Zig build script - passing command line value example

build.zig

const Builder = @import("std").build.Builder;
const std = @import("std");
pub const OptionsStep = @import("std").build.OptionsStep;

pub fn build(b: *Builder) void {

    var option = b.option(bool,"Desktop", "Set to true to build desktop focused library");

    if(option == true){
            std.log.info("TODO",.{});
    }else {
        const exe = b.addExecutable("zig_gl", "src/main.zig");
        exe.setTarget(.{.cpu_arch = .wasm32, .os_tag = .freestanding});
        exe.setOutputDir("client");

        // finally build wasm.
        b.default_step.dependOn(&exe.step);
    }
}