CODEWITHSUNDEEP
pythonpython-3.x
Remi Guan
Remi Guan

Reputation: 22282

How to decrease the code size when there is some same code

I'm sorry about I don't know how to explain this...for example, here is my code:

def get_hash(choice):
    if choice == 1:
        sha1 = hashlib.sha1()                                                               
        sha1.update('a test for sha1'.encode('utf-8'))                                  
        print(sha1.hexdigest())                                                          

    elif choice == 2:                                                                          
        sha256 = hashlib.sha256()                                                        
        sha256.update('a test for sha256'.encode('utf-8'))                              
        print(sha256.hexdigest())  

get_hash(int(input('Enter your choice between one and two: '))

Look, choice 1 and choice 2 only 'sha1' and 'sha256' are difference.

So I want to know, how to decrease the code size? Can I do some thing like 'sha{0} = hashlib.sha{0}'.format('256')?

Upvotes: 0

Views: 182

Answers (3)

Mp0int
Mp0int

Reputation: 18727

In python, everything is an object!

hashlib_mapping = {
    1: "sha1",
    2: "sha256",
    ... }

def hash(choice):
    hasher = getattr(hashlib, hashlib_mapping[choice])()
               ^1^                ^2^                 ^3^

That means, you can map values with method names. Then use getattr (1) to get related method (2) of th hashlib class and call it(3). You can even use sha method numbers as below

# Pass sha method number to define the relatd sha method. 
hasher = getattr(hashlib, "sha{num}".format(num=choice))()

hash(1)  # will use sha1
hash(224)  # will use sha224
hash(384)  # will use sha384

Upvotes: 2

YOBA
YOBA

Reputation: 2807

You can do this and keeping one argument in your function:

def hash(choice):
    map_dico = { 1: [ 'sha1', hashlib.sha1()] ,
                 2: [ 'sha256', hashlib.sha256() ]}                                                                 
    map_dico[choice][1].update('a test for {}'.format(map_dico[choice][0]).encode('utf-8'))                                  
    print(map_dico[choice][1].hexdigest())   

hash(int(input('Enter your choice between one and two: ')) )

Upvotes: 0

Morgan Thrapp
Morgan Thrapp

Reputation: 9986

You could rewrite your hash function to take the hasher as an argument.

def hash_test(hasher):                                                             
    hasher.update('a hash test'.encode('utf-8'))                                  
    print(hasher.hexdigest())     

hashes = {'sha256': hashlib.sha256(), 'sha1': hashlib.sha1()}

hash_type = input('Do you want to try sha1, or sha256?')
hasher = hashes[hash_type]
hash_test(hasher)

There's no (sane) way to create/use dynamic variables names, especially if you're trying to create objects from a library.

Upvotes: 2

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