On Mon, 2021-10-25 at 03:47 +1100, Chris Angelico wrote:
On Mon, Oct 25, 2021 at 3:43 AM Jonathan Fine <jfine2358@gmail.com> wrote:
Hi
Please forgive me if it's not already been considered. Is the following valid syntax, and if so what's the semantics? Here it is:
def puzzle(*, a=>b+1, b=>a+1): return a, b
Aside: In a functional programming language a = b + 1 b = a + 1 would be a syntax (or at least compile time) error.
I was about to ask about this. But also, how does that go together with non-required arguments? def function(arr=>np.asarray(arr)): pass Would seem like something we may be inclined to write instead of: def function(arr): arr = np.asarray(arr) (if that is legal syntax). In that case `arr` is a required parameter. Which then means that you cannot do it for optional parameters?: def function(arr1=>np.asarray(arr), arr2=>something): arr2 = np.asarray(arr2) # in case arr2 was passed in Which is fair, but feels like a slightly weird difference in usage between required and optional arguments?
There are two possibilities: either it's a SyntaxError, or it's a run-time UnboundLocalError if you omit both of them (in which case it would be perfectly legal and sensible if you specify one of them).
I'm currently inclined towards SyntaxError, since permitting it would open up some hard-to-track-down bugs, but am open to suggestions about how it would be of value to permit this.
Not sure that I am scared of this if it gives a clear exception: Parameter `a` was not passed, but it can only be omitted when parameter `b` is passed. Not as clear (or complete) as a custom message, but not terrible? Cheers, Sebastian
ChrisA _______________________________________________ Python-ideas mailing list -- python-ideas@python.org To unsubscribe send an email to python-ideas-leave@python.org https://mail.python.org/mailman3/lists/python-ideas.python.org/ Message archived at https://mail.python.org/archives/list/python-ideas@python.org/message/YVE5PM... Code of Conduct: http://python.org/psf/codeofconduct/