New submission from Camion <camion_spam-pyb...@yahoo.com>:
I don't know if this is by design (for what reason ?) or if it is a bug, but I
have noticed this quite counter-intuitive behaviour :
Doing that, it seems that the logical way to make the __repr__ and __str__
methods, would be to override respectively the parent __repr__ and _str__
methods, and calling them from the inherited versions, but for some reason, it
seems that calling super().__str__ leads to call self.__repr__.
I have written the following piece of python-3 code in which I subclass the
list class in order to make a class which supports storing names and unnamed
fields the same way you can have variable named and unnamed parameters in a
function call :
class struct(list):
def __init__(self, *args, **kwargs):
super().__init__(args)
for key, value in kwargs.items():
setattr(self, key, value)
def __repr__(self):
s = super().__repr__()[1:-1]
for key, val in self.__dict__.items():
s += ', '+key+'='+repr(val)
return 'struct('+s+')'
def __str__(self):
s = super().__str__()[1:-1]
print('Debug : super().__str__() = "'+super().__str__()+'"')
print('Debug : list(self).__str__() = "'+list(self).__str__()+'"')
print('Debug : s = "'+s+'"')
for key, val in self.__dict__.items():
s += ', '+key+'='+str(val)
return '{'+s+'}'
a = struct(1, 2, 3, a="akeja", b=21, c=True, d="lkj")
print('repr(a)="'+repr(a)+'"\n')
print('str(a)="'+str(a)+'"\n')
Executing this code in idle-3.5.2 will yield the following result :
>>>
RESTART: struct.py
repr(a)="struct(1, 2, 3, b=21, d='lkj', a='akeja', c=True)"
Debug : super().__str__() = "struct(1, 2, 3, b=21, d='lkj', a='akeja',
c=True)"
Debug : list(self).__str__() = "[1, 2, 3]"
Debug : s = "truct(1, 2, 3, b=21, d='lkj', a='akeja', c=True"
str(a)="{truct(1, 2, 3, b=21, d='lkj', a='akeja', c=True, b=21, d=lkj,
a=akeja, c=True}"
>>>
As one can see in the second debug lines, the call to `super().__str__()` which
I expect to return the result from a call to the `__str__` function from my
super class (`list`), will in fact return something which looks very much like
the expected return from `self.__repr__()`
It seems that `super().__str__()` calls `self.__repr__()` instead of
`list(self).__str__()` or even `super().__repr__()`.
----------
components: Interpreter Core
messages: 329331
nosy: Camion
priority: normal
severity: normal
status: open
title: Calling for super().__str__ seems to call self.__repr__ in list subclass
type: behavior
versions: Python 3.5
_______________________________________
Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue35174>
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