Description

assignee = None
closed_at = None
created_at = <Date 2020-03-15.16:39:23.863>
labels = ['easy', '3.11', '3.9', '3.10', 'docs']
title = '[doc] Error in functional how-to example'
updated_at = <Date 2022-03-29.07:57:47.314>
user = 'https://github.com/dxflores'

activity = <Date 2022-03-29.07:57:47.314>
actor = 'eric.smith'
assignee = 'docs@python'
closed = False
closed_date = None
closer = None
components = ['Documentation']
creation = <Date 2020-03-15.16:39:23.863>
creator = 'dxflores'
dependencies = []
files = []
hgrepos = []
issue_num = 39971
keywords = ['patch', 'easy']
message_count = 6.0
messages = ['364247', '364275', '364346', '364708', '364709', '364710']
nosy_count = 6.0
nosy_names = ['rhettinger', 'terry.reedy', 'eric.smith', 'docs@python', 'dxflores', 'slateny']
pr_nums = ['32172']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = None
url = 'https://bugs.python.org/issue39971'
versions = ['Python 3.9', 'Python 3.10', 'Python 3.11']

Activity

1. dxflores commented on Mar 15, 2020

   

   dxfloresmannequin

   on Mar 15, 2020

   MannequinAuthor

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   Hello,

   A code example from the 'functional programming how-to' raises an error.

   The simplest fix would be to remove the Ellipsis object from the 'line_list'.

   Thank you,
   Diogo

   Please check below for the commands issued:

   # https://docs.python.org/3/howto/functional.html#generator-expressions-and-list-comprehensions

   >>> line_list = ['  line 1\n', 'line 2  \n', ...]
   >>> 
   >>> # Generator expression -- returns iterator
   >>> stripped_iter = (line.strip() for line in line_list)
   >>> 
   >>> # List comprehension -- returns list
   >>> stripped_list = [line.strip() for line in line_list]
   Traceback (most recent call last):
     File "<stdin>", line 1, in <module>
     File "<stdin>", line 1, in <listcomp>
   AttributeError: 'ellipsis' object has no attribute 'strip'
2. dxflores

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3. dxflores

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4. dxflores

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   docsDocumentation in the Doc dirDocumentation in the Doc dir

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7. ericvsmith commented on Mar 16, 2020

   

   ericvsmith

   on Mar 16, 2020

   Member

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   I don't think that was meant to be a literal example. I think that "..." here means "and other strings".
8. dxflores commented on Mar 16, 2020

   

   dxfloresmannequin

   on Mar 16, 2020

   MannequinAuthor

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   Agreed, Eric. Nevertheless, I think that this example might raise unnecessary confusion to someone new to Python, and hence the reason why I decided to open the issue. Anyhow, I trust your judgement and please feel free to leave things as is and close this issue.

   PS: I really the work you did with dataclasses, and I actually explored the idea further with a small (300 LoC) library that adds runtime type checking for instances of dataclasses - if you are ever curious you can find the code on my GitHub at /dxflores/invis.

   Thank you,
   Diogo
9. terryjreedy commented on Mar 20, 2020

   

   terryjreedy

   on Mar 20, 2020

   Member

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   In think examples should run and that '...' should be replaced by something like "' \n', ''". The blank string looks ahead to the next example, which adds ' if line != ""' to the comprehension.
10. terryjreedy

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11. terryjreedy

    changed the title [-]Error on documentation - Quick fix.[/-] [+]Error in functional how-to example[/+] on Mar 20, 2020
12. terryjreedy

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14. terryjreedy commented on Mar 20, 2020

    

    terryjreedy

    on Mar 20, 2020

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    Looking around further, examples meant to be executable as is are given interactive prompts and needed doctest directives

        >>> gen  #doctest: +ELLIPSIS
        <generator object generate_ints at ...>

    I think that this example should get the same treatment. Non-executable examples are usually clearly non-executable because then contain undefined names line 'expr2' and 'sequence2', whereas this example starts by defining 'line_list'.
15. iritkatriel

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16. iritkatriel

    changed the title [-]Error in functional how-to example[/-] [+][doc] Error in functional how-to example[/+] on Mar 20, 2022
17. iritkatriel

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18. iritkatriel

    changed the title [-]Error in functional how-to example[/-] [+][doc] Error in functional how-to example[/+] on Mar 20, 2022
19. ezio-melotti

    transferred this issue fromon Apr 10, 2022
20. iritkatriel

    closed this as completedon Jun 25, 2022

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