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Why is “if not someobj:” better than “if someobj == None:” in Python?
...a __nonzero__ special method (as do numeric built-ins, int and float), it calls this method. It must either return a bool value which is then directly used, or an int value that is considered False if equal to zero.
Otherwise, if the object has a __len__ special method (as do container built-ins, li...
Difference between a Postback and a Callback
I keep on hearing this words ' callback ' and ' postback ' tossed around.
What is the difference between two ?
6 Answers...
How to find the size of localStorage
...ly developing a site that will make use of HTML5's localStorage. I've read all about the size limitations for different browsers. However, I haven't seen anything on how to find out the current size of a localStorage instance. This question seems to indicate that JavaScript doesn't have a built in...
How to select html nodes by ID with jquery when the id contains a dot?
...res both an id and a separate class to match; it's valid and not always totally redundant.
The correct way to select a literal ‘.’ in CSS is to escape it: “#id\.moreid”. This used to cause trouble in some older browsers (in particular IE5.x), but all modern desktop browsers support it.
The...
Inheritance and Overriding __init__ in python
...
The book is a bit dated with respect to subclass-superclass calling. It's also a little dated with respect to subclassing built-in classes.
It looks like this nowadays:
class FileInfo(dict):
"""store file metadata"""
def __init__(self, filename=None):
super(FileInfo,...
How to save all the variables in the current python session?
I want to save all the variables in my current python environment. It seems one option is to use the 'pickle' module. However, I don't want to do this for 2 reasons:
...
Why is the order in dictionaries and sets arbitrary?
...der:
>>> {'bar': None, 'foo': None}
{'foo': None, 'bar': None}
All slots except 3 and 4 are empty, looping over the table first lists slot 3, then slot 4, so 'foo' is listed before 'bar'.
bar and baz, however, have hash values that are exactly 8 apart and thus map to the exact same slot...
Reference requirements.txt for the install_requires kwarg in setuptools setup.py file
...nts.txt and setup.py , so I was hoping to pass a file handle to the install_requires kwarg in setuptools.setup .
20 An...
Define a lambda expression that raises an Exception
...ur goal is to avoid a def, this obviously doesn't cut it. It does, however allow you to conditionally raise exceptions, e.g.:
y = lambda x: 2*x if x < 10 else raise_(Exception('foobar'))
Alternatively you can raise an exception without defining a named function. All you need is a strong stom...
Is there common street addresses database design for all addresses of the world? [closed]
...dresses? It should be so simple to use, fast to query and dynamic to store all street addresses of the world which is identifying just by one id Thanks a lot
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