Merge pull request #512 from tjhance/test_property

Get `cpython/test_property.py` to pass

from_cpython/Lib/test/test_property.py

-# expected: fail
 # Test case for property
 # more tests are in test_descr
 

src/runtime/descr.cpp

@@ -34,6 +34,33 @@ static Box* memberGet(BoxedMemberDescriptor* self, Box* inst, Box* owner) {
     Py_FatalError("unimplemented");
 }
 
+static void propertyDocCopy(BoxedProperty* prop, Box* fget) {
+    assert(prop);
+    assert(fget);
+    Box* get_doc;
+    try {
+        get_doc = getattrInternal(fget, "__doc__", NULL);
+    } catch (ExcInfo e) {
+        if (!e.matches(Exception)) {
+            throw;
+        }
+        get_doc = NULL;
+    }
+
+    if (get_doc) {
+        if (prop->cls == property_cls) {
+            prop->prop_doc = get_doc;
+        } else {
+            /* If this is a property subclass, put __doc__
+            in dict of the subclass instance instead,
+            otherwise it gets shadowed by __doc__ in the
+            class's dict. */
+            setattr(prop, "__doc__", get_doc);
+        }
+        prop->getter_doc = true;
+    }
+}
+
 static Box* propertyInit(Box* _self, Box* fget, Box* fset, Box** args) {
     RELEASE_ASSERT(isSubclass(_self->cls, property_cls), "");
     Box* fdel = args[0];
@@ -44,6 +71,12 @@ static Box* propertyInit(Box* _self, Box* fget, Box* fset, Box** args) {
     self->prop_set = fset;
     self->prop_del = fdel;
     self->prop_doc = doc;
+    self->getter_doc = false;
+
+    /* if no docstring given and the getter has one, use that one */
+    if ((doc == NULL || doc == None) && fget != NULL) {
+        propertyDocCopy(self, fget);
+    }
 
     return None;
 }
@@ -93,17 +126,31 @@ static Box* propertyDel(Box* self, Box* obj) {
 static Box* property_copy(BoxedProperty* old, Box* get, Box* set, Box* del) {
     RELEASE_ASSERT(isSubclass(old->cls, property_cls), "");
 
-    if (!get)
+    if (!get || get == None)
         get = old->prop_get;
-    if (!set)
+    if (!set || set == None)
         set = old->prop_set;
-    if (!del)
+    if (!del || del == None)
         del = old->prop_del;
 
     // Optimization for the case when the old propery is not subclassed
-    if (old->cls == property_cls)
-        return new BoxedProperty(get, set, del, old->prop_doc);
-    return runtimeCall(old->cls, ArgPassSpec(4), get, set, del, &old->prop_doc, NULL);
+    if (old->cls == property_cls) {
+        BoxedProperty* prop = new BoxedProperty(get, set, del, old->prop_doc);
+
+        prop->getter_doc = false;
+        if ((old->getter_doc && get != None) || !old->prop_doc)
+            propertyDocCopy(prop, get);
+
+        return prop;
+    } else {
+        Box* doc;
+        if ((old->getter_doc && get != None) || !old->prop_doc)
+            doc = None;
+        else
+            doc = old->prop_doc;
+
+        return runtimeCall(old->cls, ArgPassSpec(4), get, set, del, &doc, NULL);
+    }
 }
 
 static Box* propertyGetter(Box* self, Box* obj) {

src/runtime/types.h

@@ -778,6 +778,7 @@ public:
     Box* prop_set;
     Box* prop_del;
     Box* prop_doc;
+    bool getter_doc;
 
     BoxedProperty(Box* get, Box* set, Box* del, Box* doc)
         : prop_get(get), prop_set(set), prop_del(del), prop_doc(doc) {}

test/tests/property.py

@@ -83,3 +83,87 @@ class C(object):
 c = C()
 c.p = "worked"
 print c.p
+
+print 'test the setting of __doc__'
+class C(object):
+    @property
+    def f(self):
+        """doc string of f"""
+print C.f.__doc__
+
+print 'test the setting of __doc__ with a __get__'
+class Desc(object):
+    def __get__(self, obj, typ):
+        print 'desc called'
+        return "blah"
+class ObjWithDocDesc(object):
+    __doc__ = Desc()
+class C(object):
+    f = property(ObjWithDocDesc)
+print C.f.__doc__
+
+print 'test the setting of __doc__ with a __get__ throwing an exception (should get swallowed)'
+class Desc(object):
+    def __get__(self, obj, typ):
+        raise ValueError("arbitrary exception")
+class ObjWithDocDesc(object):
+    __doc__ = Desc()
+class C(object):
+    f = property(ObjWithDocDesc)
+print C.f.__doc__
+
+print 'test the setting of __doc__ with a __get__ throwing an exception (should not get swallowed)'
+class Desc(object):
+    def __get__(self, obj, typ):
+        raise BaseException("not a subclass of Exception")
+class ObjWithDocDesc(object):
+    __doc__ = Desc()
+try:
+    class C(object):
+        f = property(ObjWithDocDesc)
+except BaseException as e:
+    print e.message
+
+print 'test the setting of a __doc__ when you copy it'
+class Desc(object):
+    def __get__(self, obj, typ):
+        print 'desc called'
+        return "blah"
+class ObjWithDocDesc(object):
+    __doc__ = Desc()
+prop = property(ObjWithDocDesc)
+print 'made prop'
+print prop.__doc__
+def g():
+    """doc of g"""
+    return 5
+prop2 = prop.getter(g)
+print 'made prop2'
+print prop2.__doc__
+prop3 = prop.setter(lambda self, val : None)
+print prop3.__doc__
+prop4 = prop.deleter(lambda self, val : None)
+print prop4.__doc__
+
+print 'test the setting of a __doc__ when you copy it when using a subclass of property'
+class PropertySubclass(property):
+    pass
+class Desc(object):
+    def __get__(self, obj, typ):
+        print 'desc called'
+        return "blah"
+class ObjWithDocDesc(object):
+    __doc__ = Desc()
+prop = PropertySubclass(ObjWithDocDesc)
+print 'made prop'
+print prop.__doc__
+def g():
+    """doc of g"""
+    return 5
+prop2 = prop.getter(g)
+print 'made prop2'
+print prop2.__doc__
+prop3 = prop.setter(lambda self, val : None)
+print prop3.__doc__
+prop4 = prop.deleter(lambda self, val : None)
+print prop4.__doc__