How do you get the last arrow key pressed using curses?

Question

I'm writing a Python snake game using curses, but am having some trouble controlling the snake, my current code for controlling the snake is placed inside the main loop and looks like this:

while True:
    char = screen.getch()
    if char == 113: exit()  # q
    elif char == curses.KEY_RIGHT: snake.update(RIGHT)
    elif char == curses.KEY_LEFT: snake.update(LEFT)
    elif char == curses.KEY_UP: snake.update(UP)
    elif char == curses.KEY_DOWN: snake.update(DOWN)
    else snake.update()
    time.sleep(0.1)

However the code seems to treat the keys pressed as a que (so the snake will stop when it runs out of arrow-presses), whereas I actually want it to retrieve the last arrow key that was pressed.

How can I retrieve the last arrow key that was pressed?

Rethink your design (a `direction` variable would be suitable) and this problem disappears. — You, Sep 06 '10 at 13:30
That completely depends on how you layout your program. As it is now, it looks like movement depends on input — a more suitable dependency would be to have movement depend on time only, and poll (non-blocking) for key events, changing a variable `direction` when these occur. That's how I see it, anyway. — You, Sep 06 '10 at 21:37
It's the non-blocking poll part that I'm struggling with, `curses.halfdelay()` seems to solve that problem. — Zaz, Sep 07 '10 at 10:15

Zaz · Accepted Answer · 2010-09-08T19:43:15.927

4

Set screen.nodelay(1):

screen.nodelay(1)
while True:
    char = screen.getch()
    if char == 113: break  # q
    elif char == curses.KEY_RIGHT: snake.update(RIGHT)
    elif char == curses.KEY_LEFT: snake.update(LEFT)
    elif char == curses.KEY_UP: snake.update(UP)
    elif char == curses.KEY_DOWN: snake.update(DOWN)
    else: snake.update()
    time.sleep(0.1)

edited Sep 08 '10 at 19:43

answered Sep 06 '10 at 21:18

Zaz

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I've discovered that `curses.halfdelay()` can cause some weird bugs, `screen.nodelay()` + `time.sleep()` seems to work better. – Zaz Sep 08 '10 at 19:46

How do you get the last arrow key pressed using curses?

1 Answers1