use <auto> filename path

dtool/src/dtoolutil/load_dso.cxx

@@ -20,8 +20,10 @@
 
 static Filename resolve_dso(const DSearchPath &path, const Filename &filename) {
   if (filename.is_local()) {
-    if (path.is_empty()||
-        ((path.get_num_directories()==1)&&(path.get_directory(0)=="."))) {
+    if ((path.get_num_directories()==1)&&(path.get_directory(0)=="<auto>")) {
+      // This is a special case, meaning to search in the same
+      // directory in which libp3dtool.dll, or the exe, was started
+      // from.
       Filename dtoolpath = ExecutionEnvironment::get_dtool_name();
       DSearchPath spath(dtoolpath.get_dirname());
       return spath.find_file(filename);

dtool/src/prc/configVariableSearchPath.I

@@ -30,6 +30,59 @@ ConfigVariableSearchPath(const string &name,
 #else
   ConfigVariableBase(name, VT_search_path, string(), flags),
 #endif
+  _default_value(Filename(".")),
+  _local_modified(initial_invalid_cache())
+{
+  // A SearchPath variable implicitly defines a default value of the empty
+  // string.  This is just to prevent the core variable from
+  // complaining should anyone ask for its solitary value.
+  if (_core->get_default_value() == (ConfigDeclaration *)NULL) {
+    _core->set_default_value("");
+  }
+  _core->set_used();
+}
+
+////////////////////////////////////////////////////////////////////
+//     Function: ConfigVariableSearchPath::Constructor
+//       Access: Published
+//  Description: 
+////////////////////////////////////////////////////////////////////
+INLINE ConfigVariableSearchPath::
+ConfigVariableSearchPath(const string &name, 
+                         const DSearchPath &default_value,
+                         const string &description, int flags) :
+#ifdef PRC_SAVE_DESCRIPTIONS
+  ConfigVariableBase(name, VT_search_path, description, flags),
+#else
+  ConfigVariableBase(name, VT_search_path, string(), flags),
+#endif
+  _default_value(default_value),
+  _local_modified(initial_invalid_cache())
+{
+  // A SearchPath variable implicitly defines a default value of the empty
+  // string.  This is just to prevent the core variable from
+  // complaining should anyone ask for its solitary value.
+  if (_core->get_default_value() == (ConfigDeclaration *)NULL) {
+    _core->set_default_value("");
+  }
+  _core->set_used();
+}
+
+////////////////////////////////////////////////////////////////////
+//     Function: ConfigVariableSearchPath::Constructor
+//       Access: Published
+//  Description: 
+////////////////////////////////////////////////////////////////////
+INLINE ConfigVariableSearchPath::
+ConfigVariableSearchPath(const string &name, 
+                         const string &default_value,
+                         const string &description, int flags) :
+#ifdef PRC_SAVE_DESCRIPTIONS
+  ConfigVariableBase(name, VT_search_path, description, flags),
+#else
+  ConfigVariableBase(name, VT_search_path, string(), flags),
+#endif
+  _default_value(Filename(default_value)),
   _local_modified(initial_invalid_cache())
 {
   // A SearchPath variable implicitly defines a default value of the empty
@@ -74,6 +127,16 @@ get_value() const {
   return _cache;
 }
 
+////////////////////////////////////////////////////////////////////
+//     Function: ConfigVariableSearchPath::get_default_value
+//       Access: Published
+//  Description: 
+////////////////////////////////////////////////////////////////////
+INLINE const DSearchPath &ConfigVariableSearchPath::
+get_default_value() const {
+  return _default_value;
+}
+
 ////////////////////////////////////////////////////////////////////
 //     Function: ConfigVariableSearchPath::clear_local_value
 //       Access: Published

dtool/src/prc/configVariableSearchPath.cxx

@@ -46,10 +46,11 @@ reload_search_path() {
       _cache.append_directory(Filename::from_os_specific(expanded));
     }
   }
-  _cache.append_path(_postfix);
 
-  if (_cache.is_empty()) {
-    // An empty search path implicitly has "." on it.
-    _cache.append_directory(".");
+  if (num_unique_references == 0) {
+    // An empty search path implicitly has the default value.
+    _cache = _default_value;
   }
+
+  _cache.append_path(_postfix);
 }

dtool/src/prc/configVariableSearchPath.h

@@ -48,10 +48,19 @@ PUBLISHED:
   INLINE ConfigVariableSearchPath(const string &name, 
                                   const string &description = string(), 
                                   int flags = 0);
+  INLINE ConfigVariableSearchPath(const string &name, 
+                                  const DSearchPath &default_value,
+                                  const string &description, 
+                                  int flags = 0);
+  INLINE ConfigVariableSearchPath(const string &name, 
+                                  const string &default_value,
+                                  const string &description, 
+                                  int flags = 0);
   INLINE ~ConfigVariableSearchPath();
 
   INLINE operator const DSearchPath & () const;
   INLINE const DSearchPath &get_value() const;
+  INLINE const DSearchPath &get_default_value() const;
 
   INLINE bool clear_local_value();
 
@@ -77,6 +86,7 @@ PUBLISHED:
 private:
   void reload_search_path();
 
+  DSearchPath _default_value;
   DSearchPath _prefix, _postfix;
 
   AtomicAdjust::Integer _local_modified;