#------------------------------------------------------------------------------ # # Copyright (c) 2005, 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: David C. Morrill # Original Date: 06/21/2002 # # Rewritten as a C-based type extension: 06/21/2004 # #------------------------------------------------------------------------------ """ Defines the 'core' traits for the Traits package. A trait is a type definition that can be used for normal Python object attributes, giving the attributes some additional characteristics: Initialization: Traits have predefined values that do not need to be explicitly initialized in the class constructor or elsewhere. Validation: Trait attributes have flexible, type-checked values. Delegation: Trait attributes' values can be delegated to other objects. Notification: Trait attributes can automatically notify interested parties when their values change. Visualization: Trait attributes can automatically construct (automatic or programmer-defined) user interfaces that allow their values to be edited or displayed) .. note:: 'trait' is a synonym for 'property', but is used instead of the word 'property' to differentiate it from the Python language 'property' feature. """ #------------------------------------------------------------------------------- # Imports: #------------------------------------------------------------------------------- from __future__ import absolute_import import sys from types import FunctionType, MethodType NoneType = type(None) # Python 3's types does not include NoneType from . import trait_handlers from .ctraits import cTrait from .trait_errors import TraitError from .trait_base import (SequenceTypes, Self, Undefined, Missing, TypeTypes, add_article) from .trait_handlers import (TraitHandler, TraitInstance, TraitFunction, TraitCoerceType, TraitCastType, TraitEnum, TraitCompound, TraitMap, TraitString, ThisClass, TraitType, _arg_count, _read_only, _write_only, _undefined_get, _undefined_set) #------------------------------------------------------------------------------- # Constants: #------------------------------------------------------------------------------- # Mapping from 'ctrait' default value types to a string representation: KindMap = { 0: 'value', 1: 'value', 2: 'self', 3: 'list', 4: 'dict', 5: 'list', 6: 'dict', 7: 'factory', 8: 'method' } #------------------------------------------------------------------------------- # Editor factory functions: #------------------------------------------------------------------------------- PasswordEditor = None MultilineTextEditor = None SourceCodeEditor = None HTMLTextEditor = None PythonShellEditor = None DateEditor = None TimeEditor = None def password_editor ( auto_set=True, enter_set=False ): """ Factory function that returns an editor for passwords. """ global PasswordEditor if PasswordEditor is None: from traitsui.api import TextEditor PasswordEditor = TextEditor( password = True , auto_set = auto_set, enter_set = enter_set ) return PasswordEditor def multi_line_text_editor ( auto_set=True, enter_set=False ): """ Factory function that returns a text editor for multi-line strings. """ global MultilineTextEditor if MultilineTextEditor is None: from traitsui.api import TextEditor MultilineTextEditor = TextEditor( multi_line = True, auto_set = auto_set, enter_set = enter_set ) return MultilineTextEditor def code_editor ( ): """ Factory function that returns an editor that treats a multi-line string as source code. """ global SourceCodeEditor if SourceCodeEditor is None: from traitsui.api import CodeEditor SourceCodeEditor = CodeEditor() return SourceCodeEditor def html_editor ( ): """ Factory function for an "editor" that displays a multi-line string as interpreted HTML. """ global HTMLTextEditor if HTMLTextEditor is None: from traitsui.api import HTMLEditor HTMLTextEditor = HTMLEditor() return HTMLTextEditor def shell_editor ( ): """ Factory function that returns a Python shell for editing Python values. """ global PythonShellEditor if PythonShellEditor is None: from traitsui.api import ShellEditor PythonShellEditor = ShellEditor() return PythonShellEditor def time_editor ( ): """ Factory function that returns a Time editor for editing Time values. """ global TimeEditor if TimeEditor is None: from traitsui.api import TimeEditor TimeEditor = TimeEditor() return TimeEditor def date_editor ( ): """ Factory function that returns a Date editor for editing Date values. """ global DateEditor if DateEditor is None: from traitsui.api import DateEditor DateEditor = DateEditor() return DateEditor #------------------------------------------------------------------------------- # 'CTrait' class (extends the underlying cTrait c-based type): #------------------------------------------------------------------------------- class CTrait ( cTrait ): """ Extends the underlying C-based cTrait type. """ #--------------------------------------------------------------------------- # Allows a derivative trait to be defined from this one: #--------------------------------------------------------------------------- def __call__ ( self, *args, **metadata ): handler = self.handler if isinstance( handler, TraitType ): dict = (self.