ENH: allow cache to override config file

CMakeSystemConfig.cmake.in

@@ -3,21 +3,23 @@
 # in, which need not be the source directory
 #
 SET (CMAKE_WORDS_BIGENDIAN    @CMAKE_WORDS_BIGENDIAN@ )
-SET (CMAKE_USE_SPROC          @CMAKE_USE_SPROC@ CACHE BOOL)
-SET (CMAKE_USE_PTHREADS       @CMAKE_USE_PTHREADS@ CACHE BOOL)
-SET (CMAKE_HP_PTHREADS        @CMAKE_HP_PTHREADS@ CACHE BOOL)
-SET (CMAKE_LIB_EXT            @CMAKE_LIB_EXT@ CACHE STRING)
-SET (CMAKE_RANLIB             "@RANLIB@" CACHE STRING)
-SET (CMAKE_AR                 "@CMAKE_AR@" CACHE STRING)
-SET (CMAKE_CXX_COMPILER       "@CXX@" CACHE FILEPATH)
-SET (CMAKE_CXX_FLAGS          "@CXXFLAGS@" CACHE STRING)
-SET (CMAKE_TEMPLATE_FLAGS     "@CMAKE_TEMPLATE_FLAGS@" CACHE STRING)
-SET (CMAKE_C_COMPILER         "@CC@" CACHE FILEPATH)
-SET (CMAKE_C_FLAGS            "@CFLAGS@" CACHE STRING)
-SET (CMAKE_SHLIB_CFLAGS       "@CMAKE_SHLIB_CFLAGS@" CACHE STRING)
-SET (CMAKE_SHLIB_BUILD_FLAGS  "@CMAKE_SHLIB_BUILD_FLAGS@" CACHE STRING)
-SET (CMAKE_SHLIB_SUFFIX       @CMAKE_SHLIB_SUFFIX@ CACHE STRING)
-SET (CMAKE_THREAD_LIBS        "@CMAKE_THREAD_LIBS@" CACHE STRING)
-SET (CMAKE_DL_LIBS            "@CMAKE_DL_LIBS@" CACHE STRING)
-SET (CMAKE_SHLIB_LINK_FLAGS   "@CMAKE_SHLIB_LINK_FLAGS@" CACHE STRING)
-SET (CMAKE_SHLIB_LD_LIBS      "@CMAKE_SHLIB_LD_LIBS@" CACHE STRING)
+SET (CMAKE_USE_SPROC          @CMAKE_USE_SPROC@ CACHE_NO_REPLACE BOOL)
+SET (CMAKE_USE_PTHREADS       @CMAKE_USE_PTHREADS@ CACHE_NO_REPLACE BOOL)
+SET (CMAKE_HP_PTHREADS        @CMAKE_HP_PTHREADS@ CACHE_NO_REPLACE BOOL)
+SET (CMAKE_LIB_EXT            @CMAKE_LIB_EXT@ CACHE_NO_REPLACE STRING)
+SET (CMAKE_RANLIB             "@RANLIB@" CACHE_NO_REPLACE STRING)
+SET (CMAKE_AR                 "@CMAKE_AR@" CACHE_NO_REPLACE STRING)
+SET (CMAKE_CXX_COMPILER       "@CXX@" CACHE_NO_REPLACE FILEPATH)
+SET (CMAKE_CXX_FLAGS          "@CXXFLAGS@" CACHE_NO_REPLACE STRING)
+SET (CMAKE_TEMPLATE_FLAGS     "@CMAKE_TEMPLATE_FLAGS@" CACHE_NO_REPLACE STRING)
+SET (CMAKE_C_COMPILER         "@CC@" CACHE_NO_REPLACE FILEPATH)
+SET (CMAKE_C_FLAGS            "@CFLAGS@" CACHE_NO_REPLACE STRING)
+SET (CMAKE_SHLIB_CFLAGS       "@CMAKE_SHLIB_CFLAGS@" CACHE_NO_REPLACE STRING)
+SET (CMAKE_SHLIB_BUILD_FLAGS  "@CMAKE_SHLIB_BUILD_FLAGS@" CACHE_NO_REPLACE STRING)
+SET (CMAKE_SHLIB_SUFFIX       @CMAKE_SHLIB_SUFFIX@ CACHE_NO_REPLACE STRING)
+SET (CMAKE_THREAD_LIBS        "@CMAKE_THREAD_LIBS@" CACHE_NO_REPLACE STRING)
+SET (CMAKE_DL_LIBS            "@CMAKE_DL_LIBS@" CACHE_NO_REPLACE STRING)
+SET (CMAKE_SHLIB_LINK_FLAGS   "@CMAKE_SHLIB_LINK_FLAGS@" CACHE_NO_REPLACE STRING)
+SET (CMAKE_SHLIB_LD_LIBS      "@CMAKE_SHLIB_LD_LIBS@" CACHE_NO_REPLACE STRING)
+SET (CMAKE_SHLIB_LD_LIBS      "@CMAKE_SHLIB_LD_LIBS@" CACHE_NO_REPLACE_NO_REPLACE STRING)
+

