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5    Perl 的特点、历史和许可证

5.1    Perl 的基本特点

　　别期望在一刻钟内就能领略Perl的所有神奇之处, 这种情况很像吃香蕉, 用不着吃完整只香蕉后才知其味，每咬一口都是享受，并促使你再咬下一口，再下一口。 　　　　　　　　　　　　　　　　　　　　　　----Larry Wall

上面这段话是 Perl 项目发起人劳利·华尔( Larry Wall )对学习 Perl 语言的一段经典评论，希望大家都能找到这种感觉。

　　Perl 是 Practical Extraction and Report Language (实用摘录和报告语言)的简称，是由 Larry Wall 所发起的。现在其最新版本为5.0，但是大家急切期待是 Perl 6.0 的诞生，不过本次讲座中我们还是以 5.0 为基础。

　　Perl 的设计目标是帮助 UNIX 用户完成一些常见的任务，这些任务对于 Shell 来说过于沉重或对移植性要求过于严格。Perl 语言中包含了 C、C++、shell,script、sed、awk 这几个语言的语法,它最初的目的就是用来取代 UNIX 中 sed/awk 与 脚本语言的组合,用来汇整信息，产生报表。因此 Perl 语言要远远比前面讲的 BASH 复杂和功能强大。

　　Perl 的设计原则或者说 Perl 的设计哲学是以实用为第一优先，也就是力图使 Perl 语言容易使用、有效率、而且完整。

　　Perl 是按 GNU Public License 和 Artictic License 两种许可证形式分发的，其实质是开源软件、自由软件的，原先运行于 UNIX 和类 UNIX 系统，现在已可以方便地在OS/2，Windows 9x，Windows/NT等系统下运行。

　　Perl 是一种解释运行的语言，和 BASH 程序一样，一般 Perl 程序的第一行需注明自己是一个 Perl 程序而不是 Shell 程序，所以一般将下面一行语句：
　　#! /usr/bin/perl 　　作为文件的第一行。

　　Perl 由于引入了模块的设计思想，随着版本的改进，功能越来越强。现在 Perl 的功能已经超乎原先设计时的想象，几乎任何事都可以做到，也变成每一部工作站必备的标准工具了。Perl 最为著名的一点就是他对字符串的处理，由于 Internet 对文字信息处理的巨大需求，使得 Perl 的应用如日中天，而且 Perl 语言也的确是一个非常优秀的文字信息处理语言。


5.2    Perl 的发展历史

最早发布的 Perl 1.0 版是在1987年底出现的，现在已经过去十多年了。下面是 Perl 首席开发者 Larry Wall 对 Perl 发展历程的一个简单回顾：

    Perl 0 introduced Perl to my officemates.
    Perl 1 introduced Perl to the world, and changed /\(...\|...\)/ to
        /(...|...)/.  \(Dan Faigin still hasn't forgiven me. :-\)
    Perl 2 introduced Henry Spencer's regular expression package.
    Perl 3 introduced the ability to handle binary data (embedded nulls).
    Perl 4 introduced the first Camel book.  Really.  We mostly just
        switched version numbers so the book could refer to 4.000.
    Perl 5 introduced everything else, including the ability to
        introduce everything else.

Perl 从诞生到现在(Year 2000)，他的主要开发参与者有 10 位，他们分别是：
　　Larry Wall,
　　Andy Dougherty,
　　Tom Christiansen,
　　Charles Bailey,
　　Nick Ing-Simmons,
　　Chip Salzenberg,
　　Tim Bunce,
　　Malcolm Beattie,
　　Gurusamy Sarathy,
　　Graham Barr.

下面是一个关于 Perl 历史上各种发行版本的汇总表：

 开发者  版本号         发布日期        备注 
 ===========================================================================


 Larry   0              Classified.     Don't ask.


 Larry   1.000          1987-Dec-18


          1.001..10     1988-Jan-30
          1.011..14     1988-Feb-02


 Larry   2.000          1988-Jun-05


          2.001         1988-Jun-28


 Larry   3.000          1989-Oct-18


          3.001         1989-Oct-26
          3.002..4      1989-Nov-11
          3.005         1989-Nov-18
          3.006..8      1989-Dec-22
          3.009..13     1990-Mar-02
          3.014         1990-Mar-13
          3.015         1990-Mar-14
          3.016..18     1990-Mar-28
          3.019..27     1990-Aug-10     User subs.
          3.028         1990-Aug-14
          3.029..36     1990-Oct-17
          3.037         1990-Oct-20
          3.040         1990-Nov-10
          3.041         1990-Nov-13
          3.042..43     1990-Jan-??
          3.044         1991-Jan-12


 Larry   4.000          1991-Mar-21


          4.001..3      1991-Apr-12
          4.004..9      1991-Jun-07
          4.010         1991-Jun-10
          4.011..18     1991-Nov-05
          4.019         1991-Nov-11     Stable.
          4.020..33     1992-Jun-08
          4.034         1992-Jun-11
          4.035         1992-Jun-23
 Larry    4.036         1993-Feb-05     Very stable.


