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How to import the class within the same directory or sub directory?
...
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...
Use of 'prototype' vs. 'this' in JavaScript?
...hich can be accessed with Object.getPrototypeOf(myObject) or with myObject.__proto__ in some browsers. The proto property indicates the object's parent in the prototype chain (or the object from which this object inherits). The prototype property (which is only on functions) indicated the object t...
What is the __del__ method, How to call it?
I am reading a code. There is a class in which __del__ method is defined. I figured out that this method is used to destroy an instance of the class. However, I cannot find a place where this method is used. The main reason for that is that I do not know how this method is used, probably not like ...
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 avoid having class data shared among instances?
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You want this:
class a:
def __init__(self):
self.list = []
Declaring the variables inside the class declaration makes them "class" members and not instance members. Declaring them inside the __init__ method makes sure that a new instance of th...
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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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 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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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...
Creating C macro with ## and __LINE__ (token concatenation with positioning macro)
...PASTE2(x, y) TOKENPASTE(x, y)
#define UNIQUE static void TOKENPASTE2(Unique_, __LINE__)(void) {}
Then, __LINE__ gets expanded to the line number during the expansion of UNIQUE (since it's not involved with either # or ##), and then the token pasting happens during the expansion of TOKENPASTE.
It ...