编程时怎么把函数当做变量使用？ 第1页

       foreach 角色 in 角色数组:  角色.攻击()     

       //把技能ID和执行这个技能的函数联系起来 bool dispatchSpell(spellID id) {    switch(id){        case spellFireball:            return Fireball();        case spellFirebolt:            return Firebolt();        //依此类推，列出其他法术        ...        //如果法术id非法，返回false        default:           ASSERT(false); //debug版还是直接崩掉吧           return false;    } }  //给角色数据结构里面声明一个defaultSpell变量： roleType { ... spellID defaultSpell; ... }  //现在，直接循环调用角色数组里面每个角色的defaultSpell: foreach role in rolielist:     dispatchSpell(role.defaultSpell);     

       bool cast(spellID id) {  //根据法术id读取规则  spellConfig = loadSpellConfig(id);  //执行资源检定操作  resourceCheck(id);  //判断先决条件  ...  //执行角色动画  ...  //处理光影效果  ...  //制造法术实体（火球、暴风雪、子弹乃至刀光剑影，全都可以是法术实体）  ...  //计算影响范围  ...  //被击中目标效果处理（身上带火、呼叫、乱跑等）  ...  //伤害计算  ... }     

       foreach role in roleList {  cast(role.defaultSpell); }     

       #include <stdio.h> #include <unistd.h>  struct FuncTable {         void (*begin)(void);         void (*run)(unsigned int s);         void (*end)(void); };  void begin_f() {         printf("Begin
"); }  void run_f(unsigned int s) {         printf("Run %d seconds
", s);         sleep(s); }  void end_f() {         printf("End
"); }  int main(int argc, char *argv[]) {         struct FuncTable ft = {                 .begin = begin_f,                 .run   = run_f,                 .end   = end_f,         };          ft.begin();         ft.run(3);         ft.end();                          return 0; }     

       $ gcc -o mytest mytest.c -Wall $ ./mytest Begin Run 3 seconds End     

       #include <stdio.h> #include <stdlib.h> #include <string.h>  /* abstract interface declaration */ struct Hero {         char name[256];         void *funcTable;         void *privateData; };  struct HeroFuncTable {         void (*SetTarget)(struct Hero * obj, int x, int y);         void (*Move)(struct Hero * obj);         void (*Hit)(struct Hero * obj);         void (*SkillA)(struct Hero * obj); };  struct HeroPrivateData {         int x, y; };  void HeroSetTarget(struct Hero * obj, int newx, int newy) {         struct HeroPrivateData * rdata =                 (struct HeroPrivateData*)obj->privateData;         rdata->x = newx;         rdata->y = newy; }  void HeroMove(struct Hero * obj) {         struct HeroPrivateData * rdata =                 (struct HeroPrivateData*)obj->privateData;         printf("%s move to: [%d, %d]
", obj->name, rdata->x, rdata->y); }  void HeroHit(struct Hero * obj) {         struct HeroPrivateData * rdata =                 (struct HeroPrivateData*)obj->privateData;         printf("%s hit target at: [%d, %d]
", obj->name, rdata->x, rdata->y); }  void HeroSkillA (struct Hero * obj) {         struct HeroPrivateData * rdata =                 (struct HeroPrivateData*)obj->privateData;          printf("%s is using skillA on: [%d, %d]
", obj->name, rdata->x, rdata->y); }     

       /* Class Karma */ void KarmaSkillB (struct Hero *obj, int arg) {         struct HeroPrivateData * rdata =                 (struct HeroPrivateData*)obj->privateData;          printf("Karma is using skillB * %d at: [%d, %d]
", arg, rdata->x, rdata->y); }  struct KarmaFuncTable {         void (*SetTarget)(struct Hero * obj, int x, int y);         void (*Move)(struct Hero * obj);         void (*Hit)(struct Hero * obj);         void (*SkillA)(struct Hero * obj);         void (*SkillB)(struct Hero * obj, int arg); } karmaFuncTable = {         HeroSetTarget,         HeroMove,         HeroHit,         HeroSkillA,         KarmaSkillB };  struct Hero * MakeKarma (int initx, int inity) {         struct Hero * obj = malloc (sizeof(struct Hero));         struct HeroPrivateData * rdata = malloc (sizeof(struct HeroPrivateData));         strcpy(obj->name, "Karma");         obj->funcTable = (struct KarmaFuncTable*) &karmaFuncTable;         obj->privateData = rdata;          rdata->x = initx;         rdata->y = inity;          return obj; }     

