xmake-style

Xmake Configuration Style & Conventions

xmake.lua is Lua, but idiomatic xmake code looks less like Lua and more like a declarative configuration. Following the conventions below keeps files readable, fast to parse, and consistent with the style used throughout xmake and xmake-repo.

1. The description / script split (the single most important rule)

xmake.lua has two domains and they have very different rules.

Description domain — keep it declarative

This is the top-level body of target(), option(), package(), task(), rule(), and their set_xxx/add_xxx calls.

target("app")
    set_kind("binary")
    add_files("src/*.cpp")
    add_defines("DEBUG")
    add_syslinks("pthread")

Rules for the description domain:

• Treat it as config, not code. Basic if is_plat(...) and for _, x in ipairs({...}) are fine; complex logic is not.
• It is parsed multiple times. Every set_/add_ call may run more than once as xmake re-enters the file at different configuration stages. Never print() here (you will see it twice), and never do expensive work (I/O, git, network, shell).
• Many APIs are forbidden or read-only here. os.getenv is read-only; most mutating os.* calls are blocked.
• If logic is not a trivial if or for, move it to the script domain.

Script domain — put complex logic here

Anything inside on_load, on_config, before_build, after_build, on_install, on_test, etc., is the script domain. It runs once per lifecycle hook and has the full xmake Lua environment.

target("app")
    set_kind("binary")
    add_files("src/*.cpp")
    on_load(function (target)
        if is_plat("linux", "macosx") then
            target:add("links", "pthread", "m", "dl")
        end
    end)
    after_build(function (target)
        import("core.project.config")
        os.cp(target:targetfile(), path.join(config.buildir(), "dist"))
    end)