__dict__ or {}).copy() dict.update( metadata ) return handler( *args, **dict ) metadata.setdefault( 'parent', self ) return Trait( *(args + ( self, )), **metadata ) #--------------------------------------------------------------------------- # (Python) property definitions: #--------------------------------------------------------------------------- def __get_default ( self ): kind, value = self.default_value() if kind in ( 2, 7, 8 ): return Undefined if kind in ( 4, 6 ): return value.copy() if kind in ( 3, 5 ): return value[:] return value default = property( __get_default ) def __get_default_kind ( self ): return KindMap[ self.default_value()[0] ] default_kind = property( __get_default_kind ) def __get_trait_type ( self ): handler = self.handler if handler is not None: return handler else: from .trait_types import Any return Any trait_type = property( __get_trait_type ) def __get_inner_traits ( self ): handler = self.handler if handler is not None: return handler.inner_traits() return () inner_traits = property( __get_inner_traits ) #--------------------------------------------------------------------------- # Returns whether or not this trait is of a specified trait type: #--------------------------------------------------------------------------- def is_trait_type ( self, trait_type ): """ Returns whether or not this trait is of a specified trait type. """ return isinstance( self.trait_type, trait_type ) #--------------------------------------------------------------------------- # Returns the user interface editor associated with the trait: #--------------------------------------------------------------------------- def get_editor ( self ): """ Returns the user interface editor associated with the trait. """ from traitsui.api import EditorFactory # See if we have an editor: editor = self.editor if editor is None: # Else see if the trait handler has an editor: handler = self.handler if handler is not None: editor = handler.get_editor( self ) # If not, give up and use a default text editor: if editor is None: from traitsui.api import TextEditor editor = TextEditor # If the result is not an EditorFactory: if not isinstance( editor, EditorFactory ): # Then it should be a factory for creating them: args = () traits = {} if type( editor ) in SequenceTypes: for item in editor[:]: if type( item ) in SequenceTypes: args = tuple( item ) elif isinstance( item, dict ): traits = item if traits.get( 'trait', 0 ) is None: traits = traits.copy() traits[ 'trait' ] = self else: editor = item editor = editor( *args, **traits ) # Cache the result: self.editor = editor # Return the resulting EditorFactory object: return editor #--------------------------------------------------------------------------- # Returns the help text for a trait: #--------------------------------------------------------------------------- def get_help ( self, full = True ): """ Returns the help text for a trait. Parameters ---------- full : bool Indicates whether to return the value of the *help* attribute of the trait itself. Description ----------- If *full* is False or the trait does not have a **help** string, the returned string is constructed from the **desc** attribute on the trait and the **info** string on the trait's handler. """ if full: help = self.help if help is not None: return help handler = self.handler if handler is not None: info = 'must be %s.' % handler.info() else: info = 'may be any value.' desc = self.desc if self.desc is None: return info.capitalize() return 'Specifies %s and %s' % ( desc, info ) #--------------------------------------------------------------------------- # Returns a description of the trait: #--------------------------------------------------------------------------- def full_info ( self, object, name, value ): """ Returns a description of the trait. """ handler = self.handler if handler is not None: return handler.full_info( object, name, value ) return 'any value' #--------------------------------------------------------------------------- # Returns a description of the trait: #--------------------------------------------------------------------------- def info ( self ): """ Returns a description of the trait. """ handler = self.handler if handler is not None: return handler.info() return 'any value' #--------------------------------------------------------------------------- # Returns the pickleable form of a CTrait object: #--------------------------------------------------------------------------- def __reduce_ex__ ( self, protocol ): return ( __newobj__, ( self.