可以由调用者自定义的通用谓词？

Question

我有一堆这样定义的谓词，每个谓词检查不同的 http 状态代码：

readonly Predicate<HttpResponseData> createdHttpStatusPredicate = (HttpResponseData responseData) => {
    return responseData.StatusCode == HttpStatusCode.Created;
};

readonly Predicate<HttpResponseData> okHttpStatusPredicate = (HttpResponseData responseData) => {
    return responseData.StatusCode == HttpStatusCode.OK;
};

...

我像这样将它们传递到以下方法中（代码已经稍微简化以删除不相关的细节）：

public static async Task<HttpResponseData> HttpCaller(HttpMethod requestMethod, Predicate<HttpResponseData> predicate)
{
    HttpResponseData response = await SendHttpRequest(requestMethod);

    if (predicate(response) == true)
        return response;
    else
        return null;
}

这是一个将一个谓词发送到上述方法的示例调用：

HttpResponseData data = await HttpRequestUtils.HttpCaller(HttpMethod.Post, createdHttpStatusPredicate);

我想知道，我是否可以将所有谓词组合到某个通用谓词中，或者以某种方式指定要在我调用 HttpCaller 时在谓词中查找的 http 状态？

是的，我知道上面的例子没有多大意义，因为我可以直接将我正在寻找的 http 状态传递给 HttpCaller 而无需通过谓词，但在我的情况下，HttpCaller 可以接收我的复杂的谓词也作为输入，基于从哪里调用HttpCaller

Answer 1

接下来的两种方法可以用来去掉所有只检查HttpStatusCode的谓词。

---

1。创建一个为给定的HttpStatusCode 创建Predicate 的方法：

public static Predicate<HttpResponseData> CreatePredicateByHttpStatusCode(HttpStatusCode status)
{
    return r => r.StatusCode == status;
}

然后当你需要一个只检查给定HttpStatusCode的Predicate时使用这个方法：

var result = await HttpCaller(httpMethod, CreatePredicateByHttpStatusCode(HttpStatusCode.OK));

---

2。创建方法 HttpCaller 的重载，它接受 HttpStatusCode 并且只检查给定的 HttpStatusCode：

// This is your current method. It accepts a common Predicate that is used
// to check for complex conditions.
public static async Task<HttpResponseData> HttpCaller(HttpMethod requestMethod, Predicate<HttpResponseData> predicate)
{
    HttpResponseData response = await SendHttpRequest(requestMethod);

    if (predicate(response) == true)
        return response;
    else
        return null;
}

// This is a new Method. It accepts HttpStatusCode instead of the Predicate.
// It can be used for checking only for HttpStatusCode.
public static async Task<HttpResponseData> HttpCaller(HttpMethod requestMethod, HttpStatusCode status)
{
    // Here your original method HttpCaller is used.
    return await HttpCaller(requestMethod, r => r.StatusCode == status);
}

当您只需要检查HttpStatusCode时，可以使用HttpCaller的重载形式：

var result = await HttpCaller(httpMethod, HttpStatusCode.OK);