overloading.py

Function overloading for Python 3

overloading is a module that provides function and method dispatching based on the types and number of runtime arguments.

When an overloaded function is invoked, the dispatcher compares the supplied arguments to available signatures and calls the implementation providing the most accurate match:

@overload
def biggest(items: Iterable[int]):
    return max(items)

@overload
def biggest(items: Iterable[str]):
    return max(items, key=len)

>>> biggest([2, 0, 15, 8, 7])
15
>>> biggest(['a', 'abc', 'bc'])
'abc'

Features

• Function validation during registration and comprehensive resolution rules guarantee a well-defined outcome at invocation time.
• Supports the typing module introduced in Python 3.5.
• Supports optional parameters.
• Supports variadic signatures (*args and **kwargs).
• Supports class-/staticmethods.
• Evaluates both positional and keyword arguments.
• No dependencies beyond the standard library

Documentation

The full documentation is available at https://overloading.readthedocs.org/.

Installation

pip3 install overloading

To use extended type hints on Python versions prior to 3.5, install the typing module from PyPI:

pip3 install typing

Compatibility

The library is primarily targeted at Python versions 3.3 and above, but Python 3.2 is still supported for PyPy compatibility.

The Travis CI test suite covers CPython 3.3/3.4/3.5 and PyPy3.