Simple callable argument inspection & filtering
Project description
argset provides a simple interface for determining whether a callable takes an argument with a given name, filtering a dict of potential arguments down to just those that a callable accepts, and determining any required arguments that are missing from a dict of potential arguments.
Installation
argset requires Python 3.6 or higher. Just use pip for Python 3 (You have pip, right?) to install argset and its dependencies:
python3 -m pip install argset
Examples
Inspecting a function’s arguments:
>>> from argset import argset >>> def my_func(foo, bar): ... print(f"foo={foo!r}") ... print(f"bar={bar!r}") ... >>> a = argset(my_func) >>> "foo" in a True >>> "quux" in a False
Filtering a set of arguments to just those accepted by the function:
>>> a.select({"foo": 42, "bar": 23, "quux": 17}) {'foo': 42, 'bar': 23} >>> my_func(**a.select({"foo": 42, "bar": 23, "quux": 17})) foo=42 bar=23
Same as above, but now the function takes **kwargs:
>>> from argset import argset >>> def my_func2(foo, **kwargs): ... print(f"foo={foo!r}") ... for k, v in kwargs.items(): ... print(f"{k}={v!r}") ... >>> a2 = argset(my_func2) >>> "foo" in a2 True >>> "quux" in a2 True >>> a2.select({"foo": 42, "bar": 23, "quux": 17}) {'foo': 42, 'bar': 23, 'quux': 17} >>> my_func2(**a2.select({"foo": 42, "bar": 23, "quux": 17})) foo=42 bar=23 quux=17
API
argset(func: Callable) -> ArgSet
Inspects a callable and returns a summary of its arguments as an ArgSet
class ArgSet
A representation of the arguments taken by a callable. It has the following attributes & properties:
- required_positional_only: int
The number of arguments that are positional-only and do not have default values
- optional_positional_only: int
The number of arguments that are positional-only and have a default value
- positional_only: int
The total number of positional-only arguments
- required_args: frozenset[str]
The names of all positional-or-keyword or keyword-only arguments that do not have default values
- optional_args: frozenset[str]
The names of all positional-or-keyword or keyword-only arguments that have default values
- argnames: frozenset[str]
The names of all positional-or-keyword or keyword-only arguments
- takes_args: bool
Whether the callable has an argument of the form *args
- takes_kwargs: bool
Whether the callable has an argument of the form **kwargs
ArgSet objects support the in operator; an expression of the form argname in a returns True iff argname is in a.argnames or a.takes_kwargs is True.
ArgSet objects have the following methods:
ArgSet.select(kwargs: Dict[str, Any]) -> Dict[str, Any]
Returns all items in kwargs where the key is the name of a positional-or-keyword or keyword-only argument accepted by the callable. If takes_kwargs is True, the return value is a copy of kwargs.
ArgSet.missing(kwargs: Dict[str, Any]) -> FrozenSet[str]
Returns all keys in required_args that do not appear in kwargs
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