[Python-ideas] Syntax for allowing extra keys when unpacking a dict as keyword arguments

Eric V. Smith eric at trueblade.com
Fri Apr 12 16:19:28 EDT 2019

On 4/12/2019 4:00 PM, Anders Hovmöller wrote:
>> On 12 Apr 2019, at 19:16, Eric V. Smith <eric at trueblade.com> wrote:
>> 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.
> Could you expand on "that I don't control"? Where do these come from?

Their names come from a config file. I dynamically load them and call 
them. I wrote some of them, other people wrote others. It's an internal 
corporate app, and there are a lot of callables, all with different 
release schedules and controlled by different teams. Over time, the 
interface to these callables has expanded. First, it took just x, then a 
few of them needed x and y, and others needed x and z.

I realize this isn't the greatest interface, and in an ideal world we 
would have come up with a better way to specify this. But it evolved 
over time, and it is what it is.

> We have similar used cases in libs we've created but there we define that the API is that you must do **_ to be compatible with future versions of the lib.

Unfortunately I don't control the interface or the source to the code 
I'm calling, so the best I've been able to do is only call each function 
with the parameters I know it expects, based on its signature. At least 
the parameter names are well defined.


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