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Why does Python code use len() function instead of a length method?
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Strings do have a length method: __len__()
The protocol in Python is to implement this method on objects which have a length and use the built-in len() function, which calls it for you, similar to the way you would implement __iter__() and use the built-in ...
Python: Bind an Unbound Method?
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All functions are also descriptors, so you can bind them by calling their __get__ method:
bound_handler = handler.__get__(self, MyWidget)
Here's R. Hettinger's excellent guide to descriptors.
As a self-contained example pulled from Keith's comment:
def bind(instance, func, as_name=None):
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What is the purpose of the single underscore “_” variable in Python?
What is the meaning of _ after for in this code?
5 Answers
5
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Reference — What does this symbol mean in PHP?
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_ Alias for gettext()
The underscore character '_' as in _() is an alias to the gettext() function.
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`if __name__ == '__main__'` equivalent in Ruby
...f there isn't really a good, clean way of doing this.
EDIT: Found it.
if __FILE__ == $0
foo()
bar()
end
But it's definitely not common.
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Serializing class instance to JSON
...N for your class.
A simple solution would be to call json.dumps() on the .__dict__ member of that instance. That is a standard Python dict and if your class is simple it will be JSON serializable.
class Foo(object):
def __init__(self):
self.x = 1
self.y = 2
foo = Foo()
s = js...
How to read a (static) file from inside a Python package?
...he other answers]
import os, mypackage
template = os.path.join(mypackage.__path__[0], 'templates', 'temp_file')
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Python dictionary: Get list of values for list of keys
...n list-comp:
Build list and throw exception if key not found: map(mydict.__getitem__, mykeys)
Build list with None if key not found: map(mydict.get, mykeys)
Alternatively, using operator.itemgetter can return a tuple:
from operator import itemgetter
myvalues = itemgetter(*mykeys)(mydict)
# use ...
What's a correct and good way to implement __hash__()?
What's a correct and good way to implement __hash__() ?
6 Answers
6
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Is it possible to implement a Python for range loop without an iterator variable?
...ou can just live with the extra i variable.
Here is the option to use the _ variable, which in reality, is just another variable.
for _ in range(n):
do_something()
Note that _ is assigned the last result that returned in an interactive python session:
>>> 1+2
3
>>> _
3
F...