Class DeferredConfigList

traitlets/config/loader.py:423–462

Config value for loading config from a list of strings Interpretation is deferred until it is loaded into the trait. This class is only used for values that are not listed in the configurable classes. When config is loaded, `trait.from_string_list` will be used. If an error i

class DeferredConfigList(t.List[t.Any], DeferredConfig):
    """Config value for loading config from a list of strings

    Interpretation is deferred until it is loaded into the trait.

    This class is only used for values that are not listed
    in the configurable classes.

    When config is loaded, `trait.from_string_list` will be used.

    If an error is raised in `.from_string_list`,
    the original string list is returned.

    .. versionadded:: 5.0
    """

    def get_value(self, trait: TraitType[t.Any, t.Any]) -> t.Any:
        """Get the value stored in this string"""
        if hasattr(trait, "from_string_list"):
            src = list(self)
            cast = trait.from_string_list
        else:
            # only allow one item
            if len(self) > 1:
                raise ValueError(
                    f"{trait.name} only accepts one value, got {len(self)}: {list(self)}"
                )
            src = self[0]
            cast = trait.from_string

        try:
            return cast(src)
        except Exception:
            # exception casting from string,
            # let the original value lie.
            # this will raise a more informative error when config is loaded.
            return src

    def __repr__(self) -> str:
        return f"{self.__class__.__name__}({self._super_repr()})"


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