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How do I override __getattr__ in Python without breaking the default behavior?
I want to override the __getattr__ method on a class to do something fancy but I don't want to break the default behavior.
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Catching an exception while using a Python 'with' statement
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from __future__ import with_statement
try:
with open( "a.txt" ) as f :
print f.readlines()
except EnvironmentError: # parent of IOError, OSError *and* WindowsError where available
print 'oops'
If you want differ...
How do I use a Boolean in Python?
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checker = None
if some_decision:
checker = True
if checker:
# some stuff
[Edit]
For more information: http://docs.python.org/library/functions.html#bool
Your code works too, since 1 is converted to True when necessary.
Actually Python...
In which case do you use the JPA @JoinTable annotation?
...ble named Task and add a foreign key column to the task table named project_id:
Project Task
------- ----
id id
name name
project_id
This way, it will be possible to determine the project for each row in the task table. If you use this approach, in your e...
Implementing slicing in __getitem__
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The __getitem__() method will receive a slice object when the object is sliced. Simply look at the start, stop, and step members of the slice object in order to get the components for the slice.
>>> class C(object):
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What does “mro()” do?
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Follow along...:
>>> class A(object): pass
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>>> A.__mro__
(<class '__main__.A'>, <type 'object'>)
>>> class B(A): pass
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>>> B.__mro__
(<class '__main__.B'>, <class '__main__.A'>, <type 'object'>)
>>> class C(A): pa...
What does the caret operator (^) in Python do?
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It invokes the __xor__() or __rxor__() method of the object as needed, which for integer types does a bitwise exclusive-or.
share
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improv...
Design patterns or best practices for shell scripts [closed]
...etopt and getopts. Use getopt as you face less trouble.
CommandLineOptions__config_file=""
CommandLineOptions__debug_level=""
getopt_results=`getopt -s bash -o c:d:: --long config_file:,debug_level:: -- "$@"`
if test $? != 0
then
echo "unrecognized option"
exit 1
fi
eval set -- "$getopt_...
How is __eq__ handled in Python and in what order?
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The a == b expression invokes A.__eq__, since it exists. Its code includes self.value == other. Since int's don't know how to compare themselves to B's, Python tries invoking B.__eq__ to see if it knows how to compare itself to an int.
If you amend your ...
How to implement __iter__(self) for a container object (Python)
...owing will create an iterator that yields five, and then every item in some_list.
def __iter__(self):
yield 5
yield from some_list
Pre-3.3, yield from didn't exist, so you would have to do:
def __iter__(self):
yield 5
for x in some_list:
yield x
...