(i)
+
+    def get_outputs(self):
+        return self.__get_outputs()
+
+
+    #create inputs and outputs as read-only attributes
+    inputs = property(get_inputs, set_inputs, doc = "The list of this Op's input Results.")
+    outputs = property(get_outputs, __set_outputs, doc = "The list of this Op's output Results.")
+
+    def validate_update(self):
         """
-        This function attempts to repair all inputs that are broken
-        links by calling set_input on the new Result that replaced
-        them. Note that if a set_input operation invalidates one or
-        more outputs, new broken links might appear in the other ops
-        that use this op's outputs.
-
-        It is possible that the new inputs are inconsistent with this
-        op, in which case an exception will be raised and the previous
-        inputs (and outputs) will be restored.
-
-        refresh returns a list of (old_output, new_output) pairs
-        detailing the changes, if any.
+        (Abstract) This function must do two things:
+        * validate: check all the inputs in self.inputs to ensure
+                    that they have the right type for this Op, etc.
+                    If the validation fails, raise an exception.
+        * update: create output Results and set the Op's outputs
+        The existing outputs must not be changed in place.
+        The return value of validate_update is not used.
         """
-        backtrack = []
+        raise AbstractFunctionError()
+
+    def repair(self):
+        """
+        Repairs all the inputs that are broken links to use what
+        they were replaced with. Then, calls self.validate_update()
+        to validate the new inputs and make new outputs.
+        """
+        changed = False
+        repaired_inputs = []
+        old_inputs = self._inputs
+        for input in self._inputs:
+            if input.replaced:
+                changed = True
+                role = input.role.old_role
+                input = role[0].outputs[role[1]]
+            repaired_inputs.append(input)
+        if changed:
             try:
-            for i, input in enumerate(self.inputs):
-                link = input.owner
-                if isinstance(link, BrokenLink):
-                    current = link.owner.outputs[link.index]
-                    dirt = self.set_input(i, current, allow_changes)
-                    backtrack.append((i, input, dirt))
+                self.__set_inputs(repaired_inputs)
+                self.validate_update()
             except:
-            # Restore the inputs and outputs that were successfully changed.
-            for i, input, dirt in backtrack:
-                self.inputs[i] = input
-                if dirt:
-                    for old, new in dirt:
-                        new.invalidate()
-                        old.revalidate()
-                        self.outputs[self.outputs.index(new)] = old
+                self._inputs = old_inputs
                 raise
-        all_dirt = []
-        for i, input, dirt in backtrack:
-            if dirt:
-                all_dirt += dirt
-        return all_dirt
+        return changed
 
 
-    def perform(self):
+    #
+    # copy
+    #
+
+    def __copy__(self):        
         """
-        Performs the computation on the inputs and stores the results
-        in the outputs. This function should check for the validity of
-        the inputs and raise appropriate errors for debugging (for
-        executing without checks, override _perform).
-
-        An Op may define additional ways to perform the computation
-        that are more efficient (e.g. a piece of C code or a C struct
-        with direct references to the inputs and outputs), but
-        perform() should always be available in order to have a
-        consistent interface to execute graphs.
+        Shallow copy of this Op. The inputs are the exact same, but
+        the outputs are recreated because of the one-owner-per-result
+        policy.
         """
-        raise NotImplementedError
+        return self.__class__(*self.inputs)
+
 
-    def _perform(self):
+    #
+    # String representation
+    #
+
+    def __str__(self):
+        return graph.op_as_string(self.inputs, self)
+
+    def __repr__(self):
+        return str(self)
+
+
+    #
+    # perform
+    #
+    
+    def perform(self):
         """
-        Performs the computation on the inputs and stores the results
-        in the outputs, like perform(), but is not required to check
-        the existence or the validity of the inputs.
+        (abstract) Performs the computation associated to this Op,
+        places the result(s) in the output Results and gives them
+        the Computed status.
         """
-        return self.perform()
+        raise AbstractFunctionError()
 
-    @classmethod
-    def require(cls):
+
+    #
+    # C code generators
+    #
+
+    def c_var_names(self):
         """
-        Returns a set of Feature subclasses that must be used by any
-        Env manipulating this kind of op. For instance, a Destroyer
-        requires ext.DestroyHandler to guarantee that various
-        destructive operations don't interfere.
-
-        By default, this collates the __require__ field of this class
-        and the __require__ fields of all classes that are directly or
-        indirectly superclasses to this class into a set.
+        Returns ([list of input names], [list of output names]) for
+        use as C variables.
         """
-        r = set()
+        return [["i%i" % i for i in xrange(len(self.inputs))],
+                ["o%i" % i for i in xrange(len(self.outputs))]]
 
-        bases = all_bases(cls, lambda cls: hasattr(cls, '__env_require__'))
+    def c_validate(self):
+        """
+        Returns C code that checks that the inputs to this function
+        can be worked on. If a failure occurs, set an Exception
+        and insert "%(fail)s".
         
