From c62b4467b442d269c24585b7b8bf490d4cb2aed3 Mon Sep 17 00:00:00 2001
From: James Turner <zakalawe@mac.com>
Date: Thu, 10 Dec 2015 14:51:56 -0600
Subject: [PATCH] Templated helper to retrieve a subsystem

- example of naming a subsystem
---
 simgear/sound/soundmgr_openal.hxx   | 11 +++++------
 simgear/structure/subsystem_mgr.hxx | 26 ++++++++++++++++----------
 2 files changed, 21 insertions(+), 16 deletions(-)

diff --git a/simgear/sound/soundmgr_openal.hxx b/simgear/sound/soundmgr_openal.hxx
index 58168fc8..19897e32 100644
--- a/simgear/sound/soundmgr_openal.hxx
+++ b/simgear/sound/soundmgr_openal.hxx
@@ -34,7 +34,7 @@
 #include <vector>
 #include <map>
 #include <memory> // for std::auto_ptr
-     
+
 #include <simgear/compiler.h>
 #include <simgear/structure/subsystem_mgr.hxx>
 #include <simgear/math/SGMath.hxx>
@@ -55,7 +55,7 @@ public:
 
     void init();
     void update(double dt);
-    
+
     void suspend();
     void resume();
     void stop();
@@ -93,7 +93,7 @@ public:
      */
     bool add( SGSampleGroup *sgrp, const std::string& refname );
 
-    /** 
+    /**
      * Remove a sample group from the sound manager.
      * @param refname Reference name of the sample group to remove
      * @return true if successful, false otherwise
@@ -268,11 +268,12 @@ public:
     const std::string& get_vendor() { return _vendor; }
     const std::string& get_renderer() { return _renderer; }
 
+    static const char* subsystemName() { return "sound"; };
 private:
     class SoundManagerPrivate;
     /// private implementation object
     std::auto_ptr<SoundManagerPrivate> d;
-        
+
     bool _active;
     bool _changed;
     float _volume;
@@ -298,5 +299,3 @@ private:
 
 
 #endif // _SG_SOUNDMGR_OPENAL_HXX
-
-
diff --git a/simgear/structure/subsystem_mgr.hxx b/simgear/structure/subsystem_mgr.hxx
index 4139fa68..7a07f21c 100644
--- a/simgear/structure/subsystem_mgr.hxx
+++ b/simgear/structure/subsystem_mgr.hxx
@@ -39,7 +39,7 @@ private:
     std::string eventName;
     SGTimeStamp time;
 
-public: 
+public:
     TimingInfo(const std::string& name, const SGTimeStamp &t) :
         eventName(name), time(t)
     { }
@@ -153,7 +153,7 @@ public:
     INIT_DONE,      ///< subsystem is fully initialised
     INIT_CONTINUE   ///< init should be called again
   } InitStatus;
-  
+
   virtual InitStatus incrementalInit ();
 
   /**
@@ -186,7 +186,7 @@ public:
    * </p>
    */
   virtual void shutdown ();
-   
+
   /**
    * Acquire the subsystem's property bindings.
    *
@@ -267,7 +267,7 @@ public:
   void reportTiming(void);
 
   /**
-   * Place time stamps at strategic points in the execution of subsystems 
+   * Place time stamps at strategic points in the execution of subsystems
    * update() member functions. Predominantly for debugging purposes.
    */
   void stamp(const std::string& name);
@@ -324,12 +324,12 @@ public:
      *
      */
     void set_fixed_update_time(double fixed_dt);
-	 
+
 	/**
 	 * retrive list of member subsystem names
-	 */ 
+	 */
     string_list member_names() const;
-	 
+
 private:
 
     class Member;
@@ -337,10 +337,10 @@ private:
 
     typedef std::vector<Member *> MemberVec;
     MemberVec _members;
-    
+
     double _fixedUpdateTime;
     double _updateTimeRemainder;
-    
+
   /// index of the member we are currently init-ing
     unsigned int _initPosition;
 };
@@ -398,7 +398,7 @@ public:
 
     virtual void add (const char * name,
                       SGSubsystem * subsystem,
-                      GroupType group = GENERAL, 
+                      GroupType group = GENERAL,
                       double min_time_sec = 0);
 
     /**
@@ -414,6 +414,12 @@ public:
     void reportTiming();
     void setReportTimingCb(void* userData,SGSubsystemTimingCb cb) {reportTimingCb = cb;reportTimingUserData = userData;}
 
+    template<class T>
+    T* get_subsystem() const
+    {
+        return dynamic_cast<T*>(get_subsystem(T::subsystemName()));
+    }
+
 private:
     std::vector<SGSubsystemGroupRef> _groups;
     unsigned int _initPosition;
-- 
2.39.5