JS 中的组合和混合
Compostions and mixins in JS
我在使用 compostions 和 mixin 时遇到了一些麻烦。
例如，假设我们有一个 AHero 和一个 Hero1 object。
所有英雄都可以移动，所以 AHero.move() 是一回事。
现在，在开发的那一刻，我想添加 stun 和 beStunned 的可能性。所以我做了一个新的 object 看起来像这样（称为 stunTrait）：
{
stunned : false,
stun(),
beStun,
}
而且我决定给英雄们提供眩晕和被眩晕的可能性。所以我做了一个混合：
class AHero 扩展了 stunTrait(superclass).
现在我想要一个被击晕的英雄不能移动。
所以在 Ahero 中：
move(){
if(this.stunned) return;
...
}
后来我发现 stun 是个坏主意，所以我决定停止实施 stunTrait。现在我必须在我的 Ahero class 中找到所有令人震惊的东西，这有时会很困难，如果 child class 对这些令人震惊的东西做了一些其他事情，那就更难了。
有没有办法避免这种情况？更好的设计？
class Object{
constructor(x,y){
this.x = x
this.y = y
}
}
class AHero extends stunTrait(Object){
constructor(x,y,moveSpeed){
this.moveSpeed = moveSpeed;
}
move(){
super.move();
this.speed = moveSpeed;
}
}
class hero1 extends AHero{
constructor(x,y,moveSpeed){ }
}
let stunTrait = function(object){
return class extends object{
constructor(...args) {
super(...args);
this.stunned = false;
}
move(){
if(this.stunned) this.speed = 0;
}
}
}
let hero = new hero1(40, 50, 100);
hero.stunned = true;
hero.move();
// This work, bcs AHero.move() is called before stunTrait.move()
// but if for some reason, I decide that only hero1 should have stunTrait
// So : class hero1 extends stunTrait(AHero)
// stunTrait.move() will be called after, so stunned will not be applied
// How make compostion without breaking inheritance ?
OP 的给定设计决策旨在修改 class 方面已经实施的 move 行为。
因此 stun 行为不仅负责实现其 stun 特定状态处理，它还必须 决定 是否 and/or如何更改 move 行为的控制流。
为此，它不仅依赖于 move 的现有实现，还依赖于 setSpeed.
mixin 的概念确实不适合 OP 的方法，因为它只是将额外的行为混合到其他对象中。但是给定的特殊情况也必须处理 move 的命名冲突。这就是特征的用途。
如果在JavaScript中曾经真正支持applicable types，它必须能够进行组合特征和对象组合，以及方法修改，一个可能的解决方案可能看起来类似于下一个提供的解决方案。
const withStunBehavior = Trait.create(function (use, applicator) {
function moveInterceptor(proceedMove, interceptor, argsArray) {
//console.log("withStunBehavior::moveInterceptor - this.isStunned() : ", this.isStunned());
if (this.isStunned()) {
this.setSpeed(0);
}/* else {
return proceedMove.call(this);
}*/
return proceedMove.call(this);
}
applicator(function (isStunnedValue) {
isStunnedValue = !!isStunnedValue;
//console.log("withStunBehavior::applicator - isStunnedValue : ", isStunnedValue);
this.beStun = function beStun () {
isStunnedValue = true;
};
this.unban = function unban () {
isStunnedValue = false;
};
this.isStunned = function isStunned () {
return isStunnedValue;
};
}).requires([
"setSpeed",
"move"
]).around(
"move", moveInterceptor
);
});
class AHero {
constructor(stateValue) {
var
aHero = this;
aHero.getSpeed = function getSpeed () {
return stateValue.moveSpeed;
};
aHero.setSpeed = function setSpeed (speedValue) {
return (stateValue.moveSpeed = speedValue);
};
// withStunBehavior.call(aHero);
}
move() {
var
speedValue = this.getSpeed();
if (speedValue === 0) {
console.log("Hero does not move at all. Its speed is " + speedValue + ".");
} else {
console.log("Hero moves with speed " + speedValue + ".");
}
return speedValue;
}
}
class AHeroWithStunBehavior extends AHero {
constructor(stateValue) {
super(stateValue);
withStunBehavior.call(this);
}
}
var
hero = new AHero({ x: 0, y: 0, moveSpeed: 200 });
console.log("\n");
console.log("hero.getSpeed() : ", hero.getSpeed());
console.log("hero.move() : ", hero.move());
console.log("\n");
console.log("hero.setSpeed(0) : ", hero.setSpeed(0));
console.log("hero.getSpeed() : ", hero.getSpeed());