__class__, 0 ), self.__getstate__() ) #--------------------------------------------------------------------------- # Registers listeners on an assigned 'TraitValue' object's 'value' # property: #--------------------------------------------------------------------------- def _register ( self, object, name ): """ Registers listeners on an assigned 'TraitValue' object's 'value' property. """ def handler ( ): object.trait_property_changed( name, None ) tv = self._trait_value handlers = tv._handlers if handlers is None: tv._handlers = handlers = {} handlers[ ( id( object ), name ) ] = handler tv.on_trait_change( handler, 'value' ) #--------------------------------------------------------------------------- # Unregisters listeners on an assigned 'TraitValue' object's 'value' # property: #--------------------------------------------------------------------------- def _unregister ( self, object, name ): """ Unregisters listeners on an assigned 'TraitValue' object's 'value' property. """ tv = self._trait_value handlers = tv._handlers key = ( id( object ), name ) handler = handlers.get( key ) if handler is not None: del handlers[ key ] tv.on_trait_change( handler, 'value', remove = True ) # Make sure the Python-level version of the trait class is known to all # interested parties: from . import ctraits ctraits._ctrait( CTrait ) #------------------------------------------------------------------------------- # Constants: #------------------------------------------------------------------------------- ConstantTypes = ( NoneType, int, long, float, complex, str, unicode ) PythonTypes = ( str, unicode, int, long, float, complex, list, tuple, dict, FunctionType, MethodType, type, NoneType ) if sys.version_info[0] < 3: from types import InstanceType,ClassType PythonTypes = PythonTypes[:-2] + (InstanceType,ClassType) + PythonTypes[2:] CallableTypes = ( FunctionType, MethodType ) TraitTypes = ( TraitHandler, CTrait ) DefaultValues = { str: '', unicode: u'', int: 0, long: 0L, float: 0.0, complex: 0j, list: [], tuple: (), dict: {}, bool: False } DefaultValueSpecial = [ Missing, Self ] DefaultValueTypes = [ list, dict ] #------------------------------------------------------------------------------- # Function used to unpickle new-style objects: #------------------------------------------------------------------------------- def __newobj__ ( cls, *args ): """ Unpickles new-style objects. """ return cls.__new__( cls, *args ) #------------------------------------------------------------------------------- # Returns the type of default value specified: #------------------------------------------------------------------------------- def _default_value_type ( default_value ): try: return DefaultValueSpecial.index( default_value ) + 1 except: try: return DefaultValueTypes.index( type( default_value ) ) + 3 except: return 0 #------------------------------------------------------------------------------- # 'TraitFactory' class: #------------------------------------------------------------------------------- class TraitFactory ( object ): ### Need a docstring here. #--------------------------------------------------------------------------- # Initializes the object: #--------------------------------------------------------------------------- def __init__ ( self, maker_function = None ): if maker_function is not None: self.maker_function = maker_function self.__doc__ = maker_function.__doc__ #--------------------------------------------------------------------------- # Creates a CTrait instance: #--------------------------------------------------------------------------- def __call__ ( self, *args, **metadata ): return self.maker_function( *args, **metadata ) class TraitImportError ( TraitFactory ): """ Defines a factory class for deferring import problems until encountering code that actually tries to use the unimportable trait. """ #--------------------------------------------------------------------------- # Initializes the object: #--------------------------------------------------------------------------- def __init__ ( self, message ): self.message = message #--------------------------------------------------------------------------- # Creates a CTrait instance: #--------------------------------------------------------------------------- def __call__ ( self, *args, **metadata ): raise TraitError( self.message ) #------------------------------------------------------------------------------- # Returns a trait created from a TraitFactory instance: #------------------------------------------------------------------------------- _trait_factory_instances = {} def trait_factory ( trait ): global _trait_factory_instances tid = id( trait ) if tid not in _trait_factory_instances: _trait_factory_instances[ tid ] = trait() return _trait_factory_instances[ tid ] #------------------------------------------------------------------------------- # Casts a CTrait or TraitFactory to a CTrait but returns None if it is neither: #------------------------------------------------------------------------------- def trait_cast ( something ): """ Casts a CTrait, TraitFactory or TraitType to a CTrait but returns None if it is none of those. """ if isinstance( something, CTrait ): return something if isinstance( something, TraitFactory ): return trait_factory( something ) if isinstance( something, type ) and issubclass( something, TraitType ): return something().as_ctrait() if isinstance( something, TraitType ): return something.as_ctrait() return None #------------------------------------------------------------------------------- # Attempts to cast a value to a trait. Returns either a trait or the original # value: #------------------------------------------------------------------------------- def try_trait_cast ( something ): """ Attempts to cast a value to a trait. Returns either a trait or the original value. """ return trait_cast( something ) or something #------------------------------------------------------------------------------- # Returns a trait derived from its input: #------------------------------------------------------------------------------- def trait_from ( something ): """ Returns a trait derived from its input. """ from .trait_types import Any if isinstance( something, CTrait ): return something if something is None: something = Any if isinstance( something, TraitFactory ): return trait_factory( something ) if isinstance( something, type ) and issubclass( something, TraitType ): return something().as_ctrait() if isinstance( something, TraitType ): return something.as_ctrait() return Trait( something ) # Patch the reference to 'trait_from' in 'trait_handlers.py': trait_handlers.trait_from = trait_from #--- 'instance' traits --------------------------------------------------------- class _InstanceArgs ( object ): def __init__ ( self, factory, args, kw ): self.args = ( factory, ) + args self.kw = kw #--- 'creates a run-time default value' ---------------------------------------- class Default ( object ): """ Generates a value the first time it is accessed. A Default object can be used anywhere a default trait value would normally be specified, to generate a default value dynamically. """ def __init__ ( self, func = None, args = (), kw = None ): self.default_value = ( func, args, kw ) #------------------------------------------------------------------------------- # Factory function for creating C-based traits: #------------------------------------------------------------------------------- def Trait ( *value_type, **metadata ): """ Creates a trait definition. Parameters ---------- This function accepts a variety of forms of parameter lists: +-------------------+---------------+-------------------------------------+ | Format | Example | Description | +===================+===============+=====================================+ | Trait(*default*) | Trait(150.0) | The type of the trait is inferred | | | | from the type of the default value, | | | | which must be in *ConstantTypes*. | +-------------------+---------------+-------------------------------------+ | Trait(*default*, | Trait(None, | The trait accepts any of the | | *other1*, | 0, 1, 2, | enumerated values, with the first | | *other2*, ...) | 'many') | value being the default value. The | | | | values must be of types in | | | | *ConstantTypes*, but they need not | | | | be of the same type. The *default* | | | | value is not valid for assignment | | | | unless it is repeated later in the | | | | list. | +-------------------+---------------+-------------------------------------+ | Trait([*default*, | Trait([None, | Similar to the previous format, but | | *other1*, | 0, 1, 2, | takes an explicit list or a list | | *other2*, ...]) | 