Decorator to create well-behaving decorators :)

kwars_decorator.py

def decorator_with_kwargs(decorator):
    """
        There are many techniques to produce decorators that can be used with 
        arguments and without them. Accepting only keyword arguments is the simples, IMHO.
        
        >>> def execution_decorator(view, opts):
        ...     return view(**opts)         
        ...
        >>> def format_kwargs(**kwargs):
        ...     return "ARGS: %r" % kwargs
        ...            
        >>> decorator_with_kwargs(execution_decorator)(format_kwargs)
        "ARGS: {}"
        
        >>> decorator_with_kwargs(execution_decorator)()(format_kwargs)
        "ARGS: {}"
        
        >>> decorator_with_kwargs(execution_decorator)(a=True, b='')(format_kwargs)
        "ARGS: {'a': True, 'b': ''}"
        
    """
    @functools.wraps(decorator)
    def kwargs_decorator(*args, **kwargs):
        if len(args) > 1:
            raise ValueError("This decorator accepts only keyword arguments.")
        if len(args) == 1:  # No arguments            
            if not isinstance(args[0], collections.Callable):
                raise ValueError("This decorator accepts only keyword arguments.")
            return decorator(args[0], {})
        return functools.wraps(decorator)(lambda v: decorator(v, kwargs))
    return kwargs_decorator