-        for base in bases:
-            req = base.__env_require__
-            if isinstance(req, (list, tuple)):
-                r.update(req)
-            else:
-                r.add(req)
-        return r
+        You may use the variable names defined by c_var_names()
+        """
+        raise AbstractFunctionError()
 
+    def c_validate_cleanup(self):
+        """
+        Clean up things allocated by c_validate().
+        """
+        raise AbstractFunctionError()
 
-    def validate(self):
+    def c_update(self):
         """
-        This class's __validate__ function will be called, as well as
-        the __validate__ functions of all base classes down the class
-        tree. If you do not want to execute __validate__ from the base
-        classes, set the class variable __validate_override__ to True.
+        Returns C code that allocates and/or updates the outputs
+        (eg resizing, etc.) so they can be manipulated safely
+        by c_code.
+        
+        You may use the variable names defined by c_var_names()
         """
-        vfns = all_bases_collect(self.__class__, 'validate')
-        for vfn in vfns:
-            vfn(self)
+        raise AbstractFunctionError()
 
+    def c_update_cleanup(self):
+        """
+        Clean up things allocated by c_update().
+        """
+        raise AbstractFunctionError()
 
-    def __copy__(self):
+    def c_code(self):
         """
-        Copies the inputs list shallowly and copies all the outputs
-        because of the one owner per output restriction.
+        Returns C code that does the computation associated to this
+        Op. You may assume that input validation and output allocation
+        have already been done.
+        
+        You may use the variable names defined by c_var_names()
         """
-        new_inputs = copy(self.inputs)
-        # We copy the outputs because they are tied to a single Op.
-        new_outputs = [copy(output) for output in self.outputs]
-        op = self.__class__(new_inputs, new_outputs)
-        op._inputs = new_inputs
-        op._outputs = new_outputs
-        for i, output in enumerate(op.outputs):
-            # We adjust _owner and _index manually since the copies
-            # point to the previous op (self).
-            output._owner = op
-            output._index = i
-        return op
-
-
-    def __deepcopy__(self, memo):
+        raise AbstractFunctionError()
+
+    def c_code_cleanup(self):
         """
-        Not implemented. Use gof.graph.clone(inputs, outputs) to copy
-        a subgraph.
+        Clean up things allocated by c_code().
         """
-        raise NotImplementedError("Use gof.graph.clone(inputs, outputs) to copy a subgraph.")
+        raise AbstractFunctionError()
+
+
+
+#     def __init__(self, inputs, outputs, use_self_setters = False):
+#         """
+#         Initializes the '_inputs' and '_outputs' slots and sets the
+#         owner of all outputs to self.
+
+#         If use_self_setters is False, Op::set_input and Op::set_output
+#         are used, which do the minimum checks and manipulations. Else,
+#         the user defined set_input and set_output functions are
+#         called (in any case, all inputs and outputs are initialized
+#         to None).
+#         """
+#         self._inputs = [None] * len(inputs)
+#         self._outputs = [None] * len(outputs)
+
+#         if use_self_setters:
+#             for i, input in enumerate(inputs):
+#                 self.set_input(i, input, validate = False)
+#             for i, output in enumerate(outputs):
+#                 self.set_output(i, output, validate = False)
+#             self.validate()
+#         else:
+#             for i, input in enumerate(inputs):
+#                 Op.set_input(self, i, input, validate = False)
+#             for i, output in enumerate(outputs):
+#                 Op.set_output(self, i, output, validate = False)
+#             self.validate()
+        
+#         self.validate()
+
+        
+
+
+#     def set_input(self, i, input, allow_changes = False, validate = True):
+#         """
+#         Sets the ith input of self.inputs to input. i must be an
+#         integer in the range from 0 to len(self.inputs) - 1 and input
+#         must be a Result instance. The method may raise a GofTypeError
+#         or a GofValueError accordingly to the semantics of the Op, if
+#         the new input is of the wrong type or has the wrong
+#         properties.
+
+#         If i > len(self.inputs), an IndexError must be raised. If i ==
+#         len(self.inputs), it is allowed for the Op to extend the list
+#         of inputs if it is a vararg Op, else an IndexError should be
+#         raised.
+
+#         For a vararg Op, it is also allowed to have the input
+#         parameter set to None for 0 <= i < len(self.inputs), in which
+#         case the rest of the inputs will be shifted left. In any other
+#         situation, a ValueError should be raised.
+
+#         In some cases, set_input may change some outputs: for example,
+#         a change of an input from float to double might require the
+#         output's type to also change from float to double. If
+#         allow_changes is True, set_input is allowed to perform those
+#         changes and must return a list of pairs, each pair containing
+#         the old output and the output it was replaced with (they
+#         _must_ be different Result instances). See Op::set_output for
+#         important information about replacing outputs. If
+#         allow_changes is False and some change in the outputs is
+#         required for the change in input to be correct, a
+#         PropagationError must be raised.
+
+#         This default implementation sets the ith input to input and
+#         changes no outputs. It returns None.
+#         """
+#         previous = self.inputs[i]
+#         self.inputs[i] = input
+#         if validate:
+#             try:
+#                 self.validate()
+#             except:
+#                 # this call gives a subclass the chance to undo the set_outputs 
+#                 # that it may have triggered...
+#                 # TODO: test this functionality!