          5.000alpha1   1993-Jul-31
          5.000alpha2   1993-Aug-16
          5.000alpha3   1993-Oct-10
          5.000alpha4   1993-???-??
          5.000alpha5   1993-???-??
          5.000alpha6   1994-Mar-18
          5.003alpha7   1994-Mar-25
 Andy     5.000alpha8   1994-Apr-04
 Larry    5.000alpha9   1994-May-05     ext appears.
          5.000alpha10  1994-???-??
          5.000alpha11  1994-???-??
 Andy     5.000a11a     1994-Jul-07     To fit 14.
          5.000a11b     1994-Jul-14
          5.000a11c     1994-Jul-19
          5.000a11d     1994-Jul-22
 Larry    5.000alpha12  1994-???-??
 Andy     5.000a12a     1994-Aug-08
          5.000a12b     1994-Aug-15
          5.000a12c     1994-Aug-22
          5.000a12d     1994-Aug-22
          5.000a12e     1994-Aug-22
          5.000a12f     1994-Aug-24
          5.000a12g     1994-Aug-24
          5.000a12h     1994-Aug-24
 Larry    5.000beta1    1994-???-??
 Andy     5.000b1a      1994-???-??
 Larry    5.000beta2    1994-Sep-14     Core slushified.
 Andy     5.000b2a      1994-Sep-14
          5.000b2b      1994-Sep-17
          5.000b2c      1994-Sep-17
 Larry    5.000beta3    1994-Sep-??
 Andy     5.000b3a      1994-Sep-18
          5.000b3b      1994-Sep-22
          5.000b3c      1994-Sep-23
          5.000b3d      1994-Sep-27
          5.000b3e      1994-Sep-28
          5.000b3f      1994-Sep-30
          5.000b3g      1994-Oct-04
 Andy     5.000b3h      1994-Oct-07


 Larry   5.000          1994-Oct-18


 Andy     5.000a        1994-Dec-19
          5.000b        1995-Jan-18
          5.000c        1995-Jan-18
          5.000d        1995-Jan-18
          5.000e        1995-Jan-18
          5.000f        1995-Jan-18
          5.000g        1995-Jan-18
          5.000h        1995-Jan-18
          5.000i        1995-Jan-26
          5.000j        1995-Feb-07
          5.000k        1995-Feb-11
          5.000l        1995-Feb-21
          5.000m        1995-???-??
          5.000n        1995-Mar-07


 Larry   5.001          1995-Mar-13


 Andy     5.001a        1995-Mar-15
          5.001b        1995-Mar-31
          5.001c        1995-Apr-07
          5.001d        1995-Apr-14
          5.001e        1995-Apr-18     Stable.
          5.001f        1995-May-31
          5.001g        1995-May-25
          5.001h        1995-May-25
          5.001i        1995-May-30
          5.001j        1995-Jun-05
          5.001k        1995-Jun-06
          5.001l        1995-Jun-06     Stable.
          5.001m        1995-Jul-02     Very stable.
          5.001n        1995-Oct-31     Very unstable.
          5.002beta1    1995-Nov-21
          5.002b1a      1995-Nov-??
          5.002b1b      1995-Dec-04
          5.002b1c      1995-Dec-04
          5.002b1d      1995-Dec-04
          5.002b1e      1995-Dec-08
          5.002b1f      1995-Dec-08
 Tom      5.002b1g      1995-Dec-21     Doc release.
 Andy     5.002b1h      1996-Jan-05
          5.002b2       1996-Jan-14
 Larry    5.002b3       1996-Feb-02
 Andy     5.002gamma    1996-Feb-11
 Larry    5.002delta    1996-Feb-27


 Larry   5.002          1996-Feb-29     Prototypes.


 Charles  5.002_01      1996-Mar-25


         5.003          1996-Jun-25     Security release.


