remove the vm_lazy linker string and add the flag vm.lazy.

theano/compile/mode.py

@@ -67,7 +67,6 @@ predefined_linkers = {
     'c|py_nogc': gof.OpWiseCLinker(allow_gc=False),
     'c&py': gof.DualLinker(checker=check_equal),
     'vm': gof.vm.VM_Linker(use_cloop=False),
-    'vm_lazy': gof.vm.VM_Linker(use_cloop=False, lazy=True),
     'cvm': gof.vm.VM_Linker(use_cloop=True),
     'vm_nogc': gof.vm.VM_Linker(allow_gc=False, use_cloop=False),
     'cvm_nogc': gof.vm.VM_Linker(allow_gc=False, use_cloop=True),

theano/configdefaults.py

@@ -100,14 +100,14 @@ try:
                  ("Default linker used if the theano flags mode is Mode "
                   "or ProfileMode"),
                  EnumStr('cvm', 'c|py', 'py', 'c', 'c|py_nogc', 'c&py',
-                     'vm', 'vm_lazy', 'vm_nogc', 'cvm_nogc'),
+                     'vm', 'vm_nogc', 'cvm_nogc'),
                  in_c_key=False)
 except OSError:
     # g++ is not present, linker should default to python only
     AddConfigVar('linker',
                  ("Default linker used if the theano flags mode is Mode "
                   "or ProfileMode"),
-                 EnumStr('py', 'vm', 'vm_lazy', 'vm_nogc'),
+                 EnumStr('py', 'vm', 'vm_nogc'),
                  in_c_key=False)
     _logger.warning('g++ not detected ! Theano will be unable to execute '
             'optimized C-implementations (for both CPU and GPU) and will '

theano/gof/tests/test_vm.py

@@ -302,6 +302,7 @@ def test_vm_gc():
     pass
     x = theano.tensor.vector()
     p = RunOnce()(x)
+    mode = theano.Mode(linker=theano.gof.vm.VM_Linker(lazy=True))
     f = theano.function([theano.In(x, mutable=True)], [p + 1, p + 2],
-                        mode=theano.Mode(linker='vm_lazy'))
-    f([1,2,3])
+                        mode=mode)
+    f([1, 2, 3])

theano/gof/vm.py

@@ -22,6 +22,12 @@ AddConfigVar('profile',
 AddConfigVar('profile_optimizer',
         "If VM should collect optimizer profile information",
         BoolParam(False))
+AddConfigVar('vm.lazy',
+             "Useful only for the vm linkers. When lazy is None,"
+             " auto detect if lazy evaluation is needed and use the apropriate"
+             " version. If lazy it True/False, force the version used between"
+             " Loop/LoopGC and Stack.",
+        BoolParam(False))
 
 raise_with_op = link.raise_with_op
 
@@ -488,7 +494,7 @@ class VM_Linker(link.LocalLinker):
 
         lazy - Useful only when use_cloop is False. When lazy is None, auto
             detect if lazy evaluation is needed and use the apropriate
-            version. If lazy it True/False, for the version used between
+            version. If lazy it True/False, force the version used between
             Loop/LoopGC and Stack.
 
         """