On 4/12/2019 11:29 AM, Rhodri James wrote:
On 12/04/2019 16:10, Viktor Roytman wrote:
Currently, unpacking a dict in order to pass its items as keyword arguments to a function will fail if there are keys present in the dict that are invalid keyword arguments:
>>> def func(*, a): ... pass ... >>> func(**{'a': 1, 'b': 2}) Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: func() got an unexpected keyword argument 'b'
The standard approach I have encountered in this scenario is to pass in the keyword arguments explicitly like so
func( a=kwargs_dict["a"], b=kwargs_dict["b"], c=kwargs_dict["c"], )
But this grows more cumbersome as the number of keyword arguments grows.
There are a number of other workarounds, such as using a dict comprehension to select only the required keys, but I think it would be more convenient to have this be a feature of the language. I don't know what a nice syntax for this would be, or even how feasible it is.
What circumstance do you want to do this in that simply passing the dictionary as itself won't do for?
I don't want to speak for the OP, but I have a similar use case (which is why I wrote calllib). My use case is: I have number of callables that I don't control. I also have a dict of parameters that the callables might take as parameters. I want to call one of the callables, passing only the subset of parameters that that particular callable takes. Eric