'many']) | variable. | +-------------------+---------------+-------------------------------------+ | Trait(*type*) | Trait(Int) | The *type* parameter must be a name | | | | of a Python type (see | | | | *PythonTypes*). Assigned values | | | | must be of exactly the specified | | | | type; no casting or coercion is | | | | performed. The default value is the | | | | appropriate form of zero, False, | | | | or emtpy string, set or sequence. | +-------------------+---------------+-------------------------------------+ | Trait(*class*) |:: | Values must be instances of *class* | | | | or of a subclass of *class*. The | | | class MyClass:| default value is None, but None | | | pass | cannot be assigned as a value. | | | foo = Trait( | | | | MyClass) | | +-------------------+---------------+-------------------------------------+ | Trait(None, |:: | Similar to the previous format, but | | *class*) | | None *can* be assigned as a value. | | | class MyClass:| | | | pass | | | | foo = Trait( | | | | None, MyClass)| | +-------------------+---------------+-------------------------------------+ | Trait(*instance*) |:: | Values must be instances of the | | | | same class as *instance*, or of a | | | class MyClass:| subclass of that class. The | | | pass | specified instance is the default | | | i = MyClass() | value. | | | foo = | | | | Trait(i) | | +-------------------+---------------+-------------------------------------+ | Trait(*handler*) | Trait( | Assignment to this trait is | | | TraitEnum ) | validated by an object derived from | | | | **traits.TraitHandler**. | +-------------------+---------------+-------------------------------------+ | Trait(*default*, | Trait(0.0, 0.0| This is the most general form of | | { *type* | | 'stuff', | the function. The notation: | | *constant* | | TupleType) | ``{...|...|...}+`` means a list of | | *dict* | *class* || | one or more of any of the items | | *function* | | | listed between the braces. Thus, the| | *handler* | | | most general form of the function | | *trait* }+ ) | | consists of a default value, | | | | followed by one or more of several | | | | possible items. A trait defined by | | | | multiple items is called a | | | | "compound" trait. | +-------------------+---------------+-------------------------------------+ All forms of the Trait function accept both predefined and arbitrary keyword arguments. The value of each keyword argument becomes bound to the resulting trait object as the value of an attribute having the same name as the keyword. This feature lets you associate metadata with a trait. The following predefined keywords are accepted: Keywords -------- desc : str Describes the intended meaning of the trait. It is used in exception messages and fly-over help in user interfaces. label : str Provides a human-readable name for the trait. It is used to label user interface editors for traits. editor : traits.api.Editor Instance of a subclass Editor object to use when creating a user interface editor for the trait. See the "Traits UI User Guide" for more information on trait editors. comparison_mode : int Indicates when trait change notifications should be generated based upon the result of comparing the old and new values of a trait assignment: * 0 (NO_COMPARE): The values are not compared and a trait change notification is generated on each assignment. * 1 (OBJECT_IDENTITY_COMPARE): A trait change notification is generated if the old and new values are not the same object. * 2 (RICH_COMPARE): A trait change notification is generated if the old and new values are not equal using Python's 'rich comparison' operator. This is the default. rich_compare : bool Indicates whether the basis for considering a trait attribute value to have changed is a "rich" comparison (True, the default), or simple object identity (False). This attribute can be useful in cases where a detailed comparison of two objects is very expensive, or where you do not care whether the details of an object change, as long as the same object is used. .. deprecated:: 3.0.3 Use ``comparison_mode`` instead """ return _TraitMaker( *value_type, **metadata ).as_ctrait() # Handle circular module dependencies: trait_handlers.Trait = Trait #------------------------------------------------------------------------------- # '_TraitMaker' class: #------------------------------------------------------------------------------- class _TraitMaker ( object ): # Ctrait type map for special trait types: type_map = { 'event': 2, 'constant': 7 } #--------------------------------------------------------------------------- # Initialize the object: #--------------------------------------------------------------------------- def __init__ ( self, *value_type, **metadata ): metadata.setdefault( 'type', 'trait' ) self.define( *value_type, **metadata ) #--------------------------------------------------------------------------- # Define the trait: #--------------------------------------------------------------------------- def define ( self, *value_type, **metadata ): default_value_type = -1 default_value = handler = clone = None if len( value_type ) > 0: default_value = value_type[0] value_type = value_type[1:] if ((len( value_type ) == 0) and (type( default_value ) in SequenceTypes)): default_value, value_type = default_value[0], default_value if len( value_type ) == 0: default_value = try_trait_cast( default_value ) if default_value in PythonTypes: handler = TraitCoerceType( default_value ) default_value = DefaultValues.get( default_value ) elif isinstance( default_value, CTrait ): clone = default_value default_value_type, default_value = clone.default_value() metadata[ 'type' ] = clone.type elif isinstance( default_value, TraitHandler ): handler = default_value default_value = None elif default_value is ThisClass: handler = ThisClass() default_value = None else: typeValue = type( default_value ) if isinstance(default_value, basestring): string_options = self.extract( metadata, 'min_len', 'max_len', 'regex' ) if len( string_options ) == 0: handler = TraitCastType( typeValue ) else: handler = TraitString( **string_options ) elif typeValue in TypeTypes: handler = TraitCastType( typeValue ) else: metadata.setdefault( 'instance_handler', '_instance_changed_handler' ) handler = TraitInstance( default_value ) if default_value is handler.aClass: default_value = DefaultValues.get( default_value ) else: enum = [] other = [] map = {} self.do_list( value_type, enum, map, other ) if (((len( enum ) == 1) and (enum[0] is None)) and ((len( other ) == 1) and isinstance( other[0], TraitInstance ))): enum = [] other[0].allow_none() metadata.setdefault( 'instance_handler', '_instance_changed_handler' ) if len( enum ) > 0: if (((len( map ) + len( other )) == 0) and (default_value not in enum)): enum.insert( 0, default_value ) other.append( TraitEnum( enum ) ) if len( map ) > 0: other.append( TraitMap( map ) ) if len( other ) == 0: handler = TraitHandler() elif len( other ) == 1: handler = other[0] if isinstance( handler, CTrait ): clone, handler = handler, None metadata[ 'type' ] = clone.type elif isinstance( handler, TraitInstance ): metadata.setdefault( 'instance_handler', '_instance_changed_handler' ) if default_value is None: handler.allow_none() elif isinstance( default_value, _InstanceArgs ): default_value_type = 7 default_value = ( handler.create_default_value, default_value.args, default_value.kw ) elif (len( enum ) == 0) and (len( map ) == 0): aClass = handler.aClass typeValue = type( default_value ) if typeValue is dict: default_value_type = 7 default_value = ( aClass, (), default_value ) elif not isinstance( default_value, aClass ): if typeValue is not tuple: default_value = ( default_value, ) default_value_type = 7 default_value = ( aClass, default_value, None ) else: for i, item in enumerate( other ): if isinstance( item, CTrait ): if item.type != 'trait': raise TraitError, ("Cannot create a complex " "trait containing %s trait." % add_article( item.type ) ) handler = item.handler if handler is None: break other[i] = handler else: handler = TraitCompound( other ) # Save the results: self.handler = handler self.clone = clone if default_value_type < 0: if isinstance( default_value, Default ): default_value_type = 7 default_value = default_value.default_value else: if (handler is None) and (clone is not None): handler = clone.handler if handler is not None: default_value_type = handler.default_value_type if default_value_type < 0: try: default_value = handler.validate( None, '', default_value ) except: pass if default_value_type < 0: default_value_type = _default_value_type( default_value ) self.default_value_type = default_value_type self.default_value = default_value self.metadata = metadata.copy() #--------------------------------------------------------------------------- # Determine the correct TraitHandler for each item in a list: #--------------------------------------------------------------------------- def do_list ( self, list, enum, map, other ): for item in list: if item in PythonTypes: other.append( TraitCoerceType( item ) ) else: item = try_trait_cast( item ) typeItem = type( item ) if typeItem in ConstantTypes: enum.append( item ) elif typeItem in SequenceTypes: self.do_list( item, enum, map, other ) elif typeItem is dict: map.update( item ) elif typeItem in CallableTypes: other.append( TraitFunction( item ) ) elif item is ThisClass: other.append( ThisClass() ) elif isinstance( item, TraitTypes ): other.append( item ) else: other.append( TraitInstance( item ) ) #--------------------------------------------------------------------------- # Returns a properly initialized 'CTrait' instance: #--------------------------------------------------------------------------- def as_ctrait ( self ): metadata = self.metadata trait = CTrait( self.type_map.get( metadata.get( 'type' ), 0 ) ) clone = self.clone if clone is not None: trait.clone( clone ) if clone.