Source code for wabisabi.kwonly_change

"""
As this library is still in early development, the API might change.
I suggest you vendor this so that you don't create conflicts if other
libraries decide to use an older, incompatible version

If you are shipping python source code, then I've included the license
at the bottom of this file to make your life easier.
"""

from packaging.version import Version
from functools import wraps
import inspect
from warnings import warn
from .merge_docstrings import merge_docstrings

POSITIONAL_OR_KEYWORD = inspect.Parameter.POSITIONAL_OR_KEYWORD


# Keep the order of params as is,
# `previous_arg_order` and `keep_old_signature`
# should be optional positional args.
[docs]def kwonly_change(version, previous_arg_order=None, keep_old_signature=False, library_name=None, current_library_version=None): """Returns a decorator that enforces a smaller number of positional arguments. If the current library version is smaller than version in which the new signature takes effect, this deprecator will: Issue a warnign pointing to the user's code if they call a function with too many positional arguments. If you want to move the new keyword only arguments after the keyword only seperator, you should specify a list with the previous order of arguments as the parameter ``previous_arg_order``. If this parameter is not specified, it is assumed that the previous function signature allowed all parameters to be specified as either positional or keyword arguments. Parameters ---------- version: version-like Version in which the new function signature takes full effect. previous_arg_order: list of strings or ``None`` If the function previously had keyword only arguments, you should use this to specify the names of previous positional arguments. If set to none, it is assumed that the previous version of the function would accept all parameters as positional or keyword arguments. Specifying this also allows you to re-order the new keyword only. To re-iterate, you cannot swap the order of positional arguments with this deprecator. keep_old_signature: bool If set to true, the signature will reflect the previous signature of the function. This is not recommended since showing new users the keyword-only version of the signature will not cause them to write wrong code. If they follow the new signature, their code will be correct and they will avoid the ``FutureWarning``. library_name: str Friendly library name to include in warning messages current_library_version: version-like The current version of the shipped library (typically your module's ``__version__``). Examples -------- >>> from wabisabi import kwonly_change >>> import functools >>> >>> kwonly_change = functools.partial(kwonly_change, ... library_name='my super lib', ... current_library_version='0.14') >>> @kwonly_change('0.15') ... def foo_new(zap='zip', *, bar='hello', baz='world'): ... return zap + bar + baz """ if current_library_version is None: raise ValueError('Must provide a version for your library.') if library_name is None: raise ValueError('You must provide a user friendly name for your ' 'library.') def the_decorator(func): if Version(current_library_version) >= Version(version): return func new_signature = inspect.signature(func) new_arg_names = [name for name in new_signature.parameters] if previous_arg_order is None: old_nargs = len(new_signature.parameters) old_arg_names = new_arg_names[:old_nargs] else: old_nargs = len(previous_arg_order) old_arg_names = previous_arg_order # These arguments are still required as argument only keywords func_args = inspect.getfullargspec(func).args new_nargs = len(func_args) old_parameters = [] all_params = {**new_signature.parameters} for key in old_arg_names: param = all_params.pop(key) if key in func_args: kind = param.kind else: kind = POSITIONAL_OR_KEYWORD old_parameters.append( inspect.Parameter(key, kind=kind, default=param.default, annotation=param.annotation)) for key, param in all_params.items(): old_parameters.append( inspect.Parameter(key, kind=param.kind, default=param.default, annotation=param.annotation)) old_signature = new_signature.replace(parameters=old_parameters) @wraps(func) def wrapper(*args, **kwargs): if len(args) > old_nargs: # The warning should be issued here too! raise TypeError('{name}() takes {old_nargs} positional ' 'arguments but {len_args} were given' ''.format(name=func.__name__, old_nargs=old_nargs, len_args=len(args))) if len(args) > new_nargs: for key, value in zip(old_arg_names[new_nargs:len(args)], args[new_nargs:]): if key in kwargs: calling_function = inspect.stack()[1] s = SyntaxError( "In version {version} of {library_name}, the " "argument ('{key}') has " "will become a keyword only argument. You " "specified it as both a positional argument and " "a keyword argument." "".format(version=version, library_name=library_name, key=key)) s.lineno = calling_function.lineno s.filename = calling_function.filename # Even the normal syntax errors suck at telling you # the position of your error whe a statement spans # multiple lines # s.offset = # is it worth it to find where? raise s kwargs[key] = value warn("In version {version} of {library_name}, the " "argument(s): '{old_pos_args}' will become keyword-only " "argument(s). To suppress this warning, specify all " "listed argument(s) with keywords." "".format( version=version, library_name=library_name, old_pos_args=old_arg_names[new_nargs:len(args)]), FutureWarning, stacklevel=2) args = args[:new_nargs] return func(*args, **kwargs) if keep_old_signature: wrapper.__signature__ = old_signature # only add a docstring if they had one already if wrapper.__doc__ is None: return wrapper args = ', '.join(old_arg_names[new_nargs:]) warnings_string = f""" Warns ----- FutureWarning In release {version} of {library_name}, the argument(s): `{args}` will become keyword-only arguments. To avoid this warning, provide all the above arguments as keyword arguments. """ wrapper.__doc__ = merge_docstrings(wrapper, warnings_string) return wrapper return the_decorator
""" BSD 3-Clause License Copyright (c) 2018, Mark Harfouche All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: * Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. * Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. * Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. """