Allow building and installing local packages

2 files changed, 24 insertions, 1 deletions

diff --git a/README.md b/README.md
index e85612f..4a5a119 100644
--- a/README.md
+++ b/README.md
@@ -26,11 +26,18 @@ For example:
     modules/pkgs/writeXML.nix        => pkgs.writeXML
     modules/pkgs/rdsdump/default.nix => pkgs.rdsdump
 
-You can use this technics in your own projects. You can take out any modules
+You can use this techniques in your own projects. You can take out any modules
 or packages and put them into your project with your modifications without
 maintaning a fork of Nixsap.  When taking modules you have to change the
 `nixsap` namespace to something different to avoid conflicts.
 
+It is also possible to build and install packages that are overridden
+by Nixsap, for example:
+
+```
+nix-env -I nixpkgs=/path/to/vanila/nixpkgs -f /path/to/nixsap/pkgs -i nodejs-sass
+```
+
 
 Automatic unix user id
 -----------------------
diff --git a/pkgs/default.nix b/pkgs/default.nix
new file mode 100644
index 0000000..60159f8
--- /dev/null
+++ b/pkgs/default.nix
@@ -0,0 +1,16 @@
+let
+
+  inherit (import <nixpkgs/lib>) evalModules;
+
+
+  evaluated = evalModules {
+    modules = [
+      { nixpkgs.system = builtins.currentSystem; }
+      (import <nixpkgs/nixos/modules/misc/nixpkgs.nix>)
+      (import ../modules/pkgs)
+    ];
+  };
+
+  inherit (evaluated.config._module.args) pkgs;
+
+in pkgs