Source/cmSetCommand.cxx

@@ -52,36 +52,62 @@ bool cmSetCommand::Invoke(std::vector<std::string>& args)
     {
       return true;
     }
-  if(args[1] == "CACHE")
-    { 
-    const char* type = "STRING"; // default type is string
-    if(args.size() > 2)
-      {
-      type = args[2].c_str();
-      }
-    m_Makefile->AddDefinition(args[0].c_str(), "");
-    cmCacheManager::GetInstance()->AddCacheEntry(args[0].c_str(),
-                                                 "",
-						 "Value Computed by CMake",
-                                                 cmCacheManager::StringToType(type));
-    return true;
+// here are the options with the num
+//  SET VAR                               
+//  SET VAR value                             
+//  SET VAR CACHE|CACHE_NO_REPLACE        
+//  SET VAR value CACHE|CACHE_NO_REPLACE      
+//  SET VAR CACHE|CACHE_NO_REPLACE TYPE   
+//  SET VAR value CACHE|CACHE_NO_REPLACE TYPE 
+  const char* type = "STRING"; // set a default type of STRING
+  const char* value = "";// set a default value of the empty string
+  if(args.size() > 1)
+    {
+    // always expand the first argument
+    m_Makefile->ExpandVariablesInString(args[1]);
+    value = args[1].c_str();
     }
-  
-  // expand value
-  m_Makefile->ExpandVariablesInString(args[1]);
-  m_Makefile->AddDefinition(args[0].c_str(), args[1].c_str());
-
-  // should we store the result in the cache ?
-  if (args.size() > 2 && args[2] == "CACHE")
+  // get the current cache value for the variable
+  const char* cacheValue = 
+    cmCacheManager::GetInstance()->GetCacheValue(args[0].c_str());
+  // assume this will not be cached
+  bool cache = false;
+  // search the arguments for key words CACHE and CACHE_NO_REPLACE
+  for(int i = 1; i < args.size() && !cache; ++i)
     {
-    const char* type = "STRING"; // default type is string
-    if(args.size() > 3)
+    if(args[i] == "CACHE_NO_REPLACE")
       {
-      type = args[3].c_str();
+      // if already in cache, ignore entire command
+      if(cacheValue)
+        {
+        return true;
+        }
+      cache = true;
       }
+    if(args[i] == "CACHE")
+      {
+      cache == true;
+      }
+    // if this is to be cached, find the value and type
+    if(cache)
+      {
+      // if this is the 
+      if(i == 1)
+        {
+        value = "";
+        }
+      if(i+1 < args.size())
+        {
+        type = args[i+1].c_str();
+        }
+      }
+    }
+  m_Makefile->AddDefinition(args[0].c_str(), value);
+  if(cache)
+    {
     cmCacheManager::GetInstance()->AddCacheEntry(args[0].c_str(),
-                                                 args[1].c_str(),
-						 "Value Computed by CMake",
+                                                 value,
+                                                 "Value Computed by CMake",
                                                  cmCacheManager::StringToType(type));
     }
   return true;