          5.003_01      1996-Jul-31
 Nick     5.003_02      1996-Aug-10
 Andy     5.003_03      1996-Aug-28
          5.003_04      1996-Sep-02
          5.003_05      1996-Sep-12
          5.003_06      1996-Oct-07
          5.003_07      1996-Oct-10
 Chip     5.003_08      1996-Nov-19
          5.003_09      1996-Nov-26
          5.003_10      1996-Nov-29
          5.003_11      1996-Dec-06
          5.003_12      1996-Dec-19
          5.003_13      1996-Dec-20
          5.003_14      1996-Dec-23
          5.003_15      1996-Dec-23
          5.003_16      1996-Dec-24
          5.003_17      1996-Dec-27
          5.003_18      1996-Dec-31
          5.003_19      1997-Jan-04
          5.003_20      1997-Jan-07
          5.003_21      1997-Jan-15
          5.003_22      1997-Jan-16
          5.003_23      1997-Jan-25
          5.003_24      1997-Jan-29
          5.003_25      1997-Feb-04
          5.003_26      1997-Feb-10
          5.003_27      1997-Feb-18
          5.003_28      1997-Feb-21
          5.003_90      1997-Feb-25     Ramping up to the 5.004 release.
          5.003_91      1997-Mar-01
          5.003_92      1997-Mar-06
          5.003_93      1997-Mar-10
          5.003_94      1997-Mar-22
          5.003_95      1997-Mar-25
          5.003_96      1997-Apr-01
          5.003_97      1997-Apr-03     Fairly widely used.
          5.003_97a     1997-Apr-05
          5.003_97b     1997-Apr-08
          5.003_97c     1997-Apr-10
          5.003_97d     1997-Apr-13
          5.003_97e     1997-Apr-15
          5.003_97f     1997-Apr-17
          5.003_97g     1997-Apr-18
          5.003_97h     1997-Apr-24
          5.003_97i     1997-Apr-25
          5.003_97j     1997-Apr-28
          5.003_98      1997-Apr-30
          5.003_99      1997-May-01
          5.003_99a     1997-May-09
          p54rc1        1997-May-12     Release Candidates.
          p54rc2        1997-May-14


 Chip    5.004          1997-May-15     A major maintenance release.


 Tim      5.004_01      1997-Jun-13     The 5.004 maintenance track.
          5.004_02      1997-Aug-07
          5.004_03      1997-Sep-05
          5.004_04      1997-Oct-15
          5.004m5t1     1998-Mar-04     Maintenance Trials (for 5.004_05).
          5.004_04-m2   1997-May-01
          5.004_04-m3   1998-May-15
          5.004_04-m4   1998-May-19
          5.004_04-MT5  1998-Jul-21


 Malcolm  5.004_50      1997-Sep-09     The 5.005 development track.
          5.004_51      1997-Oct-02
          5.004_52      1997-Oct-15
          5.004_53      1997-Oct-16
          5.004_54      1997-Nov-14
          5.004_55      1997-Nov-25
          5.004_56      1997-Dec-18
          5.004_57      1998-Feb-03
          5.004_58      1998-Feb-06
          5.004_59      1998-Feb-13
          5.004_60      1998-Feb-20
          5.004_61      1998-Feb-27
          5.004_62      1998-Mar-06
          5.004_63      1998-Mar-17
          5.004_64      1998-Apr-03
          5.004_65      1998-May-15
          5.004_66      1998-May-29
 Sarathy  5.004_67      1998-Jun-15
          5.004_68      1998-Jun-23
          5.004_69      1998-Jun-29
          5.004_70      1998-Jul-06
          5.004_71      1998-Jul-09
          5.004_72      1998-Jul-12
          5.004_73      1998-Jul-13
          5.004_74      1998-Jul-14     5.005 beta candidate.
          5.004_75      1998-Jul-15     5.005 beta1.
          5.004_76      1998-Jul-21     5.005 beta2.
          5.005         1998-Jul-22     Oneperl.


 Sarathy  5.005_01      1998-Jul-27     The 5.005 maintenance track.
          5.005_02-T1   1998-Aug-02
          5.005_02-T2   1998-Aug-05
          5.005_02      1998-Aug-08
 Graham   5.005_03      1998-           


 Sarathy  5.005_50      1998-Jul-26     The 5.006 development track.

