3 ms·

> And then there's the issue that terminfo is a C library so a lot of languages with average to no-C FFI support cannot use it without fork()ing -- which is slo

by bhaak 2y ago

> And then there's the issue that terminfo is a C library so a lot of languages with average to no-C FFI support cannot use it without fork()ing -- which is slow. Plus terminfo is POSIX only which eliminates platforms like Windows -- which is increasingly a target now that Windows Terminal supports ANSI escape sequences. export TERM=ms-terminal Windows is POSIX. Windows NT always had a POSIX layer. Terminfo is mostly a file based database collection. You don't need to link to the C library, you just must be able to read the terminal infos. > You're missing the point. It's not about supporting the lowest common denominator -- though I'd love you to give some example of terminal emulators in common use that don't support 4-bit colours ;) The question is not about support but about how to get them to be display. Which escape sequences produces colors 8-15? The answer is different from terminal to terminal and that's the problem.

hnlmorg 2y ago
> export TERM=ms-terminal A few problems with that: 1. That then breaks any applications that look for either `xterm` or `256-colors` in the TERM string. Unfortunately these days $TERM behaves more like a User-Agent string in HTTP-land so most terminal emulators are forced to pretend to be `xterm` even when they're not. 2. `export` is a Bourne Shell-ism. Powershell's syntax looks a little more like: $Env:<variable-name> = "<new-value>" https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.core/about/about_environment_variables?view=powershell-7.4 https://learn.microsoft.com/en-us/powershell/module/microsof... > Windows is POSIX. Windows NT always had a POSIX layer. Windows is not POSIX. Windows has POSIX compatibilities in some places but POSIX defines a plethora of different things beyond just C-APIs. For example: Windows doesn't have a lot of the command line utilities defined by POSIX: https://en.wikipedia.org/wiki/List_of_POSIX_commands https://en.wikipedia.org/wiki/List_of_POSIX_commands > Terminfo is mostly a file based database collection. You don't need to link to the C library, you just must be able to read the terminal infos. mostly is doing a lot of heavy lifting there. Also reading those databases without C is non-trivial as well. For example try manually parsing the output of /usr/share/terminfo/74/tmux-256color on macOS. It's also worth noting here that there's two different database formats: terminfo and termcap. And different locations each platform (and users!) might configure those databases to reside. Also tools like `tput` do more than just look up $TERM against terminfo. There are actually a few different places where terminal capabilities are hidden. Including ANSI escape codes, which was originally used in the hardware terminal days before $TERM existed and are still expected to be supported by modern terminal emulators. Let's not forget that you also need to check if you're reading from, or writing to, a TTY. It might actually be a pipe, or even just a regular file. And while there is a standard C API for checking if a file descriptor is a TTY, `isatty()`, that itself is just a hack because there's no ABI in TTYs to return true/false if they are a TTY. So instead isatty() has to send ioctl calls to alter the state of the TTY, but a state that's only supported by TTYs (ie incompatible with pipes and regular files). It's a hack that's worked well for decades, but it's yet another class of edge cases that people take for granted. > The question is not about support but about how to get them to be display. Which escape sequences produces colors 8-15? The answer is different from terminal to terminal and that's the problem. The escape codes don't differ. There is one standard set of escape sequences for 4-bit (8->15). https://en.wikipedia.org/wiki/ANSI_escape_code#3-bit_and_4-bit https://en.wikipedia.org/wiki/ANSI_escape_code#3-bit_and_4-b... What differs is the shade of colours that are produced with those escape codes. And that's exactly why I advocate that developers should stick to 3/4-bit code. The point I'm making is that those colours are defined by the terminal and configurable by the user. Which means individuals can set a colour profile that is readable for them. This is why CLI and TUI developers should default to, and respect, those preferences. Take a read through my comment history. I'm an author of a multitude of advanced CLI and TUI applications as well as terminal emulator and thus I've discussed these topics at great lengths with other people.

by bhaak 2y ago

hnlmorg 2y ago

> export TERM=ms-terminal A few problems with that: 1. That then breaks any applications that look for either `xterm` or `256-colors` in the TERM string. Unfortunately these days $TERM behaves more like a User-Agent string in HTTP-land so most terminal emulators are forced to pretend to be `xterm` even when they're not. 2. `export` is a Bourne Shell-ism. Powershell's syntax looks a little more like: $Env:<variable-name> = "<new-value>" https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.core/about/about_environment_variables?view=powershell-7.4 https://learn.microsoft.com/en-us/powershell/module/microsof... > Windows is POSIX. Windows NT always had a POSIX layer. Windows is not POSIX. Windows has POSIX compatibilities in some places but POSIX defines a plethora of different things beyond just C-APIs. For example: Windows doesn't have a lot of the command line utilities defined by POSIX: https://en.wikipedia.org/wiki/List_of_POSIX_commands https://en.wikipedia.org/wiki/List_of_POSIX_commands > Terminfo is mostly a file based database collection. You don't need to link to the C library, you just must be able to read the terminal infos. mostly is doing a lot of heavy lifting there. Also reading those databases without C is non-trivial as well. For example try manually parsing the output of /usr/share/terminfo/74/tmux-256color on macOS. It's also worth noting here that there's two different database formats: terminfo and termcap. And different locations each platform (and users!) might configure those databases to reside. Also tools like `tput` do more than just look up $TERM against terminfo. There are actually a few different places where terminal capabilities are hidden. Including ANSI escape codes, which was originally used in the hardware terminal days before $TERM existed and are still expected to be supported by modern terminal emulators. Let's not forget that you also need to check if you're reading from, or writing to, a TTY. It might actually be a pipe, or even just a regular file. And while there is a standard C API for checking if a file descriptor is a TTY, `isatty()`, that itself is just a hack because there's no ABI in TTYs to return true/false if they are a TTY. So instead isatty() has to send ioctl calls to alter the state of the TTY, but a state that's only supported by TTYs (ie incompatible with pipes and regular files). It's a hack that's worked well for decades, but it's yet another class of edge cases that people take for granted. > The question is not about support but about how to get them to be display. Which escape sequences produces colors 8-15? The answer is different from terminal to terminal and that's the problem. The escape codes don't differ. There is one standard set of escape sequences for 4-bit (8->15). https://en.wikipedia.org/wiki/ANSI_escape_code#3-bit_and_4-bit https://en.wikipedia.org/wiki/ANSI_escape_code#3-bit_and_4-b... What differs is the shade of colours that are produced with those escape codes. And that's exactly why I advocate that developers should stick to 3/4-bit code. The point I'm making is that those colours are defined by the terminal and configurable by the user. Which means individuals can set a colour profile that is readable for them. This is why CLI and TUI developers should default to, and respect, those preferences. Take a read through my comment history. I'm an author of a multitude of advanced CLI and TUI applications as well as terminal emulator and thus I've discussed these topics at great lengths with other people.