Zig construct system | KeepCoding

If you initialize challenge scaffold by way of zig build-exe, it would generate construct.zig with detailed feedback to assist builders perceive what it does. Essentially the most frequent used instructions are:

• zig construct, default step set up is invoked
• zig construct check, check step is invoked

Right here we introduce an important idea in Zig’s construct system: step. A step describe one job, comparable to compile binary, run the check.

Step.zig defines MakeFn as step’s important interface:

pub const MakeFn = *const fn (self: *Step, prog_node: *std.Progress.Node) anyerror!void;

All different concrete steps implements it by way of composition with @fieldParentPtr. If readers do not know this idioms, consult with this post. The next are most typical used steps:

• CompileStep, used to compile binary/static library/static library
• RunStep, used to execute one program
• InstallArtifactStep, used to repeat construct artifacts to zig-out listing

std.Construct gives plenty of handy APIs to outline steps and their relation, comparable to:

• addExecutable outline a CompileStep for software binary
• addTest outline a CompileStep for check binary
• addRunArtifact outline a RunStep for one CompileStep

Steps’ relation is constructed utilizing Step.dependOn operate, and their relation assemble a directed acyclic graph(DAG), which is used to drive the entire construct course of.

Determine above present a easy DAG of steps, steps on the high are particular, and they are often invoked by zig construct ${topLevelStep}, Construct.step operate creates such high degree steps.

After clarification above, readers ought to have a deeper perceive what construct.zig does.

const std = @import("std");

pub fn construct(b: *std.Construct) void {
    const goal = b.standardTargetOptions(.{});
    const optimize = b.standardOptimizeOption(.{});
    const exe = b.addExecutable(.{
        .title = "demo",
        .root_source_file = .{ .path = "src/important.zig" },
        .goal = goal,
        .optimize = optimize,
    });
    b.installArtifact(exe);
    const run_cmd = b.addRunArtifact(exe);
    run_cmd.step.dependOn(b.getInstallStep());
    if (b.args) |args| {
        run_cmd.addArgs(args);
    }
    const run_step = b.step("run", "Run the app");
    run_step.dependOn(&run_cmd.step);
    const unit_tests = b.addTest(.{
        .root_source_file = .{ .path = "src/important.zig" },
        .goal = goal,
        .optimize = optimize,
    });
    const run_unit_tests = b.addRunArtifact(unit_tests);
    const test_step = b.step("check", "Run unit exams");
    test_step.dependOn(&run_unit_tests.step);
}