如何重构“使用”语句以避免代码重复？

Question

Let's suppose I have the following methods:

 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);
        }
    }

As you can see the only different thing is the name of the method invoked. How could I refactor these methods to apply "using" statement only once and avoid code duplication?

Answer 1

To me, what you have is fine, but if you want to factor those out you can use Func and lambdas. Something along these lines:

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> means "a function that takes an argument of type A and returns a value of type R " (and you can have Func<A, B, R> for a function that takes two arguments, etc.).

More about Func<> and lambdas in this question and this question (and many more, it's a rich topic).

Here's a live example on ideone.com (a very silly live example, but it demonstrates the concept):

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"));
    }
}

Answer 2

There's really not much duplication there. Still,

public ServiceReference1.CustomDataTimetableToolKitServicesSoapClient NewClient()
{
    return new ServiceReference1.CustomDataTimetableToolKitServicesSoapClient(EndpointConfiguratioName, Endpoint)
}

using (var client = NewClient()) {
    return soapClient.GetCountryList(AuthenticationInfo, request);
}

Also, since all of your methods take a string parameter and return a string , it would be easy to write a single method to call them all, passing the operation to call as a delegate. Unfortunately, I don't have the time to write that for you right now.

Answer 3

You can use lambda function in such way:

public string GetCarriers(string request)
{
    return Get((authInfo, request) => soapClient.GetCarriers(authInfo, request), request);
}

...

public string Get(Func<AuthenticationInfo, string, string> action, string request) {
    using (var soapClient = new ServiceReference1.CustomDataTimetableToolKitServicesSoapClient(EndpointConfiguratioName, Endpoint))
    {
        return action(AuthenticationInfo, request)
    }
}

I don't know if that compiles but you get the idea.

Edit: As @Tim S. noticed, this code could probably be shorter:

public string GetCarriers(string request)
{
    return Get(soapClient.GetCarriers, request);
}

...

public string Get(Func<AuthenticationInfo, string, string> action, string request) {
    using (var soapClient = new ServiceReference1.CustomDataTimetableToolKitServicesSoapClient(EndpointConfiguratioName, Endpoint))
    {
        return action(AuthenticationInfo, request)
    }
}

Edit 2: The client was out of scope. So correct code is:

public string GetCarriers(string request)
{
    return Get((client, authInfo, request) => client.GetCarriers(authInfo, request));
}

...

public string Get(Func<ISoapClient, AuthenticationInfo, string, string> action, string request) {
    using (var soapClient = new ServiceReference1.CustomDataTimetableToolKitServicesSoapClient(EndpointConfiguratioName, Endpoint))
    {
        return action(soapClient, AuthenticationInfo, request)
    }
}

Answer 4

If your Projekt isn't very big you could use the following (it's a bit messy and makes it easy to make a mistake):

public string getX (string request, string x)
{
    using (var soapClient = new ServiceReference1.CustomDataTimetableToolKitServicesSoapClient(EndpointConfiguratioName, Endpoint))
    {
        switch (x)
        {
            case "schedules":
                return soapClient.GetSchedules(AuthenticationInfo, request);
                break;
            case "countryList":
                return soapClient.GetCountryList(AuthenticationInfo, request);
                break;
            case "carriers":
                return soapClient.GetCarriers(AuthenticationInfo, request);
                break;
            }
        }
    }
}