/usr/share/pyshared/traits/interface_checker.py is in python-traits 4.1.0-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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#
# Copyright (c) 2008, Enthought, Inc.
# All rights reserved.
#
# This software is provided without warranty under the terms of the BSD
# license included in enthought/LICENSE.txt and may be redistributed only
# under the conditions described in the aforementioned license. The license
# is also available online at http://www.enthought.com/licenses/BSD.txt
#
# Thanks for using Enthought open source!
#
# Author: Martin Chilvers
# Date: 03/20/2008
#
#------------------------------------------------------------------------------
""" An attempt at type-safe casting.
"""
#-------------------------------------------------------------------------------
# Imports:
#-------------------------------------------------------------------------------
from __future__ import absolute_import
from types import FunctionType
from inspect import getargspec, getmro
from .has_traits import HasTraits
#-------------------------------------------------------------------------------
# Logging:
#-------------------------------------------------------------------------------
import logging
logger = logging.getLogger( __name__ )
#-------------------------------------------------------------------------------
# Constants:
#-------------------------------------------------------------------------------
# Message templates for interface errors.
BAD_SIGNATURE = ("The '%s' class signature for the '%s' method is different "
"from that of the '%s' interface.")
MISSING_METHOD = ("The '%s' class does not implement the '%s' method of the "
"'%s' interface.")
MISSING_TRAIT = ("The '%s' class does not implement the %s trait(s) of the "
"'%s' interface.")
#-------------------------------------------------------------------------------
# 'InterfaceError' class:
#-------------------------------------------------------------------------------
class InterfaceError ( Exception ):
""" The exception raised if a class does not really implement an interface.
"""
pass
#-------------------------------------------------------------------------------
# 'InterfaceChecker' class:
#-------------------------------------------------------------------------------
class InterfaceChecker ( HasTraits ):
""" Checks that interfaces are actually implemented.
"""
#---------------------------------------------------------------------------
# 'InterfaceChecker' interface:
#---------------------------------------------------------------------------
def check_implements ( self, cls, interfaces, error_mode ):
""" Checks that the class implements the specified interfaces.
'interfaces' can be a single interface or a list of interfaces.
"""
# If a single interface was specified then turn it into a list:
try:
iter( interfaces )
except TypeError:
interfaces = [ interfaces ]
# If the class has traits then check that it implements all traits and
# methods on the specified interfaces:
if issubclass( cls, HasTraits ):
for interface in interfaces:
if not self._check_has_traits_class( cls, interface,
error_mode ):
return False
# Otherwise, just check that the class implements all methods on the
# specified interface:
else:
for interface in interfaces:
if not self._check_non_has_traits_class( cls, interface,
error_mode ):
return False
return True
#---------------------------------------------------------------------------
# Private interface:
#---------------------------------------------------------------------------
def _check_has_traits_class ( self, cls, interface, error_mode ):
""" Checks that a 'HasTraits' class implements an interface.
"""
return (self._check_traits( cls, interface, error_mode ) and
self._check_methods( cls, interface, error_mode ))
def _check_non_has_traits_class ( self, cls, interface, error_mode ):
""" Checks that a non-'HasTraits' class implements an interface.
"""
return self._check_methods( cls, interface, error_mode )
def _check_methods ( self, cls, interface, error_mode ):
""" Checks that a class implements the methods on an interface.
"""
cls_methods = self._get_public_methods( cls )
interface_methods = self._get_public_methods( interface )
for name in interface_methods:
if name not in cls_methods:
return self._handle_error( MISSING_METHOD %
( self._class_name( cls ), name,
self._class_name( interface ) ), error_mode )
# Check that the method signatures are the same:
cls_argspec = getargspec( cls_methods[ name ] )
interface_argspec = getargspec( interface_methods[ name ] )
if cls_argspec != interface_argspec:
return self._handle_error( BAD_SIGNATURE %
( self._class_name( cls ), name,
self._class_name( interface ) ), error_mode )
return True
def _check_traits ( self, cls, interface, error_mode ):
""" Checks that a class implements the traits on an interface.
"""
missing = set( interface.class_traits() ).difference(
set( cls.class_traits() ) )
if len( missing ) > 0:
return self._handle_error( MISSING_TRAIT %
( self._class_name( cls ), `list( missing )`[1:-1],
self._class_name( interface ) ), error_mode )
return True
def _get_public_methods ( self, cls ):
""" Returns all public methods on a class.
Returns a dictionary containing all public methods keyed by name.
"""
public_methods = {}
for c in getmro( cls ):
# Stop when we get to 'HasTraits'!:
if c is HasTraits:
break
for name, value in c.__dict__.items():
if ((not name.startswith( '_' )) and
(type( value ) is FunctionType)):
public_methods[ name ] = value
return public_methods
def _class_name ( self, cls ):
return cls.__name__
def _handle_error ( self, msg, error_mode ):
if error_mode > 1:
raise InterfaceError( msg )
if error_mode == 1:
logger.warning( msg )
return False
# A default interface checker:
checker = InterfaceChecker()
def check_implements ( cls, interfaces, error_mode = 0 ):
""" Checks that the class implements the specified interfaces.
'interfaces' can be a single interface or a list of interfaces.
"""
return checker.check_implements( cls, interfaces, error_mode )
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