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From: Grant Edwards <invalid@invalid.invalid>
Newsgroups: comp.lang.python
Subject: Re: Keypress Input
Date: Mon, 15 Jun 2015 15:22:52 +0000 (UTC)
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On 2015-06-15, Oscar Benjamin <oscar.j.benjamin@gmail.com> wrote:

> Note that going into raw mode has other implications such as not
> being able to exit your program with ctrl-c or suspend with ctrl-z
> etc. You can explicitly process those kinds of contrl keys with
> something like:
>
> while True:
>     key = getch()
>     if 1 <= ord(key) <= 26:
>         ctrl_key = chr(ord(key) + 64)
>         print("ctrl-%c" % ctrl_key)
>         if ctrl_key == 'C':
>             break
>     else:
>         print("key: '%c'" % key)

It's probably better (at least on Linux) to just enable handling of
those characters in by setting the ISIG lflag:

    def getch():
        fd = sys.stdin.fileno()
        oldsettings = termios.tcgetattr(fd)
        try:
            tty.setraw(sys.stdin.fileno())
    
            # enable handling of ctrl-C, ctrl-Z, etc.            
            attr = termios.tcgetattr(fd)
            attr[3] |= termios.ISIG
            termios.tcsetattr(fd,termios.TCSANOW,attr)
    
            c = sys.stdin.read(1)
    
        finally:
            termios.tcsetattr(fd, termios.TCSADRAIN, oldsettings)
        return c

It would be a bit cleaner if the termios module supported the the
cfmakeraw(3) function, then you could do it this way and save a couple
of system calls:

    def getch():
        fd = sys.stdin.fileno()
        oldsettings = termios.tcgetattr(fd)
        try:
            newsettings = termios.makeraw(oldsettings)
            newsettings[3] |= termios.ISIG
            termios.tcsetattr(fd,termios.TCSANOW,newsettings)
            c = sys.stdin.read(1)
        finally:
            termios.tcsetattr(fd, termios.TCSADRAIN, oldsettings)
        return c

[I'm a bit surprised that after all these years using literal integers
to index into the attribute list is the "right" way.]
        
-- 
Grant Edwards               grant.b.edwards        Yow! Well, O.K.
                                  at               I'll compromise with my
                              gmail.com            principles because of
                                                   EXISTENTIAL DESPAIR!