Perl 音标拼音: [p'ɚl]
A {high -level } programming language , started
by {Larry Wall } in 1987 and developed as an {open source }
project . It has an eclectic heritage , deriving from the
ubiquitous {C } programming language and to a lesser extent
from {sed }, {awk }, various {Unix } {shell } languages , {Lisp },
and at least a dozen other tools and languages . Originally
developed for {Unix }, it is now available for many
{platforms }.
Perl 's elaborate support for {regular expression } matching and
substitution has made it the {language of choice } for tasks
involving {string manipulation }, whether for text or binary
data . It is particularly popular for writing {CGI scripts }.
The language 's highly flexible syntax and concise regular
expression operators , make densely written Perl code
indecipherable to the uninitiated . The syntax is , however ,
really quite simple and powerful and , once the basics have
been mastered , a joy to write .
Perl 's only {primitive } data type is the "scalar ", which can
hold a number , a string , the undefined value , or a typed
reference . Perl 's {aggregate } data types are {arrays }, which
are ordered lists of {scalars } indexed by {natural numbers },
and hashes (or "{associative arrays }") which are unordered
lists of scalars indexed by strings . A reference can point to
a scalar , array , hash , {function }, or {filehandle }. {Objects }
are implemented as references "{blessed }" with a {class } name .
Strings in Perl are {eight -bit clean }, including {nulls }, and
so can contain {binary data }.
Unlike C but like most Lisp dialects , Perl internally and
dynamically handles all memory allocation , {garbage
collection }, and type {coercion }.
Perl supports {closures }, {recursive functions }, {symbols }
with either {lexical scope } or {dynamic scope }, nested {data
structures } of arbitrary content and complexity (as lists or
hashes of references ), and packages (which can serve as
classes , optionally inheriting {methods } from one or more
other classes ). There is ongoing work on {threads },
{Unicode }, {exceptions }, and {backtracking }. Perl program
files can contain embedded documentation in {POD } (Plain Old
Documentation ), a simple markup language .
The normal Perl distribution contains documentation for the
language , as well as over a hundred modules (program
libraries ). Hundreds more are available from The
{Comprehensive Perl Archive Network }. Modules are themselves
generally written in Perl , but can be implemented as
interfaces to code in other languages , typically compiled C .
The free availability of modules for almost any conceivable
task , as well as the fact that Perl offers direct access to
almost all {system calls } and places no arbitrary limits on
data structure size or complexity , has led some to describe
Perl , in a parody of a famous remark about {lex }, as the
"Swiss Army chainsaw " of programming .
The use of Perl has grown significantly since its adoption as
the language of choice of many {World -Wide Web } developers .
{CGI } interfaces and libraries for Perl exist for several
{platforms } and Perl 's speed and flexibility make it well
suited for form processing and on -the -fly {web page } creation .
Perl programs are generally stored as {text } {source } files ,
which are compiled into {virtual machine } code at run time ;
this , in combination with its rich variety of data types and
its common use as a glue language , makes Perl somewhat hard to
classify as either a "{scripting language }" or an
"{applications language }" -- see {Ousterhout 's dichotomy }.
Perl programs are usually called "Perl scripts ", if only for
historical reasons .
Version 5 was a major rewrite and enhancement of version 4 ,
released sometime before November 1993 . It added real {data
structures } by way of "references ", un -adorned {subroutine }
calls , and {method } {inheritance }.
The spelling "Perl " is preferred over the older "PERL " (even
though some explain the language 's name as originating in the
acronym for "Practical Extraction and Report Language "). The
program that interprets /compiles Perl code is called
"perl ", typically "/usr /local /bin /perl " or "/usr /bin /perl ".
Latest version : 5 .005_03 stable , 5 .005_62 in development , as
of 1999 -12 -04 .
{(http ://perl .com /)}.
{Usenet } newsgroups : {news :comp .lang .perl .announce },
{news :comp .lang .perl .misc }.
["Programming Perl ", Larry Wall and Randal L . Schwartz ,
O 'Reilly & Associates, Inc. Sebastopol, CA. ISBN
0-93715-64-1].
