4 ms·

> So, yes, it's absolutely impossible to get key up events in tty context, and at this point it will almost certainly stay that way forever, as it's too late to

by ori_b 8y ago

> So, yes, it's absolutely impossible to get key up events in tty context, and at this point it will almost certainly stay that way forever, as it's too late to retrofit terminal emulators, drivers, and applications to understand whatever protocol for communicating key up events. Why would that be? It seems like it would just be a matter of adding another termcap entry for your specific terminal emulator, and hoping other people care enough to start implementing it in theirs. There's already no particularly consistent standard for most terminal events -- just a database of (I think turing-complete) stack VMs that tell programs how to parse whatever they read from the terminal emulator they're running under. Adding another string-named property to this table that describes key-up events would not be overly difficult.

abcdef123xyz123 8y ago
Hi > There's already no particularly consistent standard for most terminal events This is not really true anymore, almost all terminals still in use (and certainly all that are widely used) are VT100 compatible. In fact most are broadly compatible with xterm. So that is pretty much the standard now, and most new features being added to terminals don't take any account of other types of terminal at all. > It seems like it would just be a matter of adding another termcap entry for your specific terminal emulator, and hoping other people care enough to start implementing it in theirs. termcap was superseded by terminfo around the late 80s. A few applications still use it, but most are now terminfo. The termcap database on most systems is now derived from terminfo. terminfo is centrally managed as part of ncurses and stuff doesn't really get added to it just to see. The way it usually works is that one or more terminals add a feature and if it makes sense and is popular, applications will use it, and if applications use it then often it will end up in terminfo entries. Definitely if ncurses uses it, possibly if not (this can be controversial). You are right that there is no real reason a terminal couldn't send an escape sequence for key up, although it would certainly have to be something requested by the application - there are plenty of other escape sequences like that (eg the mouse, focus events). The tty doesn't really come into it, nor does the kernel or drivers, except for its own console terminal, but not many people use that very much. SGR mouse mode is an example of a terminal feature added relatively recently which has been taken up widely.
- ori_b 8y ago
  > This is not really true anymore, almost all terminals still in use (and certainly all that are widely used) are VT100 compatible. VT100 is a tiny subset of what's defined in termcap.
  - abcdef123xyz123 8y ago
    There are no terminals still in widespread use that are not VT100-compatible, by which I mean they use the escape sequence protocol originally used in the DEC terminals, although of course it has been much extended.
  - abcdef123xyz123 8y ago
    My point is that for new features, like key up would be, it is not necessary to be bound by terminfo. If some or all of xterm, VTE, konsole, rxvt-unicode and iterm2 supported it, that is a large proportion of the modern *nix terminals that people still use. And they are all VT100 compatible terminals. If you look at a lot of recent features, such as SGR mouse mode, RGB colour, underline styles, focus events - they are all based on VT100 style escape sequences, and they all started with a few terminals and existed for a good while (with applications using them) before terminfo added any sort of support.

> So, yes, it's absolutely impossible to get key up events in tty context, and at this point it will almost certainly stay that way forever, as it's too late to

by ori_b 8y ago

abcdef123xyz123 8y ago

Hi > There's already no particularly consistent standard for most terminal events This is not really true anymore, almost all terminals still in use (and certainly all that are widely used) are VT100 compatible. In fact most are broadly compatible with xterm. So that is pretty much the standard now, and most new features being added to terminals don't take any account of other types of terminal at all. > It seems like it would just be a matter of adding another termcap entry for your specific terminal emulator, and hoping other people care enough to start implementing it in theirs. termcap was superseded by terminfo around the late 80s. A few applications still use it, but most are now terminfo. The termcap database on most systems is now derived from terminfo. terminfo is centrally managed as part of ncurses and stuff doesn't really get added to it just to see. The way it usually works is that one or more terminals add a feature and if it makes sense and is popular, applications will use it, and if applications use it then often it will end up in terminfo entries. Definitely if ncurses uses it, possibly if not (this can be controversial). You are right that there is no real reason a terminal couldn't send an escape sequence for key up, although it would certainly have to be something requested by the application - there are plenty of other escape sequences like that (eg the mouse, focus events). The tty doesn't really come into it, nor does the kernel or drivers, except for its own console terminal, but not many people use that very much. SGR mouse mode is an example of a terminal feature added relatively recently which has been taken up widely.

ori_b 8y ago
> This is not really true anymore, almost all terminals still in use (and certainly all that are widely used) are VT100 compatible. VT100 is a tiny subset of what's defined in termcap.
- abcdef123xyz123 8y ago
  There are no terminals still in widespread use that are not VT100-compatible, by which I mean they use the escape sequence protocol originally used in the DEC terminals, although of course it has been much extended.
- abcdef123xyz123 8y ago
  My point is that for new features, like key up would be, it is not necessary to be bound by terminfo. If some or all of xterm, VTE, konsole, rxvt-unicode and iterm2 supported it, that is a large proportion of the modern *nix terminals that people still use. And they are all VT100 compatible terminals. If you look at a lot of recent features, such as SGR mouse mode, RGB colour, underline styles, focus events - they are all based on VT100 style escape sequences, and they all started with a few terminals and existed for a good while (with applications using them) before terminfo added any sort of support.