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__str__ cannot be overridden on unicode-derived classes #44163

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laughingboy0 mannequin opened this issue Oct 24, 2006 · 5 comments
Closed

__str__ cannot be overridden on unicode-derived classes #44163

laughingboy0 mannequin opened this issue Oct 24, 2006 · 5 comments
Labels
interpreter-core (Objects, Python, Grammar, and Parser dirs) topic-unicode type-bug An unexpected behavior, bug, or error

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@laughingboy0
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laughingboy0 mannequin commented Oct 24, 2006

BPO 1583863
Nosy @vstinner, @devdanzin
Files
  • format_unicode.patch
    		•

    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 = <Date 2010-03-22.12:57:04.963>
created_at = <Date 2006-10-24.15:57:03.000>
labels = ['interpreter-core', 'type-bug', 'expert-unicode']
title = '__str__ cannot be overridden on unicode-derived classes'
updated_at = <Date 2010-03-22.12:57:04.962>
user = 'https://bugs.python.org/laughingboy0'

    bugs.python.org fields:

    activity = <Date 2010-03-22.12:57:04.962>
actor = 'vstinner'
assignee = 'none'
closed = True
closed_date = <Date 2010-03-22.12:57:04.963>
closer = 'vstinner'
components = ['Interpreter Core', 'Unicode']
creation = <Date 2006-10-24.15:57:03.000>
creator = 'laughingboy0'
dependencies = []
files = ['13467']
hgrepos = []
issue_num = 1583863
keywords = ['patch']
message_count = 5.0
messages = ['61028', '84519', '84534', '84535', '101501']
nosy_count = 3.0
nosy_names = ['vstinner', 'ajaksu2', 'laughingboy0']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'test needed'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue1583863'
versions = ['Python 2.6']
    @laughingboy0
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    laughingboy0 mannequin commented Oct 24, 2006 

    class S(str):
   def __str__(self): return '__str__ overridden'

class U(unicode):
   def __str__(self): return '__str__ overridden'
   def __unicode__(self): return u'__unicode__ overridden'

s = S()
u = U()

    print 's:', s
    print "str(s):", str(s)
    print 's substitued is "%s"\n' % s
    print 'u:', u
    print "str(u):", str(u)
    print 'u substitued is "%s"' % u

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

    s: __str__ overridden
    str(s): __str__ overridden
    s substitued is "__str__ overridden"

    u:
    str(u): __str__ overridden
    u substitued is ""

    Results are identical for 2.4.2 and 2.5c2 (running
    under windows).

    @laughingboy0 laughingboy0 mannequin added interpreter-core (Objects, Python, Grammar, and Parser dirs) labels Oct 24, 2006
    @devdanzin
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    devdanzin mannequin commented Mar 30, 2009

    Confirmed in trunk.

    @devdanzin devdanzin mannequin added topic-unicode type-bug An unexpected behavior, bug, or error labels Mar 30, 2009
    @vstinner
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    Case "S" (type str): "%s" uses _PyObject_Str() which checks the object
    type with PyString_CheckExact().

    Case "U" (type unicode) "%s" uses PyUnicode_Check() and then calls
    PyUnicode_Format(). PyUnicode_Format() uses PyUnicode_Check() to check
    the object object. It should uses PyUnicode_CheckExact() instead.

    xxx_CheckExact() is different than xxx_Check(): exact is only true for
    the base type, whereas the the second is also true for subclass.

    @vstinner
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    Patch: Use PyUnicode_CheckExact() instead of PyUnicode_CheckExact() in
    PyUnicode_Format() to use obj.__unicode__ slot.

    @vstinner
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    Commited: r79278+r79280 (trunk), r79281 (py3k), r79282 (3.1), r79283 (2.6).

    @ezio-melotti ezio-melotti transferred this issue from another repository Apr 10, 2022
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