Issue 20402: List comprehensions should be noted in for loop documentation (original) (raw)
Created on 2014-01-27 03:24 by robla, last changed 2022-04-11 14:57 by admin. This issue is now closed.
Messages (6)
Author: Rob Lanphier (robla)
Date: 2014-01-27 03:24
The current list comprehension documentation is difficult to find for someone who doesn't know what a list comprehension is. Example of this problem: http://www.reddit.com/r/learnprogramming/comments/1w6slm/different_kind_of_for_loop_python/
Since list comprehensions are a riff off of "for" loop syntax, they should at least be noted and linked to from section 4.2 ("for statements" section) and quite possibly 5.6 ("Looping constructs")
Author: Westley MartÃnez (westley.martinez) *
Date: 2014-02-18 00:46
I'm curious what the best way to do this would be. Obviously the simplest would just be 'See also list comprehensions.' However since this is a tutorial, I was thinking of adding something like this: 'In other languages, for loops are often used to fill a sequence with data. While this method works just as well in Python, it is often better to use a list comprehension' and then there could be an example like that found here: http://docs.python.org/2/tutorial/datastructures.html#list-comprehensions
Followed by a link to more info on list comprehensions.
Author: Alexander Grigorievskiy (AlexGrig) *
Date: 2014-08-02 11:22
I have added some clarification following Westley MartÃnez recommendation. I provided references to the list comprehensions and generator expressions. I tried to make the description short.
Author: Raymond Hettinger (rhettinger) * 
Date: 2014-08-02 22:33
We do have prominent entries in the glossary and tutorial:
https://docs.python.org/2.7/glossary.html#term-list-comprehension https://docs.python.org/2.7/tutorial/datastructures.html#list-comprehensions
Moving it earlier in the tutorial is likely to do more harm than help. In teaching Python, you need some gap between learning for-loops and learning list comprehensions (the former is a prerequisite for the latter).
Author: Rob Lanphier (robla)
Date: 2014-08-04 03:57
Moving it earlier in the tutorial is likely to do more harm than help. In teaching Python, you need some gap between learning for-loops and learning list comprehensions (the former is a prerequisite for the latter).
The problem here is that many people get list comprehensions foisted on them by reading code that has them in it. Since list comprehensions aren't called "list comprehensions" in the code, but rather, they look like funny for loops, many people will turn to the for loop documentation, and as of this writing, they won't find anything.
There doesn't necessarily need to be the full example as in Alex's patch (though Alex's version seems fine to me), I think there should at least be some link to the list comprehension documentation, e.g. "It is also possible to prepend a function onto a 'for' loop. This is a :ref:list comprehensions <tut-listcomps>, and is explained further in the next chapter."
Author: Raymond Hettinger (rhettinger) *
Date: 2014-08-04 05:17
Sorry, I'm going to close this one because I believe it would make the documentation worse.
I don't believe that making a forward reference from section 4.2 to section 5.6 helps anyone.
History
Date
User
Action
Args
2022-04-11 14:57:57
admin
set
github: 64601
2014-08-04 14:06:02
ezio.melotti
set
stage: needs patch -> resolved
2014-08-04 05:17:38
rhettinger
set
status: open -> closed
resolution: rejected
messages: +
2014-08-04 03:57:44
robla
set
messages: +
2014-08-02 22:33:01
rhettinger
set
versions: - Python 3.3
nosy: + rhettinger
messages: +
assignee: docs@python -> rhettinger
2014-08-02 11:22:26
AlexGrig
set
files: + issue20402.diff
nosy: + AlexGrig
messages: +
keywords: + patch
2014-02-18 00:46:59
westley.martinez
set
nosy: + westley.martinez
messages: +
2014-02-15 15:48:12
ezio.melotti
set
keywords: + easy
nosy: + ezio.melotti
stage: needs patch
versions: + Python 2.7, Python 3.3, Python 3.4, Python 3.5
2014-01-27 03:24:16
robla
create