A simple macro that expands to different values across compilation targets.
This macro will panic at runtime if no matching value is found.
#[macro_use] extern crate cfg_table;
let var = cfg_table! {
[all(target_os = "freebsd", target_pointer_width = "64", feature = "my-feature")] => 1337, // custom
// common platforms
win32 => 32,
win64 => 64,
linux32 => 32,
linux64 => 64,
macos32 => 32,
macos64 => 64,
// pointer widths
32 => 1985,
"32" => 1985,
64 => 2003,
"64" => 2003,
_ => 123, // default value if nothing matches, this must be at the bottom
};
cfg_table! {
win32 => {
println!("You're on Windows 32-bit!");
},
win64 => {
println!("You're on Windows 64-bit!");
},
_ => {
panic!("What the heck is a \"Linux\"?");
},
};