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c#3.0中的自动属性和对象初始化器
1.匿名属性
定义属性如下：
public class Employee
{
public int Id { get; set; }
public string Name { get; set; }
public string Sex { get; set; }
public int Age { get; set; }
public string BirthDate { get; set; }
}
在C#3.0 之前的写法如下：
public class Employee
{
private int _id;
private string _name;
private string _sex;
private int _age;
private string _birthDate;
public int Id
{
get { return _id; }
set { _id = value; }
}
public string Name
{
get { return _name; }
set { _name = value; }
}
public string Sex
{
get { return _sex; }
set { _sex = value; }
}
public int Age
{
get { return _age; }
set { _age = value; }
}
public string BirthDate
{
get { return _birthDate; }
set { _birthDate = value; }
}
}
仅从代码量上就前者比后者减少了2/3的代码，这对提高效率是显而易见的，那么这些代码都到哪里去了呢？其实那些额外的代码都是由编译器为我们完成的，编译器会将那些我们“省去"的代码编译成托管IL代码的时候补进去，两者中代码在最终生成的IL代码的体积是差不多的。
上图中的IL代码中我们看到了
2.对象初始化器，原来的对象初始化都要进行先创建构造方法，然后才能进行成员的相关操作，C#3.0 提供了对象成员的直接初始化的能力，和初始化一个集合或者是数组一样来初始化对象。
相面来看，通过对象初始化器对上面的的Employee类进行进行调用：
Employee employee = new Employee { Id = 1, Name = "蓝之风", Age = 24, BirthDate =
"1984-10-21", Sex = "男" };
Console.WriteLine("编号;{0}", employee.Id);
Console.WriteLine("姓名:{0}", employee.Name);
Console.WriteLine("年龄:{0}", employee.Age);
Console.WriteLine("生日:{0}", employee.BirthDate);
Console.WriteLine("性别:{0}", employee.Sex);
Console.WriteLine("请按任意键继续...");
Console.ReadLine();
这句Employee employee = new Employee { Id = 1, Name = "蓝之风", Age = 24,
BirthDate = "1984-10-21", Sex = "男" };
就是对象的初始化，看到代码很简洁，输出的结果如下：
在C#3.0之前的做法是：
Employee employee = new Employee();
employee.Id = 1;
employee.Name = "蓝之风";
employee.Age = 24;
employee.BirthDate = "1984-10-21";
employee.Sex = "男";
Console.WriteLine("编号;{0}", employee.Id);
Console.WriteLine("姓名:{0}", employee.Name);
Console.WriteLine("年龄:{0}", employee.Age);
Console.WriteLine("生日:{0}", employee.BirthDate);
Console.WriteLine("性别:{0}", employee.Sex);
Console.WriteLine("请按任意键继续...");
Console.ReadLine();
或者通过重载构造方法的方式来初始化这些属性，二者的达到的效果是相同的，但是前者使用起来方便了些，代码量减少了许多，这个过程是怎么完成的呢？其实C#本身并没有太大的变化，这些都是在语法上的一些改变，使得编写代码的时候更方便效率更高，把一些编译器可以推断出来完成的工作让编译器来做了，编译器在编译程序的时候将我们没有实现的代码替我们实现来生成IL代码的：
method private hidebysig static void Main(string[] args) cil managed
{
.entrypoint
// 代码大小 175 (0xaf)
.maxstack 2
.locals init ([0] class CS30.Employee employee,
[1] class CS30.Employee '<>g__initLocal0')
IL_0000: nop
IL_0001: newobj instance void CS30.Employee::.ctor()
IL_0006: stloc.1
IL_0007: ldloc.1
IL_0008: ldc.i4.1
IL_0009: callvirt instance void CS30.Employee::set_Id(int32)
IL_000e: nop
IL_000f: ldloc.1
IL_0010: ldstr bytearray (DD 84 4B 4E CE 98 ) // ..KN..
IL_0015: callvirt instance void CS30.Employee::set_Name(string)
IL_001a: nop
IL_001b: ldloc.1
IL_001c: ldc.i4.s 24
IL_001e: callvirt instance void CS30.Employee::set_Age(int32)
IL_0023: nop
IL_0024: ldloc.1
IL_0025: ldstr "1984-10-21"
IL_002a: callvirt instance void CS30.Employee::set_BirthDate(string)
IL_002f: nop
IL_0030: ldloc.1
IL_0031: ldstr bytearray (37 75 ) // 7u
IL_0036: callvirt instance void CS30.Employee::set_Sex(string)
IL_003b: nop
IL_003c: ldloc.1
IL_003d: stloc.0
IL_003e: ldstr bytearray (16 7F F7 53 3B 00 7B 00 30 00 7D 00 ) // ...S;.{.0.}.
