Description

serhiy-storchaka

opened on Jun 24, 2014

Issue body actions

BPO	21861
Nosy	@rhettinger, @pitrou, @benjaminp, @PCManticore, @hynek, @serhiy-storchaka, @MojoVampire, @aisk, @Windsooon
PRs	bpo-21861: Improve _io.FileIO.__repr__ #14774 gh-66060: Use actual class name in some _io type's __repr__ #30824

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2014-06-24.17:36:58.710>
labels = ['extension-modules', 'easy', 'type-bug', 'expert-IO']
title = 'io class name are hardcoded in reprs'
updated_at = <Date 2022-01-23.10:01:52.325>
user = 'https://github.com/serhiy-storchaka'

bugs.python.org fields:

activity = <Date 2022-01-23.10:01:52.325>
actor = 'asaka'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Extension Modules', 'IO']
creation = <Date 2014-06-24.17:36:58.710>
creator = 'serhiy.storchaka'
dependencies = []
files = []
hgrepos = []
issue_num = 21861
keywords = ['patch', 'easy']
message_count = 6.0
messages = ['221476', '221990', '221993', '222011', '222939', '342684']
nosy_count = 12.0
nosy_names = ['rhettinger', 'pitrou', 'benjamin.peterson', 'stutzbach', 'Claudiu.Popa', 'hynek', 'piotr.dobrogost', 'serhiy.storchaka', 'josh.r', 'asaka', 'Windson Yang', 'Philip Dye']
pr_nums = ['14774', '30824']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue21861'
versions = ['Python 2.7', 'Python 3.3', 'Python 3.4']

Activity

1. serhiy-storchaka commented on Jun 24, 2014

   

   serhiy-storchaka

   on Jun 24, 2014

   MemberAuthor

   More actions

   >>> import io
   >>> class F(io.FileIO): pass
   ... 
   >>> f = F('/dev/null', 'r')
   >>> f
   <_io.FileIO name='/dev/null' mode='rb'>
   >>> class B(io.BufferedReader): pass
   ... 
   >>> b = B(f)
   >>> b
   <B name='/dev/null'>
   >>> class T(io.TextIOBufferedReader): pass
   io.TextIOBase(     io.TextIOWrapper(  
   >>> class T(io.TextIOWrapper): pass
   ... 
   >>> t = T(b)
   >>> t
   <_io.TextIOWrapper name='/dev/null' encoding='UTF-8'>

   Expected results are "<main.F name='/dev/null' mode='rb'>", "<main.B name='/dev/null'>" and "<main.T name='/dev/null' encoding='UTF-8'>". Usually reprs of subclass instances substitute actual module and class names.
2. serhiy-storchaka

   added

   extension-modulesC modules in the Modules dirC modules in the Modules dir

   topic-IO

   easy

   type-bugAn unexpected behavior, bug, or errorAn unexpected behavior, bug, or error

   on Jun 24, 2014
3. PCManticore commented on Jun 30, 2014

   

   PCManticoremannequin

   on Jun 30, 2014

   Mannequin

   More actions

   The same should be done for _pyio?
4. MojoVampire commented on Jun 30, 2014

   

   MojoVampiremannequin

   on Jun 30, 2014

   Mannequin

   More actions

   Is it common for C implementations to introspect to figure out their "real" name? I do this manually for reprs of my user defined classes, but I haven't noticed many built-ins that consider extensibility for the repr. Maybe I'm just not using the classes that do it or I'm overriding the repr without checking?

   I just tested, and it looks like frozenset has a subclass friendly repr, while bytearray does not as of 3.4.0. Seems like it might make sense to first determine if introspection should be the default; it would mean a little code bloat every time it's done.
5. rhettinger commented on Jul 1, 2014

   

   rhettinger

   on Jul 1, 2014

   Contributor

   More actions

   Usually reprs of subclass instances substitute actual module
   and class names.

   This is a sensible idea that makes life easier for people writing subclasses.

   +1 for your suggestion.
6. serhiy-storchaka commented on Jul 13, 2014

   

   serhiy-storchaka

   on Jul 13, 2014

   MemberAuthor

   More actions

   I now see that this issue is not so easy from C side.

   And more, it is very uncommon for either Python or C implementations (especial C implementations) to introspect to figure out their "real" name. Existing cases are rather exceptions. And in many case this is only a side effect of sharing an implementation between several classes (set and frozenset, three buffered file classes in io, etc). In many cases repr's flexibility is limited: hardcoded or omitted module name, used class's __name__ instead of __qualname__, etc.

   This should be discussed on Python-Dev maillist.
7. Windsooon commented on May 17, 2019

   

   Windsooonmannequin

   on May 17, 2019

   Mannequin

   More actions

   IIUC, in the c code we just hardcode the name "_io.FileIO" for "PyFileIO_Type" in https://github.com/python/cpython/blob/master/Modules/_io/fileio.c#L1180. If we want to get a dynamic name, we should replace the hardcode name with the module name (like "__main__"). I found this also happens on other modules like collections.
8. ezio-melotti

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

   linked a pull request that will close this issuegh-66060: Use actual class name in some `_io` type's `__repr__` #30824on Jan 9, 2024
10. erlend-aasland

    closed this as completedin #30824on Jan 9, 2024
11. erlend-aasland

    added a commit that references this issue on Jan 9, 2024

    gh-66060: Use actual class name in _io type's __repr__ (#30824)

    623b338
12. kulikjak

    added a commit that references this issue on Jan 22, 2024

    pythongh-66060: Use actual class name in _io type's __repr__ (python#…

    0327886
13. aisk

    added a commit that references this issue on Feb 11, 2024

    pythongh-66060: Use actual class name in _io type's __repr__ (python#…

    18a6235
14. Glyphack

    added a commit that references this issue on Sep 2, 2024

    pythongh-66060: Use actual class name in _io type's __repr__ (python#…

    0fed9e7

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