Canonicalise args and kwargs to kwarg-canonical form

问题

I've asked a similar question here for posarg-canonical form.

Any possible args should be converted to keyword-form, with the defaults being omitted based on the result of the is operator, the id or similar.

For example:

def myfunc(a, b=None, **kwargs):
    pass

def canonicalize(func, *args, **kwargs):
    something = inspect.signature(func)
    # Do something with args/kwargs here
    return new_args, new_kwargs

Example output:

>>> canonicalize(myfunc, 1, 2, g=3)
(1,), {'b': 2, 'g': 3}
>>> canonicalize(myfunc, 1)
(1,), {}
>>> canonicalize(myfunc, 1, b=2)
(1,), {'b': 2}
>>> canonicalize(myfunc, 1, g=3, b=None)
(1,), {'g': 3}

回答1:

You can use the following function - you basically move arguments which have a default value into whatever was in **kwargs (if it's not actually assigned to its own default value):

import inspect

def canonicalize(f, *args, **kwargs):
    sig = inspect.signature(f)
    bargs = sig.bind(*args, **kwargs)
    # Pop out the named kwargs variable defaulting to {}
    ret_kwargs = bargs.arguments.pop(inspect.getfullargspec(f).varkw, {})
    # For all possible signature values
    for k, v in sig.parameters.items():
        # If the name exists in the bound arguments and has a default value
        if k in bargs.arguments and v.default is not inspect.Parameter.empty:
            # Remove from the bound arguments dict
            val = bargs.arguments.pop(k)
            # If the value isn't the same as the default value add it to ret_kwargs
            if val is not v.default:
                ret_kwargs[k] = val

    # bargs.args here will be made up of what's left in bargs.arguments
    return bargs.args, ret_kwargs

来源：https://stackoverflow.com/questions/55900925/canonicalise-args-and-kwargs-to-kwarg-canonical-form

标签

python

variadic-functions