private static Hashtable metaModelXPathExpressions = new Hashtable(); //manter guardado o comando sql de forma a ser gerado e compilado 1 única vez private static XPathExpression getMetaModelXPathExpression(string xpath) { XPathExpression metaModelXPathExpression = (XPathExpression)(metaModelXPathExpressions[xpath]); if (metaModelXPathExpression == null) { if (metaModelXPathNavigator == null) { metaModelXPathNavigator = MetaModel.CreateNavigator(); } metaModelXPathExpression = metaModelXPathNavigator.Compile(xpath); metaModelXPathExpressions.Add(xpath, metaModelXPathExpression); } return metaModelXPathExpression; }