Some enhancement for specifying klayout paths

$KLAYOUT_HOME can now be empty which has the same effect
than setting it to /dev/null - no home folder is present and
no packages will be searched there.

$KLAYOUT_PATH can be empty which makes KLayout not choose
the installation folder as the default path location as before.

src/lay/lay/layApplication.cc

@@ -258,7 +258,10 @@ ApplicationBase::parse_cmd (int &argc, char **argv)
       }
     }
 
+    m_config_file_to_write.clear ();
+    if (! m_appdata_path.empty ()) {
       m_config_file_to_write = tl::to_string (QDir (tl::to_qstring (m_appdata_path)).absoluteFilePath (QString::fromUtf8 ("klayoutrc")));
+    }
 
     //  Hint: the order is reverse in the sense that the first one wins ...
     for (std::vector <std::string>::const_iterator p = m_klayout_path.end (); p != m_klayout_path.begin (); ) {
@@ -733,10 +736,12 @@ ApplicationBase::init_app ()
     std::vector<std::string> global_modules = scan_global_modules ();
     m_load_macros.insert (m_load_macros.begin (), global_modules.begin (), global_modules.end ());
 
+    size_t local_folders = (lay::get_appdata_path ().empty () ? 0 : 1);
+
     for (std::vector <std::string>::const_iterator p = m_klayout_path.begin (); p != m_klayout_path.end (); ++p) {
-      if (p == m_klayout_path.begin ()) {
+      if (p - m_klayout_path.begin () < local_folders) {
         mc->add_path (*p, tl::to_string (QObject::tr ("Local")), std::string (), false);
-      } else if (m_klayout_path.size () == 2) {
+      } else if (m_klayout_path.size () == 1 + local_folders) {
         mc->add_path (*p, tl::to_string (QObject::tr ("Global")), std::string (), true);
       } else {
         mc->add_path (*p, tl::to_string (QObject::tr ("Global")) + " - " + *p, std::string (), true);

src/lay/lay/layHelpSource.cc

@@ -274,13 +274,18 @@ HelpSource::initialize_index ()
     bool ok = false;
 
     const QString help_index_cache_file = QString::fromUtf8 ("help-index.xml");
-    std::string per_user_cache_file = tl::to_string (QDir (tl::to_qstring (lay::ApplicationBase::instance ()->appdata_path ())).absoluteFilePath (help_index_cache_file));
+    std::string per_user_cache_file;
+    if (! lay::ApplicationBase::instance ()->appdata_path ().empty ()) {
+      per_user_cache_file = tl::to_string (QDir (tl::to_qstring (lay::ApplicationBase::instance ()->appdata_path ())).absoluteFilePath (help_index_cache_file));
+    }
 
     //  Try to obtain the help index from the installation or application path
 
     std::vector<std::string> cache_files;
     cache_files.push_back (tl::to_string (QDir (tl::to_qstring (lay::ApplicationBase::instance ()->inst_path ())).absoluteFilePath (help_index_cache_file)));
+    if (! per_user_cache_file.empty ()) {
       cache_files.push_back (per_user_cache_file);
+    }
 
     for (std::vector<std::string>::const_iterator c = cache_files.begin (); ! ok && c != cache_files.end (); ++c) {
 
@@ -307,7 +312,7 @@ HelpSource::initialize_index ()
 
     }
 
-    if (! ok) {
+    if (! ok && ! per_user_cache_file.empty ()) {
       //  If no index is found, create one in "per_user_cache_file"
       produce_index_file (per_user_cache_file);
     }

src/lay/lay/layMacroController.cc

@@ -262,7 +262,7 @@ MacroController::drop_url (const std::string &path_or_url)
   macro->load_from (path);
   macro->set_file_path (path);
 
-  if (macro->is_autorun () || macro->show_in_menu ()) {
+  if ((macro->is_autorun () || macro->show_in_menu ()) && ! lay::ApplicationBase::instance ()->appdata_path ().empty ()) {
 
     //  install macro permanently
     if (QMessageBox::question (mp_mw,

src/lay/lay/laySystemPaths.cc

@@ -40,8 +40,9 @@ namespace lay
 std::string 
 get_appdata_path ()
 {
-  if (tl::has_env ("KLAYOUT_HOME")) {
+  const char *klayout_home_env = "KLAYOUT_HOME";
-    return tl::get_env ("KLAYOUT_HOME");
+  if (tl::has_env (klayout_home_env)) {
+    return tl::get_env (klayout_home_env);
   }
 
   QDir appdata_dir = QDir::homePath ();
@@ -105,11 +106,18 @@ get_klayout_path ()
     std::vector<std::string> klayout_path;
 
     //  generate the klayout path: the first component is always the appdata path
-    klayout_path.push_back (get_appdata_path ());
+    std::string adp = get_appdata_path ();
+    if (! adp.empty ()) {
+      klayout_path.push_back (adp);
+    }
 
-    std::string env = tl::get_env ("KLAYOUT_PATH");
+    const char *klayout_path_env = "KLAYOUT_PATH";
+
+    if (tl::has_env (klayout_path_env)) {
+      std::string env = tl::get_env (klayout_path_env);
       if (! env.empty ()) {
         split_path (env, klayout_path);
+      }
     } else {
       klayout_path.push_back (tl::get_inst_path ());
     }