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Multiple variables in a 'with' statement?
...Unlike the contextlib.nested, this guarantees that a and b will have their __exit__()'s called even if C() or it's __enter__() method raises an exception.
You can also use earlier variables in later definitions (h/t Ahmad below):
with A() as a, B(a) as b, C(a, b) as c:
doSomething(a, c)
...
Does Python have a string 'contains' substring method?
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Under the hood, Python will use __contains__(self, item), __iter__(self), and __getitem__(self, key) in that order to determine whether an item lies in a given contains. Implement at least one of those methods to make in available to your custom type.
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How to import classes defined in __init__.py
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'lib/'s parent directory must be in sys.path.
Your 'lib/__init__.py' might look like this:
from . import settings # or just 'import settings' on old Python versions
class Helper(object):
pass
Then the following example should work:
from lib.settings import Values
from l...
How do I check which version of NumPy I'm using?
...c Rodger: yeah, but your is more general to any module that cares to set a __version__.
– Esteban Küber
Oct 5 '09 at 14:13
57
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Run function from the command line
...() somewhere below the function and it will execute when you do python your_file.py
For a neater solution you can use this:
if __name__ == '__main__':
hello()
That way the function will only be executed if you run the file, not when you import the file.
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Is arr.__len__() the preferred way to get the length of an array in Python?
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my_list = [1,2,3,4,5]
len(my_list)
# 5
The same works for tuples:
my_tuple = (1,2,3,4,5)
len(my_tuple)
# 5
And strings, which are really just arrays of characters:
my_string = 'hello world'
len(my_string)
# 11
It was in...
How to import the class within the same directory or sub directory?
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Python 2
Make an empty file called __init__.py in the same directory as the files. That will signify to Python that it's "ok to import from this directory".
Then just do...
from user import User
from dir import Dir
The same holds true if the files are in a...
What's the difference between globals(), locals(), and vars()?
... the same dict each time - it's attached to the stack frame object as its f_locals attribute. The dict's contents are updated on each locals() call and each f_locals attribute access, but only on such calls or attribute accesses. It does not automatically update when variables are assigned, and assi...
How to identify platform/compiler from preprocessor macros?
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For Mac OS:
#ifdef __APPLE__
For MingW on Windows:
#ifdef __MINGW32__
For Linux:
#ifdef __linux__
For other Windows compilers, check this thread and this for several other compilers and architectures.
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Are PHP include paths relative to the file or the calling code?
...f you want to make it matter, and do an include relative to B.php, use the __FILE__ constant (or __DIR__ since PHP 5.2 IIRC) which will always point to the literal current file that the line of code is located in.
include(dirname(__FILE__)."/C.PHP");
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