Signatures, a call to action

[stoneleaf (Ethan Furman)]

@rhettinger

The list.index() method … help now reads:

index(self, value, start=0, stop=9223372036854775807, /)

Yuck, how did these implementation details leak into the language? Likewise, str.split() got altered to use a -1 magic constant. Its help now reads:

split(self, /, sep=None, maxsplit=-1)

That’s a bummer because documentation modeling language formerly used in help() is clearer:

str.split([sep[, maxsplit]])

I agree that those helps are much less helpful than they used to be, and I would love to see a completed signature language.

I also agree with Guido:

@guido

Contrary to most reactions, I find it natural and desirable to accept None as an alternative to omit an optional parameter in a wide variety of APIs. Not because I like to read or write log(2.3, None) but because I like to be able to define a simple wrapper, e.g.

def my_log(x, base=None):
    # <extra stuff here>
    return math.log(x, base)

I suspect, however, that being able to accept None (or some other sentinel) to specify “use the default value” is a separate issue from signatures.