feature: sourceOverrides

flake.nix

@@ -22,6 +22,7 @@
 
       dream2nixFor = forAllSystems (system: import ./src rec {
         pkgs = nixpkgsFor."${system}";
+        inherit lib;
         externalSources = pkgs.runCommand "dream2nix-imported" {} ''
           mkdir -p $out/npmlock2nix
           cp ${npmlock2nix}/{internal.nix,LICENSE} $out/npmlock2nix/

src/builders/default.nix

@@ -1,5 +1,6 @@
 {
   callPackage,
+  ...
 }:
 {
   python =  rec {

src/builders/python/simple-builder/default.nix

@@ -1,6 +1,7 @@
 {
   lib,
   pkgs,
+  ...
 }:
 
 {
@@ -20,7 +21,7 @@ python.pkgs.buildPythonPackage {
   nativeBuildInputs = [ pkgs.autoPatchelfHook python.pkgs.wheelUnpackHook ];
   unpackPhase = ''
     mkdir dist 
-    for file in ${lib.attrValues fetchedSources}; do
+    for file in ${builtins.toString (lib.attrValues fetchedSources)}; do
       # pick right most element of path
       fname=''${file##*/}
       fname=$(stripHash $fname)

src/default.nix

@@ -1,5 +1,6 @@
 {
   pkgs ? import <nixpkgs> {},
+  lib ? pkgs.lib,
   externalSources ?
     if builtins.getEnv "d2nExternalSources" != "" then
       builtins.getEnv "d2nExternalSources"
@@ -63,17 +64,37 @@ rec {
     {
       genericLock,
       builder ? findBuilder (parseLock genericLock),
-      fetcher ? findFetcher (parseLock genericLock)
+      fetcher ? findFetcher (parseLock genericLock),
+      sourceOverrides ? oldSources: {},
     }:
     let
-      # is generic lock is a file, read and parse it
+      # if generic lock is a file, read and parse it
       genericLock' = (parseLock genericLock);
       fetched = fetcher {
         sources = genericLock'.sources;
         sourcesCombinedHash = genericLock'.generic.sourcesCombinedHash;
       };
+      sourcesToReplace = sourceOverrides fetched.fetchedSources;
+      sourcesOverridden = lib.mapAttrs (pname: source:
+        sourcesToReplace."${pname}" or source
+      ) fetched.fetchedSources;
+      sourcesEnsuredOverridden = lib.mapAttrs (pname: source:
+        if source == "unknown" then throw ''
+          Source '${pname}' is unknown. Please override using:
+          dream2nix.buildPackage {
+            ...
+            sourceOverrides = oldSources: {
+              "${pname}" = ...;
+            };
+            ...
+          };
+        ''
+        else source
+      ) sourcesOverridden;
     in
-      fetched;
+      fetched // {
+        fetchedSources = sourcesEnsuredOverridden;
+      };
 
 
   # automatically build package defined by generic lock
@@ -81,10 +102,11 @@ rec {
     {
       genericLock,
       builder ? findBuilder (parseLock genericLock),
-      fetcher ? findFetcher (parseLock genericLock)
+      fetcher ? findFetcher (parseLock genericLock),
+      sourceOverrides ? oldSources: {},
     }@args:
     let
-      # is generic lock is a file, read and parse it
+      # if generic lock is a file, read and parse it
       genericLock' = (parseLock genericLock);
     in
     builder {

src/fetchers/combined-fetcher.nix

@@ -23,9 +23,9 @@ let
   defaultFetched = (defaultFetcher { inherit sources; }).fetchedSources;
 
   # extract the arguments from the individual fetcher calls
-  fetcherArgsAll =
+  FODArgsAll =
     let
-      fetcherArgsAll' =
+      FODArgsAll' =
         lib.mapAttrs
           (pname: fetched:
 
@@ -35,24 +35,20 @@ let
                 passthru.originalArgs = args;
               })).originalArgs
 
-            # handle non-FOD sources
-            else if lib.isDerivation fetched || lib.isStorePath fetched then
-              null
+            # handle unknown sources
+            else if fetched == "unknown" then
+              "unknown"
 
             # error out on unknown source types
             else
               throw ''
                 Error while generating FOD fetcher for combined sources.
                 Cannot classify source of '${pname}'.
-                Known source types:
-                  - FOD
-                  - derivation
-                  - store path
               ''
           )
           defaultFetched;
     in
-      lib.filterAttrs (pname: fetcherArgs: fetcherArgs != null) fetcherArgsAll';
+      lib.filterAttrs (pname: fetcherArgs: fetcherArgs != "unknown") FODArgsAll';
 
   # convert arbitrary types to string, like nix does with derivation arguments
   toString = x:
@@ -99,7 +95,7 @@ let
         popd
         rm -r workdir
         export out=$OUT_ORIG
-      '') fetcherArgsAll )}
+      '') FODArgsAll )}
 
     echo "FOD_PATH=$(${nix}/bin/nix hash-path $out)"
   '';
@@ -109,7 +105,7 @@ let
       nativeBuildInputs' = lib.foldl (a: b: a ++ b) [] (
         lib.mapAttrsToList
           (pname: fetcherArgs: (fetcherArgs.nativeBuildInputs or []))
-          fetcherArgsAll
+          FODArgsAll
       );
     in
       stdenv.mkDerivation rec {
@@ -130,9 +126,9 @@ in
   fetchedSources =
     # attrset: pname -> path of downloaded source
     lib.genAttrs (lib.attrNames sources) (pname:
-      if fetcherArgsAll ? "${pname}" then
-        "${FODAllSources}/${fetcherArgsAll."${pname}".name}"
+      if FODArgsAll ? "${pname}" then
+        "${FODAllSources}/${FODArgsAll."${pname}".name}"
       else
-        sources."${pname}"
+        defaultFetched."${pname}"
     );
 }

src/fetchers/default-fetcher.nix

@@ -37,7 +37,7 @@
         sha256 = source.hash or null;
       }
     else if source.type == "unknown" then
-      null
+      "unknown"
     else throw "unsupported source type '${source.type}'"
   ) sources;
 }