| # Copyright 2014 The Chromium Authors. All rights reserved. |
| # Use of this source code is governed by a BSD-style license that can be |
| # found in the LICENSE file. |
| |
| import inspect |
| |
| |
| def IsDirectlyConstructable(cls): |
| """Returns True if instance of |cls| can be construct without arguments.""" |
| assert inspect.isclass(cls) |
| if not hasattr(cls, '__init__'): |
| # Case |class A: pass|. |
| return True |
| if cls.__init__ is object.__init__: |
| # Case |class A(object): pass|. |
| return True |
| # Case |class (object):| with |__init__| other than |object.__init__|. |
| args, _, _, defaults = inspect.getargspec(cls.__init__) |
| if defaults is None: |
| defaults = () |
| # Return true if |self| is only arg without a default. |
| return len(args) == len(defaults) + 1 |
