traitsui.context_value module

Defines some helper classes and traits used to define ‘bindable’ editor values. These classes and associated traits are designed to simplify writing editors by allowing the editor factory to specify a context value instance for attributes and have the value on the editor be synchronized with the corresponsing value rom the context.

The factory should look something like this:

class MyEditorFactory(EditorFactory):

    #: The minimum value.
    minimum = CVInt

    #: The suffix for the data.
    suffix = CVType(Str)

The editor class needs to have traits which correspond to the context value traits, and should be able to react to changes to them:

class MyEditor(Editor):

    #: The minimum value.
    minimum = Int()

    #: The suffix for the data.
    suffix = Str()

This can then be used in views, with values either as constants or as instances of ContextValue (abbreviated as CV):

class MyObject(HasTraits):

    #: An important value.
    my_value = Str()

    #: The minimum value.
    my_minimum = Int(10)

    traits_view = View(
        Item(
            'my_value',
            editor=MyEditorFactory(
                minimum=CV('my_minimum'),
                suffix='...',
            ),
        )
    )

traitsui.context_value.CV

Define a shorthand name for a ContextValue:

traitsui.context_value.CVFloat = CVType(Float)

Float or Context value trait

traitsui.context_value.CVInt = CVType(Int)

Int or Context value trait

traitsui.context_value.CVStr = CVType(Str)

Str or Context value trait

traitsui.context_value.CVType(type, **metadata)

Factory that creates a union of a trait type and a ContextValue trait.

This also sets up one-way synchronization to the editor if no other synchronization is specified.

Parameters:

• type (trait type) – The trait type that is expected for constant values.

• **metadata – Additional metadata for the trait.

Returns:

cv_type_trait – A trait which can either hold a constant of the specified type or an instance of the ContextValue class.

Return type:

trait

class traitsui.context_value.ContextValue(name)

Bases: HasStrictTraits

Defines the name of a context value that can be bound to an editor

Resolution of the name follows the same rules as for context values in Item objects: if there is no dot in it then it is treated as an attribute of the ‘object’ context value, other wise the first part specifies the object in the context and the rest are dotted attribute look-ups.

name = Str()

The extended trait name of the value that can be bound to the editor (e.g. ‘selection’ or ‘handler.selection’):

traitsui.context_value.InstanceOfContextValue = Instance(ContextValue, allow_none=False)

Shorthand for an Instance of ContextValue trait.