delegatefn 0.2.0

Signature-preserving function delegation

A tiny utility for preserving signature information (parameter names, annotations, and docstrings) when delegating one function to another.

Works for keyword arguments only; positional arguments are not supported.

Installation

pip install delegatefn

Usage

from delegatefn import delegate
import inspect

def foo(a, b, c):
    """This is the docstring for foo."""

@delegate(foo)
def bar(**kwargs):
    """This is the docstring for bar."""

assert foo.__doc__ == bar.__doc__ == "This is the docstring for foo."
assert inspect.signature(bar).parameters.keys() == {"a", "b", "c"}

Limitations

Unfortunately, there isn't an easy way to combine docstrings from multiple functions. Instead, delegate lets you decide which function's docstring to use.

from delegatefn import delegate

def foo(a, b, c):
    """This is the docstring for foo."""

@delegate(foo, delegate_docstring=False)
def bar(**kwargs):
    """This is the docstring for bar."""

assert foo.__doc__ != bar.__doc__ == "This is the docstring for bar."

Acknowledgements

This approach was inspired by fast.ai.