IL_0043: ldloc.0
IL_0044: callvirt instance int32 CS30.Employee::get_Id()
IL_0049: box [mscorlib]System.Int32
IL_004e: call void [mscorlib]System.Console::WriteLine(string,
object)
IL_0053: nop
IL_0054: ldstr bytearray (D3 59 0D 54 3A 00 7B 00 30 00 7D 00 ) // .Y.T:.{.0.}.
IL_0059: ldloc.0
IL_005a: callvirt instance string CS30.Employee::get_Name()
IL_005f: call void [mscorlib]System.Console::WriteLine(string,
object)
IL_0064: nop
IL_0065: ldstr bytearray (74 5E 84 9F 3A 00 7B 00 30 00 7D 00 ) // t^..:.{.0.}.
IL_006a: ldloc.0
IL_006b: callvirt instance int32 CS30.Employee::get_Age()
IL_0070: box [mscorlib]System.Int32
IL_0075: call void [mscorlib]System.Console::WriteLine(string,
object)
IL_007a: nop
IL_007b: ldstr bytearray (1F 75 E5 65 3A 00 7B 00 30 00 7D 00 ) // .u.e:.{.0.}.
IL_0080: ldloc.0
IL_0081: callvirt instance string CS30.Employee::get_BirthDate()
IL_0086: call void [mscorlib]System.Console::WriteLine(string,
object)
IL_008b: nop
IL_008c: ldstr bytearray (27 60 2B 52 3A 00 7B 00 30 00 7D 00 ) // '`+R:.{.0.}.
IL_0091: ldloc.0
IL_0092: callvirt instance string CS30.Employee::get_Sex()
IL_0097: call void [mscorlib]System.Console::WriteLine(string,
object)
IL_009c: nop
IL_009d: ldstr bytearray (F7 8B 09 63 FB 4E 0F 61 2E 95 E7 7E ED 7E 2E 00 // ...c.N.a...~.~..
2E 00 2E 00 ) // ....
IL_00a2: call void [mscorlib]System.Console::WriteLine(string)
IL_00a7: nop
IL_00a8: call string [mscorlib]System.Console::ReadLine()
IL_00ad: pop
IL_00ae: ret
} // end of method Program::Main
3总结：
自动属性和对象初始化器都是C#3.0提供的语法级别的功能改进，是一种语法糖，是编写代码的效率更高，将一些重复性的工作交给编译器来做，但是这种改变，也增加了代码的不透明性，这点在隐式类型中体现的更为突出，增加了代码理解的难度，这些仅仅是提供给代码编写人员的一种选择，如果不喜欢也可以按照原来的方式来书写自己的代码也未尝不可。
上图中的IL代码中我们看到了
2.对象初始化器，原来的对象初始化都要进行先创建构造方法，然后才能进行成员的相关操作，C#3.0 提供了对象成员的直接初始化的能力，和初始化一个集合或者是数组一样来初始化对象。
相面来看，通过对象初始化器对上面的的Employee类进行进行调用：
Employee employee = new Employee { Id = 1, Name = "蓝之风", Age = 24, BirthDate =
"1984-10-21", Sex = "男" };
Console.WriteLine("编号;{0}", employee.Id);
Console.WriteLine("姓名:{0}", employee.Name);
Console.WriteLine("年龄:{0}", employee.Age);
Console.WriteLine("生日:{0}", employee.BirthDate);
Console.WriteLine("性别:{0}", employee.Sex);
Console.WriteLine("请按任意键继续...");
Console.ReadLine();
这句Employee employee = new Employee { Id = 1, Name = "蓝之风", Age = 24,
BirthDate = "1984-10-21", Sex = "男" };
就是对象的初始化，看到代码很简洁，输出的结果如下：
在C#3.0之前的做法是：
Employee employee = new Employee();
employee.Id = 1;
employee.Name = "蓝之风";
employee.Age = 24;
employee.BirthDate = "1984-10-21";
employee.Sex = "男";
Console.WriteLine("编号;{0}", employee.Id);
Console.WriteLine("姓名:{0}", employee.Name);
Console.WriteLine("年龄:{0}", employee.Age);
Console.WriteLine("生日:{0}", employee.BirthDate);
Console.WriteLine("性别:{0}", employee.Sex);
Console.WriteLine("请按任意键继续...");
Console.ReadLine();
