CODEWITHSUNDEEP
python
TMS
TMS

Reputation: 373

Python: how to modify/edit the string printed to screen and read it back?

I'd like to print a string to command line / terminal in Windows and then edit / change the string and read it back. Anyone knows how to do it? Thanks

print "Hell"
Hello!  <---Edit it on the screen
s = raw_input()
print s
Hello!

Upvotes: 8

Views: 9468

Answers (5)

Dingu Sagar
Dingu Sagar

Reputation: 98

I had this same use-case for a command-line application.

Finally found a hack to do this.

# pip install pyautogui gnureadline

import pyautogui
import readline
from threading import Thread


def editable_input(text):
    Thread(target=pyautogui.write, args=(text,)).start()
    modified_input = input()
    return modified_input


a = editable_input("This is a random text")
print("Received input : ", a)

The trick here is use pyautogui to send the text from keyboard. But we want to do this immediately after the input(). Since input() is a blocking call, we can run the pyautogui command in a different thread. And have an input function immediately after that in the main thread.

gnureadline is for making sure we can press left and right arrow keys to move the cursor in a terminal without printing escape characters.

Tested this on Ubuntu 20, python 3.7

Upvotes: 2

andyhasit
andyhasit

Reputation: 15309

If it's for your own purposes, then here's a dirty wee hack using the clipboard without losing what was there before:

def edit_text_at_terminal(text_to_edit):
    import pyperclip

    # Save old clipboard contents so user doesn't lose them
    old_clipboard_contents = pyperclip.paste()

    #place text you want to edit in the clipboard
    pyperclip.copy(text_to_edit)

    # If you're on Windows, and ctrl+v works, you can do this:
    import win32com.client
    shell = win32com.client.Dispatch("WScript.Shell")
    shell.SendKeys("^v")

    # Otherwise you should tell the user to type ctrl+v
    msg = "Type ctrl+v (your old clipboard contents will be restored):\n"

    # Get the new value, the old value will have been pasted
    new_value= str(raw_input(msg))

    # restore the old clipboard contents before returning new value
    pyperclip.copy(old_clipboard_contents )
    return new_value

Note that ctrl+v doesn't work in all terminals, notably the Windows default (there are ways to make it work, though I recommend using ConEmu instead).

Automating the keystrokes for other OSs will involve a different process.

Please remember this is a quick hack and not a "proper" solution. I will not be held responsible for loss of entire PhD dissertations momentarily stored on your clipboard.

For a proper solution there are better approaches such as curses for Linux, and on Windows it's worth looking into AutHotKey (perhaps throw up an input box, or do some keystrokes/clipboard wizardry).

Upvotes: 0

Remi
Remi

Reputation: 21175

os.sys.stdout is write only, but you can erase some characters of the last line with \b or the whole line with \r, as long as you did not write a carriage return.

(however, see also my question about limitations to the standard python console/terminal)

I once made some output exercise (including a status bar) to write,erase or animate if you will, perhaps it is helpfull:

from __future__ import print_function
import sys, time

# status generator
def range_with_status(total):
    n=0
    while n<total:
        done = '#'*(n+1)
        todo = '-'*(total-n-1)
        s = '<{0}>'.format(done+todo)
        if not todo:
            s+='\n'
        if n>0:
            s = '\r'+s
        sys.stdout.write(s)
        sys.stdout.flush()
        yield n
        n+=1

print ('doing something ...')
for i in range_with_status(10):
    time.sleep(0.1)

print('ready')
time.sleep(0.4)


print ('And now for something completely different ...')
time.sleep(0.5)
msg = 'I am going to erase this line from the console window.'
sys.stdout.write(msg); sys.stdout.flush()
time.sleep(1)
sys.stdout.write('\r' + ' '*len(msg))
sys.stdout.flush()
time.sleep(0.5)
print('\rdid I succeed?')  
time.sleep(4)

Upvotes: 0

Karl Knechtel
Karl Knechtel

Reputation: 61537

raw_input accepts a parameter for a "prompt message", so use that to output the message, and then prepend it to what you get back. However, this won't allow you to backspace into the prompt, because it's a prompt and not really part of the input.

s = "Hell" + raw_input("Hell")
print s

Upvotes: 0

AlG
AlG

Reputation: 15157

You could do some ANSI trickery to make it look like you are editing on screen. Check out this link (also similar to this SO post on colors).

This would only work on certain terminals and configurations. ymmv.

This python script worked in my Cygwin terminal on Win7:

print 'hell'
print '\033[1A\033[4CO!'

Ends up printing hellO! on one line. The 2nd print moves the cursor up one line (Esc[1A) then over 4 characters (Esc[4C]) and then prints the 'O!'.

It wouldn't let you read it back though... only a 1/2 answer.

Upvotes: 3

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