On Mon, 2021-10-25 at 03:47 +1100, Chris Angelico wrote: > On Mon, Oct 25, 2021 at 3:43 AM Jonathan Fine <jfine2...@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
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