+#                 self.set_input(i, previous, True, False)
+
+
+#     def set_output(self, i, output, validate = True):
+#         """
+#         Sets the ith output to output. The previous output, which is
+#         being replaced, must be invalidated using Result::invalidate.
+#         The new output must not already have an owner, or its owner must
+#         be self. It cannot be a broken link, unless it used to be at this
+#         spot, in which case it can be reinstated.
+
+#         For Ops that have vararg output lists, see the regulations in
+#         Op::set_input.
+#         """
+#         if isinstance(output.owner, BrokenLink) \
+#            and output.owner.owner is self \
+#            and output.owner.index == i:
+#             output.revalidate()
+#         else:
+#             output.set_owner(self, i) # this checks for an already existing owner
+#         previous = self.outputs[i]
+#         if previous:
+#             previous.invalidate()
+#         self.outputs[i] = output
+#         if validate:
+#             try:
+#                 self.validate()
+#             except:
+#                 self.set_output(i, previous, False)
+
+
+#     def _dontuse_repair(self, allow_changes = False):
+#         """
+#         This function attempts to repair all inputs that are broken
+#         links by calling set_input on the new Result that replaced
+#         them. Note that if a set_input operation invalidates one or
+#         more outputs, new broken links might appear in the other ops
+#         that use this op's outputs.
+
+#         It is possible that the new inputs are inconsistent with this
+#         op, in which case an exception will be raised and the previous
+#         inputs (and outputs) will be restored.
+
+#         refresh returns a list of (old_output, new_output) pairs
+#         detailing the changes, if any.
+#         """
+#         backtrack = []
+#         try:
+#             for i, input in enumerate(self.inputs):
+#                 link = input.owner
+#                 if isinstance(link, BrokenLink):
+#                     current = link.owner.outputs[link.index]
+#                     dirt = self.set_input(i, current, allow_changes)
+#                     backtrack.append((i, input, dirt))
+#         except:
+#             # Restore the inputs and outputs that were successfully changed.
+#             for i, input, dirt in backtrack:
+#                 self.inputs[i] = input
+#                 if dirt:
+#                     for old, new in dirt:
+#                         new.invalidate()
+#                         old.revalidate()
+#                         self.outputs[self.outputs.index(new)] = old
+#             raise
+#         all_dirt = []
+#         for i, input, dirt in backtrack:
+#             if dirt:
+#                 all_dirt += dirt
+#         return all_dirt
+
+        
+#     def perform(self):
+#         """
+#         Performs the computation on the inputs and stores the results
+#         in the outputs. This function should check for the validity of
+#         the inputs and raise appropriate errors for debugging (for
+#         executing without checks, override _perform).
+
+#         An Op may define additional ways to perform the computation
+#         that are more efficient (e.g. a piece of C code or a C struct
+#         with direct references to the inputs and outputs), but
+#         perform() should always be available in order to have a
+#         consistent interface to execute graphs.
+#         """
+#         raise NotImplementedError
+
+#     def _perform(self):
+#         """
+#         Performs the computation on the inputs and stores the results
+#         in the outputs, like perform(), but is not required to check
+#         the existence or the validity of the inputs.
+#         """
+#         return self.perform()
+
+#     @classmethod
+#     def require(cls):
+#         """
+#         Returns a set of Feature subclasses that must be used by any
+#         Env manipulating this kind of op. For instance, a Destroyer
+#         requires ext.DestroyHandler to guarantee that various
+#         destructive operations don't interfere.
+
+#         By default, this collates the __require__ field of this class
+#         and the __require__ fields of all classes that are directly or
+#         indirectly superclasses to this class into a set.
+#         """
+#         r = set()
+
+#         bases = all_bases(cls, lambda cls: hasattr(cls, '__env_require__'))
+
+#         for base in bases:
+#             req = base.__env_require__
+#             if isinstance(req, (list, tuple)):
+#                 r.update(req)
+#             else:
+#                 r.add(req)
+#         return r
+
+
+#     def validate(self):
+#         """
+#         This class's __validate__ function will be called, as well as
+#         the __validate__ functions of all base classes down the class
+#         tree. If you do not want to execute __validate__ from the base
+#         classes, set the class variable __validate_override__ to True.
+#         """
+#         vfns = all_bases_collect(self.__class__, 'validate')
+#         for vfn in vfns:
+#             vfn(self)
+
+
+#     def __copy__(self):
+#         """
+#         Copies the inputs list shallowly and copies all the outputs
+#         because of the one owner per output restriction.
+#         """
+#         new_inputs = copy(self.inputs)
+#         # We copy the outputs because they are tied to a single Op.
+#         new_outputs = [copy(output) for output in self.outputs]
+#         op = self.__class__(new_inputs, new_outputs)
+#         op._inputs = new_inputs
+#         op._outputs = new_outputs
+#         for i, output in enumerate(op.outputs):
+#             # We adjust _owner and _index manually since the copies
+#             # point to the previous op (self).
+#             output._owner = op
+#             output._index = i
+#         return op
+
+
+#     def __deepcopy__(self, memo):
+#         """
+#         Not implemented. Use gof.graph.clone(inputs, outputs) to copy
+#         a subgraph.
+#         """
+#         raise NotImplementedError("Use gof.graph.clone(inputs, outputs) to copy a subgraph.")
 
