@@ -365,6 +365,8 @@ positional and may use other names.
365365* ``alias `` is an optional str parameter that provides an alternative
366366 name for the field. This alternative name is used in the synthesized
367367 ``__init__ `` method.
368+ * ``converter `` is an optional parameter that specifies a
369+ callable used to convert values when assigning to the field.
368370
369371It is an error to specify more than one of ``default ``,
370372``default_factory `` and ``factory ``.
@@ -526,6 +528,52 @@ This includes, but is not limited to, the following semantics:
526528 dataclass must be explicitly annotated as e.g. ``x: ClassVar[Final[int]] =
527529 3 ``.
528530
531+ Converters
532+ ^^^^^^^^^^
533+
534+ The ``converter `` parameter can be specified in a field definition to provide a callable
535+ used to convert values when assigning to the associated attribute. This feature allows for automatic type
536+ conversion and validation during attribute assignment.
537+
538+ Converter behavior:
539+
540+ * The converter is used for all attribute assignment, including assignment
541+ of default values, assignment in synthesized ``__init__ `` methods
542+ and direct attribute setting (e.g., ``obj.attr = value ``).
543+ * The converter is not used when reading attributes, as the attributes should already have been converted.
544+
545+ Typing rules for converters:
546+
547+ * The ``converter `` must be a callable that must accept a single positional argument
548+ (but may accept other optional arguments, which are ignored for typing purposes).
549+ * The type of the first positional parameter provides the type of the synthesized ``__init__ `` parameter
550+ for the field.
551+ * The return type of the callable must be assignable to the field's declared type.
552+ * If ``default `` or ``default_factory `` are provided, the type of the default value should be
553+ assignable to the first positional parameter of the ``converter ``.
554+
555+ Example usage:
556+
557+ .. code-block :: python
558+
559+ def str_or_none (x : Any) -> str | None :
560+ return str (x) if x is not None else None
561+
562+ @custom_dataclass
563+ class Example :
564+ int_field: int = custom_field(converter = int )
565+ str_field: str | None = custom_field(converter = str_or_none)
566+ path_field: pathlib.Path = custom_field(
567+ converter = pathlib.Path,
568+ default = " default/path.txt"
569+ )
570+
571+ # Usage
572+ example = Example(" 123" None , " some/path"
573+ # example.int_field == 123
574+ # example.str_field == None
575+ # example.path_field == pathlib.Path("some/path")
576+
529577
530578
531579^^^^^^^^^^^^^^^^^^
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