Python 3.4 - if __name__ == '__main__'
"When the Python interpreter reads a source file, it executes all of the code found in it.
Before executing the code, it will define a few special variables. For example, if the python interpreter is running that module (the source file) as the main program, it sets the special
In the case of your script, let's assume that it's executing as the main function, e.g. you said something like
One reason for doing this is that sometimes you write a module (a
https://stackoverflow.com/questions/419163/what-does-if-name-main-do
https://www.youtube.com/watch?v=sugvnHA7ElY
Before executing the code, it will define a few special variables. For example, if the python interpreter is running that module (the source file) as the main program, it sets the special
__name__
variable to have a value "__main__"
. If this file is being imported from another module, __name__
will be set to the module's name.In the case of your script, let's assume that it's executing as the main function, e.g. you said something like
python threading_example.py
on the command line. After setting up the special variables, it will execute the import
statement and load those modules. It will then evaluate the def
block, creating a function object and creating a variable called myfunction
that points to the function object. It will then read the if
statement and see that __name__
does equal "__main__"
, so it will execute the block shown there.One reason for doing this is that sometimes you write a module (a
.py
file) where it can be executed directly. Alternatively, it can also be
imported and used in another module. By doing the main check, you can
have that code only execute when you want to run the module as a program
and not have it execute when someone just wants to import your module
and call your functions themselves."https://stackoverflow.com/questions/419163/what-does-if-name-main-do
https://www.youtube.com/watch?v=sugvnHA7ElY
Comments