 

gof/result.py

@@ -5,37 +5,32 @@ value that is the input or the output of an Op.
 
 """
 
-import unittest
-
-from err import GofError
 from utils import AbstractFunctionError
-
 from python25 import all
 
 
-__all__ = ['is_result', 'ResultBase', 'BrokenLink', 'BrokenLinkError' ]
+__all__ = ['is_result',
+           'ResultBase',
+           'BrokenLink',
+           'BrokenLinkError',
+           'StateError',
+           'Empty',
+           'Allocated',
+           'Computed',
+           ]
 
 
 class BrokenLink:
-    """
-    This is placed as the owner of a Result that was replaced by
-    another Result.
-    """
-
-    __slots__ = ['owner', 'index']
-
-    def __init__(self, owner, index):
-        self.owner = owner
-        self.index = index
-
-    def __nonzero__(self):
-        return False
+    """The owner of a Result that was replaced by another Result"""
+    __slots__ = ['old_role']
+    def __init__(self, role): self.old_role = role
+    def __nonzero__(self): return False
 
+class BrokenLinkError(Exception): 
+    """The owner is a BrokenLink"""
 
-class BrokenLinkError(GofError):
-    """
-    """
-    pass
+class StateError(Exception):
+    """The state of the Result is a problem"""
 
 
 # ResultBase state keywords
@@ -61,6 +56,7 @@ class ResultBase(object):
     _data - anything
     constant - Boolean
     state - one of (Empty, Allocated, Computed)
+    name - string
 
     Properties:
     role - (rw)
@@ -89,33 +85,17 @@ class ResultBase(object):
     expressions).
     
     """
-    class BrokenLink:
-        """The owner of a Result that was replaced by another Result"""
-        __slots__ = ['old_role']
-        def __init__(self, role): self.old_role = role
-        def __nonzero__(self): return False
 
-    class BrokenLinkError(Exception): 
-        """The owner is a BrokenLink"""
+    __slots__ = ['_role', 'constant', '_data', 'state', '_name']
 
-    class StateError(Exception):
-        """The state of the Result is a problem"""
-
-    __slots__ = ['_role', 'constant', '_data', 'state']
-
-    def __init__(self, role=None, data=None, constant=False):
+    def __init__(self, role=None, data=None, constant=False, name=None):
         self._role = role
-        self.constant = constant
         self._data = [None]
-        if data is None: #None is not filtered
-            self._data[0] = None
         self.state = Empty
-        else:
-            try:
-                self._data[0] = self.data_filter(data)
-            except AbstractFunctionError:
-                self._data[0] = data
-            self.state = Computed
+        self.constant = False
+        self.__set_data(data)
+        self.constant = constant # can only lock data after setting it
+        self.name = name
 
     #
     # role 
@@ -144,7 +124,7 @@ class ResultBase(object):
 
     def __get_owner(self):
         if self._role is None: return None
-        if self.replaced: raise ResultBase.BrokenLinkError()
+        if self.replaced: raise BrokenLinkError()
         return self._role[0]
 
     owner = property(__get_owner, 
@@ -156,7 +136,7 @@ class ResultBase(object):
 
     def __get_index(self):
         if self._role is None: return None
-        if self.replaced: raise ResultBase.BrokenLinkError()
+        if self.replaced: raise BrokenLinkError()
         return self._role[1]
 
     index = property(__get_index,
@@ -171,35 +151,39 @@ class ResultBase(object):
         return self._data[0]
 
     def __set_data(self, data):
-        if self.replaced: raise ResultBase.BrokenLinkError()
-        if self.constant: raise Exception('cannot set constant ResultBase')
+        if self.replaced:
+            raise BrokenLinkError()
+        if data is self._data[0]:
+            return
+        if self.constant:
+            raise Exception('cannot set constant ResultBase')
         if data is None:
             self._data[0] = None
             self.state = Empty
             return
-        if data is self or data is self._data[0]: return
         try:
-            self._data[0] = self.data_filter(data)
-        except AbstractFunctionError: #use default behaviour
+            self.validate(data)
+        except AbstractFunctionError:
+            pass
         self._data[0] = data
-        if isinstance(data, ResultBase):
-            raise Exception()
         self.state = Computed
         
     data = property(__get_data, __set_data,
                     doc = "The storage associated with this result")
 
-    def data_filter(self, data):
-        """(abstract) Return an appropriate _data based on data.
+    def validate(self, data):
+        """(abstract) Raise an exception if the data is not of an
+        acceptable type.
 
-        If a subclass overrides this function, then that overriding
-        implementation will be used in __set_data to map the argument to
-        self._data.  This gives a subclass the opportunity to ensure that
-        the contents of self._data remain sensible.
+        If a subclass overrides this function, __set_data will use
+        it to check that the argument can be used properly. This gives
+        a subclass the opportunity to ensure that the contents of
+        self._data remain sensible.
         
         """
         raise AbstractFunctionError()
 
+
     #
     # alloc
     #
@@ -229,18 +213,99 @@ class ResultBase(object):
     #
 
     def __get_replaced(self):
-        return isinstance(self._role, ResultBase.BrokenLink)
+        return isinstance(self._role, BrokenLink)
 
     def __set_replaced(self, replace):
         if replace == self.replaced: return
         if replace:
-            self._role = ResultBase.BrokenLink(self._role)
+            self._role = BrokenLink(self._role)
         else:
             self._role = self._role.old_role
 
     replaced = property(__get_replaced, __set_replaced, doc = "has this Result been replaced?")
 
