Getting function as string then run it

Question

I have script like:

from string import digits, uppercase, lowercase, punctuation
from itertools import product

chars = lowercase + uppercase + digits + punctuation

for n in range(1,  2+1):
    for comb in product(chars, repeat=n):
        print ''.join(comb)

it works fine. Imagine chars is giving by an external user so:

import sys
from string import digits, uppercase, lowercase, punctuation
from itertools import product

chars = sys.argv[1] # sys.argv[1] is 'lowercase+uppercase+digits+punctuation'

for n in range(1,  2+1):
    for comb in product(chars, repeat=n):
        print ''.join(comb)

when run script.py: It has not the result when you say:

chars = lowercase + uppercase + digits + punctuation

Now how can I get the previous result?

When you say chars = 'lowercase+uppercase+digits+punctuation' the program doen't work. because lowercase and etc are functions not string... how can the the python these are not string and thy are functions — MLSC
– MLSC, Commented Feb 14, 2016 at 12:48
Well, yes... because they're strings. If you want the attributes of string with those names, you must tell Python as much. Trivial research will tell you how. — jonrsharpe
– jonrsharpe, Commented Feb 14, 2016 at 12:49
A hint: string.lowercase == getattr(string, 'lowercase') assuming that you have imported string — user2390182
– user2390182, Commented Feb 14, 2016 at 12:51

timgeb · Accepted Answer · 2016-02-14 12:53:51Z

You can use a dictionary mapping the user input to the corresponding strings.

>>> input_to_chars = {
...     'lowercase': lowercase,
...     'uppercase': uppercase,
...     'digits': digits,
...     'punctuation': punctuation
... }

Construct chars from the user input like this:

>>> inp = raw_input('what character sets do you want? ')
what character sets do you want? lowercase+uppercase+digits+punctuation
>>> chars = ''.join(input_to_chars[i] for i in inp.split('+'))
>>> chars
'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789!"#$%&\'()*+,-./:;<=>?@[\\]^_`{|}~'

Or with the hint from @schwobaseggl in the comments:

>>> import string
>>> inp = raw_input('what character sets do you want? ')
what character sets do you want? lowercase+uppercase+digits+punctuation
>>> chars = ''.join(getattr(string, i) for i in inp.split('+'))
>>> chars
'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789!"#$%&\'()*+,-./:;<=>?@[\\]^_`{|}~'

The dictionary solution is easy to extend, the getattr solution is good if you don't want to extend your program to accept user inputs which are not attributes of string.

Collectives™ on Stack Overflow

Getting function as string then run it

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related