[PYTHON] Phenomenon that characters disappear when trying to enter one character without Enter

I want to enter one character

The input () function doesn't read unless you hit the enter key. I want to omit pressing the enter key. So I searched for a way to avoid hitting the enter key.

import sys
import tty
import termios
def getch():
    fd = sys.stdin.fileno()
    old = termios.tcgetattr(fd)
    try:
        tty.setraw(fd)
        return sys.stdin.read(1)
    finally:
        termios.tcsetattr(fd, termios.TCSADRAIN, old)

It seems that this can be done for mac Reference source: https://torina.top/detail/428/

Run

while True:
    print('input:',end='')
    key = getch()
    print(key)
#Ends with esc
    if key == chr(27):
        break

The letters disappear!

Input: a
Input: f
[Cursor here]

I was able to ... ** Input: has disappeared! !! ** **

(When I enter one character, it suddenly appears and it feels as if it was there from the beginning)

Target

input:[Cursor here]

I want you to be

Conclusion

while True:
    print('\r input:',end='')
    key = getch()
    print(key)
    if key == chr(27):
        break

If you do it in the place where you don't want to erase \ r,input:did not disappear! !! I'm not sure why, but it's the result of trial and error. Apparently, you should put characters such as \ r and \ n in the string before getch ().

It seems that it is necessary to force the output (addition)

print('key :', end='', flush=True)

I was able to display it. Everything is not reflected on the screen until the line break is output, If you do print ('key:', end ='') somewhere else, it will be output without line breaks, so it's a mess. ..

I think I can do various things with this

s = []
while 1:
    print('\r'+''.join(s), end='')
    char = getch()
#Ends with esc
    if char == chr(27):
        break
#When you press enter\Is r entered? Ignore because the cursor is at the left end
    elif char == chr(13):
        continue
#Delete one character with backspace
    elif char == chr(127):
        if len(s) != 0:
            s.pop()
            print('\b ',end='')
        continue
    s.append(char)
print('')

Now I'm typing one character at a time, but I was able to display it each time! If you add a little more processing, you can convert from lowercase to uppercase at the same time you hit it! Wow!