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What is the difference between class and instance attributes?
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Only the mutable types are shared. Like for int and str they still attached with each instances rather than class.
– Babu
Jul 17 '14 at 11:59
11
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Mac zip compress without __MACOSX folder?
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When I had this problem I've done it from command line:
zip file.zip uncompressed
EDIT, after many downvotes: I was using this option for some time ago and I don't know where I learnt it, so I can't give you a better explanation. Chris Johnson's answer is correct, but ...
How to save all the variables in the current python session?
...s()[key]
except TypeError:
#
# __builtins__, my_shelf, and imported modules can not be shelved.
#
print('ERROR shelving: {0}'.format(key))
my_shelf.close()
To restore:
my_shelf = shelve.open(filename)
for key in my_shelf:
globals()[key]=my_shelf[key]
my_she...
“Inner exception” (with traceback) in Python?
My background is in C# and I've just recently started programming in Python. When an exception is thrown I typically want to wrap it in another exception that adds more information, while still showing the full stack trace. It's quite easy in C#, but how do I do it in Python?
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How to suppress “unused parameter” warnings in C?
... annoyance with this is it can be misleading if you use the variable later and forget ro remove the unused line. this is why GCC's unused is nice.
– ideasman42
Nov 7 '12 at 13:58
6...
How do I override __getattr__ in Python without breaking the default behavior?
...oo has no attribute called bar. If the attribute is one you don't want to handle, raise AttributeError:
class Foo(object):
def __getattr__(self, name):
if some_predicate(name):
# ...
else:
# Default behaviour
raise AttributeError
However, un...
How do I avoid capturing self in blocks when implementing an API?
I have a working app and I'm working on converting it to ARC in Xcode 4.2. One of the pre-check warnings involves capturing self strongly in a block leading to a retain cycle. I've made a simple code sample to illustrate the issue. I believe I understand what this means but I'm not sure the "corre...
What does “hashable” mean in Python?
...ue which never changes during its lifetime (it needs a __hash__() method), and can be compared to other objects (it needs an __eq__() or __cmp__() method). Hashable objects which compare equal must have the same hash value.
Hashability makes an object usable as a dictionary key and a set member...
python: How do I know what type of exception occurred?
...ns, but no one seems to want to tell you why, which is essential to understanding when you can break the "rule". Here is an explanation. Basically, it's so that you don't hide:
the fact that an error occurred
the specifics of the error that occurred (error hiding antipattern)
So as long as you ...
Format date and time in a Windows batch script
In a Windows (Windows XP) batch script I need to format the current date and time for later use in files names, etc.
33 An...