/usr/lib/python2.7/dist-packages/traits/adapter.py is in python-traits 4.1.0-1ubuntu4.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 | #-------------------------------------------------------------------------------
#
# Copyright (c) 2007, Enthought, Inc.
# All rights reserved.
#
# This software is provided without warranty under the terms of the BSD
# license included in /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: 07/18/2007
#
#-------------------------------------------------------------------------------
""" An extension to PyProtocols to simplify the declaration of adapters.
"""
#-------------------------------------------------------------------------------
# Imports:
#-------------------------------------------------------------------------------
from __future__ import absolute_import
# Standard library imports:
import weakref
# Traits imports:
from .has_traits import HasTraits
from .trait_types import Any, Bool, Expression
# PyProtocols imports:
from .protocols.api import addClassAdvisor, declareAdapter, declareImplementation, Protocol
#-------------------------------------------------------------------------------
# 'Adapter' class:
#-------------------------------------------------------------------------------
class Adapter ( HasTraits ):
""" The base class for all traits adapters.
In Traits, an *adapter* is a special type of class whose role is to
transform some type of object which does not implement a specific interface,
or set of interfaces, into one that does.
This class is provided as a convenience. If you subclass this class, the
only things you need to add to the subclass definition are:
* An implements() function call declaring which interfaces the adapter
class implements on behalf of the object is is adapting.
* A declaration for the **adaptee** trait, usually as an Instance of
a particular class.
* The actual implementations of the interfaces declared in the
implements() call. Usually the implementation code is written in
terms of the **adaptee** trait.
"""
#-- Trait Definitions ------------------------------------------------------
# The object that is being adapted.
adaptee = Any
#-- Constructor ------------------------------------------------------------
def __init__ ( self, adaptee ):
""" Constructor.
We have to declare an explicit constructor because adapters are
created by PyProtocols itself, which knows nothing about traits.
"""
super( Adapter, self ).__init__()
self.adaptee = adaptee
#-------------------------------------------------------------------------------
# 'DefaultAdapterFactory' class:
#-------------------------------------------------------------------------------
class DefaultAdapterFactory ( HasTraits ):
""" An adapter factory for producing cached or categorized adapters.
"""
#-- 'DefaultAdapterFactory' Interface --------------------------------------
# The adapter class that this factory creates instances of
klass = Any
# Does the factory generate cached adapters?
# If an adapter is cached then the factory will produce at most one
# adapter per instance.
cached = Bool( False )
# An expression that is used to select which instances of a particular
# type can be adapted by this factory.
#
# The expression is evaluated in a namespace that contains a single name
# 'adaptee', which is bound to the object that this factory is attempting
# to adapt (e.g. 'adaptee.is_folder').
when = Expression
#-- Private Interface ------------------------------------------------------
# If this is a cached adapter factory, then this mapping will contain
# the adapters keyed by weak references to the adapted objects.
_adapters = Any
#-------------------------------------------------------------------------------
# 'IAdapterFactory' interface:
#-------------------------------------------------------------------------------
def __call__ ( self, object ):
""" Creates an adapter for the specified object.
Returns **None** if the factory cannot perform the required
adaptation.
"""
namespace = { 'adaptee': object }
if eval( self.when_, namespace, namespace ):
if self.cached:
adapter = self._adapters.get( object )
if adapter is None:
self._adapters[ object ] = adapter = self.klass( object )
return adapter
return self.klass( object )
return None
#---------------------------------------------------------------------------
# Private interface:
#---------------------------------------------------------------------------
def __adapters_default ( self ):
""" Trait initializer.
"""
return weakref.WeakKeyDictionary()
#-------------------------------------------------------------------------------
# 'adapts' function:
#-------------------------------------------------------------------------------
def adapts ( from_, to, extra = None, factory = None, cached = False,
when = '' ):
""" A class advisor for declaring adapters.
Parameters
----------
``from_`` : type or interface
What the adapter adapts *from*, or a list of such types or interfaces
(the '_' suffix is used because 'from' is a Python keyword).
to : type or interface
What the adapter adapts *to*, or a list of such types or interfaces.
factory : callable
An (optional) factory for actually creating the adapters. This is
any callable that takes a single argument which is the object to
be adapted. The factory should return an adapter if it can
perform the adaptation and **None** if it cannot.
The following arguments are ignored if *factory* is specified:
cached : Boolean
Should the adapters be cached? If an adapter is cached, then the
factory will produce at most one adapter per instance.
when : A Python expression
Selects which instances of a particular type can be adapted by this
factory. The expression is evaluated in a namespace that contains a
single name *adaptee*, which is bound to the object to be adapted
(e.g., 'adaptee.is_folder').
"""
if extra is not None:
adapter, from_, to = from_, to, extra
else:
adapter = None
def callback ( klass ):
""" Called when the class has been created. """
# What the adapter adapts from:
if type( from_ ) is not list:
for_items = [ from_ ]
else:
for_items = from_
# The things we adapt from have to be split into two lists for
# PyProtocols, one containing Python types (i.e. classes) and one
# containing protocols (i.e. interfaces):
for_types = []
for_protocols = []
for item in for_items:
if isinstance( item, Protocol ):
for_protocols.append( item )
else:
for_types.append( item )
# What the adapter adapts to:
if type( to ) is not list:
provides = [ to ]
else:
provides = to
# Tell PyProtocols that the adapter class implements the protocols that
# it adapts to:
declareImplementation( klass, instancesProvide = provides )
# If a factory was specified then use it:
if factory is not None:
f = factory
# If the adapter is cached or has a 'when' expression then create a
# default factory:
elif cached or (when != ''):
f = DefaultAdapterFactory( klass = klass,
cached = cached,
when = when or 'True' )
# Otherwise, just use the adapter class itself:
else:
f = klass
# Tell PyProtocols about the factory:
declareAdapter( f, provides, forProtocols = for_protocols,
forTypes = for_types )
return klass
if adapter is not None:
callback( adapter )
else:
addClassAdvisor( callback )
|