Don't hardcode the version number in the nix package

Author: mmarx

nix/pkgs/rulewerk/default.nix

@@ -16,7 +16,7 @@
 in
   stdenv.mkDerivation rec {
     pname = "rulewerk";
-    version = "0.10.0-SNAPSHOT";
+    version = "unstable-latest";
     src = gitignoreSource ../../..;
 
     modules = [
@@ -114,15 +114,18 @@ in
     installPhase = ''
       runHook preInstall
 
+      # find the version number from the generated artifacts
+      vers=$(basename ${pname}-core/target/${pname}-core-*.jar | cut -d'-' -f3- | sed -e 's/.jar$//')
+
       mkdir -p $out/bin $out/share/java
       find $out/lib -type f -regex '.+\(\.lastUpdated\|resolver-status\.properties\|_remote\.repositories\|maven-metadata-local\.xml\)' -delete
       for module in ${toString modules}
       do
-        cp ${pname}-$module/target/${pname}-$module-${version}.jar $out/share/java
+        cp ${pname}-$module/target/${pname}-$module-$vers.jar $out/share/java
       done
 
-      cp rulewerk-client/target/standalone-rulewerk-client-${version}.jar $out/share/java
-      makeWrapper ${jdk}/bin/java $out/bin/${pname} --add-flags "-jar $out/share/java/standalone-rulewerk-client-${version}.jar"
+      cp rulewerk-client/target/standalone-rulewerk-client-$vers.jar $out/share/java
+      makeWrapper ${jdk}/bin/java $out/bin/${pname} --add-flags "-jar $out/share/java/standalone-rulewerk-client-$vers.jar"
       makeWrapper ${maven}/bin/mvn $out/bin/mvn --add-flags "-DdependenciesFromNix.repo=$out/lib"
 
       runHook postInstall