feat(lib): add helper lib.importPackages

This makes the repo initialization simpler (see examples)

examples/dream2nix-repo-flake/flake.nix

@@ -13,18 +13,14 @@
     ...
   }: let
     system = "x86_64-linux";
-    pkgs = nixpkgs.legacyPackages.${system};
-    lib = nixpkgs.lib;
-    packageModuleNames = builtins.attrNames (builtins.readDir ./packages);
   in {
     # all packages defined inside ./packages/
-    packages.${system} =
-      lib.genAttrs packageModuleNames
-      (moduleName:
-        dream2nix.lib.evalModules {
-          modules = ["${./packages}/${moduleName}" ./settings.nix];
-          packageSets.nixpkgs = pkgs;
-          specialArgs.self = self;
-        });
+    packages.${system} = dream2nix.lib.importPackages {
+      projectRoot = ./.;
+      # can be changed to ".git" or "flake.nix" to get rid of .project-root
+      projectRootFile = ".project-root";
+      packagesDir = "/packages";
+      packageSets.nixpkgs = nixpkgs.legacyPackages.${system};
+    };
   };
 }

examples/dream2nix-repo/default.nix

@@ -7,17 +7,14 @@
 }: let
   dream2nix = import dream2nixSource;
   nixpkgs = import dream2nix.inputs.nixpkgs {};
-  lib = nixpkgs.lib;
-
-  packageModuleNames = builtins.attrNames (builtins.readDir ./packages);
-
-  packages =
-    lib.genAttrs packageModuleNames
-    (moduleName:
-      dream2nix.lib.evalModules {
-        modules = ["${./packages}/${moduleName}" ./settings.nix];
-        packageSets.nixpkgs = nixpkgs;
-      });
+  # all packages defined inside ./packages/
+  packages = dream2nix.lib.importPackages {
+    projectRoot = ./.;
+    # can be changed to ".git" to get rid of .project-root
+    projectRootFile = ".project-root";
+    packagesDir = "/packages";
+    packageSets.nixpkgs = nixpkgs;
+  };
 in
   # all packages defined inside ./packages/
   packages

modules/flake-parts/lib.nix

@@ -7,16 +7,49 @@
   flake.options.lib = lib.mkOption {
     type = lib.types.lazyAttrsOf lib.types.raw;
   };
+  flake.config.lib.importPackages = args @ {
+    projectRoot,
+    projectRootFile,
+    packagesDir,
+    ...
+  }: let
+    packagesDirPath =
+      if ! builtins.isString packagesDir
+      then throw "packagesDir must be a string"
+      else projectRoot + "/${packagesDir}";
+    forwardedArgs = builtins.removeAttrs args [
+      "projectRoot"
+      "projectRootFile"
+      "packagesDir"
+    ];
+  in
+    lib.mapAttrs
+    (
+      module: type:
+        self.lib.evalModules (forwardedArgs
+          // {
+            modules = [
+              (packagesDirPath + "/${module}")
+              {
+                paths.projectRoot = projectRoot;
+                paths.projectRootFile = projectRootFile;
+                paths.package = "/${packagesDir}/${module}";
+              }
+            ];
+          })
+    )
+    (builtins.readDir packagesDirPath);
+
   flake.config.lib.evalModules = args @ {
     packageSets,
     modules,
-    # If set, returns the result coming form nixpgs.lib.evalModules as is,
+    # If set, returns the result coming form nixpkgs.lib.evalModules as is,
     # otherwise it returns the derivation only (.config.public).
     raw ? false,
     specialArgs ? {},
     ...
   }: let
-    forawardedArgs = builtins.removeAttrs args [
+    forwardedArgs = builtins.removeAttrs args [
       "packageSets"
       "raw"
     ];
@@ -24,7 +57,7 @@
     evaluated =
       lib.evalModules
       (
-        forawardedArgs
+        forwardedArgs
         // {
           modules =
             args.modules