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Consider the following Python 3 code:
class A:
b = LongRunningFunctionWithSideEffects()
When will LongRunningFunctionWithSideEffects() be called? At the moment the module is imported? Or at the moment the class is first used in some way?
879
Python has no command for declaring a variable. A variable is created the moment you first assign a value to it.
Create Class VariablesA class variable is declared inside of class, but outside of any instance method or __init__() method. By convention, typically it is placed right below the class header and before the constructor method and other methods.
In C++, class variables are initialized in the same order as they appear in the class declaration.
The __init__ method is the Python equivalent of the C++ constructor in an object-oriented approach. The __init__ function is called every time an object is created from a class. The __init__ method lets the class initialize the object's attributes and serves no other purpose. It is only used within classes.
At the moment the module is imported
test.py:
def x():
print('x')
class A:
x = x()
then
Python 3.6.7 (default, Oct 22 2018, 11:32:17)
[GCC 8.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import test
x
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