Modules

#             
#     Modules        

#               .py     
#         Python              
#       C     Python  


#      
import sys


print('The command line arguments are:')
for item in sys.argv:
    print(item)

print('The PYTHONPATH is', sys.path,'
')

#            
# Python            ，    .pyc
#                  

#    improt     from...import

from math import sqrt
print('Square root of 16 is', sqrt(16))



#                           
#      __name__     

if __name__ == '__main__':
    print('This program is being run by itself')
else:
    print('I am being imported from another module')

def say_hi():
    print('Hi, this is mymodule speaking.')

__version__ = '0.1'

#       module         mymodule   environment path 
import mymodule

mymodule.say_hi()
print('Version', mymodule.__version__)

from mymodule import say_hi,__version__

say_hi()
print('Version', __version__)

#       from mymodule import *
#      say_hi       ，     __version__