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变色龙代码

最近的新玩具: https://github.com/coolwanglu/quine-chameleon

受mame的100个语言的quine-relay的启发，我想可否做一个完全图，即多个语言互相转换。
这样的程序英文叫multiquines，Wikipedia上有介绍，程序运行时需要指定一个参数，比如输出语言，然后程序会输出自身代码的对应那种语言的版本。如果指定参数就是这个程序源代码所使用的语言，那就是quine了。

网上有一个5种语言的multiquines，我看了看，不是太优美。我一开始就是朝着multiquines的方向写。然而后来注意到，不指定任何参数的时候对multiquines来说是没定义的（或者什么都不应该输出），这个有点浪费，于是我做了ouroboros（就像quine-relay那样）和随机转换两种模式。

再后来我注意到反而是不指定参数这部分更有趣，而且为了同时支持带参数和不带参数，需要各种判断，造成代码臃肿。于是我就把这两部分拆开，目前在源码中分别叫chameleon.*和multiquines.*。分别进行优化。

写这个东西最大的乐趣当然是不断加入新的语言。我开始不久就把自己熟悉的语言放进去了，然后慢慢添加新语言，不会的就现学现卖。基本上需要的语言特性和函数有如下几个

- 支持双引号定义的字符串，支持反斜杠转义
- 将字符串按分隔符切成数组
- 生成随机数
- 支持命令行参数
- 数组查找
- 字符串转义，或者json输出，或者字符串／正则式替换
- 输出（不带换行）

按目前的设计，第一条决定了一个语言是否能很容易的加入。这里比quine-relay难的地方在于，任何两个语言都要互相输出，所以最好能有一个公共的转义和还原的标准。而quine-relay中每个语言只需要考虑下一个语言的转义就好了，更方便预处理，支持新语言（比如whitespace，brainfuck）以及其他特性（比如字符串压缩）

我在写这个玩具的过程中也很自然的学习了一些新语言。之前为了写dunnet.js而研究了emacs lisp，这里还加入了其他lisp系列比如clojure，racket，发现写写脚本也还挺顺手的。只可惜scheme由于标准库太小以及srfi实现不统一没能加入。另外就是接触了之前完全不想接触的perl和awk，发现不但没有想像中的可怕，反而挺好用的。

ruby出乎我的意料，一直是各个语言中最短的，尤其multiquines的原始代码（不包含数据）只有80个字节！然而一般python就够我用了，也没有太大动力学新的。coffeescirpt和javascript经过不断优化也冲到了前面，不错！

其他值得一提的是，即使是之前比较陌生的go，lua，vala，我都能很快上手，一方面说明了文档齐全，互联网时代获取知识非常容易，另一方面我也觉得现代编程语言比较类似，语言本身已经成为了工具，脑子里有一些大概念就可以畅行无阻了。当然具体细节还是要慢慢学习和熟悉。

至于C家族，你们就乖乖在最后好好歇着吧。。。
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