emulationstation: detach sources acquisition

pkgs/by-name/em/emulationstation/package.nix

@@ -1,31 +1,26 @@
-{ lib
-, SDL2
-, alsa-lib
-, boost
-, cmake
-, curl
-, fetchFromGitHub
-, freeimage
-, freetype
-, libGL
-, libGLU
-, libvlc
-, pkg-config
-, rapidjson
-, stdenv
+{
+  lib,
+  SDL2,
+  alsa-lib,
+  boost,
+  callPackage,
+  cmake,
+  curl,
+  freeimage,
+  freetype,
+  libGL,
+  libGLU,
+  libvlc,
+  pkg-config,
+  rapidjson,
+  stdenv,
 }:
 
-stdenv.mkDerivation (finalAttrs: {
-  pname = "emulationstation";
-  version = "2.11.2";
-
-  src = fetchFromGitHub {
-    owner = "RetroPie";
-    repo = "EmulationStation";
-    rev = "v${finalAttrs.version}";
-    fetchSubmodules = true;
-    hash = "sha256-J5h/578FVe4DXJx/AvpRnCIUpqBeFtmvFhUDYH5SErQ=";
-  };
+let
+  sources = callPackage ./sources.nix { };
+in
+stdenv.mkDerivation {
+  inherit (sources.emulationstation) pname version src;
 
   nativeBuildInputs = [
     SDL2
@@ -46,12 +41,12 @@ stdenv.mkDerivation (finalAttrs: {
     rapidjson
   ];
 
-  strictDeps = true;
-
   cmakeFlags = [
     (lib.cmakeBool "GL" true)
   ];
 
+  strictDeps = true;
+
   installPhase = ''
     runHook preInstall
 
@@ -70,6 +65,10 @@ stdenv.mkDerivation (finalAttrs: {
     popd
   '';
 
+  passthru = {
+    inherit sources;
+  };
+
   meta = {
     homepage = "https://github.com/RetroPie/EmulationStation";
     description = "Flexible emulator front-end supporting keyboardless navigation and custom system themes (forked by RetroPie)";
@@ -78,4 +77,4 @@ stdenv.mkDerivation (finalAttrs: {
     maintainers = with lib.maintainers; [ AndersonTorres edwtjo ];
     platforms = lib.platforms.linux;
   };
-})
+}

pkgs/by-name/em/emulationstation/sources.nix

@@ -0,0 +1,21 @@
+{
+  fetchFromGitHub,
+}:
+
+{
+  emulationstation = let
+    self = {
+      pname = "emulationstation";
+      version = "2.11.2";
+
+      src = fetchFromGitHub {
+        owner = "RetroPie";
+        repo = "EmulationStation";
+        rev = "v${self.version}";
+        fetchSubmodules = true;
+        hash = "sha256-J5h/578FVe4DXJx/AvpRnCIUpqBeFtmvFhUDYH5SErQ=";
+      };
+    };
+  in
+    self;
+}