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"""
Legacy API wrapper.
>>> from legacy_api_wrap import legacy_api
>>> @legacy_api('d', 'c')
... def fn(a, b=None, *, c=2, d=1, e=3):
... return c, d, e
>>> fn(12, 13, 14) == (2, 14, 3)
True
"""
from functools import wraps
from inspect import signature, Parameter
from warnings import warn
from typing import Sequence
from get_version import get_version
__version__ = get_version(__file__)
INF = float("inf")
POS_TYPES = {Parameter.POSITIONAL_ONLY, Parameter.POSITIONAL_OR_KEYWORD}
def legacy_api(*old_positionals: Sequence[str]):
"""
Legacy API wrapper.
You want to change the API of a function:
>>> def fn(a, b=None, d=1, c=2, e=3):
... return c, d, e
Add a the decorator and modify the parameters after the ``*``:
>>> @legacy_api('d', 'c')
... def fn(a, b=None, *, c=2, d=1, e=3):
... return c, d, e
And the function can be called using one of both signatures.
>>> fn(12, 13, 14) == (2, 14, 3)
True
Parameters
----------
old_positionals
The positional parameter names that the old function had after the new function’s ``*``.
"""
def wrapper(fn):
sig = signature(fn)
par_types = [p.kind for p in sig.parameters.values()]
has_var = Parameter.VAR_POSITIONAL in par_types
n_required = sum(1 for p in sig.parameters.values() if p.default is Parameter.empty)
n_positional = INF if has_var else sum(1 for p in par_types if p in POS_TYPES)
@wraps(fn)
def fn_compatible(*args, **kw):
if len(args) > n_positional:
args, args_rest = args[:n_positional], args[n_positional:]
if args_rest:
if len(args_rest) > len(old_positionals):
n_max = n_positional + len(old_positionals)
raise TypeError(
f"{fn.__name__}() takes from {n_required} to {n_max} parameters, "
f"but {len(args)+len(args_rest)} were given."
)
warn(
f"The specified parameters {old_positionals[:len(args_rest)]!r} are no longer positional. "
f"Please specify them like `{old_positionals[0]}={args_rest[0]!r}`",
DeprecationWarning,
stacklevel=2,
)
kw = {**kw, **dict(zip(old_positionals, args_rest))}
return fn(*args, **kw)
return fn_compatible
return wrapper
|
