Path: csiph.com!fu-berlin.de!uni-berlin.de!not-for-mail
From: Chris Angelico <rosuav@gmail.com>
Newsgroups: comp.lang.python
Subject: Re: Suggestion: make sequence and map interfaces more similar
Date: Thu, 31 Mar 2016 23:48:48 +1100
Lines: 53
Message-ID: <mailman.254.1459428536.28225.python-list@python.org>
References: <CABbU2U_DsSC=6d0HOwgGnzQZ0=r6U2sf_zOJP0U_w7_i0RrOKQ@mail.gmail.com> <CAPTjJmqjgnDvzS7=_YRf+T78GYz7J26FzWGfwrygYLeq2E9FeA@mail.gmail.com> <CABbU2U9m-35UqK5KqRj7Y_oLdq_dgH3_EScLb4Sf3UNB4oCgmQ@mail.gmail.com> <CAPTjJmp1x-5=gEwBB=n-kt6YeVd6OiN_BGh5tNoL7UPYNqKb8w@mail.gmail.com> <mailman.176.1459309120.28225.python-list@python.org> <56fb677f$0$11121$c3e8da3@news.astraweb.com> <lf5twjoo2w8.fsf@ling.helsinki.fi> <56fba7d3$0$1616$c3e8da3$5496439d@news.astraweb.com> <lf5h9fouumu.fsf@ling.helsinki.fi> <56fbc518$0$1593$c3e8da3$5496439d@news.astraweb.com> <mailman.203.1459343574.28225.python-list@python.org> <56fbf73d$0$1591$c3e8da3$5496439d@news.astraweb.com> <mailman.222.1459364926.28225.python-list@python.org> <56fc8e09$0$1600$c3e8da3$5496439d@news.astraweb.com> <mailman.240.1459410739.28225.python-list@python.org> <56fcfdc6$0$1612$c3e8da3$5496439d@news.astraweb.com> <56FD086F.2090301@rece.vub.ac.be> <mailman.251.1459425470.28225.python-list@python.org> <87poualt87.fsf@elektro.pacujo.net>
Mime-Version: 1.0
Content-Type: text/plain; charset=UTF-8
In-Reply-To: <87poualt87.fsf@elektro.pacujo.net>
Precedence: list
Xref: csiph.com comp.lang.python:106150

On Thu, Mar 31, 2016 at 11:36 PM, Marko Rauhamaa <marko@pacujo.net> wrote:
> Chris Angelico <rosuav@gmail.com>:
>
>> On Thu, Mar 31, 2016 at 10:22 PM, Antoon Pardon
>> <antoon.pardon@rece.vub.ac.be> wrote:
>> Okay. I'll put a slightly different position: Prove that your proposal
>> is worth discussing by actually giving us an example that we can
>> discuss.
>
> Sorry for missing most of the arguments here, but if you are talking
> about treating lists as special cases of dicts, I have occasionally
> instinctively wanted something like this:
>
>     >>> fields = [ "x", "y", "z" ]
>     >>> selector = (1, 1, 0)
>     >>> list(map(fields.get, selector))
>     Traceback (most recent call last):
>     File "<stdin>", line 1, in <module>
>     AttributeError: 'list' object has no attribute 'get'
>
> Or course, I could:
>
>     >>> list(map(fields.__getitem__, selector))
>     ['y', 'y', 'x']
>
> but that would abuse a dunder method. So I will need to:
>
>     >>> list(map(lambda i: fields[i], selector))
>     ['y', 'y', 'x']
>
> or (most likely):
>
>     >>> new_fields = []
>     >>> for i in selector:
>     ...   new_fields.append(fields[i])
>     ...
>     >>> new_fields
>     ['y', 'y', 'x']
>
>
> This tiny problem of mine could be remedied by adding a get method to
> lists.

Or, even more likely and even more Pythonic:

>>> [fields[i] for i in selector]
['y', 'y', 'x']

As soon as you get past the easy and obvious case of an existing
function, filter and map quickly fall behind comprehensions in utility
and readability.

ChrisA