From 0d6acb1df8c20bb21f4d328cf2c35d0cbb6d7ea3 Mon Sep 17 00:00:00 2001
From: Ben Boeckel <mathstuf@gmail.com>
Date: Fri, 2 Aug 2013 15:44:15 -0400
Subject: [PATCH] variable_watch: Add a deleter for the client data

The client data is arbitrary and the callback may be called an
unspecified number of times, so the cmVariableWatch must be the one to
delete the client data in the end (if it is needed at all).
---
 Source/cmVariableWatch.cxx |  4 +++-
 Source/cmVariableWatch.h   | 13 +++++++++++--
 2 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/Source/cmVariableWatch.cxx b/Source/cmVariableWatch.cxx
index 21b910dea6..21acd3b7e8 100644
--- a/Source/cmVariableWatch.cxx
+++ b/Source/cmVariableWatch.cxx
@@ -53,11 +53,13 @@ cmVariableWatch::~cmVariableWatch()
 }
 
 void cmVariableWatch::AddWatch(const std::string& variable,
-                               WatchMethod method, void* client_data /*=0*/)
+                               WatchMethod method, void* client_data /*=0*/,
+                               DeleteData delete_data /*=0*/)
 {
   cmVariableWatch::Pair* p = new cmVariableWatch::Pair;
   p->Method = method;
   p->ClientData = client_data;
+  p->DeleteDataCall = delete_data;
   cmVariableWatch::VectorOfPairs* vp = &this->WatchMap[variable];
   cmVariableWatch::VectorOfPairs::size_type cc;
   for ( cc = 0; cc < vp->size(); cc ++ )
diff --git a/Source/cmVariableWatch.h b/Source/cmVariableWatch.h
index 45273e5ae2..d666815982 100644
--- a/Source/cmVariableWatch.h
+++ b/Source/cmVariableWatch.h
@@ -26,6 +26,7 @@ class cmVariableWatch
 public:
   typedef void (*WatchMethod)(const std::string& variable, int access_type,
     void* client_data, const char* newValue, const cmMakefile* mf);
+  typedef void (*DeleteData)(void* client_data);
 
   cmVariableWatch();
   ~cmVariableWatch();
@@ -34,7 +35,7 @@ public:
    * Add watch to the variable
    */
   void AddWatch(const std::string& variable, WatchMethod method,
-                void* client_data=0);
+                void* client_data=0, DeleteData delete_data=0);
   void RemoveWatch(const std::string& variable, WatchMethod method);
 
   /**
@@ -67,7 +68,15 @@ protected:
   {
     WatchMethod Method;
     void*        ClientData;
-    Pair() : Method(0), ClientData(0) {}
+    DeleteData   DeleteDataCall;
+    Pair() : Method(0), ClientData(0), DeleteDataCall(0) {}
+    ~Pair()
+      {
+      if (this->DeleteDataCall && this->ClientData)
+        {
+        this->DeleteDataCall(this->ClientData);
+        }
+      }
   };
 
   typedef std::vector< Pair* > VectorOfPairs;