Description

assignee = None
closed_at = None
created_at = <Date 2013-12-21.10:40:25.122>
labels = ['type-feature', 'docs']
title = 'Missing documentation for argparse.ArgumentTypeError'
updated_at = <Date 2022-02-04.07:08:15.442>
user = 'https://bugs.python.org/arnaut-billings'

activity = <Date 2022-02-04.07:08:15.442>
actor = 'ukarroum'
assignee = 'docs@python'
closed = False
closed_date = None
closer = None
components = ['Documentation']
creation = <Date 2013-12-21.10:40:25.122>
creator = 'arnaut-billings'
dependencies = []
files = []
hgrepos = []
issue_num = 20039
keywords = ['patch']
message_count = 5.0
messages = ['206723', '206768', '206783', '327986', '363839']
nosy_count = 7.0
nosy_names = ['bethard', 'docs@python', 'paul.j3', 'arnaut-billings', 'nchammas', 'rahul-kumi', 'ukarroum']
pr_nums = ['31125']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue20039'
versions = ['Python 3.3']

Activity

1. arnaut-billings commented on Dec 21, 2013

   

   arnaut-billingsmannequin

   on Dec 21, 2013

   MannequinAuthor

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   There is no documentation for argparse.ArgumentTypeError:

   http://docs.python.org/3/library/unittest.html

   Though it does appear in an example and its usage is simple enough to decipher what it means, it would none the less look more professional if there was formal documentation for it. Not only on what it is, but when it should actually be used, etc...
2. arnaut-billings

   assigned

   docspython

   on Dec 21, 2013
3. arnaut-billings

   added

   docsDocumentation in the Doc dirDocumentation in the Doc dir

   on Dec 21, 2013
4. paulj3 commented on Dec 21, 2013

   

   paulj3mannequin

   on Dec 21, 2013

   Mannequin

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   In argparse.py the status of ArgumentTypeError is ambiguous.

   ArgumentError is listed as a public class, ArgumentTypeError is not. It also says 'All other classes in this module are considered implementation details.'

   ArgumentTypeError is a subclass of Exception (with no added functionality).

   ArgumentTypeError is raised only once, in the FileType class (which is both a scripting convenience and example of a custom type). As you note it is also used in the documentation example. There is also one such example in test_argparse.py.

   It is caught once, where it is converted into an ArgumentError. It is handled much like a ValueError or TypeError - except that its message is passed through unchanged.

   In http://bugs.python.org/issue13824 I use it several times in the FileContext class for just this reason.

   In fact ArgumentTypeError could be documented as a footnote to the type block, saying to the effect: 'An ArgumentTypeError may be raised (instead of a ValueError or TypeError) to produce a custom error message.'

   Normally an ArgumentTypeError is not passed back to the user code, consistent with the claim that it is not public.

   --------------

   Along the same line, should ArgumentError be documented better? Currently it is just mentioned at the end, as a replacement for an optparse error class.

   As best I can tell, the user code will only see an ArgumentError if the ArgumentParser.error method is customized. Otherwise that error is caught and converted into a system exit. Maybe the error paragraph in the documentation should get a sentence about ArgumentError.

   In test_argparse.py, ArgumentError is used extensively (with a custom error method).
5. arnaut-billings commented on Dec 21, 2013

   

   arnaut-billingsmannequin

   on Dec 21, 2013

   MannequinAuthor

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   It seems what you're saying is that the ArgumentTypeError class should not be public, but being able to raise is should be public. If that's the case, I think it would be more clear to have an argparse.raiseArgumentTypeError method and document when it should be used.

   If such classes are meant to be private, why not prepend their names with an underscore and remove them from the __all__ list? (I thought a leading underscore meant that a module level variable was private to that module.)
6. ezio-melotti

   added

   type-featureA feature request or enhancementA feature request or enhancement

   on Feb 15, 2014
7. paulj3 commented on Oct 18, 2018

   

   paulj3mannequin

   on Oct 18, 2018

   Mannequin

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   A related closed request: https://bugs.python.org/issue30220

   that wants to test ValueError for non-generic message, instead of using ArgumentTypeError.
8. nchammas commented on Mar 10, 2020

   

   nchammasmannequin

   on Mar 10, 2020

   Mannequin

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   Just a note that I also went looking for the docs for argparse.ArgumentTypeError after coming across it in this (highly viewed) post:

   https://stackoverflow.com/a/14117511/877069
9. ezio-melotti

   transferred this issue fromon Apr 10, 2022
10. erlend-aasland

    added this to Argparse issueson May 19, 2022
11. erlend-aasland

    moved this to Doc issues in Argparse issueson May 19, 2022
12. slateny commented on Nov 19, 2023

    

    slateny

    on Nov 19, 2023

    Contributor

    More actions

    Added to argparse by #103289
13. slateny

    closed this as completedon Nov 19, 2023

Issue actions