On Fri, Jul 10, 2020, 6:54 AM Jonathan Fine <[email protected]> wrote:
> Hi All
>
> SUMMARY
> This is a longish post. It looks at the idea in general terms, and
> outlines a way to get the desired semantics (by not syntax) with Python as
> it is today. And this would be forward compatible with the new syntax, if
> provided later.
>
This post was filled with inspiring ideas for me. Thank you.
> PRESENT
> I like the idea of allowing
> >>> d[1, 2, 3, a=4, b=5]
> and will explore it further.
>
> First, we can already write
> >>> f(1, 2, 3, a=4, b=5)
> but that only works for the get operation. For set the present behaviour is
> >>> f(1, 2, 3, a=4, b=5) = None
> SyntaxError: can't assign to function call
> and I see no good reason to change that.
>
> Going further, I'd say that allowing both
> >>> d[something] = value
> >>> value = d[something]
> is essential to the difference between f(something) and d[something]. Both
> are expressions, but only one of them can be assigned to.
>
> Here goes. First syntax.
> >>> value = d[K(1, 2, 3, a=4, b=5)]
> >>> d[K(1, 2, 3, a=4, b=5)] = value
>
My mind instantly went to the idea of using this syntax as a way write
single line mathematical function definitions:
f[x, y] = x + y
The example function doesn't even require the suggested K() object since no
kwargs or defaults are used.
Of course one would need to instantiate any these single line functions
using a little bit of boilerplate up top. But this could be when you
provide the docstring:
f = MathFunction("Simple math function")
f[x, y] = x + y
And calling them would use a different bracket type (parentheses):
>>> f(1,2)
3
...but these are surmountable hurdles.
>
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