[Python-ideas] Before and after the colon in funciton defs.
tjreedy at udel.edu
Tue Sep 20 18:59:27 CEST 2011
On 9/20/2011 10:00 AM, Sven Marnach wrote:
> I actually *do* use the default argument hack for early binding
> myself. My main points were that the current status quo isn't too
> bad, there are alternatives if the function signature is really
> important, and that the cases which require both using closures *and*
> having a clean signature are too rare to justify yet another
> confusing-for-beginners syntax. (When I started learning Python in
> 1998, the language was praised for having a small language core. I
> didn't hear this very often in more recent times.)
I have noticed the same. The big syntax additions are generators,
comprehensions, decorators, and the with statement. The switch to
unicode doesn't change syntax but can complicate text processing.
> Assuming a new syntax *is* necessary -- there is no objective way to
> decide this after all -- I don't particularly like the proposed square
> bracket syntax because
> a) it puts the information at the wrong place. The first line of the
> function definition is for the outside appearance of the function,
> including signature and annotations. Separating the internal
> information on early bound variables from the signature is the
> primary goal of the proposal after all.
> b) it does not make the intention of early binding very clear.
> c) it consists of a list of the form [i=i] or [tuple=tuple, len=len]
> in most use cases, making it necessary to type every name that
> shall use early binding twice.
> That's why I would prefer a syntax that explicitly declares the names
> that should use early binding, similar to "global" or "nonlocal"
> statements, if such a syntax is deemed necessary at all.
The problem with an earlybind statement in the body is that it is in the
body, which should be runtime stuff. I would prefer something in the
header. A semi-colon or other char would be sufficient syntactically:
def f(a; len, alist=): alist.append(a); return len(alist)
where a bare identifier like 'len' *means* 'len=len'.
Terry Jan Reedy
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