def _GetBuildRuleFamily(self):
        if self._BuildRuleFamily == None:
            ToolDefinition = self.Workspace.ToolDef.ToolsDefTxtDatabase
            if TAB_TOD_DEFINES_BUILDRULEFAMILY not in ToolDefinition \
               or self.ToolChain not in ToolDefinition[TAB_TOD_DEFINES_BUILDRULEFAMILY] \