console.log("hero.move() : ", hero.move());
console.log("\n");
console.log("hero.setSpeed(100) : ", hero.setSpeed(100));
console.log("hero.getSpeed() : ", hero.getSpeed());
console.log("hero.move() : ", hero.move());
console.log("\n");
console.log("hero.isStunned : ", hero.isStunned);
console.log("hero.beStun : ", hero.beStun);
console.log("hero.unban : ", hero.unban);
var
stunningHero = new AHeroWithStunBehavior({ x: 40, y: 50, moveSpeed: 130 });
console.log("\n");
console.log("stunningHero.isStunned : ", stunningHero.isStunned);
console.log("stunningHero.beStun : ", stunningHero.beStun);
console.log("stunningHero.unban : ", stunningHero.unban);
console.log("\n");
console.log("stunningHero.getSpeed() : ", stunningHero.getSpeed());
console.log("stunningHero.move() : ", stunningHero.move());
console.log("\n");
console.log("stunningHero.setSpeed(0) : ", stunningHero.setSpeed(0));
console.log("stunningHero.getSpeed() : ", stunningHero.getSpeed());
console.log("stunningHero.move() : ", stunningHero.move());
console.log("\n");
console.log("stunningHero.setSpeed(90) : ", stunningHero.setSpeed(90));
console.log("stunningHero.getSpeed() : ", stunningHero.getSpeed());
console.log("stunningHero.move() : ", stunningHero.move());
console.log("\n");
console.log("stunningHero.beStun() : ", stunningHero.beStun());
console.log("stunningHero.move() : ", stunningHero.move());
console.log("\n");
console.log("stunningHero.setSpeed(160) : ", stunningHero.setSpeed(160));
console.log("stunningHero.getSpeed() : ", stunningHero.getSpeed());
console.log("stunningHero.move() : ", stunningHero.move());
console.log("\n");
console.log("stunningHero.unban() : ", stunningHero.unban());
console.log("stunningHero.move() : ", stunningHero.move());
console.log("\n");
console.log("stunningHero.setSpeed(160) : ", stunningHero.setSpeed(160));
console.log("stunningHero.getSpeed() : ", stunningHero.getSpeed());
console.log("stunningHero.move() : ", stunningHero.move());
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我在使用 compostions 和 mixin 时遇到了一些麻烦。 例如，假设我们有一个 AHero 和一个 Hero1 object。 所有英雄都可以移动，所以 AHero.move() 是一回事。 现在，在开发的那一刻，我想添加 stun 和 beStunned 的可能性。所以我做了一个新的 object 看起来像这样（称为 stunTrait）：
{
stunned : false,
stun(),
beStun,
}
而且我决定给英雄们提供眩晕和被眩晕的可能性。所以我做了一个混合： class AHero 扩展了 stunTrait(superclass).
现在我想要一个被击晕的英雄不能移动。 所以在 Ahero 中：
move(){
if(this.stunned) return;
...
}
后来我发现 stun 是个坏主意，所以我决定停止实施 stunTrait。现在我必须在我的 Ahero class 中找到所有令人震惊的东西，这有时会很困难，如果 child class 对这些令人震惊的东西做了一些其他事情，那就更难了。
有没有办法避免这种情况？更好的设计？
class Object{
constructor(x,y){
this.x = x
this.y = y
}
}
class AHero extends stunTrait(Object){
constructor(x,y,moveSpeed){
this.moveSpeed = moveSpeed;
}
move(){
super.move();
this.speed = moveSpeed;
}
}
class hero1 extends AHero{
constructor(x,y,moveSpeed){ }
}
let stunTrait = function(object){
return class extends object{
constructor(...args) {
super(...args);
this.stunned = false;
}
move(){
if(this.stunned) this.speed = 0;
}
}
}
let hero = new hero1(40, 50, 100);
hero.stunned = true;
hero.move();
// This work, bcs AHero.move() is called before stunTrait.move()
// but if for some reason, I decide that only hero1 should have stunTrait
// So : class hero1 extends stunTrait(AHero)
// stunTrait.move() will be called after, so stunned will not be applied
// How make compostion without breaking inheritance ?