 
+    #
+    # C code generators
+    #
+
+
+    def c_extract(self):
+        get_from_list = """
+        PyObject* py_%(name)s = PyList_GET_ITEM(%(name)s_storage, 0);
+        Py_XINCREF(py_%(name)s);
+        """
+        return self.c_data_extract() + get_from_list
+
+    def c_data_extract(self):
+        """
+        The code returned from this function must be templated using "%(name)s",
+        representing the name that the caller wants to call this Result.
+        The Python object self.data is in a variable called "py_%(name)s" and
+        this code must declare a variable named "%(name)s" of a type appropriate
+        to manipulate from C. Additional variables and typedefs can be produced.
+        If the data is improper, set an appropriate error message and insert
+        "%(fail)s".
+        """
+        raise AbstractFunction()
+
+
+    def c_sync(self, var_name):
+        set_in_list = """
+        PyList_SET_ITEM(%(name)s_storage, 0, py_%(name)s);
+        Py_XDECREF(py_%(name)s);
+        """
+        return self.c_data_sync() + set_in_list
+
+    def c_data_sync(self):
+        """
+        The code returned from this function must be templated using "%(name)s",
+        representing the name that the caller wants to call this Result.
+        The returned code may set "py_%(name)s" to a PyObject* and that PyObject*
+        will be accessible from Python via result.data. Do not forget to adjust
+        reference counts if "py_%(name)s" is changed from its original value!
+        """
+        raise AbstractFunction()
+
+    #
+    # name
+    #
+
+    def __get_name(self):
+        if self._name:
+            return self._name
+        elif self._role:
+            return "%s.%i" % (self.owner.__class__, self.owner.outputs.index(self))
+        else:
+            return None
+    def __set_name(self, name):
+        if name is not None and not isinstance(name, str):
+            raise TypeError("Name is expected to be a string, or None.")
+        self._name = name
+
+    name = property(__get_name, __set_name,
+                    doc = "Name of the Result.")
+
+
+    #
+    # String representation
+    #
+
+    def __str__(self):
+        name = self.name
+        if name:
+            if self.state is Computed:
+                return name + ":" + str(self.data)
+            else:
+                return name
+        elif self.state is Computed:
+            return str(self.data)
+        else:
+            return "<?>"
+
+    def __repr__(self):
+        return self.name or "<?>"
+                                            
     
     #################
     # NumpyR Compatibility
@@ -252,26 +317,26 @@ class ResultBase(object):
     def set_value(self, value):
         self.data = value #may raise exception
 
-class _test_ResultBase(unittest.TestCase):
-    def test_0(self):
-        r = ResultBase()
-    def test_1(self):
-        r = ResultBase()
-        assert r.state is Empty
-
-        r.data = 0
-        assert r.data == 0
-        assert r.state is Computed
-        
-        r.data = 1
-        assert r.data == 1
-        assert r.state is Computed
-
-        r.data = None
-        assert r.data == None
-        assert r.state is Empty
-
-if __name__ == '__main__':
-    unittest.main()
 
+#     def c_data_extract(self):
+#         return """
+#         PyArrayObject* %%(name)s;
+#         if (py_%%(name)s == Py_None)
+#             %%(name)s = NULL;
+#         else
+#             %%(name)s = (PyArrayObject*)(py_%%(name)s);
+#         typedef %(dtype)s %%(name)s_dtype;
+#         """ % dict(dtype = self.dtype)
+
+#     def c_data_sync(self):
+#         return """
+#         if (!%(name)s) {
+#             Py_XDECREF(py_%(name));
+#             py_%(name)s = Py_None;
+#         }
+#         else if ((void*)py_%(name)s != (void*)%(name)s) {
+#             Py_XDECREF(py_%(name));
+#             py_%(name)s = (PyObject*)%(name)s;
+#         }
+#         """
 

gof/utils.py

@@ -12,6 +12,15 @@ class AbstractFunctionError(Exception):
     function has been left out of an implementation class.
     """
 
+def attr_checker(*attrs):
+    def f(candidate):
+        for attr in attrs:
+            if not hasattr(candidate, attr):
+                return False
+        return True
+    f.__doc__ = "Checks that the candidate has the following attributes: %s" % ", ".join(["'%s'"%attr for attr in attrs])
+    return f
+
 
 def all_bases(cls, accept):
     rval = set([cls])
@@ -34,21 +43,6 @@ def all_bases_collect(cls, raw_name):
 
 
 
-def uniq_features(_features, *_rest):
-    """Return a list such that no element is a subclass of another"""
-    # used in Env.__init__ to 
-    features = [x for x in _features]
-    for other in _rest:
-        features += [x for x in other]
-    res = []
-    while features:
-        feature = features.pop()
-        for feature2 in features:
-            if issubclass(feature2, feature):
-                break
-        else:
-            res.append(feature)
-    return res