[Python-ideas] Attribute-Getter Syntax Proposal

Brett Cannon brett at python.org
Fri Mar 8 13:37:48 EST 2019

On Fri, Mar 8, 2019 at 8:57 AM Samuel Li <samuel.wgx at gmail.com> wrote:

> Don't know if this has been suggested before. Instead of writing something
> like
> >>> map(lambda x: x.upper(), ['a', 'b', 'c'])
> I suggest this syntax:
> >>> map(.upper(), ['a', 'b', 'c'])

Do note you get the same results with `map(str.upper, ['a', 'b', 'c'])`.

> This would also work for attributes:
> >>> map(.real, [1j, 2, 3+4j])
> Internally, this would require translating
> .attribute -> lambda x: x.attribute
> and
> .method(*args, **kwargs) -> lambda x: x.method(*args, **kwargs)
> This translation should only take place where a "normal" attribute lookup
> makes no sense (throws a SyntaxError); i.e. foo.bar works as before,
> foo(.bar) would previously throw a SyntaxError, so the new syntax applies
> and the .bar is interpreted as an attrgetter.
> This is of course only a cosmetic improvement over operator.attrgetter and
> operator.methodcaller, but I think it's nice enough to warrant
> consideration.
> If you like this idea or think it's utter garbage, feel free to discuss.

Sorry, I'm personally not a fan as it looks like you have a typo in your
code, e.g. you left of 'x' or something before the dot.
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