Use the memoize function for faked arguments only when needed.

It's important to note that memoizing every object would mean that
theoretically all objects passed through get_faked would get memoized. This
would have been a possible memory leak, which we should avoid.
Obviously the previous solution proposed in #649 was still better, but this
issue was a new one. Also using str() around keys was not a good idea.

Refs #649.

jedi/cache.py

@@ -91,18 +91,6 @@ def memoize_method(method):
     return wrapper
 
 
-def memoize_function(obj):
-    """ A normal memoize function for memoizing free functions. """
-    cache = obj.cache = {}
-
-    def memoizer(*args, **kwargs):
-        key = str(args) + str(kwargs)
-        if key not in cache:
-            cache[key] = obj(*args, **kwargs)
-        return cache[key]
-    return memoizer
-
-
 def cache_star_import(func):
     @time_cache("star_import_cache_validity")
     def wrapper(self):

jedi/evaluate/compiled/__init__.py

@@ -222,10 +222,12 @@ class CompiledObject(Base):
         module = self.get_parent_until()
         faked_subscopes = []
         for name in dir(self.obj):
-            f = fake.get_faked(module.obj, self.obj, name)
-            if f:
-                f.parent = self
-                faked_subscopes.append(f)
+            try:
+                faked_subscopes.append(
+                    fake.get_faked(module.obj, self.obj, parent=self, name=name)
+                )
+            except fake.FakeDoesNotExist:
+                pass
         return faked_subscopes
 
     def is_scope(self):
@@ -445,16 +447,15 @@ def _parse_function_doc(doc):
 
 
 def _create_from_name(evaluator, module, parent, name):
-    faked = fake.get_faked(module.obj, parent.obj, name)
-    # only functions are necessary.
-    if faked is not None:
-        faked.parent = parent
-        return faked
+    try:
+        return fake.get_faked(module.obj, parent.obj, parent=parent, name=name)
+    except fake.FakeDoesNotExist:
+        pass
 
     try:
         obj = getattr(parent.obj, name)
     except AttributeError:
-        # happens e.g. in properties of
+        # Happens e.g. in properties of
         # PyQt4.QtGui.QStyleOptionComboBox.currentText
         # -> just set it to None
         obj = None
@@ -527,9 +528,9 @@ def create(evaluator, obj, parent=None, module=None):
         if parent is None and obj != _builtins:
             return create(evaluator, obj, create(evaluator, _builtins))
 
-        faked = fake.get_faked(module and module.obj, obj)
-        if faked is not None:
-            faked.parent = parent
-            return faked
+        try:
+            return fake.get_faked(module and module.obj, obj, parent=parent)
+        except fake.FakeDoesNotExist:
+            pass
 
     return CompiledObject(evaluator, obj, parent)

jedi/evaluate/compiled/fake.py

@@ -9,7 +9,6 @@ import inspect
 import types
 
 from jedi._compatibility import is_py3, builtins, unicode, is_py34
-from jedi.cache import memoize_function
 from jedi.parser import ParserWithRecovery, load_grammar
 from jedi.parser import tree as pt
 from jedi.evaluate.helpers import FakeName
@@ -44,6 +43,10 @@ if is_py3:
         NOT_CLASS_TYPES += (types.DynamicClassAttribute,)
 
 
+class FakeDoesNotExist(Exception):
+    pass
+
+
 def _load_faked_module(module):
     module_name = module.__name__
     if module_name == '__builtin__' and not is_py3:
@@ -143,13 +146,35 @@ def _faked(module, obj, name):
             return search_scope(cls, name)
 
 
-@memoize_function
-def get_faked(module, obj, name=None):
+def memoize_faked(obj):
+    """
+    A typical memoize function that ignores issues with non hashable results.
+    """
+    cache = obj.cache = {}
+
+    def memoizer(*args, **kwargs):
+        key = (obj, args, frozenset(kwargs.items()))
+        try:
+            result = cache[key]
+        except TypeError:
+            return obj(*args, **kwargs)
+        except KeyError:
+            result = obj(*args, **kwargs)
+            if result is not None:
+                cache[key] = obj(*args, **kwargs)
+            return result
+        else:
+            return result
+    return memoizer
+
+
+@memoize_faked
+def _get_faked(module, obj, name=None):
     obj = type(obj) if is_class_instance(obj) else obj
     result = _faked(module, obj, name)
     if result is None or isinstance(result, pt.Class):
         # We're not interested in classes. What we want is functions.
-        return None
+        raise FakeDoesNotExist
     else:
         # Set the docstr which was previously not set (faked modules don't
         # contain it).
@@ -162,6 +187,12 @@ def get_faked(module, obj, name=None):
         return result
 
 
+def get_faked(module, obj, name=None, parent=None):
+    faked = _get_faked(module, obj, name)
+    faked.parent = parent
+    return faked
+
+
 def is_class_instance(obj):
     """Like inspect.* methods."""
     try: