pydispatch.robustapply — GRASS Python Library documentation

# Source code for pydispatch.robustapply

    """Robust apply mechanism

    Provides a function "call", which can sort out
    what arguments a given callable object can take,
    and subset the given arguments to match only
    those which are acceptable.
    """

    import sys

    if sys.hexversion >= 0x3000000:
        im_func = "__func__"
        im_self = "__self__"
        im_code = "__code__"
        func_code = "__code__"
    else:
        im_func = "im_func"
        im_self = "im_self"
        im_code = "im_code"
        func_code = "func_code"

    def function(receiver):
        """Get function-like callable object for given receiver

        returns (function_or_method, codeObject, fromMethod)

        If fromMethod is true, then the callable already
        has its first argument bound
        """
        if hasattr(receiver, "__call__"):
            # Reassign receiver to the actual method that will be called.
            if hasattr(receiver.__call__, im_func) or hasattr(receiver.__call__, im_code):
                receiver = receiver.__call__
        if hasattr(receiver, im_func):
            # an instance-method...
            return receiver, getattr(getattr(receiver, im_func), func_code), 1
        elif not hasattr(receiver, func_code):
            raise ValueError("unknown receiver type %s %s" % (receiver, type(receiver)))
        return receiver, getattr(receiver, func_code), 0

    def robustApply(receiver, *arguments, **named):
        """Call receiver with arguments and an appropriate subset of named"""
        receiver, codeObject, startIndex = function(receiver)
        acceptable = codeObject.co_varnames[
            startIndex + len(arguments) : codeObject.co_argcount
        ]
        for name in codeObject.co_varnames[startIndex : startIndex + len(arguments)]:
            if name in named:
                raise TypeError(
                    """Argument %r specified both positionally and as a keyword"""
                    """ for calling %r""" % (name, receiver)
                )
        if not (codeObject.co_flags & 8):
            # fc does not have a **kwds type parameter, therefore
            # remove unacceptable arguments.
            for arg in list(named):
                if arg not in acceptable:
                    del named[arg]
        return receiver(*arguments, **named)

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