funchacks

👋 Introduction

Funchacks is a fun module that provides a small package of utilities.

Dynamic signature change without compile, eval and exec? That was the main idea of the project! But this path is a little dangerous, so the part could not be implemented, but if possible it will be implemented in the next versions!

⚙️ Installation

pip install funchacks

🚀 Quick start

• 🔎 Function locals

from funchacks import inspections


def foo() -> None:
    some_local_var = 1
    other_var = 2

>>> dict(inspections.getlocals(foo.__code__))
{"some_local_var": 1, "other_var": 2}

• 🔗 Dynamic function signature

(!) Note: if you add positional only or positional arguments, then there must be *args in the function signature. Accordingly, if you add keyword only or keyword arguments - **kwargs.

import inspect
from typing import Any

from funchacks import sig

@sig.change_args(
    sig.posonly("first"),
    sig.arg("second"),
)
def foo(*args: Any) -> None:
    """
    !!! Note:
        Temporarily positional only arguments are available only for
        the signature, there may be errors when calling the function.
    """

>>> inspect.Signature.from_callable(foo)
(first, /, second, *args)

@sig.change_args(
    sig.kwarg("first", None),
    sig.kwonly("second"),
)
def bar(**kwargs: Any) -> None:
    """
    !!! Note:
        Temporarily keyword only arguments are available only for
        the signature, there may be errors when calling the function.
    """

>>> inspect.Signature.from_callable(bar)
(first=None, *, second, **kwargs)

@sig.change_args(
    sig.arg("first"),
    sig.kwarg("second", None)
)
def baz(*args: Any, **kwargs: Any) -> None:
    """This should work.

    But how to access the arguments? locals?...
    """
    # All wrapped function has __sig__ attribute
    # that contains function signature.
    lvars = sig.Bind.from_locals(locals(), in_=baz)

    assert lvars.args() == ["first"]
    assert lvars.kwargs() == ["second"]

    return lvars.get("first") + lvars.get("second")

>>> inspect.Signature.from_callable(baz)
(first, second=None, *args, **kwargs)

>>> baz(1, 2)
3

Signature from function.

def spam(a, /, b, c=None, *, d) -> None:
    pass


@sig.from_function(spam)
def eggs(*args: Any, **kwargs: Any) -> None:
    pass

>>> inspect.Signature.from_callable(eggs)
(a, /, b, c=None, *, d)

Making small wrap.

from types import CodeType

from funchacks import make_wrap, WrapFunction


def foo() -> None:
    some_local = 1
    other_local = 2

wrap = make_wrap(foo)
wrap_from_func = WrapFunction.from_function(foo)

>>> dict(wrap.flocals)
{'some_local': 1, 'other_local': 2}
>>> isinstance(wrap, WrapFunction)
True
>>> dict(wrap.flocals) == dict(wrap_from_func.flocals)
True
>>> isinstance(wrap.code, CodeType)
True