[Python-Dev] PEP 3102: Keyword-only arguments (original) (raw)

Edward Loper edloper at gradient.cis.upenn.edu
Mon May 1 15:39:00 CEST 2006

Fred L. Drake, Jr. wrote:

On Sunday 30 April 2006 22:50, Edward Loper wrote: > I see two possible reasons:

Another use case, observed in the wild: - An library function is written to take an arbitrary number of positional arguments using *args syntax. The library is released, presumably creating dependencies on the specific signature of the function. In a subsequent version of the function, the function is determined to need additional information. The only way to add an argument is to use a keyword for which there is no positional equivalent.

This falls under the "first subproposal" from Terry's email:

There are two subproposals: first, keyword-only args after a variable number of positional args, which requires allowing keyword parameter specifications after the *args parameter, and second, keyword-only args after a fixed number number of positional args, implemented with a naked '*'. To the first, I said "The rationale for this is pretty obvious.". To the second, I asked, and still ask, "Why?".

I was trying to come up with use cases for the "second subproposal."

-Edward

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