EXTENDS挑战:预处理器函数宏和类类oop

Question

背景

我一直在使用C预处理器来管理和"编译"包含多个文件和构建目标的半大型JavaScript项目.这使全面进入C预处理指令一样#include,#define,#ifdef等从JavaScript中.这是一个示例构建脚本,因此您可以测试示例代码:

#!/bin/bash
export OPTS="-DDEBUG_MODE=1 -Isrc"
for FILE in `find src/ | egrep '\.js?$'`
do
  echo "Processing $FILE"
  cat $FILE  \
  | sed 's/^\s*\/\/#/#/'  \
  | cpp $OPTS  \
  | sed 's/^[#:<].*// ; /^$/d'  \
  > build/`basename $FILE`;
done

创建一个src和一个build目录,然后放入.js文件src.

---

便利宏

最初,我只是想要预处理器的东西#include,也许还有几个#ifdef,但我想,有一些方便的宏也不是很好吗？随后进行了实验.

#define EACH(o,k)     for (var k in o) if (o.hasOwnProperty(k))

很酷,所以现在我可以这样写:

EACH (location, prop) {
  console.log(prop + " : " location[prop]);
}

它将扩展到:

for (var prop in location) if (location.hasOwnProperty(prop)) {
  console.log(prop + " : " location[prop]);
}

foreach怎么样？

#define FOREACH(o,k,v)   var k,v; for(k in o) if (v=o[k], o.hasOwnProperty(k))
// ...
FOREACH (location, prop, val) { console.log(prop + " : " + val) }

注意我们是如何潜入v=o[k]内部if条件,因此不会干扰应遵循这个宏的调用花括号.

---

类似OOP

让我们从一个NAMESPACE宏和一个不起眼但有用的js模式开始......

#define NAMESPACE(ns)    var ns = this.ns = new function()

new function(){ ... }做一些整洁的东西.它将匿名函数作为构造函数调用,因此最终不需要额外的函数()来调用它,并且在其中this引用由构造函数创建的对象,换句话说,就是命名空间本身.这也允许我们在名称空间中嵌套名称空间.

这是我的全套类OOP宏:

#define NAMESPACE(ns) var ns=this.ns=new function()

#define CLASS(c)      var c=this;new function()

#define CTOR(c)       (c=c.c=this.constructor=$$ctor).prototype=this;\
                      function $$ctor

#define PUBLIC(fn)    this.fn=fn;function fn
#define PRIVATE(fn)   function fn
#define STATIC(fn)    $$ctor.fn=fn;function fn

正如您所看到的,这些宏在Variable Object(为了方便)和this(从必要性)中定义了许多东西.这是一些示例代码:

NAMESPACE (Store) {

  CLASS (Cashier) {

    var nextId = 1000;

    this.fullName = "floater";

    CTOR (Cashier) (fullName) {
      if (fullName) this.fullName = fullName;
      this.id = ++nextId;
      this.transactions = 0;
    }

    PUBLIC (sell) (item, customer) {
      this.transactions += 1;
      customer.inventory.push(item);
    }

    STATIC (hire) (count) {
      var newCashiers = [];
      for (var i=count; i--;) {
        newCashiers.push(new Cashier());
      }
      return newCashiers;
    }
  }

  CLASS (Customer) {

    CTOR (Customer) (name) {
      this.name = name;
      this.inventory = [];
      this.transactions = 0;
    }

    PUBLIC (buy) (item, cashier) {
      cashier.sell(this, item);
    }
  }
}

---

EXTENDS怎么样？

所以这就引出了我的问题......我们如何实现EXTENDS作为一个宏来包装通常的"克隆原型,复制构造函数属性"js原型继承？除了要求EXTENDS出现在类定义之后,我还没有找到一种方法,这很愚蠢.这个实验需要EXTENDS或它没用.只要它们给出相同的结果,可以随意更改其他宏.

编辑 - 这些可能会对EXTENDS有用; 在此列出完整性.

#define EACH(o,k)   for(var k in o)if(o.hasOwnProperty(k))
#define MERGE(d,s)  EACH(s,$$i)d[$$i]=s[$$i]
#define CLONE(o)    (function(){$$C.prototype=o;return new $$C;function $$C(){}}())

在此先感谢任何帮助,建议或热烈的讨论.:)

Answer 1

我想我刚刚完成了自己的挑战。我已经为所声明的类的超类的 CLASS 声明宏添加了第二个（可选）参数。

我最初的实现在构造函数周围创建了很多内联垃圾，因此我决定将一些便利函数包装在宏帮助器对象中以避免冗余。

以下是我的类类 OOP 宏的当前版本：

// class-like oo

#ifndef BASE
  #define BASE  $$_
#endif

#define COLLAPSE(code)      code

#define NAMESPACE(ns)       var ns=BASE._ns(this).ns=new function()

