[Python-Dev] Re: "groupby" iterator

[Thomas Heller]

Paul Moore <pf_moore at yahoo.co.uk> writes:

> [Phillip J. Eby]
>> Yes.  Really the whole extract thing isn't that useful, except to get
>> extra speed over using 'lambda x: x.foo' or whatever, which is what
>> I'd probably use in any code that wasn't composing functions or
>> compiling an OO query language.  :)
>
> [Thomas Heller]
>> Hm, couldn't "lambda ob: ob.foo.bar" return exactly the same thing
>> as
>
>> "extract(extract(attr='foo'), attr='bar')"
>
>> ? In other words: return specialized C implemented functions for
>> simple lambda expressions?
>
> I agree with Thomas - rather than adding yet more specialised
> functions, it would seem more sensible to optimize lambda - probably
> via special cases like this.

One question that remains is: do a handful of these specialized
functions make it possible to replace the remaining uses lambda
completely?

Looking at parts of my codebase nearly all uses of lambda are
'lambda self: self.someattr'.

The remaining occurences have not yet been ported to the idioms of newer
Pythons.

Thomas