Method from_kind

tables/atom.py:421–491

Create an Atom from a PyTables kind. Optional item size, shape and default value may be specified as the itemsize, shape and dflt arguments, respectively. Bear in mind that not all atoms support a default item size:: >>> Atom.from_kind('int', itemsize=2,

(
        cls,
        kind: str,
        itemsize: int | None = None,
        shape: Shape = (),
        dflt: Any = None,
    )

    @classmethod
    def from_kind(
        cls,
        kind: str,
        itemsize: int | None = None,
        shape: Shape = (),
        dflt: Any = None,
    ) -> Atom:
        """Create an Atom from a PyTables kind.

        Optional item size, shape and default value may be
        specified as the itemsize, shape and dflt
        arguments, respectively. Bear in mind that not all atoms support
        a default item size::

            >>> Atom.from_kind('int', itemsize=2, shape=(2, 2))
            Int16Atom(shape=(2, 2), dflt=0)
            >>> Atom.from_kind('int', shape=(2, 2))
            Int32Atom(shape=(2, 2), dflt=0)
            >>> Atom.from_kind('int', shape=1)
            Int32Atom(shape=(1,), dflt=0)
            >>> Atom.from_kind('string', dflt=b'hello')
            Traceback (most recent call last):
            ...
            ValueError: no default item size for kind ``string``
            >>> Atom.from_kind('Float')
            Traceback (most recent call last):
            ...
            ValueError: unknown kind: 'Float'

        Moreover, some kinds with atypical constructor signatures
        are not supported; you need to use the proper
        constructor::

            >>> Atom.from_kind('enum') #doctest: +ELLIPSIS
            Traceback (most recent call last):
            ...
            ValueError: the ``enum`` kind is not supported...

        """
        kwargs: dict[str, Any] = {"shape": shape}
        if kind not in atom_map:
            raise ValueError(f"unknown kind: {kind!r}")
        # This incompatibility detection may get out-of-date and is
        # too hard-wired, but I couldn't come up with something
        # smarter.  -- Ivan (2007-02-08)
        if kind in ["enum"]:
            raise ValueError(
                "the ``%s`` kind is not supported; "
                "please use the appropriate constructor" % kind
            )
        # If no `itemsize` is given, try to get the default type of the
        # kind (which has a fixed item size).
        if itemsize is None:
            if kind not in deftype_from_kind:
                raise ValueError("no default item size for kind ``%s``" % kind)
            type_ = deftype_from_kind[kind]
            kind, itemsize = split_type(type_)
        kdata = atom_map[kind]