How to turn all called function arguments into one (Python 3)

Question

I am building a terminal simulator in Python, and i have the commands stored in arguments, like:

def ls(a):
    for item in os.listdir():
        print item

a = input('Command: ')
a = a.split()

The terminal works like this:

Ask user for input
Splits the input
Uses the first part of input to search a function in locals
If there is one, uses the rest part of input as argument
Calls the function

And i have a problem with cd command.

def cd(a):
    if a == None:
        print('cd')
        print('Change directories')
    else:
        os.chdir(os.getcwd() + '/' + a())

It works when you make it enter a folder without spaces, like when you type cd Windows in the prompt, it works. But the problems start when you try to enter a folder that has spaces in it. When i type, for example, cd Documents Copy, it either enters the folder Documents if there is one, or crashes.

How i can fix it? I had a thought about turning all called function arguments into one, but i dont know how to do that, and there might be other ways.

You might try enclosing arguments with quotes if they contain spaces, like real terminals do. — TigerhawkT3, May 11 '16 at 18:26
But that doesnt work, because it splits the input, like if i will enter cd "Documents Copy", the first part will be cd, second one "Documents, and the third one Copy" — HackerGamerLV, May 11 '16 at 18:29
You may have to do more complex parsing. Creating a terminal is not a trivial task. — TigerhawkT3, May 11 '16 at 18:30
Yes, I got that. I suggest reading up on the syntax of some real terminals so you can get a better idea of what wheels you'll need to reinvent for this project. — TigerhawkT3, May 11 '16 at 18:34

score 1 · Accepted Answer · edited May 23 '17 at 12:16

1

You need a more sophisticated split() function -- see Split a string by spaces — preserving quoted substrings answer for a potential solution.

UPDATE

If you had a subdirectory called "the dog" with a space in it, in your interpreter you could do:

Command: cd "the dog"

The code modifications would be roughly as follows:

import shlex
import os

def ls(a):
    for item in os.listdir():
        print(item)

def cd(a):
    if a == None:
        print('cd')
        print('Change directories')
    else:
        os.chdir(os.getcwd() + '/' + a)

a = input('Command: ')
a = shlex.split(a)

if len(a) > 1:
    locals()[a[0]](a[1][:99])
    print()
else:
    locals()[a[0]](None)
    print()

edited May 23 '17 at 12:16

Community

1
1

answered May 11 '16 at 18:34

cdlane

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How can i use it in my code? – HackerGamerLV May 11 '16 at 18:46
@HackerGamerLV, I've added some example usage code & information. – cdlane May 11 '16 at 18:55
Hmm...thank you, i will try it! – HackerGamerLV May 11 '16 at 19:51
Thank you, that was just what i needed. – HackerGamerLV May 11 '16 at 21:32

How to turn all called function arguments into one (Python 3)

1 Answers1