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Python if __name__ = ' __main__': analysis;


When you open a.Py file, often at the bottom of the code to see if __name__ = ='__main__': now, to introduce the role of the.



Module is the object, and all the modules have a built-in __name__. value depends on the attributes of a module __name__ to you how to apply. If a module import module, then __name__ module is usually module file name, without a path or file name extension. But you can also like a standard program direct operation module, in this case, the value of __name__ will be a special default "__main__".



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Run the.Py file directly in CMD, and the value of __name__ is'__main__';



In import, after a.Py file, the value of __name__ is not'__main__';



To use if __name__ = ='__main__'to determine whether it is in the direct operation of the.Py file



Such as:



#Test.py



Class Test:



Def __init (self): pass #pass is written to maintain code integrity, without any effect, do, nothing



Def, f (self): print,'Hello, World,'



If __name__:

='__main__'


Test ().F ()



#End





You type in CMD:



C:>python Test.py



Hello, World,

!


Note: "__name__ ='__main__'" is established





You enter again in CMD:



C:>python



>>>import Test



The __name__

of the >>>Test.__name__ #Test module


'Test'



>>>__name__ # current program __name__



'__main__'



No matter what, in Test.py "__name__ ='__main__'" are not set up

!


So the next line of code never runs until

!

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