`traitlets.traitlets:default`

source: /traitlets/traitlets.py :1200

Signature

def default ( name : str ) → DefaultHandler

Summary

A decorator which assigns a dynamic default for a Trait on a HasTraits object.

Parameters

name: The str name of the Trait on the object whose default should be generated.

Notes

Unlike observers and validators which are properties of the HasTraits instance, default value generators are class-level properties.

Besides, default generators are only invoked if they are registered in subclasses of this_type.

class A(HasTraits):
    bar = Int()

    @default('bar')
    def get_bar_default(self):
        return 11

class B(A):
    bar = Float()  # This trait ignores the default generator defined in
                   # the base class A

class C(B):

    @default('bar')
    def some_other_default(self):  # This default generator should not be
        return 3.0                 # ignored since it is defined in a
                                   # class derived from B.a.this_class.

Aliases

traitlets.default