20 reflects, MD5 encrypted, and the logging module logs (review)

1, reflection

　　Keywords:　　

　　　　The getattr a string, to find the member subject
　　　　hasattr according to a string, it is determined whether there is a subject that member
　　　　setattr according to a string, to set a target moving member (RAM)
　　　　delattr according to a string, to judge a set target moving member (RAM)

　　A simple example:

　　　　1, defines five functions, and a number in the file handler

def f1():
    print("F1")
def f2():
    print("F2")
def f3():
    print("F3")
def f4():
    print("F4")
def f5():
    print("F5")

f0 = 9

　　　　2, and then create a run file. The digital input to the transfer function corresponding to

from types Import FunctionType
 Import Handler
 the while True:
     Print ( "" " 
    function the system supports: 
        1.f1 
        2.f2 
        3.f3 
        4.f4 
        5.f5 
        6.f6 
    " "" ) 
    Val = the INPUT ( " Please enter function to execute: " )
     iF the hasattr (Handler, Val):     # determines whether or not normal 
        func_or_val = getattr (Handler, Val)   # the parameter string, block to find members of the same name 
        iF the isinstance (func_or_val, FunctionType) : 
            func_or_val ()
        the else :
             Print (func_or_val)
     the else :
         Print ( ' attribute name entered does not exist ' )
 # summary. The string parameter (second parameter), to the object (the first parameter) to find the members with the same name

　　When a relatively large amount of data, it is impossible to determine write a bunch of reflection is particularly important at this time.　

　　to sum up:

　　　　What is reflected: string parameter (second parameter), to the object (the first parameter) to find members of the same name (the sentence: the form of the operation target character string attributes associated)

 

 

2, md5 encryption

　　In python md5 encryption module depends on hashlib

　　The usual md5 encryption, easily knocked library crack. This is when you need salt.

　　A simple example is as follows:

Import hashlib 
the SALT = B ' asdasd ' 


DEF MD5 (pwd): 
    obj = hashlib.md5 (the SALT)    # salt the SALT 
    obj.update (pwd.encode ( ' UTF-. 8 ' )) 

    # acquires the ciphertext 
    V = obj.hexdigest ()
     return v

　　# Because md5 is not reversible, so the md5 decryption. Take data is encrypted and plaintext to encrypt, and then to compare, leading to the conclusion.

 

 

3, the log.

　　Has been written once before, do not repeat it.