Utils

A simple utility to import something by its string name.

traitlets.import_item(name: str) → Any

Import and return bar given the string foo.bar.

Calling bar = import_item("foo.bar") is the functional equivalent of executing the code from foo import bar.

Parameters:

name (string) – The fully qualified name of the module/package being imported.

Returns:

mod – The module that was imported.

Return type:

module object

traitlets.signature_has_traits(cls: Type[T]) → Type[T]

Return a decorated class with a constructor signature that contain Trait names as kwargs.

This is a way to expand the signature of the HasTraits class constructor. This enables auto-completion of trait-names in IPython and xeus-python when having Jedi>=0.15 by adding trait names with their default values in the constructor signature.

Example:

from inspect import signature

from traitlets import HasTraits, Int, Unicode, signature_has_traits

@signature_has_traits
class Foo(HasTraits):
    number1 = Int()
    number2 = Int()
    value = Unicode('Hello')

    def __init__(self, arg1, **kwargs):
        self.arg1 = arg1

        super(Foo, self).__init__(**kwargs)

print(signature(Foo))  # <Signature (arg1, *, number1=0, number2=0, value='Hello', **kwargs)>

Links

class traitlets.link(source: Any, target: Any, transform: Any = None)

Link traits from different objects together so they remain in sync.

Parameters:

• source ((object / attribute name) pair)

• target ((object / attribute name) pair)

• transform (iterable with two callables (optional)) – Data transformation between source and target and target and source.

Examples

>>> class X(HasTraits):
...     value = Int()

>>> src = X(value=1)
>>> tgt = X(value=42)
>>> c = link((src, "value"), (tgt, "value"))

Setting source updates target objects: >>> src.value = 5 >>> tgt.value 5

class traitlets.directional_link(source: Any, target: Any, transform: Any = None)

Link the trait of a source object with traits of target objects.

Parameters:

• source ((object, attribute name) pair)

• target ((object, attribute name) pair)

• transform (callable (optional)) – Data transformation between source and target.

Examples

>>> class X(HasTraits):
...     value = Int()

>>> src = X(value=1)
>>> tgt = X(value=42)
>>> c = directional_link((src, "value"), (tgt, "value"))

Setting source updates target objects: >>> src.value = 5 >>> tgt.value 5

Setting target does not update source object: >>> tgt.value = 6 >>> src.value 5