Add init_code mechanism to register code in module init fn

doc/extending/cop.txt

@@ -57,6 +57,11 @@ There are less methods to define for an Op than for a Type:
 
       Allows you to specify special g++ arguments to add/exclude
 
+    .. method:: c_init_code()
+
+      Allows you to specify code that will be executed once when the
+      module is initialized, before anything else is executed.
+
     .. method:: c_support_code()
 
       Allows you to specify helper functions/structs that the

doc/extending/ctype.txt

@@ -90,6 +90,11 @@ the most important ones:
 
         Allows to specify special compiler arguments to add/exclude.
 
+    .. method:: c_init_code()
+
+        Allows you to specify code that will be executed once when the
+        module is initialized, before anything else is executed.
+
     .. method:: c_support_code()
 
         Allows to add helper functions/structs that the :ref:`type` needs.

theano/gof/cc.py

@@ -774,6 +774,21 @@ class CLinker(link.Linker):
                 pass
         return utils.uniq(ret)
 
+    def init_code(self):
+        """
+        Return a list of code snippets that have to be inserted
+        in the module initialization code.
+        The return value will not contain duplicates.
+        """
+        ret = []
+        for x in [y.type for y in self.variables] + [
+            y.op for y in self.node_order]:
+            try:
+                ret += x.c_init_code()
+            except utils.MethodNotDefined:
+                pass
+        return utils.uniq(ret)
+
     def c_compiler(self):
         c_compiler = None
         for x in [y.type for y in self.variables] + [
@@ -1277,6 +1292,8 @@ class CLinker(link.Linker):
         mod.add_function(instantiate)
         for header in self.headers():
             mod.add_include(header)
+        for init_code_block in self.init_code():
+            mod.add_init_code(init_code_block)
 
         return mod
 

theano/gof/op.py

@@ -174,6 +174,17 @@ class CLinkerObject(object):
         """
         raise utils.MethodNotDefined("c_no_compile_args", type(self), self.__class__.__name__)
 
+    def c_init_code(self):
+        """
+        Optional: return a list of code snippets to be inserted in module
+        initialization.
+
+        :Exceptions:
+         - `MethodNotDefined`: the subclass does not override this method
+        """
+        raise utils.MethodNotDefined("c_init_code", type(self),
+                                     self.__class__.__name__)
+
 
 class CLinkerOp(CLinkerObject):
     """

theano/tensor/type.py

@@ -7,6 +7,7 @@ import theano
 from theano import config
 from theano.gof import Constant, hashtype, Type, Variable
 from theano.gof.python25 import any
+from theano.gof.utils import MethodNotDefined
 from theano import scalar as scal