RT:有人問(wèn)Net里面的.CCtor和Ctor是什么?首先說(shuō)答案,.CCtor是靜態(tài)構(gòu)造函數(shù),.Ctor是非靜態(tài)構(gòu)造函數(shù)。通過(guò)例子分析下這兩個(gè)特殊的函數(shù),本篇看下。
先上例子:
public class ABC{ public ABC(){ } int i=0x10;}public class BBC:ABC{ public BBC(){ } int i = 0x20;} static void Main(string[] args) { BBC bBC = new BBC(); }
簡(jiǎn)單點(diǎn)來(lái)說(shuō),類BBC的非靜態(tài)構(gòu)造函數(shù)就是BBC.Ctor,也就是構(gòu)造函數(shù)BBC(){}.同理ABC的非靜態(tài)構(gòu)造函數(shù)ABC.Ctor也就是ABC(){}
作用為什么Roslyn編譯器要加上一個(gè)這種函數(shù),就是為了循環(huán)往上初始化父類。直到Object.Ctor為止,也就是初始化到最基礎(chǔ)的Object類為止才不會(huì)初始化,一層層的向上執(zhí)行。
以上面例子為例
運(yùn)行的過(guò)程如下:
1.new BBC()2.BBC.Ctor3.ABC.Ctor4.Object.Ctor
也就是說(shuō),有多少個(gè)父類,它統(tǒng)統(tǒng)初始化。方便以后調(diào)用,比如ABC類里面有個(gè)變量i,就是此時(shí)被初始化的,如果沒(méi)有被初始化,如果需要用到就會(huì)報(bào)錯(cuò)。這里注意,如果BBC類里面有全局變量,則優(yōu)先于ABC里面的全局變量i初始化。
代碼最后我們看下它的底層代碼BBC bBC = new BBC() Program+BBC..ctor
00007FF862D006D7 48 B9 50 21 DF 62 F8 7F 00 00 mov rcx,7FF862DF2150h 00007FF862D006E1 E8 7A 02 B0 5F call CORINFO_HELP_NEWSFAST (07FF8C2800960h) 00007FF862D006E6 48 89 45 20 mov qword ptr [rbp+20h],rax 00007FF862D006EA 48 8B 4D 20 mov rcx,qword ptr [rbp+20h] 00007FF862D006EE E8 05 E7 0D 00 call Test_.Program+BBC..ctor() (07FF862DDEDF8h)
int i=0x10 public ABC(){}
00007FF862D015C7 E8 44 64 C2 5F call 00007FF8C2927A10 00007FF862D015CC 48 8B 4D 40 mov rcx,qword ptr [rbp+40h] 00007FF862D015D0 C7 41 08 10 00 00 00 mov dword ptr [rcx+8],10h 00007FF862D015D7 48 8B 4D 40 mov rcx,qword ptr [rbp+40h] 00007FF862D015DB FF 15 4F FA F6 FF call qword ptr [CLRStub[MethodDescPrestub]@00007FF862C71030 (07FF862C71030h)] 00007FF862D015E1 90 nop 00007FF862D015E2 90 nop 00007FF862D015E3 FF 15 2F 63 12 00 call qword ptr [CLRStub[MethodDescPrestub]@00007FF862E27918 (07FF862E27918h)]
public BBC(){}
00007FF862D0157B E8 60 D8 0D 00 call Test_.Program+ABC..ctor() (07FF862DDEDE0h) 00007FF862D01580 90 nop 00007FF862D01581 90 nop
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