供cocos2d-x通常使用的方法，我有一個(gè)好臉色。這項(xiàng)研究真的獎(jiǎng)勵(lì)。

向?qū)紫?#xff0c;定義，實(shí)施一系列連續(xù)動(dòng)作。

對(duì)于我們的行動(dòng)能回調(diào)函數(shù)，我們必須申報(bào)并加以實(shí)施。

void callBack();void callBack_1(Node* node);void callBack_2(Node* node,const char* str);void Nice::callBack(){log("Nice::callBack()");}void Nice::callBack_1(Node* node){log("This tag is %d",node->getTag());}void Nice::callBack_2(Node* node,const char* str){log("This tag is %d, and str is %s",node->getTag(), str);}//然后就開始創(chuàng)建我們偉大的精靈了。sp_area = Sprite::create("newAlwaysShow.png");//sp_area is a class member ,Sprite* ap_area;sp_area->setTag(1314);auto sp_another = Sprite::create();sp_another->setTag(520);addChild(sp_another);addChild(sp_area);//翻滾吧。可愛的精靈們！/*CallFunc 創(chuàng)建的函數(shù)必須是無參數(shù)的CallFuncN 創(chuàng)建的函數(shù)能夠是一個(gè)至多個(gè)參數(shù)*/sp_area->runAction(Sequence::create(MoveTo::create(2, Vec2(200, 200)),CallFunc::create(CC_CALLBACK_0(Nice::callBack, this)),CallFuncN::create(CC_CALLBACK_1(Nice::callBack_2, this, "I have tow parameter")),NULL));//這樣寫完之后。發(fā)現(xiàn)runAction里面的東西好平淡（平淡有時(shí)候才不是真呢！

），于是我就瞎寫一通。殘忍的把它變成了這個(gè)樣子。 sp_area->runAction(Sequence::create(MoveTo::create(2, Vec2(200, 200)), CallFunc::create(CC_CALLBACK_0(Nice::callBack, this)), CallFunc::create([&]()->void{log("Done1");log("This tag is %d", sp_area->getTag());}), CallFunc::create(std::bind(&Nice::callBack, this)), CallFuncN::create(CC_CALLBACK_1(Nice::callBack_1, this)),//1314 CallFuncN::create(CC_CALLBACK_0(Nice::callBack_1, this, sp_another)),//520 CallFuncN::create([](Node* node){log("this tag is %d", node->getTag());}),//1314 CallFuncN::create(std::bind(&Nice::callBack_1, this, sp_area)),//1314 CallFuncN::create(std::bind(&Nice::callBack_1, this, sp_another)),//520 CallFuncN::create(CC_CALLBACK_1(Nice::callBack_2, this, "I have tow parameter")), NULL));

好吧，他如今已經(jīng)面目全非了。事實(shí)上這么多行也僅僅是用到了兩種方法而已，第一種lambda表達(dá)式。另外一種std::bind()。

（尼瑪，你在逗我嗎？不是還有CC_CALLBACK_0嗎？）
額。既然這樣就讓我們來看下源代碼吧。

// new callbacks based on C++11 #define CC_CALLBACK_0(__selector__,__target__, ...) std::bind(&__selector__,__target__, ##__VA_ARGS__) #define CC_CALLBACK_1(__selector__,__target__, ...) std::bind(&__selector__,__target__, std::placeholders::_1, ##__VA_ARGS__) #define CC_CALLBACK_2(__selector__,__target__, ...) std::bind(&__selector__,__target__, std::placeholders::_1, std::placeholders::_2, ##__VA_ARGS__) #define CC_CALLBACK_3(__selector__,__target__, ...) std::bind(&__selector__,__target__, std::placeholders::_1, std::placeholders::_2, std::placeholders::_3, ##__VA_ARGS__)

果不其然，宏僅僅是表面。內(nèi)在還是偷偷的和std::bind勾搭在一起了！


我們來看下這個(gè)到處勾搭的宏是怎么定義的～～～
#define CC_CALLBACK_0(__selector__,__target__, ...) std::bind(&__selector__,__target__, ##__VA_ARGS__)
#define CC_CALLBACK_0( 方法,目標(biāo), 可變參數(shù)) std::bind(&取方法的地址,目標(biāo), 可變參數(shù))
PS:在定義宏的時(shí)候是不能用...來當(dāng)作前面的...作為可變參數(shù)的，必需要使用##__VA_ARGS__這個(gè)偉大的第三者來替換掉


可變參數(shù)在整個(gè)cocos-x中也還是用到非常多的。比方創(chuàng)建Sequence::create就是運(yùn)動(dòng)了，不然你怎么能在創(chuàng)建一連串的動(dòng)作的時(shí)候傳入那么多的參數(shù)的說。

