altprintf

altprintf is a string template language. It was designed with a very specific goal in mind: allowing users to customize a program's functionality through the use of format strings.

• Cool format specifiers, like conditionals.
• UTF-8 character width sensitive alignment
• Nesting expressions
• Robust
  • the library makes no memory allocations
  • an advanced error reporting system
  • fuzz testing based on the grammar in the docs
• Template strings are compiled into a custom binary format
  • this saves resources when reusing the same template

Note that altprintf is not designed to replace printf. It is designed with the specific use case of providing user-specified templates to customize output.

Here is an example format string to build a statusline for something like swaybar.

{win} {fetching?⇄ }{locked?閉 }{mail?〒{mail} }{cpu:> 3}% {temp}c {bat} {time}

Which could result in a string like:

mochiro.moe -- Mozilla Firefox 〒4   3% 49c 45 08:56

You need a compatible meson implementation. If you want man pages, you also need scdoc.

Example:

$meson setup build
$ninja -C build

See the man pages