[SOLVED] Python - how to process console input without newline?

CollieJim · 05-20-2018, 08:36 AM

I need to process console input but it does not include any end-of-line indication.

The application is a remote control for an entertainment system using a Raspberry Pi/Arduino combination to receive commands and drive the IR LEDs, and a Bluetooth keyboard.

I need to be able to receive a single character as it is keyed. I don't want to have to press Enter.

How can it be done? Is a C module needed?

Thanks

teckk · 05-20-2018, 10:34 AM

https://docs.python.org/2/library/ms...ml#console-i-o
https://docs.python.org/2/library/select.html

https://stackoverflow.com/questions/...ading-keypress
https://stackoverflow.com/questions/...ress-in-python

Edit:
I tried this, it gives a number for each key press, doesn't need anything extra

Code:

#! /usr/bin/python

import curses

def main(stdscr):
    # do not wait for input when calling getch
    stdscr.nodelay(1)
    while True:
        # get keyboard input, returns -1 if none available
        c = stdscr.getch()
        if c != -1:
            # print numeric value
            stdscr.addstr(str(c) + ' ')
            stdscr.refresh()
            # return curser to start position
            stdscr.move(0, 0)

if __name__ == '__main__':
    curses.wrapper(main)

CollieJim · 05-20-2018, 11:05 AM

Thanks. Just what I need.

I initially tried the code in Emacs' shell and immediately got 1758 spaces and a blinking cursor. Characters entered were echoed, but no numbers. I thought before I say anything I should try it in konsole. It worked well there.

teckk · 05-20-2018, 11:10 AM

You might want to slow down that infinite loop so that it doesn't hog
all of your cpu, it was just an example.

Code:

import curses, time

def main(stdscr):
    # do not wait for input when calling getch
    stdscr.nodelay(1)
    while True:
        time.sleep(.1)
        # get keyboard input, returns -1 if none available
        c = stdscr.getch()
        ........

ntubski · 05-20-2018, 11:44 AM

Quote:

Originally Posted by CollieJim

I initially tried the code in Emacs' shell and immediately got 1758 spaces and a blinking cursor.

It should work in M-x term, but M-x shell doesn't give you a fully functional terminal for handling curses programs.