c# - 如何重构 "using"语句以避免代码重复？

Question

假设我有以下方法:

 public string GetSchedules(string request)
    {
        using (var soapClient = new ServiceReference1.CustomDataTimetableToolKitServicesSoapClient(EndpointConfiguratioName, Endpoint))
        {
            return soapClient.GetSchedules(AuthenticationInfo, request);
        }
    }

    public string GetCountryList(string request)
    {
        using (var soapClient = new ServiceReference1.CustomDataTimetableToolKitServicesSoapClient(EndpointConfiguratioName, Endpoint))
        {
            return soapClient.GetCountryList(AuthenticationInfo, request);
        }
    }

    public string GetCarriers(string request)
    {
        using (var soapClient = new ServiceReference1.CustomDataTimetableToolKitServicesSoapClient(EndpointConfiguratioName, Endpoint))
        {
            return soapClient.GetCarriers(AuthenticationInfo, request);
        }
    }

如您所见，唯一不同的是所调用方法的名称。我如何重构这些方法以仅应用一次“using”语句并避免代码重复？

Answer 1

对我来说，你所拥有的很好，但如果你想将它们排除在外，你可以使用 Func和 lambda 。沿着这些线的东西:

public string GetSchedules(string request)
{
    return Worker((c) => c.GetSchedules(AuthenticationInfo, request));
}

public string GetCountryList(string request)
{
    return Worker((c) => c.GetCountryList(AuthenticationInfo, request));
}

public string GetCarriers(string request)
{
    return Worker((c) => c.GetCarriers(AuthenticationInfo, request));
}

private string Worker(Func<SoapClientClassGoesHere, string> f)
{
    using (var soapClient = new ServiceReference1.CustomDataTimetableToolKitServicesSoapClient(EndpointConfiguratioName, Endpoint))
    {
        return f(soapClient);
    }
}

Func<A, R>意思是“一个接受类型为 A 的参数并返回一个类型为 R 的值的函数”(对于一个接受两个 参数的函数，你可以有 Func<A, B, R>，等等)。

更多关于 Func<>和 lambdas 在 this question和 this question (还有很多，这是一个内容丰富的话题)。

这是一个 live example on ideone.com (一个非常愚蠢的实例，但它演示了这个概念):

using System;
using System.Collections.Generic;

class Foo {
    public string GetSchedules(string request)
    {
        return Worker((c) => c[request]);
    }

    public string GetCountryList(string request)
    {
        return Worker((c) => c[request].ToUpper());
    }

    public string GetCarriers(string request)
    {
        return Worker((c) => c[request].ToLower());
    }

    private string Worker(Func<Dictionary<string,string>, string> f)
    {
        var d = new Dictionary<string, string>();
        d.Add("1", "One");
        d.Add("2", "Two");
        d.Add("3", "Three");
        return f(d);
    }
}

public class Test
{
    public static void Main()
    {
        var f = new Foo();
        Console.WriteLine(f.GetSchedules("1"));
        Console.WriteLine(f.GetCountryList("1"));
        Console.WriteLine(f.GetCarriers("1"));
    }
}