Add clear() method

Author: smgallo

classes/ETL/VariableStore.php

@@ -68,11 +68,22 @@ public function __construct($store = null, Log $logger = null)
         }
     }  // __construct()
 
+    /**
+     * Clear the variables in the store
+     */
+
+    public function clear()
+    {
+        $this->variables = array();
+    }
+
     /**
      * Set a variable in the store.  If a variable should be overwritten use overwrite() instead.
      * Setting a variable to a NULL value will unset the variable.  If the variable is already set,
-     * do not overwrite and issue a warning.  We issue a warning because it may be the case that the
-     * developer is expecting a value to be updated and want to alter them that it is not.
+     * do not overwrite and issue a warning. This is done so that variables set early in a process
+     * (such as ETL) are not blindly changed causing unexpected results.  We issue a warning because
+     * it may be the case that the developer is expecting a value to be updated and want to alert
+     * them that it is not.
      *
      * @param string $var The name of the variable to set
      * @param scalar $value The value of the variable