impl

build.zig

@@ -1,25 +0,0 @@
-const std = @import("std");
-
-pub fn build(b: *std.Build) void {
-    const target = b.standardTargetOptions(.{});
-    const optimize = b.standardOptimizeOption(.{});
-
-    const exe = b.addExecutable(.{
-        .name = "zmodule",
-        .root_source_file = b.path("src/main.zig"),
-        .target = target,
-        .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);
-}

main.zig

@@ -0,0 +1,52 @@
+const std = @import("std");
+
+const Render = struct {
+    const depends = .{};
+};
+
+const Window = struct {
+    const depends = .{Render};
+};
+
+const ImGui = struct {
+    const depends = .{ Render, Window };
+};
+
+const App = struct {
+    const depends = .{ImGui};
+};
+
+fn append(comptime T: type, comptime list: []const T, comptime val: T) []const T {
+    return list ++ [1]T{val};
+}
+
+fn contains(comptime T: type, comptime haystack: []const T, comptime needle: T) bool {
+    return std.mem.indexOfScalar(T, haystack, needle) != null;
+}
+
+pub fn dependencies(mod: type) []const type {
+    // todo add a "before" and "after" that impose ordering constraints but don't bring the items in as depednencies.
+
+    const Ctx = struct {
+        all: []const type = &.{},
+        mark: []const type = &.{},
+
+        fn visit(ctx: *@This(), x: type) void {
+            if (contains(type, ctx.all, x)) return;
+            if (contains(type, ctx.mark, x)) @compileError("cycle");
+            ctx.mark = append(type, ctx.mark, x);
+            for (x.depends) |dep| ctx.visit(dep);
+            ctx.all = append(type, ctx.all, x);
+        }
+    };
+
+    var ctx: Ctx = .{};
+    ctx.visit(mod);
+    return ctx.all;
+}
+
+pub fn main() !void {
+    inline for (dependencies(App)) |dep| {
+        std.debug.print("{s}\n", .{@typeName(dep)});
+    }
+}

src/main.zig

@@ -1,24 +0,0 @@
-const std = @import("std");
-
-pub fn main() !void {
-    // Prints to stderr (it's a shortcut based on `std.io.getStdErr()`)
-    std.debug.print("All your {s} are belong to us.\n", .{"codebase"});
-
-    // stdout is for the actual output of your application, for example if you
-    // are implementing gzip, then only the compressed bytes should be sent to
-    // stdout, not any debugging messages.
-    const stdout_file = std.io.getStdOut().writer();
-    var bw = std.io.bufferedWriter(stdout_file);
-    const stdout = bw.writer();
-
-    try stdout.print("Run `zig build test` to run the tests.\n", .{});
-
-    try bw.flush(); // don't forget to flush!
-}
-
-test "simple test" {
-    var list = std.ArrayList(i32).init(std.testing.allocator);
-    defer list.deinit(); // try commenting this out and see if zig detects the memory leak!
-    try list.append(42);
-    try std.testing.expectEqual(@as(i32, 42), list.pop());
-}