OP 的给定设计决策旨在修改 class 方面已经实施的 move 行为。
因此 stun 行为不仅负责实现其 stun 特定状态处理，它还必须 决定 是否 and/or如何更改 move 行为的控制流。
为此，它不仅依赖于 move 的现有实现，还依赖于 setSpeed.
mixin 的概念确实不适合 OP 的方法，因为它只是将额外的行为混合到其他对象中。但是给定的特殊情况也必须处理 move 的命名冲突。这就是特征的用途。
如果在JavaScript中曾经真正支持applicable types，它必须能够进行组合特征和对象组合，以及方法修改，一个可能的解决方案可能看起来类似于下一个提供的解决方案。
const withStunBehavior = Trait.create(function (use, applicator) {
function moveInterceptor(proceedMove, interceptor, argsArray) {
//console.log("withStunBehavior::moveInterceptor - this.isStunned() : ", this.isStunned());
if (this.isStunned()) {
this.setSpeed(0);
}/* else {
return proceedMove.call(this);
}*/
return proceedMove.call(this);
}
applicator(function (isStunnedValue) {
isStunnedValue = !!isStunnedValue;
//console.log("withStunBehavior::applicator - isStunnedValue : ", isStunnedValue);
this.beStun = function beStun () {
isStunnedValue = true;
};
this.unban = function unban () {
isStunnedValue = false;
};
this.isStunned = function isStunned () {
return isStunnedValue;
};
}).requires([
"setSpeed",
"move"
]).around(
"move", moveInterceptor
);
});
class AHero {
constructor(stateValue) {
var
aHero = this;
aHero.getSpeed = function getSpeed () {
return stateValue.moveSpeed;
};
aHero.setSpeed = function setSpeed (speedValue) {
return (stateValue.moveSpeed = speedValue);
};
// withStunBehavior.call(aHero);
}
move() {
var
speedValue = this.getSpeed();
if (speedValue === 0) {
console.log("Hero does not move at all. Its speed is " + speedValue + ".");
} else {
console.log("Hero moves with speed " + speedValue + ".");
}
return speedValue;
}
}
class AHeroWithStunBehavior extends AHero {
constructor(stateValue) {
super(stateValue);
withStunBehavior.call(this);
}
}
var
hero = new AHero({ x: 0, y: 0, moveSpeed: 200 });
console.log("\n");
console.log("hero.getSpeed() : ", hero.getSpeed());
console.log("hero.move() : ", hero.move());
console.log("\n");
console.log("hero.setSpeed(0) : ", hero.setSpeed(0));
console.log("hero.getSpeed() : ", hero.getSpeed());
console.log("hero.move() : ", hero.move());
console.log("\n");
console.log("hero.setSpeed(100) : ", hero.setSpeed(100));
console.log("hero.getSpeed() : ", hero.getSpeed());
console.log("hero.move() : ", hero.move());
console.log("\n");
console.log("hero.isStunned : ", hero.isStunned);
console.log("hero.beStun : ", hero.beStun);
console.log("hero.unban : ", hero.unban);
var
stunningHero = new AHeroWithStunBehavior({ x: 40, y: 50, moveSpeed: 130 });
console.log("\n");
console.log("stunningHero.isStunned : ", stunningHero.isStunned);
console.log("stunningHero.beStun : ", stunningHero.beStun);
console.log("stunningHero.unban : ", stunningHero.unban);
console.log("\n");
console.log("stunningHero.getSpeed() : ", stunningHero.getSpeed());
console.log("stunningHero.move() : ", stunningHero.move());
console.log("\n");
console.log("stunningHero.setSpeed(0) : ", stunningHero.setSpeed(0));
console.log("stunningHero.getSpeed() : ", stunningHero.getSpeed());
console.log("stunningHero.move() : ", stunningHero.move());
console.log("\n");
console.log("stunningHero.setSpeed(90) : ", stunningHero.setSpeed(90));
console.log("stunningHero.getSpeed() : ", stunningHero.getSpeed());
console.log("stunningHero.move() : ", stunningHero.move());
console.log("\n");
console.log("stunningHero.beStun() : ", stunningHero.beStun());
console.log("stunningHero.move() : ", stunningHero.move());
console.log("\n");
console.log("stunningHero.setSpeed(160) : ", stunningHero.setSpeed(160));
console.log("stunningHero.getSpeed() : ", stunningHero.getSpeed());
console.log("stunningHero.move() : ", stunningHero.move());
console.log("\n");
console.log("stunningHero.unban() : ", stunningHero.unban());
console.log("stunningHero.move() : ", stunningHero.move());
console.log("\n");
console.log("stunningHero.setSpeed(160) : ", stunningHero.setSpeed(160));
console.log("stunningHero.getSpeed() : ", stunningHero.getSpeed());
console.log("stunningHero.move() : ", stunningHero.move());
