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#-------------------------------------------------------------------------------
#
# Trait definitions useful when creating templatizable classes.
#
# Written by: David C. Morrill
#
# Date: 07/26/2007
#
# (c) Copyright 2007 by Enthought, Inc.
#
#-------------------------------------------------------------------------------
""" Trait definitions useful when creating templatizable classes.
"""
#-------------------------------------------------------------------------------
# Imports:
#-------------------------------------------------------------------------------
from traits.api \
import Instance, Int, Float, Str, List, Bool, Range, TraitType, Undefined
from itemplate_data_source \
import ITemplateDataSource
#-------------------------------------------------------------------------------
# Trait definitions:
#-------------------------------------------------------------------------------
# Data source template trait:
TDataSource = Instance( ITemplateDataSource, template = 'datasource' )
# Templatizable object trait:
def TInstance ( *args, **kw ):
kw[ 'template' ] = 'instance'
return Instance( *args, **kw )
# A list of templatizable object traits:
def TList( *args, **kw ):
kw[ 'template' ] = 'instance'
return List( *args, **kw )
# Simple, copyable template traits:
TInt = Int( template = 'copy' )
TFloat = Float( template = 'copy' )
TStr = Str( template = 'copy' )
TBool = Bool( template = 'copy' )
def TRange ( *args, **kw ):
kw[ 'template' ] = 'copy'
return Range( *args, **kw )
def TEnum ( *args, **kw ):
kw[ 'template' ] = 'copy'
return Enum( *args, **kw )
#-------------------------------------------------------------------------------
# 'TDerived' trait:
#-------------------------------------------------------------------------------
class TDerived ( TraitType ):
""" Defines a trait property for handling attributes whose value depends
upon the templatizable traits of an object.
Note that the implementation of the *activate_template* method is not
allowed to read the value of any **TDerived** traits, it may only set
them.
"""
# Base trait metadata:
metadata = { 'template': 'derived',
'transient': True }
def get ( self, object, name ):
name += '_'
value = object.__dict__.get( name, Undefined )
if value is not Undefined:
return value
object.activate_template()
value = object.__dict__.get( name, Undefined )
if value is not Undefined:
return value
object.__dict__[ name ] = None
return None
def set ( self, object, name, value ):
xname = name + '_'
old = object.__dict__.get( xname, Undefined )
if old is not value:
object.__dict__[ xname ] = value
object.trait_property_changed( name, old, value )
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