#define CLASS(c,__ARGS...)  var c=[BASE._class(this),[__ARGS][0]]; \
                            new function()

#define CTOR(c)             BASE._extend($$_##c,c[1],this); \
                            c=c[0].c=$$_##c; function $$_##c

#define PUBLIC(fn)          BASE._public(this).fn=fn;function fn

#define PRIVATE(fn)         function fn

#define STATIC(fn)          BASE._static(this).fn=fn;function fn

// macro helper object

COLLAPSE(var BASE=new function(){

  function Clone(){};

  function clone (obj) {
    Clone.prototype=obj; return new Clone;
  };

  function merge (sub, sup) { 
    for (var p in sup) if (sup.hasOwnProperty(p)) sub[p]=sup[p]; 
  };

  this._extend = function (sub, sup, decl) {
    if (sup) {
      merge(sub, sup);
      sub.prototype=clone(sup.prototype);
      sub.prototype.constructor=sub;
    };
    if (decl) {
      merge(sub.prototype, decl);
      decl._static=sub;
      decl._public=sub.prototype;
    };
  };

  this._static=this._ns=this._class=function (obj) {
    return (obj._static || obj); 
  };

  this._public=function (obj) {
    return (obj._public || obj); 
  };

})

...这是一个测试命名空间...

//#include "macros.js"

NAMESPACE (Store) {

  CLASS (Cashier) {

    var nextId = 1000;

    this.fullName = "floater";

    CTOR (Cashier) (fullName) {
      if (fullName) this.fullName = fullName;
      this.id = ++nextId;
      this.transactions = 0;
    }

    PUBLIC (sell) (item, customer) {
      this.transactions += 1;
      customer.inventory.push(item);
    }

    STATIC (hire) (count) {
      var newCashiers = [];
      for (var i=count; i--;) {
        newCashiers.push(new Cashier());
      }
      return newCashiers;
    }
  }

  // Customer extends Cashier, just so we can test inheritance

  CLASS (Customer, Cashier) {

    CTOR (Customer) (name) {
      this.name = name;
      this.inventory = [];
      this.transactions = 0;
    }

    PUBLIC (buy) (item, cashier) {
      cashier.sell(this, item);
    }

    CLASS (Cart) {

      CTOR (Cart) (customer) {
        this.customer = customer;
        this.items = [];
      }
    }

  }
}

...这是输出...

var $$_=new function(){ function Clone(){}; function clone (obj) { Clone.prototype=obj; return new Clone; }; function merge (sub, sup) { for (var p in sup) if (sup.hasOwnProperty(p)) sub[p]=sup[p]; }; this._extend = function (sub, sup, decl) { if (sup) { merge(sub, sup); sub.prototype=clone(sup.prototype); sub.prototype.constructor=sub; }; if (decl) { merge(sub.prototype, decl); decl._static=sub; decl._public=sub.prototype; }; }; this._static=this._ns=this._class=function (obj) { return (obj._static || obj); }; this._public=function (obj) { return (obj._public || obj); }; }
var Store=$$_._ns(this).Store=new function() {
  var Cashier=[$$_._class(this),[][0]]; new function() {
    var nextId = 1000;
    this.fullName = "floater";
    $$_._extend($$_Cashier,Cashier[1],this); Cashier=Cashier[0].Cashier=$$_Cashier; function $$_Cashier (fullName) {
      if (fullName) this.fullName = fullName;
      this.id = ++nextId;
      this.transactions = 0;
    }
    $$_._public(this).sell=sell;function sell (item, customer) {
      this.transactions += 1;
      customer.inventory.push(item);
    }
    $$_._static(this).hire=hire;function hire (count) {
      var newCashiers = [];
      for (var i=count; i--;) {
        newCashiers.push(new Cashier());
      }
      return newCashiers;
    }
  }
  var Customer=[$$_._class(this),[Cashier][0]]; new function() {
    $$_._extend($$_Customer,Customer[1],this); Customer=Customer[0].Customer=$$_Customer; function $$_Customer (name) {
      this.name = name;
      this.inventory = [];
      this.transactions = 0;
    }
    $$_._public(this).buy=buy;function buy (item, cashier) {
      cashier.sell(this, item);
    }
    var Cart=[$$_._class(this),[][0]]; new function() {
      $$_._extend($$_Cart,Cart[1],this); Cart=Cart[0].Cart=$$_Cart; function $$_Cart (customer) {
        this.customer = customer;
        this.items = [];
      }
    }
  }
}

继承、内部类和嵌套命名空间似乎工作得很好。您认为，这是一种在 js 中实现类似类 OOP 和代码重用的有用方法吗？如果我错过了什么，请告诉我。