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This expected behavior has not been implemented by the trait that got passed to 'after'."].join(""));else throw new k("Passing identical trait references to both 'apply' and 'after' is a contradiction that violates the composition rules.");else throw new h("Any trait passed to 'after' has to be registered before via 'use'.");else throw new h("'after(<Trait|Function>)' excepts as its sole argument explicitly either a 'Trait' or a 'Function' type.");else throw new n(["\u2026 invalid chaining of '",b,"().after()'"].join(""));else throw new k("Please do not spoof the context of 'use'.");else throw new k("Please do not spoof the context of 'apply'.");return m};L.before=function(c){var b,d,e,f,l,m;if(G(this))if(f=this.valueOf(),m=f.parentLink,w(m))if(e=m.getSetup(),d=e.chainData,b=d.recentCalleeName,v(b,"before"))if(x(c))if(b=m.valueOf(),b=b.traitList,0<=b.indexOf(c))if(b=f.trait,b!==c)if(l=f.methodName,f={},c.call(f),g(f[l]))d.recentCalleeName="before",e.useTraits.rules.push(new A({type:"beforeApply",trait:c,fromTrait:b,methodName:l}));else throw new k(["Please consider applying '",l,"' directly. This expected behavior has not been implemented by the trait that got passed to 'before'."].join(""));else throw new k("Passing identical trait references to both 'apply' and 'before' is a contradiction that violates the composition rules.");else throw new h("Any trait passed to 'before' has to be registered before via 'use'.");else throw new h("'before(<Trait|Function>)' excepts as its sole argument explicitly either a 'Trait' or a 'Function' type.");else throw new n(["\u2026 invalid chaining of '",b,"().before()'"].join(""));else throw new k("Please do not spoof the context of 'use'.");else throw new k("Please do not spoof the context of 'apply'.");return m};L.apply=ha;sa.without=fa;sa.apply=ha;ra.after=function(c){var b,d,e,f;if(w(this))if(e=this.getSetup(),d=e.chainData,b=d.recentCalleeName,v(b,"after"))if(x(c))if(b=this.valueOf(),b=b.traitList,0<=b.indexOf(c))if(b=this.getChild(),f=b.valueOf(),b=f.trait,b!==c)if(f=f.methodName,b={},c.call(b),g(b[f]))d.recentCalleeName="after",e.useTraits.rules.push(new A({type:"afterWrap",trait:c,methodName:f}));else throw new k(["Please consider applying '",f,"' directly. This expected behavior has not been implemented by the trait that got passed to 'after'."].join(""));else throw new k("Passing identical trait references to both 'apply' and 'after' is a contradiction that violates the composition rules.");else throw new h("Any trait passed to 'after' has to be registered before via 'use'.");else throw new h("'after(<Trait|Function>)' excepts as its sole argument explicitly either a 'Trait' or a 'Function' type.");else throw new n(["\u2026 invalid chaining of '",b,"().after()'"].join(""));else throw new k("Please do not spoof the context of 'use'.");return this};ra.before=function(c){var b,d,e,f;if(w(this))if(e=this.getSetup(),d=e.chainData,b=d.recentCalleeName,v(b,"before"))if(x(c))if(b=this.valueOf(),b=b.traitList,0<=b.indexOf(c))if(b=this.getChild(),f=b.valueOf(),b=f.trait,b!==c)if(f=f.methodName,b={},c.call(b),g(b[f]))d.recentCalleeName="before",e.useTraits.rules.push(new A({type:"beforeWrap",trait:c,methodName:f}));else throw new k(["Please consider applying '",f,"' directly. This expected behavior has not been implemented by the trait that got passed to 'before'."].join(""));else throw new k("Passing identical trait references to both 'apply' and 'before' is a contradiction that violates the composition rules.");else throw new h("Any trait passed to 'before' has to be registered before via 'use'.");else throw new h("'before(<Trait|Function>)' excepts as its sole argument explicitly either a 'Trait' or a 'Function' type.");else throw new n(["\u2026 invalid chaining of '",b,"().before()'"].join(""));else throw new k("Please do not spoof the context of 'use'.");return this};A.prototype.execute=function(c,b){var d=this.valueOf();ob[d.type](d,c,b)};return r.Trait={create:function(c){var b,d,e;g(c=F(c))&&(e={chainData:{isTerminated:!1,recentCalleeName:"use"},useTraits:{root:null,rules:[]},applicator:{body:null,proxy:{},root:{},modifiers:[],requires:[],canRequire:!0,didRequire:!1}},b=e.applicator.root,b.requires=cb.bind(e),b.before=Va.bind(e),b.after=Xa.bind(e),b.before.stateful=Wa.bind(e),b.after.stateful=Ya.bind(e),b.afterReturning=Za.bind(e),b.afterThrowing=$a.bind(e),b.afterFinally=ab.bind(e),b.around=bb.bind(e),b=eb.bind(e),d=db.bind(e),c(b,d),e=mb(e));return e},isTrait:qa,isApplicable:x}})(Function("return this")());</script>