三、代 碼剖析
讓我們更細致地分析一下前面的C# 3.0代碼:
var classes = new List＜MyClass＞
{
new MyClass
{
nameofClass = "ScIEnce",
studentNames = {"Laura", "George"}
},
new MyClass
{
nameofClass = "Commerce",
studentNames = {"Bill", "Hillary"}
}
};
對於編譯器來說，它具有與下面代碼相同的效果：
var classes = new List＜MyClass＞();
var __c1 = new MyClass ();
__c1.nameofClass = "ScIEnce";
__c1.studentNames.Add("Laura");
__c1.studentNames.Add("George");
classes.Add (__c1);
var __c2 = new MyClass();
__c2.nameofClass = "Commerce";
__c2.studentNames.Add("Bill");
__c2.studentNames.Add("Hillary");
classes.Add (__c2);
如果激活ILDASM並且打開了編譯的二進制代碼形式，那 麼你能夠看到如圖１類似的內容。
圖1.示例代碼片斷的編譯的二進制形式
如果你雙擊在ILDASM中的Main結點，那麼你會看到下列代碼：
.method private hidebysig static void Main(string[] args) cil managed
{
.entrypoint
//代碼大小 138 (0x8a)
.maxstack 3
.locals init ([0] class [mscorlib] System.Collections.Generic.List`1
＜class CollectionInitializer.Program/MyClass＞
classes,
[1] class [mscorlib]System.Collections.Generic.List`1
＜class CollectionInitializer.Program/MyClass＞
'＜tampa＞ f__0',
[2] class CollectionInitializer.Program/MyClass
'＜tampa＞f__1',
[3] class CollectionInitializer.Program/MyClass
'＜tampa＞f__2')
IL_0000: nop
IL_0001: nop
IL_0002: newobj instance void class [mscorlib]System.Collections.
Generic.List`1＜class CollectionInitializer.
Program/MyClass ＞::.ctor()
IL_0007: stloc.1
IL_0008: ldloc.1
IL_0009: nop
IL_000a: newobj instance void CollectionInitializer.
Program/MyClass::.ctor()
IL_000f: stloc.2
IL_0010: ldloc.2
IL_0011: ldstr "ScIEnce"
IL_0016: stfld string CollectionInitializer.
Program/MyClass::nameofClass
IL_001b: nop
IL_001c: ldloc.2
IL_001d: ldfld class [mscorlib]System.Collections.Generic.List`1
＜string＞ CollectionInitializer.
Program/MyClass::studentNames
IL_0022: ldstr "Laura"
IL_0027: callvirt instance void class [mscorlib]System.
Collections.Generic.List`1＜string ＞::Add(!0)
IL_002c: nop
IL_002d: ldloc.2
IL_002e: ldfld class [mscorlib]System.Collections.Generic.List`1
＜string＞ CollectionInitializer.
Program/MyClass::studentNames
IL_0033: ldstr "George"
IL_0038: callvirt instance void class [mscorlib]System.Collections.
Generic.List`1＜string＞::Add(! 0)
IL_003d: nop
IL_003e: nop
IL_003f: ldloc.2
IL_0040: nop
IL_0041: callvirt instance void class [mscorlib]System.Collections.
Generic.List`1＜class CollectionInitializer.
Program/MyClass＞::Add(!0)
IL_0046: nop
IL_0047: ldloc.1
IL_0048: nop
IL_0049: newobj instance void CollectionInitializer.
Program/MyClass::.ctor()
IL_004e: stloc.3
IL_004f: ldloc.3
IL_0050: ldstr "Commerce"
IL_0055: stfld string CollectionInitializer.
Program/MyClass::nameofClass
IL_005a: nop
IL_005b: ldloc.3
IL_005c: ldfld class [mscorlib] System.Collections.Generic.List`1
＜string＞ CollectionInitializer.
Program/MyClass::studentNames
IL_0061: ldstr "Bill"
IL_0066: callvirt instance void class [mscorlib]System.Collections.
Generic.List`1＜string ＞::Add(!0)
IL_006b: nop
IL_006c: ldloc.3
IL_006d: ldfld class [mscorlib]System.Collections.Generic.List`1
＜string＞ CollectionInitializer.
Program/MyClass::studentNames
IL_0072: ldstr "Hillary"
IL_0077: callvirt instance void class [mscorlib]System.Collections.
Generic.List`1＜string＞::Add(! 0)
IL_007c: nop
IL_007d: nop
IL_007e: ldloc.3
IL_007f: nop
IL_0080: callvirt instance void class [mscorlib]System.Collections.
Generic.List`1＜class CollectionInitializer.
Program/MyClass＞::Add(!0)
IL_0085: nop
IL_0086: ldloc.1
IL_0087: nop
IL_0088: stloc.0
IL_0089: ret
} //Program::Main方法結束
四、小結
從前面的一些代碼片斷中你可以看到，C# 3.0 在語法方面邁出了很大的一步。
集合初始化器，作為C# 3.0新引入的特 征之一，提供了一種新的語法來初始化集合對象。這種簡單的語法把集合對象的 創建和初始化結合到一個步驟中。