       /* Class Jax */ struct JaxPrivateData {     int x, y;     int range; };  void JaxSetRange(struct Hero * obj, int rg) {         struct JaxPrivateData * rdata =                 (struct JaxPrivateData*)obj->privateData;          rdata->range = rg; }  void JaxHit(struct Hero * obj) {         struct JaxPrivateData * rdata =                 (struct JaxPrivateData*)obj->privateData;          printf("Jax hit target at: %d[%d, %d]
", rdata->range, rdata->x, rdata->y); }  void JaxSkillA(struct Hero * obj) {         struct JaxPrivateData * rdata =                 (struct JaxPrivateData*)obj->privateData;          printf("Jax is using SkillA at: %d[%d, %d]
", rdata->range, rdata->x, rdata->y); }  void JaxSkillB(struct Hero * obj) {         struct JaxPrivateData * rdata =                 (struct JaxPrivateData*)obj->privateData;          printf("Jax is using SkillB at: %d[%d, %d]
", rdata->range, rdata->x, rdata->y); }  struct JaxFuncTable {         void (*SetTarget)(struct Hero * obj, int x, int y);         void (*SetRange)(struct Hero * obj, int rg);         void (*Move)(struct Hero * obj);         void (*Hit)(struct Hero * obj);         void (*SkillA)(struct Hero * obj);         void (*SkillB)(struct Hero * obj); } jaxFuncTable = {         HeroSetTarget,         JaxSetRange,         HeroMove,         JaxHit,         JaxSkillA,         JaxSkillB };  struct Hero * MakeJax (int initx, int inity, int initr) {         struct Hero * obj = malloc (sizeof(struct Hero));         struct JaxPrivateData * rdata = malloc (sizeof(struct JaxPrivateData));         strcpy(obj->name, "Jax");         obj->funcTable = (struct JaxFuncTable*) &jaxFuncTable;         obj->privateData = rdata;          rdata->x     = initx;         rdata->y     = inity;         rdata->range = initr;          return obj; }     

       /* Do some test */ void KarmaDoSomething(struct Hero *h) {         struct KarmaFuncTable *f = h->funcTable;          f->SetTarget(h, 10, 20);         f->Move(h);         f->Hit(h);         f->SkillA(h);         f->SkillB(h, 100); }  void JaxDoSomething(struct Hero *h) {         struct JaxFuncTable *f = h->funcTable;          f->SetTarget(h, 50, 88);         f->SetRange(h, 8);         f->Move(h);         f->Hit(h);         f->SkillA(h);         f->SkillB(h); }  int main(int argc, char *argv[]) {         struct Hero * heros[2];          heros[0] = MakeKarma(0, 0);         heros[1] = MakeJax(0, 0, 5);          printf("-- Welcome Karma do something for us --
");         KarmaDoSomething(heros[0]);         printf("
");         printf("-- Welcome Jax do something for us --
");         JaxDoSomething(heros[1]);          return 0; }     

       $ gcc -o hero hero.c -Wall $ ./hero  -- Welcome Karma do something for us -- Karma move to: [10, 20] Karma hit target at: [10, 20] Karma is using skillA on: [10, 20] Karma is using skillB * 100 at: [10, 20]  -- Welcome Jax do something for us -- Jax move to: [50, 88] Jax hit target at: 8[50, 88] Jax is using SkillA at: 8[50, 88] Jax is using SkillB at: 8[50, 88]     

       skill[0] = function() { xxx }; skill[1] = function() { xxx }; skill[2] = function() { xxx };     

       if ( a == 0 )   xxx else if ( a == 1 )   xxx else if ( a == 2 )   xxx