用c#4.0避免过载地狱

我使用的是C#4.0，我如何避免编写大量类似方法的问题，因为它们每个参数都是唯一的（新的参数特性如何避免过载？）

谢谢你，而不是这个：

void Method(string param1, string param2) { }
void Method(string param1, string param2, string param3) { }
void Method(string param1, string param2, string param3, string param4) { }
void Method(string param1, string param2, string param3, int int4) { }
//etc...

您可以只使用一个方法和所有想要的参数，并使用命名参数调用它，如下所示：

void Method(string param1, string param2 = "default2", 
            string param3 = "default3", int int4 = 12, int lastParam = 12) { }

Method(param1: "myString", int4: 23);
//or...
Method(param1: "myString", param4: "string2", int4: 23);

这样称呼它：

void Method(string param1, string param2 = "default2", 
            string param3 = "default3", int int4 = 12, int lastParam = 12) { }

Method(param1: "myString", int4: 23);
//or...
Method(param1: "myString", param4: "string2", int4: 23);

---

只需包含您想要设置的内容，其余内容将是您在方法签名中指定的默认值。

假设您有一个类Employee，如下所述，它有3个构造函数

public class Employee
{
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public string Qualification { get; set; }
    public string MiddleName { get; set; }

    public Employee(string firstName, string lastName)
    {
        FirstName= firstName;
        LastName= lastName;
        Qualification= "N/A";
        MiddleName= string.Empty;
    }
    public Employee(string firstName, string lastName, string qualification)
    {
        FirstName= firstName;
        LastName= lastName;
        Qualification= qualification;
        MiddleName= string.Empty;

    }
    public Employee(string firstName, string lastName, string qualification,
        string middleName)
    {
        FirstName= firstName;
        LastName= lastName;
        Qualification= qualification;
        MiddleName= middleName
    }
}

public class Employee
{
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public string Qualification { get; set; }
    public string MiddleName { get; set; }

    public Employee(string firstName, string lastName,
            string qualification = "N/A", string middleName = "")
    {
        FirstName= firstName;
        LastName= lastName;
        Qualification= qualification;
        MiddleName = middleName;
    }
}

使用C#4.0，您需要创建一个构造函数，如下所示，它将替换所有3个构造函数

public class Employee
{
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public string Qualification { get; set; }
    public string MiddleName { get; set; }

    public Employee(string firstName, string lastName)
    {
        FirstName= firstName;
        LastName= lastName;
        Qualification= "N/A";
        MiddleName= string.Empty;
    }
    public Employee(string firstName, string lastName, string qualification)
    {
        FirstName= firstName;
        LastName= lastName;
        Qualification= qualification;
        MiddleName= string.Empty;

    }
    public Employee(string firstName, string lastName, string qualification,
        string middleName)
    {
        FirstName= firstName;
        LastName= lastName;
        Qualification= qualification;
        MiddleName= middleName
    }
}

public class Employee
{
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public string Qualification { get; set; }
    public string MiddleName { get; set; }

    public Employee(string firstName, string lastName,
            string qualification = "N/A", string middleName = "")
    {
        FirstName= firstName;
        LastName= lastName;
        Qualification= qualification;
        MiddleName = middleName;
    }
}

可以通过以下方式调用此构造函数

Employee emp = new Employee("Adil", "Mughal");
Employee emp = new Employee("Adil", "Mughal", middleName: "Ahmed");
Employee emp = new Employee("Adil", qualification:"BS");
Employee emp = new Employee("ABC", lastName: "EFG", qualification: "BS");
Employee emp = new Employee("XYZ", middleName: "MNO");

在C#4.0中，可以使用可选参数

---

我认为语法中没有大括号。@Martinho-Woops同时回答了一个javascript对象问题：）修复了如果该方法使用了所有参数，而我尝试只传入其中一些参数会怎么样？@dotnetdev-将默认值设为所有可能无法传入的参数，当您不指定特定参数时，这些默认值将被使用/传递到方法中，即使默认值是

null

，因为你已经可以在C#3中对属性进行初始化了。对于你的第一个版本，我会让参数较少的构造函数调用参数较多的构造函数并传递默认值。这是一个无用的观点，因为第二个选项更好，但只是在星期天吹毛求疵：）在C#3中，我可能会考虑重写该方法以接受参数集合对象。像Nick Comments一样，可以使用属性初始值设定项方便地初始化该对象。但是对于C#4.0来说，直接在方法中使用可选参数似乎更明智。