delegatefn 0.4.2

Signature-preserving function delegation

delegatefn

A Python package for adding the parameters of a delegatee function to a delegator function, while keeping the original parameters of the delegator function.

Installation

To install delegatefn, use pip:

pip install delegatefn

Usage

To use the delegate decorator function, import it from delegatefn:

from delegatefn import delegate

Then, decorate your delegator function with the delegate decorator, passing in the delegatee function as an argument:

@delegate(delegatee)
def delegator(c: int, d: int, e: int, **kwargs):
    ...

The delegator function will now have the parameters of delegatee added to it, while keeping its original parameters.

You can also customize the behavior of the delegate decorator by passing in the following keyword arguments:

• kwonly: A boolean value indicating whether the parameters of delegatee should be converted to keyword-only arguments. The default value is True.

• delegate_docstring: A boolean value indicating whether the docstring of delegatee should be used as the docstring of the delegator function. The default value is True.

• ignore: An iterable of strings containing the names of the parameters of delegatee that should be ignored. The default value is an empty set.

Here is an example of how to use these keyword arguments:

@delegate(delegatee, kwonly=True, delegate_docstring=True, ignore={"a", "b"})
def delegator(c: int, d: int, e: int, **kwargs):
    ...

Example

Here is an example of how to use the delegate decorator:

from delegatefn import delegate

def delegatee(a: int, b: int, **kwargs):
    ...

@delegate(delegatee)
def delegator(c: int, d: int, e: int, **kwargs):
    ...

The delegator function will now have the parameters a: int, b: int, and kwargs added to it, in addition to its original parameters c: int, d: int, and e: int.

Acknowledgements

This approach was inspired by fast.ai.