diff --git a/change_log.txt b/change_log.txt
index 46188013..a69b9654 100644
--- a/change_log.txt
+++ b/change_log.txt
@@ -3,7 +3,7 @@
 - bugfix compilation did fail when a prefilter did modify an {extends} tag (Forum Topic 23966)
 - bugfix template inheritance could fail if nested {block} tags in childs did contain {$smarty.block.child} (Issue #127)
 - bugfix template inheritance could fail if {block} tags in childs did have similar name as used plugins (Issue #128)
-- enhancement to allow variable constant names like {$smarty.const.{$foo}} (Forum Topic 23970)
+- added abstract method declaration doCompile() in Smarty_Internal_TemplateCompilerBase (Forum Topic 23969)
 
 06.01.2013
 - Allow '://' URL syntax in template names of stream resources  (Issue #129)
diff --git a/libs/sysplugins/smarty_internal_templatecompilerbase.php b/libs/sysplugins/smarty_internal_templatecompilerbase.php
index 5eeb8ef6..11fc2144 100644
--- a/libs/sysplugins/smarty_internal_templatecompilerbase.php
+++ b/libs/sysplugins/smarty_internal_templatecompilerbase.php
@@ -136,6 +136,14 @@ abstract class Smarty_Internal_TemplateCompilerBase {
      */
     public $known_modifier_type = array();
 
+    /**
+     * Methode to compile a Smarty template
+     *
+     * @param  mixed $_content template source
+     * @return bool true if compiling succeeded, false if it failed
+     */
+    abstract protected function doCompile($_content);
+
     /**
      * Initialize compiler
      */