强制重新评估命令启用

Question

我为eclipse打印命令添加了一个处理程序，如下所示：

  <handler
        class="org.acme.PrintHandler"
        commandId="org.eclipse.ui.file.print">
     <activeWhen>
        <with variable="activePart">
           <test property="org.acme.printable" />
        </with>
     </activeWhen>
  </handler>

哪个真的很好。但是有时，即使活动部分没有更改，命令的启用也会更改。因此，我想强制对该activeWhen零件进行重新评估。我该怎么做呢？

我尝试过这样的事情：

    ICommandService service = (ICommandService) PlatformUI.getWorkbench().getService(ICommandService.class);
    Command printCommand = service.getCommand("org.eclipse.ui.file.print");
    EvaluationContext context = new EvaluationContext(null, lastEditor);
    context.addVariable(ISources.ACTIVE_PART_NAME, lastEditor);
    ExecutionEvent event = new ExecutionEvent(printCommand, Collections.EMPTY_MAP, null, context);

    // this does nothing
    printCommand.setEnabled(context);
    // this does nothing as well
    service.refreshElements("org.eclipse.ui.file.print", null);
    // this executes the command 
    // (but at least re-evaluates it's enablement before)
    printCommand.executeWithChecks(event);

Answer 1

我认为该IEvaluationService.requestEvaluation方法可以满足您的要求：

IEvaluationService evalService = (IEvaluationService) PlatformUI.getWorkbench().getService(IEvaluationService.class);

evalService.requestEvaluation("org.acme.printable");

JavaDoc说

请求此服务重新评估包含给定属性名称的属性测试器的所有已注册核心表达式。