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bundles / traitlets 5.16.2 / traitlets / traitlets / Union / __init__

function

traitlets.traitlets:Union.__init__

source: /traitlets/traitlets.py:2428

Signature

def __init__(self, trait_types: t.Any, **kwargs: t.Any) → None

Summary

Construct a Union trait.

Extended Summary

This trait allows values that are allowed by at least one of the specified trait types. A Union traitlet cannot have metadata on its own, besides the metadata of the listed types.

Parameters

trait_types : sequence

The list of trait types of length at least 1.

**kwargs

Extra kwargs passed to TraitType

Notes

Union([Float(), Bool(), Int()]) attempts to validate the provided values with the validation function of Float, then Bool, and finally Int.

Parsing from string is ambiguous for container types which accept other collection-like literals (e.g. List accepting both [] and () precludes Union from ever parsing Union([List(), Tuple()]) as a tuple; you can modify behaviour of too permissive container traits by overriding _literal_from_string_pairs in subclasses. Similarly, parsing unions of numeric types is only unambiguous if types are provided in order of increasing permissiveness, e.g. Union([Int(), Float()]) (since floats accept integer-looking values).

Aliases

  • traitlets.Union.__init__