那么接下來就來看看源代碼吧。

（又是源代碼－ －）

Sequece::create是分平臺(tái)實(shí)現(xiàn)的（分為win和其它）#if (CC_TARGET_PLATFORM == CC_PLATFORM_WP8) || (CC_TARGET_PLATFORM == CC_PLATFORM_WINRT)// WP8 in VS2012 does not support nullptr in variable args lists and variadic templates are also not supportedtypedef FiniteTimeAction* M;static Sequence* create(M m1, std::nullptr_t listEnd) { return variadicCreate(m1, NULL); }static Sequence* create(M m1, M m2, std::nullptr_t listEnd) { return variadicCreate(m1, m2, NULL); }static Sequence* create(M m1, M m2, M m3, std::nullptr_t listEnd) { return variadicCreate(m1, m2, m3, NULL); }static Sequence* create(M m1, M m2, M m3, M m4, std::nullptr_t listEnd) { return variadicCreate(m1, m2, m3, m4, NULL); }static Sequence* create(M m1, M m2, M m3, M m4, M m5, std::nullptr_t listEnd) { return variadicCreate(m1, m2, m3, m4, m5, NULL); }static Sequence* create(M m1, M m2, M m3, M m4, M m5, M m6, std::nullptr_t listEnd) { return variadicCreate(m1, m2, m3, m4, m5, m6, NULL); }static Sequence* create(M m1, M m2, M m3, M m4, M m5, M m6, M m7, std::nullptr_t listEnd) { return variadicCreate(m1, m2, m3, m4, m5, m6, m7, NULL); }static Sequence* create(M m1, M m2, M m3, M m4, M m5, M m6, M m7, M m8, std::nullptr_t listEnd) { return variadicCreate(m1, m2, m3, m4, m5, m6, m7, m8, NULL); }static Sequence* create(M m1, M m2, M m3, M m4, M m5, M m6, M m7, M m8, M m9, std::nullptr_t listEnd) { return variadicCreate(m1, m2, m3, m4, m5, m6, m7, m8, m9, NULL); }static Sequence* create(M m1, M m2, M m3, M m4, M m5, M m6, M m7, M m8, M m9, M m10, std::nullptr_t listEnd) { return variadicCreate(m1, m2, m3, m4, m5, m6, m7, m8, m9, m10, NULL); }// On WP8 for variable argument lists longer than 10 items, use the other create functions or variadicCreate with NULL as the last argumentstatic Sequence* variadicCreate(FiniteTimeAction* item, ...); #elsestatic Sequence* create(FiniteTimeAction *action1, ...) CC_REQUIRES_NULL_TERMINATION; #endifSequence* Sequence::create(FiniteTimeAction *action1, ...) {va_list params;va_start(params, action1);Sequence *ret = Sequence::createWithVariableList(action1, params);//傳給了createWithVariableList讓他來處理va_end(params);return ret; }Sequence* Sequence::createWithVariableList(FiniteTimeAction *action1, va_list args) {FiniteTimeAction *now;FiniteTimeAction *prev = action1;bool bOneAction = true;while (action1){now = va_arg(args, FiniteTimeAction*);//假設(shè)第二個(gè)動(dòng)作存在if (now){prev = createWithTwoActions(prev, now);bOneAction = false;}//假設(shè)第二個(gè)動(dòng)作不存在else{// If only one action is added to Sequence, make up a Sequence by adding a simplest finite time action.if (bOneAction){prev = createWithTwoActions(prev, ExtraAction::create());}break;}}return ((Sequence*)prev); }
我們就依照他的思路來實(shí)現(xiàn)一個(gè)可變參數(shù)的函數(shù)

void manyArgument(int num, ...);void Nice::manyArgument(int num, ...){va_list params;//va_start函數(shù)的第二個(gè)參數(shù)要和manyArgument的第一個(gè)參數(shù)一樣va_start(params, num);int now;log("fist is %d", num);while (true){now = va_arg(params, int);if (now != -1){log("now is %d", now);}else{break;}}va_end(params);}manyArgument(1, 2, 3, 4, -1);

能夠發(fā)現(xiàn)多個(gè)參數(shù)的的時(shí)候必需要有一個(gè)能夠終止的條件（比如最后一個(gè)為-1）。可是假設(shè)在中途就要傳入-1怎么辦？
這個(gè)時(shí)候僅僅能把傳入的參數(shù)改為int*
? ? void manyArgument(int* num, ...);
然后再把最后終止的條件換為!= null,可是這樣在傳入?yún)?shù)的時(shí)候就麻煩（有得必有失）

void manyArgument(int* num, ...);void Nice::manyArgument(int* num, ...){va_list params;//va_start函數(shù)的第二個(gè)參數(shù)要和manyArgument的第一個(gè)參數(shù)一樣va_start(params, num);int* now;log("fist is %d", *num);while (true){now = va_arg(params, int*);if (now != nullptr){log("now is %d", *now);}else{break;}}va_end(params);}int arr[] {3,6,9,12};manyArgument(arr, arr+1, arr+2, arr+3, nullptr);


接著試試定義一個(gè)可變參數(shù)得宏 ?##__VA_ARGS__ 就代表著前面?zhèn)魅脒M(jìn)來的可變參數(shù)

#define MANYARGUMENT(__num__, ...) manyArgument(__num__, ##__VA_ARGS__)MANYARGUMENT(arr, arr+1, arr+2, nullptr);
別忘記我們還有std::placeholders::_1 占位沒有玩過呢＝ ＝

auto add_num = std::bind(&Nice::add, this, std::placeholders::_1, std::placeholders::_2, 10);log("sum is %d", add_num(1, 1));//12log("sum is %d", add_num(1, 1, 2));//12log("sum is %d", add_num(1, 1, 2, 4));//12//不管怎么改變參數(shù)的第三位也是固定死了是10的，奇妙的是竟然能傳入四個(gè)參數(shù)，明擺著就是僅僅認(rèn)定前兩個(gè)參數(shù)是有效的，后面的統(tǒng)統(tǒng)無效。

學(xué)到這里。

貌似對(duì)這個(gè)流程還是比較清楚的嘛。盡管可能還有很多其它的僅僅是沒有發(fā)現(xiàn)，可是我們還有很多其它的時(shí)間沒實(shí)用呀！

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