CMake package finder: use environment variables instead of global cmake registry

Benefits:

• workspace-scoped discovery of CMake / ArmarX packages
• global cmake registry might not be available if disabled by the user => incorrect list of packages

source/ArmarXCore/core/system/cmake/CMakePackageFinder.cpp

@@ -50,10 +50,14 @@
 #include <memory>
 #include <ctime>
 #include <mutex>
+#include <cstdlib>
 
 #define SCRIPT_PATH "ArmarXCore/core/system/cmake/FindPackageX.cmake"
 #define CACHE_PATH "/ArmarXCMakeCache_" + (getenv("USER")?getenv("USER"):"DUMMY_USER")
 
+extern char ** environ;
+
+
 namespace armarx
 {
     std::string getHomeDir()
@@ -435,23 +439,41 @@ namespace armarx
     {
         std::vector<std::string> result;
         using namespace std::filesystem;
-        auto home = getHomeDir();
-        if (!home.empty())
-        {
-            path p = path {home} / ".cmake" / "packages";
-            if (is_directory(p))
+
+        char ** env;
+
+        env = environ;
+
+        for (; *env; ++env) {
+            const std::string envVar(*env);
+            ARMARX_DEBUG << "Retrieved environment variable " << envVar;
+
+            const std::vector<std::string> elements = simox::alg::split(envVar, "=");
+            if(not (elements.size() == 2))
             {
-                for (const path& entry : boost::make_iterator_range(directory_iterator(p), {}))
+                continue;
+            }
+
+            const std::string& envVarName = elements.front();
+            const std::string& envVarValue = elements.back();
+
+            if(simox::alg::ends_with(envVarName, "_DIR"))
+            {
+                const std::string packageName = simox::alg::remove_suffix(envVarName, "_DIR");
+                auto pckFinder = CMakePackageFinder {packageName, envVarValue, true};
+
+                ARMARX_DEBUG << "Package name: " << packageName;
+                ARMARX_DEBUG << "Path: " << envVarValue;
+
+                // check if this is really a package
+                if (pckFinder.packageFound() && !pckFinder.getBuildDir().empty())
                 {
-                    const std::string pkg = entry.filename().string();
-                    auto pckFinder = CMakePackageFinder {pkg, "", true};
-                    if (pckFinder.packageFound() && !pckFinder.getBuildDir().empty())
-                    {
-                        result.push_back(pkg);
-                    }
+                    ARMARX_VERBOSE << "Found package " << packageName;
+                    result.push_back(packageName);
                 }
             }
         }
+
         return result;
     }