__dict__ is not None: trait.__dict__ = clone.__dict__.copy() trait.default_value( self.default_value_type, self.default_value ) handler = self.handler if handler is not None: trait.handler = handler validate = getattr( handler, 'fast_validate', None ) if validate is None: validate = handler.validate trait.set_validate( validate ) post_setattr = getattr( handler, 'post_setattr', None ) if post_setattr is not None: trait.post_setattr = post_setattr trait.is_mapped( handler.is_mapped ) # Note: The use of 'rich_compare' metadata is deprecated; use # 'comparison_mode' metadata instead: rich_compare = metadata.get( 'rich_compare' ) if rich_compare is not None: trait.rich_comparison( rich_compare is True ) comparison_mode = metadata.get( 'comparison_mode' ) if comparison_mode is not None: trait.comparison_mode( comparison_mode ) trait.value_allowed( metadata.get( 'trait_value', False ) is True ) if len( metadata ) > 0: if trait.__dict__ is None: trait.__dict__ = metadata else: trait.__dict__.update( metadata ) return trait #--------------------------------------------------------------------------- # Extract a set of keywords from a dictionary: #--------------------------------------------------------------------------- def extract ( self, from_dict, *keys ): to_dict = {} for key in keys: if key in from_dict: to_dict[ key ] = from_dict[ key ] del from_dict[ key ] return to_dict #------------------------------------------------------------------------------- # Factory function for creating C-based trait properties: #------------------------------------------------------------------------------- def Property ( fget = None, fset = None, fvalidate = None, force = False, handler = None, trait = None, **metadata ): """ Returns a trait whose value is a Python property. Parameters ---------- fget : function The "getter" function for the property. fset : function The "setter" function for the property. fvalidate : function The validation function for the property. The method should return the value to set or raise TraitError if the new value is not valid. force : bool Indicates whether to use only the function definitions specified by **fget** and **fset**, and not look elsewhere on the class. handler : function A trait handler function for the trait. trait : Trait or value A trait definition or a value that can be converted to a trait that constrains the values of the property trait. Description ----------- If no getter, setter or validate functions are specified (and **force** is not True), it is assumed that they are defined elsewhere on the class whose attribute this trait is assigned to. For example:: class Bar(HasTraits): # A float traits Property that should be always positive. foo = Property(Float) # Shadow trait attribute _foo = Float def _set_foo(self,x): self._foo = x def _validate_foo(self, x): if x <= 0: raise TraitError( 'foo property should be a positive number') return x def _get_foo(self): return self._foo You can use the **depends_on** metadata attribute to indicate that the property depends on the value of another trait. The value of **depends_on** is an extended name specifier for traits that the property depends on. The property will a trait change notification if any of the traits specified by **depends_on** change. For example:: class Wheel ( Part ): axle = Instanced( Axle ) position = Property( depends_on = 'axle.chassis.position' ) For details of the extended trait name syntax, refer to the on_trait_change() method of the HasTraits class. """ metadata[ 'type' ] = 'property' # If no parameters specified, must be a forward reference (if not forced): if (not force) and (fset is None): sum = ((fget is not None) + (fvalidate is not None) + (trait is not None)) if sum <= 1: if sum == 0: return ForwardProperty( metadata ) handler = None if fget is not None: trait = fget if trait is not None: trait = trait_cast( trait ) if trait is not None: fvalidate = handler = trait.handler if fvalidate is not None: fvalidate = handler.validate