Question

我想将lambda传递给函数，但需要一个带有单个参数的lambda。如果我将两个参数传递给lambda，TypeScript会根据需要抛出错误，但如果省略lambda中的任何参数则不会抱怨。如何让TypeScript要求传递单个参数lambda？

function foo(fn: (x) => any) { }

foo(() => "bla");     // Bad, but no error
foo((x) => "bla");    // Good, no error
foo((x, y) => "bla"); // Bad, with error

Answer 1

从语义上讲，@Override protected String doInBackground(String[] params) { // do above Server call here ArrayList<NameValuePair> postParameters = new ArrayList<NameValuePair>(); postParameters.add(new BasicNameValuePair("Name", name )); postParameters.add(new BasicNameValuePair("Email", email )); postParameters.add(new BasicNameValuePair("Password", password)); String responseString = null; try { HttpClient httpclient = new DefaultHttpClient(); HttpPost httppost = new HttpPost("http://hitachipick.azurewebsites.net/SQLQuery.php"); // no idea what this does :) httppost.setEntity(new UrlEncodedFormEntity(postParameters)); // This is the line that send the request HttpResponse response = httpclient.execute(httppost); HttpEntity entity = response.getEntity(); InputStream is = entity.getContent(); } catch (Exception e) { Log.e("log_tag", "Error in http connection "+e.toString()); } return""; } @Override protected void onPostExecute(String message) { //process message } }和x => "bla"完全相同。他们都完全忽略了第一个参数（以及其他所有参数）

通过要求() => "bla" lambda，你基本上会说，“我想要一些我可以用一个参数调用的东西”，(x) => any符合要求，() => "bla"没有。

Answer 2

这实际上是预期的行为，无论好坏。见https://github.com/Microsoft/TypeScript/wiki/FAQ#why-are-functions-with-fewer-parameters-assignable-to-functions-that-take-more-parameters

不幸的是，我无法获得您想要的行为。

我可以要求lambda参数吗？

2 个答案: