C#3.0 为我们带来什么（3） —— 初始化器

C#3.0 为我们带来什么（3） —— 初始化器 对比代码 c#2.0         Employee e1;         private void ee1()         {             e1 = new Employee(1);             e1.Age = 25;             e1.Name = "james";         } c#3.0         Employee 2;         private void ee2()         {             e2 = new Employee(2) { Age = 25, Name = "james" };         } 与自动属性一样，初始化器的c#3.0的最大特点就是语法简化。 来看下IL代码 c#2.0 .method private hidebysig instance void  ee1() cil managed {   // 代码大小       45 (0x2d)   .maxstack  8   IL_0000:  nop   IL_0001:  ldarg.0   IL_0002:  ldc.i4.1   IL_0003:  newobj     instance void WindowsFormsApplication1.Employee::.ctor(int32)   IL_0008:  stfld      class WindowsFormsApplication1.Employee WindowsFormsApplication1.TestInitializer::e1   IL_000d:  ldarg.0   IL_000e:  ldfld      class WindowsFormsApplication1.Employee WindowsFormsApplication1.TestInitializer::e1   IL_0013:  ldc.i4.s   25   IL_0015:  callvirt   instance void WindowsFormsApplication1.Employee::set_Age(int32)   IL_001a:  nop   IL_001b:  ldarg.0   IL_001c:  ldfld      class WindowsFormsApplication1.Employee WindowsFormsApplication1.TestInitializer::e1   IL_0021:  ldstr      "james"   IL_0026:  callvirt   instance void WindowsFormsApplication1.Employee::set_Name(string)   IL_002b:  nop   IL_002c:  ret } // end of method TestInitializer::ee1 c#3.0 .method private hidebysig instance void  ee2() cil managed {   // 代码大小       37 (0x25)   .maxstack  3   .locals init ([0] class WindowsFormsApplication1.Employee '<>g__initLocal0')   IL_0000:  nop   IL_0001:  ldarg.0   IL_0002:  ldc.i4.2   IL_0003:  newobj     instance void WindowsFormsApplication1.Employee::.ctor(int32)   IL_0008:  stloc.0   IL_0009:  ldloc.0   IL_000a:  ldc.i4.s   25   IL_000c:  callvirt   instance void WindowsFormsApplication1.Employee::set_Age(int32)   IL_0011:  nop   IL_0012:  ldloc.0   IL_0013:  ldstr      "james"   IL_0018:  callvirt   instance void WindowsFormsApplication1.Employee::set_Name(string)   IL_001d:  nop   IL_001e:  ldloc.0   IL_001f:  stfld      class WindowsFormsApplication1.Employee WindowsFormsApplication1.TestInitializer::e2   IL_0024:  ret } // end of method TestInitializer::ee2c#2.0中是这样来赋给age值的   IL_0008:  stfld      class WindowsFormsApplication1.Employee WindowsFormsApplication1.TestInitializer::e1 （将参数压入堆栈）   IL_000d:  ldarg.0   IL_000e:  ldfld      class WindowsFormsApplication1.Employee WindowsFormsApplication1.TestInitializer::e1   IL_0013:  ldc.i4.s   25c#3.0是这样的   IL_0008:  stloc.0（从堆栈中弹出到局部变量）   IL_0009:  ldloc.0   IL_000a:  ldc.i4.s   25 也就是e1的对象载入简化了。看代码大小也能发现新写法的优势。 对应的就是集合初始化 c# 2.0             List<Employee> list1 = new List<Employee>();             list1.Add(e1); c# 3.0             List<Employee> list2 = new List<Employee>             {                 new Employee(3) { Age = 25, Name = "james" },                 new Employee(4) { Age = 26, Name = "tony" }             };对应的IL c#2.0 .method public hidebysig instance void  dd() cil managed {   // 代码大小       21 (0x15)   .maxstack  2   .locals init ([0] class [mscorlib]System.Collections.Generic.List`1<class WindowsFormsApplication1.Employee> list1)   IL_0000:  nop   IL_0001:  newobj     instance void class [mscorlib]System.Collections.Generic.List`1<class WindowsFormsApplication1.Employee>::.ctor()   IL_0006:  stloc.0   IL_0007:  ldloc.0   IL_0008:  ldarg.0   IL_0009:  ldfld      class WindowsFormsApplication1.Employee WindowsFormsApplication1.TestInitializer::e1   IL_000e:  callvirt   instance void class [mscorlib]System.Collections.Generic.List`1<class WindowsFormsApplication1.Employee>::Add(!0)   IL_0013:  nop   IL_0014:  ret } // end of method TestInitializer::dd c#3.0

.method public hidebysig instance void  newdd() cil managed {   // 代码大小       23 (0x17)   .maxstack  2   .locals init ([0] class [mscorlib]System.Collections.Generic.List`1<class WindowsFormsApplication1.Employee> list2,            [1] class [mscorlib]System.Collections.Generic.List`1<class WindowsFormsApplication1.Employee> '<>g__initLocal1')   IL_0000:  nop   IL_0001:  newobj     instance void class [mscorlib]System.Collections.Generic.List`1<class WindowsFormsApplication1.Employee>::.ctor()   IL_0006:  stloc.1   IL_0007:  ldloc.1   IL_0008:  ldarg.0   IL_0009:  ldfld      class WindowsFormsApplication1.Employee WindowsFormsApplication1.TestInitializer::e1   IL_000e:  callvirt   instance void class [mscorlib]System.Collections.Generic.List`1<class WindowsFormsApplication1.Employee>::Add(!0)   IL_0013:  nop   IL_0014:  ldloc.1   IL_0015:  stloc.0   IL_0016:  ret } // end of method TestInitializer::newdd 两个的init是不同的，至于为什么3.0里会由编译器init出来第二个参数我还不大明白，还请各位看客指点。难道还会真的倒退了？ 看到这里大家也该明白如何写代码才是最好的了吧。

posted on 2008-01-06 17:46 tianyamoon 阅读( ...) 评论( ...) 编辑 收藏

转载于:https://www.cnblogs.com/tianyamoon/archive/2008/01/06/1027966.html

相关资源：C# 3.0与.NET 3.5高级编程