rearg()

Creates a function that invokes `func` with arguments rearranged according to the specified indexes. The argument value at the first index is provided as the first argument, the argument value at the second index is provided as the second argument, and so on. Arguments not specified in `indexes` maintain their original order after the rearranged arguments.

Implementation

Args: func: Function to rearrange arguments for. *indexes: The specified argument indexes. Returns: A new function with rearranged arguments for `func`.

Example

                            def example(a, b, c):
    return a, b, c
rearranged = rearg(example, 2, 0, 1)
rearranged(1, 2, 3)
                        

Expected output: (3, 1, 2)

Source Code

                        def rearg(func: Callable[..., R], *indexes: int) -> Callable[..., R]:

    # Normalize a single list/tuple argument

    if len(indexes) == 1 and isinstance(indexes[0], (list, tuple)):
        idxs = tuple(indexes[0])
    else:
        idxs = indexes

    def wrapper(*args: Any, **kwargs: Any) -> R:
        # Pick valid indices in the order given
        valid = [i for i in idxs if isinstance(i, int) and 0 <= i < len(args)]
        # Reordered portion
        reordered = [args[i] for i in valid]
        # Append the args not yet used
        remaining = [args[i] for i in range(len(args)) if i not in valid]
        return func(*reordered, *remaining, **kwargs)

    # Copy metadata for introspection
    wrapper.__name__    = func.__name__
    wrapper.__doc__     = func.__doc__
    wrapper.__wrapped__ = func # type: ignore

    return wrapper
                    