关于 Perl 发展历史的更详细信息大家可以从这里得到。


5.3    Perl 的使用许可证

我们应该知道 Perl 是一个开放源码的优秀软件，你可以自由的下载该软件去使用和研究，但是 Perl 使用的并不是我们熟知的 GPL 许可证，而是 Artistic 许可证，虽然 Artistic 许可证和 GPL 很类似。简单的说就是 Artistic 许可证比 GPL 的要宽松，你可以出售包含Artistic“包” 的产品，但是绝对不能出售Artistic“包”，不像GPL那么死板。 Artistic 许可证之所以不涉及源码问题是因为 Perl 不存在这个问题。可能大部分人都还不太了解这个许可证。下面是 Artistic 许可证的英文原文，有兴趣的同学可以自己看一遍。

 

The "Artistic License"

Preamble

The intent of this document is to state the conditions under which a Package may be copied, such that the Copyright Holder maintains some semblance of artistic control over the development of the package, while giving the users of the package the right to use and distribute the Package in a more-or-less customary fashion, plus the right to make reasonable modifications.

Definitions

"Package" refers to the collection of files distributed by the Copyright Holder, and derivatives of that collection of files created through textual modification.

"Standard Version" refers to such a Package if it has not been modified, or has been modified in accordance with the wishes of the Copyright Holder as specified below.

"Copyright Holder" is whoever is named in the copyright or copyrights for the package.

"You" is you, if you're thinking about copying or distributing this Package.

"Reasonable copying fee" is whatever you can justify on the basis of media cost, duplication charges, time of people involved, and so on. (You will not be required to justify it to the Copyright Holder, but only to the computing community at large as a market that must bear the fee.)

"Freely Available" means that no fee is charged for the item itself, though there may be fees involved in handling the item. It also means that recipients of the item may redistribute it under the same conditions they received it.

  1. You may make and give away verbatim copies of the source form of the Standard Version of this Package without restriction, provided that you duplicate all of the original copyright notices and associated disclaimers.

  2. You may apply bug fixes, portability fixes and other modifications derived from the Public Domain or from the Copyright Holder. A Package modified in such a way shall still be considered the Standard Version.

  3. You may otherwise modify your copy of this Package in any way, provided that you insert a prominent notice in each changed file stating how and when you changed that file, and provided that you do at least ONE of the following:

    1. place your modifications in the Public Domain or otherwise make them Freely Available, such as by posting said modifications to Usenet or an equivalent medium, or placing the modifications on a major archive site such as uunet.uu.net, or by allowing the Copyright Holder to include your modifications in the Standard Version of the Package.
    2. use the modified Package only within your corporation or organization.
    3. rename any non-standard executables so the names do not conflict with standard executables, which must also be provided, and provide a separate manual page for each non-standard executable that clearly documents how it differs from the Standard Version.
    4. make other distribution arrangements with the Copyright Holder.

  4. You may distribute the programs of this Package in object code or executable form, provided that you do at least ONE of the following:

    1. distribute a Standard Version of the executables and library files, together with instructions (in the manual page or equivalent) on where to get the Standard Version.
    2. accompany the distribution with the machine-readable source of the Package with your modifications.
    3. give non-standard executables non-standard names, and clearly document the differences in manual pages (or equivalent), together with instructions on where to get the Standard Version.
    4. make other distribution arrangements with the Copyright Holder.

  5. You may charge a reasonable copying fee for any distribution of this Package. You may charge any fee you choose for support of this Package. You may not charge a fee for this Package itself. However, you may distribute this Package in aggregate with other (possibly commercial) programs as part of a larger (possibly commercial) software distribution provided that you do not advertise this Package as a product of your own. You may embed this Package's interpreter within an executable of yours (by linking); this shall be construed as a mere form of aggregation, provided that the complete Standard Version of the interpreter is so embedded.

  6. The scripts and library files supplied as input to or produced as output from the programs of this Package do not automatically fall under the copyright of this Package, but belong to whomever generated them, and may be sold commercially, and may be aggregated with this Package. If such scripts or library files are aggregated with this Package via the so-called "undump" or "unexec" methods of producing a binary executable image, then distribution of such an image shall neither be construed as a distribution of this Package nor shall it fall under the restrictions of Paragraphs 3 and 4, provided that you do not represent such an executable image as a Standard Version of this Package.

  7. C subroutines (or comparably compiled subroutines in other languages) supplied by you and linked into this Package in order to emulate subroutines and variables of the language defined by this Package shall not be considered part of this Package, but are the equivalent of input as in Paragraph 6, provided these subroutines do not change the language in any way that would cause it to fail the regression tests for the language.

  8. Aggregation of this Package with a commercial distribution is always permitted provided that the use of this Package is embedded; that is, when no overt attempt is made to make this Package's interfaces visible to the end user of the commercial distribution. Such use shall not be construed as a distribution of this Package.

  9. The name of the Copyright Holder may not be used to endorse or promote products derived from this software without specific prior written permission.

  10. THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.

The End

 

 




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