if (fvalidate is not None) or (trait is not None): if 'editor' not in metadata: if (trait is not None) and (trait.editor is not None): metadata[ 'editor' ] = trait.editor return ForwardProperty( metadata, fvalidate, handler ) if fget is None: metadata[ 'transient' ] = True if fset is None: fget = _undefined_get fset = _undefined_set else: fget = _write_only elif fset is None: fset = _read_only metadata[ 'transient' ] = True if trait is not None: trait = trait_cast( trait ) handler = trait.handler if (fvalidate is None) and (handler is not None): fvalidate = handler.validate if ('editor' not in metadata) and (trait.editor is not None): metadata[ 'editor' ] = trait.editor metadata.setdefault( 'depends_on', getattr( fget, 'depends_on', None ) ) if ((metadata.get( 'depends_on' ) is not None) and getattr( fget, 'cached_property', False )): metadata.setdefault( 'cached', True ) n = 0 trait = CTrait( 4 ) trait.__dict__ = metadata.copy() if fvalidate is not None: n = _arg_count( fvalidate ) trait.property( fget, _arg_count( fget ), fset, _arg_count( fset ), fvalidate, n ) trait.handler = handler return trait Property = TraitFactory( Property ) class ForwardProperty ( object ): """ Used to implement Property traits where accessor functions are defined implicitly on the class. """ def __init__ ( self, metadata, validate = None, handler = None ): self.metadata = metadata.copy() self.validate = validate self.handler = handler #------------------------------------------------------------------------------- # Dictionary used to handle return type mapping special cases: #------------------------------------------------------------------------------- SpecialNames = { ### 'int': trait_factory( Int ), ### 'long': trait_factory( Long ), ### 'float': trait_factory( Float ), ### 'complex': trait_factory( Complex ), ### 'str': trait_factory( Str ), ### 'unicode': trait_factory( Unicode ), ### 'bool': trait_factory( Bool ), ### 'list': trait_factory( List ), ### 'tuple': trait_factory( Tuple ), ### 'dict': trait_factory( Dict ) } #-- Date Trait definition ---------------------------------------------------- #Date = Instance(datetime.date, metadata = { 'editor': date_editor }) #-- Time Trait definition ---------------------------------------------------- #Time = Instance(datetime.time, metadata = { 'editor': time_editor }) #------------------------------------------------------------------------------- # Create predefined, reusable trait instances: #------------------------------------------------------------------------------- # Generic trait with 'object' behavior: generic_trait = CTrait( 8 ) #------------------------------------------------------------------------------- # User interface related color and font traits: #------------------------------------------------------------------------------- def Color ( *args, **metadata ): """ Returns a trait whose value must be a GUI toolkit-specific color. Description ----------- For wxPython, the returned trait accepts any of the following values: * A wx.Colour instance * A wx.ColourPtr instance * an integer whose hexadecimal form is 0x*RRGGBB*, where *RR* is the red value, *GG* is the green value, and *BB* is the blue value Default Value ------------- For wxPython, 0x000000 (that is, white) """ from traitsui.toolkit_traits import ColorTrait return ColorTrait( *args, **metadata ) Color = TraitFactory( Color ) def RGBColor ( *args, **metadata ): """ Returns a trait whose value must be a GUI toolkit-specific RGB-based color. Description ----------- For wxPython, the returned trait accepts any of the following values: * A tuple of the form (*r*, *g*, *b*), in which *r*, *g*, and *b* represent red, green, and blue values, respectively, and are floats in the range from 0.0 to 1.0 * An integer whose hexadecimal form is 0x*RRGGBB*, where *RR* is the red value, *GG* is the green value, and *BB* is the blue value Default Value ------------- For wxPython, (0.0, 0.0, 0.0) (that is, white) """ from traitsui.toolkit_traits import RGBColorTrait return RGBColorTrait( *args, **metadata ) RGBColor = TraitFactory( RGBColor ) def Font ( *args, **metadata ): """ Returns a trait whose value must be a GUI toolkit-specific font. Description ----------- For wxPython, the returned trait accepts any of the following: * a wx.Font instance * a wx.FontPtr instance * a string describing the font, including one or more of the font family, size, weight, style, and typeface name. Default Value ------------- For wxPython, 'Arial 10' """ from traitsui.toolkit_traits import FontTrait return FontTrait( *args, **metadata ) Font = TraitFactory( Font )