From 245655b7a16d2030a8768bd8158042b6b5e7412e Mon Sep 17 00:00:00 2001
From: "Yury G. Kudryashov" <urkud.urkud@gmail.com>
Date: Sat, 1 Sep 2007 18:26:13 +0000
Subject: [PATCH] Added support for overridable variants of package. For
 details read comments near getVersion function, gettext is the current
 example.

svn path=/nixpkgs/trunk/; revision=9235
---
 .../{gettext-0.14.6.nix => 0.14.6.nix}        |  0
 .../gettext/{gettext-0.15.nix => 0.15.nix}    |  0
 .../{gettext-0.16.x.nix => 0.16.x.nix}        |  0
 .../development/libraries/gettext/default.nix |  9 +++++++-
 pkgs/top-level/all-packages.nix               | 21 ++++++++++++++++++-
 5 files changed, 28 insertions(+), 2 deletions(-)
 rename pkgs/development/libraries/gettext/{gettext-0.14.6.nix => 0.14.6.nix} (100%)
 rename pkgs/development/libraries/gettext/{gettext-0.15.nix => 0.15.nix} (100%)
 rename pkgs/development/libraries/gettext/{gettext-0.16.x.nix => 0.16.x.nix} (100%)

diff --git a/pkgs/development/libraries/gettext/gettext-0.14.6.nix b/pkgs/development/libraries/gettext/0.14.6.nix
similarity index 100%
rename from pkgs/development/libraries/gettext/gettext-0.14.6.nix
rename to pkgs/development/libraries/gettext/0.14.6.nix
diff --git a/pkgs/development/libraries/gettext/gettext-0.15.nix b/pkgs/development/libraries/gettext/0.15.nix
similarity index 100%
rename from pkgs/development/libraries/gettext/gettext-0.15.nix
rename to pkgs/development/libraries/gettext/0.15.nix
diff --git a/pkgs/development/libraries/gettext/gettext-0.16.x.nix b/pkgs/development/libraries/gettext/0.16.x.nix
similarity index 100%
rename from pkgs/development/libraries/gettext/gettext-0.16.x.nix
rename to pkgs/development/libraries/gettext/0.16.x.nix
diff --git a/pkgs/development/libraries/gettext/default.nix b/pkgs/development/libraries/gettext/default.nix
index 9ceea47d22c..54a0d36cf76 100644
--- a/pkgs/development/libraries/gettext/default.nix
+++ b/pkgs/development/libraries/gettext/default.nix
@@ -1 +1,8 @@
-import ./gettext-0.14.6.nix
+args:
+rec {
+	recurseForDerivations = true;
+	default = v_0_14_6;
+	v_0_14_6 = (import ./0.14.6.nix) args;
+	v_0_15 = (import ./0.15.nix) args;
+	v_0_16_x = (import ./0.16.x.nix) args;
+}
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index b771e4daa75..e629b9902e9 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -129,6 +129,23 @@ rec {
   # a default value if the attribute doesn't exist.
   getConfig = attrPath: default: library.getAttr attrPath default config;
 
+  # Return user-choosen version of given package. If you define package as
+  #
+  # pkgname_alts =
+  # {
+  #   v_0_1 = ();
+  #   v_0_2 = ();
+  #   default = v_0_1;
+  #   recurseForDerivations = true;
+  # };
+  # pkgname = getVersion "name" pkgname_alts;
+  #
+  # user will be able to write in his configuration.nix something like
+  # environment = { versions = { name = v_0_2; }; }; and pkgname will be equal
+  # to pkgname_alts.v_0_2. Using alts.default by default.
+  getVersion = name: alts: builtins.getAttr
+    (getConfig [ "environment" "versions" name ] "default") alts;
+
   # The contents of the configuration file found at $NIXPKGS_CONFIG or
   # $HOME/.nixpkgs/config.nix.
   config =
@@ -1439,7 +1456,9 @@ rec {
     inherit fetchurl stdenv;
   };
 
-  gettext = import ../development/libraries/gettext {
+  gettext = getVersion "gettext" gettext_alts;
+
+  gettext_alts = import ../development/libraries/gettext {
     inherit fetchurl stdenv;
   };