Table of contents
②from module name import function name
(1) module
A Python module (Module) is a Python file ending with .py . A module can define functions, classes, and variables, and it can also contain executable code.
The role of the module : There are many different modules in python , and each module can help us quickly realize some functions , such as implementing time-related functions, you can use the time module. We can think of a module as a toolkit , and each toolkit has various tools for us to use to achieve various functions. In short, a module is a Python file, which contains classes, functions, variables, etc., which we can use (import modules to use)
(2) How to import modules
Modules need to be imported before use. The import syntax is as follows :
Precautions:
• from can be omitted, just import directly• The as alias can be omitted• Use "." to determine the hierarchical relationship• The import of the module is generally written at the beginning of the code file
Common combinations such as:
import module namefrom module name import classes, variables, methods, etc.from module name import *import module name as aliasfrom module name import function name as alias
① import module name
Basic syntax:
Case: Import time module
② from module name import function name
Basic syntax:
Case: Import the sleep method in the time module
③ from module name import *
Basic syntax:
Case: Import all methods in the time module
④ as defines an alias
Basic syntax:
case:
(3) Custom modules
Just write the code normally in the Python code file, and use the import and from keywords as importing Python built-in modules to use. For example, create a new Python file, name it my_module1.py , and define the test function
Note: Each Python file can be used as a module, and the name of the module is the name of the file . That is to say, the custom module name must conform to the identifier naming rules
(4) Test module
In actual development, when a developer writes a module, in order to make the module achieve the desired effect in the project, the developer will add some test information to the py file, for example , in the my_module1.py file Add test code test(1,1)
Problem : At this point, whether it is the current file or other files that have imported the module, the `test` function call will be automatically executed when running
solution:
if __main__ == "__main__" means that only when the program is directly executed will it enter the if , if it is imported, the if cannot enter
Notice:
Note: When importing multiple modules , and there is a function with the same name in the module . When this function with the same name is called, the function of the module imported later is called
__all__
If there is a `__all__` variable in a module file, only the elements in this list can be imported when using `from xxx import *`
