#
# Copyright 2015 Mikko Korpela
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
import sys
import dis
__VERSION__ = '0.5'
if sys.version > '3':
long = int
def overrides(method):
"""Decorator to indicate that the decorated method overrides a method in superclass.
The decorator code is executed while loading class. Using this method should have minimal runtime performance
implications.
This is based on my idea about how to do this and fwc:s highly improved algorithm for the implementation
fwc:s algorithm : http://stackoverflow.com/a/14631397/308189
my answer : http://stackoverflow.com/a/8313042/308189
How to use:
from overrides import overrides
class SuperClass(object):
def method(self):
return 2
class SubClass(SuperClass):
@overrides
def method(self):
return 1
:raises AssertionError if no match in super classes for the method name
:return method with possibly added (if the method doesn't have one) docstring from super class
"""
# nop for now due to py3 compatibility
return method
# for super_class in _get_base_classes(sys._getframe(2), method.__globals__):
# if hasattr(super_class, method.__name__):
# if not method.__doc__:
# method.__doc__ = getattr(super_class, method.__name__).__doc__
# return method
# raise AssertionError('No super class method found for "%s"' % method.__name__)
def _get_base_classes(frame, namespace):
return [_get_base_class(class_name_components, namespace) for class_name_components in _get_base_class_names(frame)]
def _get_base_class_names(frame):
"""Get baseclass names from the code object"""
co, lasti = frame.f_code, frame.f_lasti
code = co.co_code
i = 0
extended_arg = 0
extends = []
while i <= lasti:
c = code[i]
op = ord(c)
i += 1
if op >= dis.HAVE_ARGUMENT:
oparg = ord(code[i]) + ord(code[i+1])*256 + extended_arg
extended_arg = 0
i += 2
if op == dis.EXTENDED_ARG:
extended_arg = oparg*int(65536)
if op in dis.hasconst:
if type(co.co_consts[oparg]) == str:
extends = []
elif op in dis.hasname:
if dis.opname[op] == 'LOAD_NAME':
extends.append(('name', co.co_names[oparg]))
if dis.opname[op] == 'LOAD_ATTR':
extends.append(('attr', co.co_names[oparg]))
items = []
previous_item = []
for t, s in extends:
if t == 'name':
if previous_item:
items.append(previous_item)
previous_item = [s]
else:
previous_item += [s]
if previous_item:
items.append(previous_item)
return items
def _get_base_class(components, namespace):
obj = namespace[components[0]]
for component in components[1:]:
obj = getattr(obj, component)
return obj
