Getting to Understand the Zig package manager(0.15.1)

Zig has a way interesting of integrating packages to a project. And the project can keep track of what has been pulled in for the project. Zig provides a fetch command. This command can download pieces of zig code using github url. But you have to manually add reference of it to your build system to be used properly.

tl;dr;

So, Here is the short description of how to add packages in a project in sequence.

1. use zig fetch --save to import the package to the project.
2. update build.zig to define the dependency, get and define names of modules of the dependencies and finaly link it to the executable

here is sequence template of updating build.zig file

// build.zig already has build function , our modification has to be inside the build function 
pub fn build(b: *std.Build) void {
    // define the dependencies
    const new_package_dep = b.dependency("package-name", .{
        .target = target,
        .optimize = optimize,
    });

    // Get the module from the dependency
    const new_package = new_package_dep.module("module-name");
    // add your c library artifact here
    
    /// somewhere here the exe is already defined 
    
    // Add it to your executable
    exe.root_module.addImport("package-name", new_package);
    // link your c library here as artifact
}

Getting into details with example : raylib

Lets try to integrate raylib plugin for your project. It is written in C language and we are mporting it inside zig project. Inside your projects command line you need to type this

zig fetch --save git+https://github.com/raylib-zig/raylib-zig#devel

this command downloads the package in to the local cache. Then it updates the build.zig.zon like this.

.dependencies = .{
    .raylib_zig = .{
        .url = "git+https://github.com/raylib-zig/raylib-zig?ref=devel#<a-generated-hash-data>",
        .hash = "<a-generated-hash-data>",
    },
},

till this point this looks same as any other package manager. Think of npm for comapriason

• npm install <package-name> becomes zig fetch --save <package-url>
• for npm package.json gets updated and package.json.lock also gets updated with unique hash values. In zig, the build.zig.zon gets updated with the package hash.

Fine and dandy right ! Not quite. Here comes the interesting part.

this package that you installed needs to be manually linked with your build system. This is where you get to dig into the build.zig file. You need to manually add it as the dependency of the project like this

// defining the dependency
const raylib_dep = b.dependency("raylib_zig", .{
    .target = target,
    .optimize = optimize,
});

// define importable modules for the project to be utilized
// This is where modules from the dependency are accessed
// main raylib module
const raylib = raylib_dep.module("raylib"); 
// raygui module
const raygui = raylib_dep.module("raygui"); 

// Define the artifact to be linked to with the executable
// raylib C library
const raylib_artifact = raylib_dep.artifact("raylib"); 

then link the artifact to the exe that is already defined in the build.zig file.

// This is where the modules are added to your executable
exe.linkLibrary(raylib_artifact); // specific to linking c based libraries
exe.root_module.addImport("raylib", raylib); // common for zig libraries
exe.root_module.addImport("raygui", raygui); // common for zig libraries

Now, I think we are ready to build. give it a try. If it doe not build re check the codes added in the zig.build file.

Hope this helps !!!