Python Reflect Example

Python provide hasattr(), getattr(), setattr() and delattr() function for us to verify ( hasattr() ), get ( getattr() ), set ( setattr() ) or delete ( delattr() ) objects properties. We can use these functions to implement reflect feature in python. This example will tell you how to use them.

1. Python Reflect Example Steps.

1. 1. Create a PyDev project in eclipse. You can read the article How To Run Python In Eclipse With PyDev.
   2. Create a python package com.dev2qa.example.reflect.

1. Create two modules commons ( commons.py ) and visit ( visit.py ) in reflect package.
2. Below is the commons.py source code.

   ''' Below functions are commons module attributes, you can use python built-in function getattr(commons, 'function_name_str') to get them and execute. '''
   def auth(user_name, password):
       if(user_name == "hello" and password == "123456"):
           print("User account correct.")
       else:
           print("User account incorrect.")
   
   
   def exit():
       print("User exit the system.")
   
   
   def welcome():
       print("Welcome to this system. ")

3. Below is visits.py source code. There are two functions in this module run() and run_reflect(). run() function do not use python reflect,  run_reflect() function use python builtin hasattr(), getattr() function to implement python reflect. You can see the code comments for detail explanation.

   # First import commons module from it's package.
   from com.dev2qa.example.reflect import commons
   
   # This function do not use python reflect. 
   def run():
       # Get user input.
       inp = input("Input command：  ").strip()
       
       # Split the input string into list.
       args = inp.split(" ")
       
       # Get the first command.
       cmd = args[0]
       
       # Run different command use if else to check, this way is not effective when there are so many if else.
       if cmd == "auth":
           user_name = args[1]
           password = args[2]
           commons.auth(user_name, password)
           
       elif cmd == "exit":
           commons.exit()
       
       elif cmd == "welcome":
           commons.welcome()
       
       else:
           print("404")
   
   # This function use python hasattr(), getattr() function to inplement reflect.
   def run_reflect():
       # Get user input command and arguments.
       inp = input("Input command：  ").strip()
       args = inp.split(" ")
       cmd = args[0]
       
       # If commons module contains cmd attribute.
       if hasattr(commons,cmd):
           
           # Get the cmd attribute value from the commons module.
           func = getattr(commons,cmd)
           
           # Because it is a function, so we can run the function.
           
           # If user input three argument.
           if(len(args) == 3):
               # Get username and password.
               user_name = args[1]
               password = args[2]
               
               # Execute the function with input arguments.
               func(user_name, password)
           else:    
               func()
       else:
           print("404")
       
   
   if __name__ == '__main__':
       #run()
       run_reflect()