# http://www-01.ibm.com/support/knowledgecenter/SSLVMB_21.0.0/com.ibm.spss.statistics.help/idh_pref_general.htm

import inspect
import functools
import warnings

warnings.simplefilter("always")

class check_deprecated_args(object):

    """
    Class decorator that checks whether deprecated parameters with non-default
    arguments are used


    Parameters
    ----------
    deprecated_params : tuple
        tuple of strings of parameters that should raise a DeprecationWarning,
        if they are used with non-default arguments
    methods : tuple, optional
        tuple of strings of method names that include deprecated parameters

    Raises
    ------
    DeprecationWarning : if deprecated parameters are used with
        non-default arguments in the class's constructor.
    """

    def __init__(self, deprecated_params, methods=("__init__",)):
        self.deprecated_params = deprecated_params
        self.methods = methods

    def _used_deprecated(self, used_param, used_arg, default_arg):
        is_deprecated = used_param in self.deprecated_params
        if default_arg != used_arg and is_deprecated:
            return {used_param: used_arg}
        return {}

    def _check_method(self, method, *used_args, **used_kwargs):
        argspec = inspect.getargspec(method)
        default_params = argspec.args[1:]
        default_args = argspec.defaults
        res = {}

        # -- positional args
        for used_param_pos, used_arg in enumerate(used_args):
            used_param = default_params[used_param_pos]
            default_arg = default_args[used_param_pos]
            res.update(self._used_deprecated(used_param, used_arg, default_arg))

        # -- keyword args
        for pos, (used_param, used_arg) in enumerate(used_kwargs.items()):
            default_arg = default_args[pos]
            is_deprecated = used_param in self.deprecated_params
            res.update(self._used_deprecated(used_param, used_arg, default_arg))

        if res:
            deprec = self.deprecated_params
            old = ["%s:%%(%s)s" % (p, p) for p in deprec if p in res]
            old =  ", ".join(old) % res
            msg = "you're using obsolete args [%s]" % old
            warnings.warn(msg, DeprecationWarning)

    def __call__(self, cls):
        @functools.wraps(cls)
        def inner(*used_args, **used_kwargs):
            for method in self.methods:
                method = getattr(cls, method)
                self._check_method(method, *used_args, **used_kwargs)
                return getattr(cls, "self")
        return inner

if __name__ == "__main__":
    @check_deprecated_args(deprecated_params=("old", "older"))
    class Foo(object):
        def __init__(self, old=True, older=None, new="yaay"):
            pass
        def bar(self, old, new):
            return old, new

    f = Foo(new="great", old="obsolete", older="stop using it")
    #print repr(f)
    #f.bar(old="ancient", new="novel")