@aboutweb/proxyclass 中文文档教程
proxy-class
一种组织多重继承的无缝方式。
如果可以的话,你应该总是喜欢其他模式,比如装饰器或注释,因为 javascript 不支持这个有充分的理由:
- must have the same arguments signiture
- hard to isolate instances
- overhead
ProxyClass(...mixins
)
使用 ProxyScope 来反映对所有 mixins
的 prototype
的所有更改。
ProxyClass.hasInstance(...mixins
)
允许通过覆盖所有 Subclass[Symbols.hasInstance]
来使用 instanceof
。 警告:这会使 instanceof 的开销更高。
Examples
const EventEmitter = require('events');
const listen = ["on", "once"];
class ArrayEmitter extends ProxyClass.hasInstance(Array, EventEmitter) {
constructor(options) {
let { data } = options;
super(...data);
listen.forEach((property) => {
let type = options[property];
if(type) {
for(let event in type) {
let listeners = type[event];
if(!Array.isArray(listeners)) {
listeners = [listeners];
}
listeners.forEach((listener) => {
this[property](event, listener)
});
}
}
});
this.emit("push", data);
}
push(...args) {
super.push(...args);
this.emit("push", args);
}
}
let input = ["fubar", "haha"];
let ae = new ArrayEmitter({
data : input,
on : {
push(...args) {
console.log("every push", args);
}
},
once : {
push(...args) {
console.log("inital push", args);
}
}
});
ae.push("last");
//will be true
na instanceof ArrayEmitter;
na instanceof Array;
na instanceof EventEmitter;
深层类
class A {
constructor() {
this.aProp = true;
this.shared = "sharedA";
}
get isA() {
return true;
}
get sharedA() {
return this.shared;
}
sharedAFn() {
return this.shared;
}
}
class B { get isB() { return true; } }
class C extends ProxyClass.hasInstance(A, B) {
get isC() { return true; }
}
class D {
get isD() { return true; }
}
class E extends ProxyClass.hasInstance(C, D) {
constructor() {
super();
this.eProp = true;
}
get isE() { return true; }
};
//You can also inline your class
var F = ProxyClass.hasInstance(class {
constructor(someArg) {
this.someArg = someArg;
this.fProp = true;
}
get isF() {
return true;
}
}, E);
var e = new E();
//all of this will return true
e instanceof Object;
e instanceof A;
e instanceof B;
e instanceof C;
e instanceof D;
e instanceof E;
e.isA;
e.isB;
e.isC;
e.isD;
e.isE;
e.aProp;
e.eProp;
var f = new F("fubar");
//same as e plus
f instanceof F;
f.isF;
f.fProp;
f.someArg == "fubar";
Isolation
所有类成员函数都将使用它们自己的隔离上下文进行调用。
expect(e.shared).toEqual("sharedE");
expect(e.sharedA).toEqual("sharedA");
expect(e.sharedAFn()).toEqual("sharedA");
Dependancies
Licence
国际学习中心
proxy-class
A seemless way to organize multi inheritance.
Caution this function uses ES6 Proxies, Sets and Symbols. Use Ring.js or similar libaries, if you want an ES5 approach.
You should always prefer other patterns like decorators or annotions if you can, because javascript does not support this for good reasons:
- must have the same arguments signiture
- hard to isolate instances
- overhead
ProxyClass(...mixins
)
Uses ProxyScope to reflects all changes to prototype
of all mixins
.
ProxyClass.hasInstance(...mixins
)
Allows the use of instanceof
by overwriting all Subclass[Symbols.hasInstance]
. Caution: this will make instanceof more expensive.
Examples
const EventEmitter = require('events');
const listen = ["on", "once"];
class ArrayEmitter extends ProxyClass.hasInstance(Array, EventEmitter) {
constructor(options) {
let { data } = options;
super(...data);
listen.forEach((property) => {
let type = options[property];
if(type) {
for(let event in type) {
let listeners = type[event];
if(!Array.isArray(listeners)) {
listeners = [listeners];
}
listeners.forEach((listener) => {
this[property](event, listener)
});
}
}
});
this.emit("push", data);
}
push(...args) {
super.push(...args);
this.emit("push", args);
}
}
let input = ["fubar", "haha"];
let ae = new ArrayEmitter({
data : input,
on : {
push(...args) {
console.log("every push", args);
}
},
once : {
push(...args) {
console.log("inital push", args);
}
}
});
ae.push("last");
//will be true
na instanceof ArrayEmitter;
na instanceof Array;
na instanceof EventEmitter;
Deep Classes
class A {
constructor() {
this.aProp = true;
this.shared = "sharedA";
}
get isA() {
return true;
}
get sharedA() {
return this.shared;
}
sharedAFn() {
return this.shared;
}
}
class B { get isB() { return true; } }
class C extends ProxyClass.hasInstance(A, B) {
get isC() { return true; }
}
class D {
get isD() { return true; }
}
class E extends ProxyClass.hasInstance(C, D) {
constructor() {
super();
this.eProp = true;
}
get isE() { return true; }
};
//You can also inline your class
var F = ProxyClass.hasInstance(class {
constructor(someArg) {
this.someArg = someArg;
this.fProp = true;
}
get isF() {
return true;
}
}, E);
var e = new E();
//all of this will return true
e instanceof Object;
e instanceof A;
e instanceof B;
e instanceof C;
e instanceof D;
e instanceof E;
e.isA;
e.isB;
e.isC;
e.isD;
e.isE;
e.aProp;
e.eProp;
var f = new F("fubar");
//same as e plus
f instanceof F;
f.isF;
f.fProp;
f.someArg == "fubar";
Isolation
All class member function will get called with their own isolated context.
expect(e.shared).toEqual("sharedE");
expect(e.sharedA).toEqual("sharedA");
expect(e.sharedAFn()).toEqual("sharedA");
Dependancies
Licence
ISC
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