Python与Perl的简单比较.ppt

廖海仁 2011.9.15,Python与Perl的简单比较,语言简介,Perl,Python,由C/sed/awk/shell演化而来 适合文本处理、系统管理，不适合操作系统开发、多线程编程,从ABC语言继承而来，主要受Modula-3影响，结合Unix shell与C的习惯 面向对象、解释性、胶水语言,优 点,Perl,Python,强大的正则表达式匹配功能 复杂灵活的数据结构 Unicode支持(相对AWK/C) 自然语言（也是缺点） 智能语言（也是缺点）,简单、易学 高层语言 可移植性 面向对象 规范的代码（可读性强） 图形功能（GUI) 数值计算功能(NumPy),缺 点,Perl,Python,自然语言，代码晦涩难懂 智能语言，可能产生臆断，编程陷阱多 不是很优美，很多方法做事，有时让编程者无所适从 动态类型语言，不是很可靠，性能问题 不适合多线程、底层编程、GUI编程 易学难精,强行缩进 运行速度不够快（比较编译型语言） 动态语言、解释型语言，调试困难（Perl不完全是解释型的）,创始人,Larry Wall (Perl) Larry Wall,Guido van Rossum(Python),Languist(语言学家） Perl Many ways to accompany the same task Constructs interact in context-sentitive and sometimes quite subtle ways mush like natural language,Mathematician（数学家） Python: High degree of uniformity Orthogonal design,设计理念,Design Principle of Perl,Zen of Python (Tim Peters),Theres More Than One Way To Do It Easy things should be easy, and hard things should be possible,Beautiful is better than ugly. Explicit is better than implicit. Simple is better than complex. Complex is better than complicated. Flat is better than nested. Sparse is better than dense. Readability counts. Special cases arent special enough to break the rules. Although practicality beats purity. Errors should never pass silently. Unless explicitly silenced. In the face of ambiguity, refuse the temptation to guess. There should be one- and preferably only one -obvious way to do it. Although that way may not be obvious at first unless youre Dutch. Now is better than never. Although never is often better than *right* now. If the implementation is hard to explain, its a bad idea. If the implementation is easy to explain, it may be a good idea. Namespaces are one honking great idea - lets do more of those!,Fundamental principles of human language (I),Expressiveness is more important than learnability Its quite OK to speak in “baby talk” if you happen to be a baby A language can be useful even before you have learned the whole language There are often several good ways to say roughly the same thing Every linguistic utterance gets meaning from many contexts at once Effiicent communication requires a certain amount of linguistic complexity Semantic networks do not gennerally map well into orthogonal spaces Shortcuts abound; common expressions should be shorter than uncommon expressions,Fundamental principles of human language (II),Not everything can be easy to express; its OK if some things are hard but possible Languages are naturally punctuated by pauses, intonation, stress, pacing, etc. Healthy culture is more important than specific technology to a languages success Its OK to speak with an accent as long as you can make yourself understood For any living language, evolution is not preventable over the long term Its particularly important for written documents to be evaluated in historical context.,Perl or Python ?,Perl拥护者,Python拥护者,正则匹配的近乎完美语言,You can do everything in Python that you can in Perl, but you can read your code after you do it 简单易学,Perl 6 Vs Python 3,Perl 6,Python 3,Resign of the whole language,Not a total rewrite or a total resign, though a break with backward compatibility,Data Structures,Perl,Python,Scalars Arrays Hashes （Perl treat everything as mutable),Numbers Strings Lists Dictionaries /Sets Tuples (Immutable Lists),关于Python的两个问题,数值与字符串 （对应Perl 之Scalar) 参数传递方式（