["Learning Perl" by Randal L. Schwartz, O'Reilly & Associates,
Inc., Sebastopol, CA].
[{Jargon File}]
(1999-12-04)Practical Extraction and Report Language (
PERL )
Perl : /
perl /,
n . [
Practical Extraction and Report Language ,
a .
k .
a .
Pathologically Eclectic Rubbish Lister ]
An interpreted language developed by Larry Wall ,
author of patch (
1 )
and rn (
1 )).
Superficially resembles awk ,
but is much hairier ,
including many facilities reminiscent of sed (
1 )
and shells and a comprehensive Unix system -
call interface .
Unix sysadmins ,
who are almost always incorrigible hackers ,
generally consider it one of the languages of choice ,
and it is by far the most widely used tool for making ‘
live ’
web pages via CGI .
Perl has been described ,
in a parody of a famous remark about lex (
1 ),
as the Swiss -
Army chainsaw of Unix programming .
Though Perl is very useful ,
it would be a stretch to describe it as pretty or elegant ;
people who like clean ,
spare design generally prefer Python .
See also Camel Book ,
TMTOWTDI .
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operators - What does =~ do in Perl? - Stack Overflow man perlop "perlop - Perl operators and precedence" (at least in UNIX-like) answers this question: "Binary "=~" binds a scalar expression to a pattern match " – U Windl Commented Apr 1, 2020 at 21:11
variables - What is the meaning of @_ in Perl? - Stack Overflow perldoc perlvar is the first place to check for any special-named Perl variable info Quoting: @_: Within a subroutine the array @_ contains the parameters passed to that subroutine More details can be found in perldoc perlsub (Perl subroutines) linked from the perlvar: Any arguments passed in show up in the array @_
What does the - gt; arrow do in Perl? - Stack Overflow Perl arrow operator has one other use: Class−>method invokes subroutine method in package Class though it's completely different than your code sample Only including it for completeness for the question in the title
如何从零开始学习 Perl? - 知乎 Learning Perl (豆瓣) 开始。快速浏览加实践下书上代码,两天就可以读个大概。 不过小骆驼书只覆盖了Perl Programming最基础的一部分知识,当你需要用Perl做面对对象或者大型程序编程时,有必要去读一下神兽书—— Intermediate Perl (豆瓣) 。
Perl 是一门冷门的语言吗,关注者和问题数这么少? - 知乎 怎么说呢?在处理文本领域,Perl不是冷门,相反,它是最有竞争力的一门编程语言之一。正则表达式和Perl融合得很好。你不妨试试,给自己一个机会。 知乎上关注度不高和这门语言流行度不一定正相关。 鞋子合脚不,穿了才知道。
客观地说,Perl 是不是快死了? - 知乎 近些年来感觉到所谓流行趋势的没落,个人觉得还有一部分原因是由于perl 6 和perl 5的割裂。 perl 6的雄心太庞大,编译器非要自己实现自己,进展异常缓慢, 说到底没有大公司的支持,perl语言死肯定不会死,但也不会再那么“流行”起来
Whats the use of lt; gt; in Perl? - Stack Overflow So, if the shell is handing you a bunch of file names, and you'd like to go through each one's data in turn, perl's <> operator gives you a nice way of doing that it puts the next line of the next file (or stdin if no files are named) into $_ (the default scalar) Here is a poor man's grep: while(<>) { print if m pattern ; } Running this script:
operators - What is the difference between || and or in Perl . . . From Perl documentation: OR List operators On the right side of a list operator, it has very low precedence, such that it controls all comma-separated expressions found there
敢问 Perl 比 Python 好在哪里? - 知乎 从我对Python的少量了解来看,Perl大概有这么几个优势: 性能稍微好一点,不过十分不显著。而且Perl的Moose对象系统会造成10%左右的性能损失。如果你用Perl构建比较复杂的系统,使用了Moose,那对Python的性能优势应当会被抹回去。 Perl的灵活程度据说比Python要高。
What does exactly perl -pi -e do? - Stack Overflow You can inspect the code actually used by Perl with the core module B::Deparse This compiler backend module is activated with the option -MO=Deparse