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پشم سنگ عایق الاستومری
شنبه 1 فروردین‌ماه سال 1388
توسط: آلفا پک

پرل چیست؟

لیست فیلم‌های سینمایی که قرار است، نوروز امسال از تلویزیون پخش شود را می‌توانید اینجا ببینید. گرچه خیلی از این فیلم‌ها را علاقه‌مندان سینما، قبل از پخش در تلویزیون دیده‌اند، اما شاید دیدن دوبله این فیلم‌ها هم جالب باشد

اینجا هم لیست کامل به صورت pdf

منبع : 1پزشک



پرل زبان برنامه نویسی و اسکریپت نویسی تفسیری و سطح بالا ، شی گرا و یک زبان سمت سرور قدرتمند است که در آزمایشگاه Jet Propulsion ناسا توسط لری وال در سال 1987 طراحی شد.
زبان پرل بطور وسیعی ساختار خود را از زبان C , و بعضی از خصوصیات خود را مدیون زبانهای : AWK , LISP , SED , SH می باشد .

کاربرد پرل
پرل را امروزه در زمینه های هوش مصنوعی-ژنتیک -نظامی -تحقیقاتی - صنعتی و بطور گسترده ای در اینترنت و شبکه میتوان یافت .
نوشتن یک: بانک اطلاعاتی - صفحه گسترده - سیستم عامل - و یا یک وب سرور شاید عاقلانه به نظر نرسد ولی در پرل امکانپذیر است .
زبان پرل قدرت بسیاری در پردازش متن دارد که بخاطر داشتن (Regular Expression) است بطور مثال : یک رشته را اسمبل و به عنوان یک فرمان سیستمی اجرا کند

 

پرل به عنوان یک زبان قابل حمل
جالب است بدانید نرم افزاری که شما تحت سیستم عامل LINUX و یا MAC نوشته اید به طور قطع روی سیستم عامل WINDOWS و UNIX هم اجرا میشود.
مفسر پرل متن برنامه ‬را ‬خوانده ‬و ‬همزمان ‬تفسیر ‬کرده ‬و ‬اجرا ‬می ‬کند‬. در حال حاضر پرل را در بیش از 40 سیستم عامل میتوان بکار گرفت
و کتابخانه CPAN بیش از 11000 مازول را با کد منبع در اختیار تان می گذارد که روزانه به این تعداد افزوده میشود.

پرل و برنامه های 3 بعدی
گستره استفاده پرل به عنوان زبانی برای ایجاد برنامه های 3 بعدی تا حدی است که تا چندی پیش متخصصین Graphcomp در تستی زبان C و PERL
را برای اجرای برنامه 3 بعدی بر روی 3 سیستم عامل متفاوت : VISTA , UBUNTU , FEDORA با سخت افزار یکسان به کار گرفتند. در این میان
پرل توانست با استفاده بهینه از منابع سیستم برتری خود را در این زمینه اثبات کند .
نتایج تست Graphcomp : http://graphcomp.com/pogl.cgi?v=0111s3m3

پرل و CGI
با پا به عرصه گذاشتن CGI به صفحات وب زبان پرل به خاطر قدرت بالا در پردازش متن و تطبیق الگو (Regular Expressions) در جمله زبانهایی قرار گرفت
که بطور وسیعی برای نوشتن CGI بکار گرفته میشود . در این میان وب سایت های پر ترافیک مانند :Livejournal.com, Ticketmaster.com Amzon.com , IMDB.com, از زبان پرل استفاده میکنند.

پرل و شبکه
به خاطر قدرت بسیار پرل درزمینه برنامه نویسی سیستمهای شبکه بسیاری از متخصصین شبکه و هکرها از این قافله عقب نمانده
و امروزه شاهد این هستیم که بسیاری از برنامه های : مدیریت شبکه , سیستم های Spidering , و Exploite ها به زبان پرل نوشته میشود.

پرل به عنوان یک زبان چسبنده (Glue Language)
پرل به عنوان یک زبان چسبنده می تواند در زبان های دیگر مورد استفاده قرار گیرد . نکته دیگر این که , با نصب بسته VisualPerl شما , در کنار ASP.NET میتوhنید با پرل نیز یرنامه نویسی کنید. به طور مثال می توانید در برنامه های .NET از پرل برای پردازش متن و یا هر چیز دیگری استفاده کنید این قابلیت تنها به .NET محدود نمیشود و پرل را می توان در دیگر زبان های برنامه نویسی بدون در نظر گرفتن پلتفرم ان استفاده کنید .

حرف آخر
نکته ای که باعث محبوبیت زبان پرل در میان برنامه نویسان شده است رایگان و اپن سورس بودن این زبان میباشد * می توانید متن آن را به رایگان از اینترنت دریافت و در توسعه آن همکاری کنید
منبع : انجمن برنامه نویسان پرل

History

Larry Wall began work on Perl in 1987, while working as a programmer at Unisys,[6] and released version 1.0 to the comp.sources.misc newsgroup on December 18, 1987.[7] The language expanded rapidly over the next few years. Perl 2, released in 1988, featured a better regular expression engine. Perl 3, released in 1989, added support for binary data streams.

Originally the only documentation for Perl was a single (increasingly lengthy) man page. In 1991, Programming perl (known to many Perl programmers as the "Camel Book") was published and became the de facto reference for the language. At the same time, the Perl version number was bumped to 4—not to mark a major change in the language but to identify the version that was documented by the book.

Perl 4 went through a series of maintenance releases, culminating in Perl 4.036 in 1993. At that point, Wall abandoned Perl 4 to begin work on Perl 5.

Initial design of Perl 5 continued into 1994. The perl5-porters mailing list was established in May 1994 to coordinate work on porting Perl 5 to different platforms. It remains the primary forum for development, maintenance, and porting of Perl 5.[8]

Perl 5 was released on October 17, 1994. It was a nearly complete rewrite of the interpreter, and it added many new features to the language, including objects, references, lexical (my) variables, and modules. Importantly, modules provided a mechanism for extending the language without modifying the interpreter. This allowed the core interpreter to stabilize, even as it enabled ordinary Perl programmers to add new language features.

As of 2009, Perl 5 is still being actively maintained. Important features and some essential new language constructs—including Unicode support, threads, improved support for object oriented programming, and many other enhancements—have been added along the way.

On December 18, 2007, the 20th anniversary of Perl 1.0, Perl 5.10.0 was released. Perl 5.10.0 includes notable new features, which bring it closer to Perl 6. Some of these new features are a new switch statement (called "given"/"when"), regular expressions updates, and the so-called smart match operator, "~~".[9] In December 2008, Perl 5.8.9 was released.

One of the most important events in Perl 5 history took place outside of the language proper and was a consequence of its module support. On October 26, 1995, the Comprehensive Perl Archive Network (CPAN) was established as a repository for Perl modules and Perl itself. At the time of writing, it carries more than 15,000 modules by more than 7,000 authors. CPAN is widely regarded as one of the greatest strengths of Perl in practice.

[edit] Name

Perl was originally named "Pearl," after the Parable of the Pearl from the Gospel of Matthew. Larry Wall wanted to give the language a short name with positive connotations; he claims that he considered (and rejected) every three- and four-letter word in the dictionary. He also considered naming it after his wife Gloria. Wall discovered the existing PEARL programming language before Perl's official release and changed the spelling of the name.

When referring to the language, the name is normally capitalized (Perl). When referring to the interpreter program itself, the name is often uncapitalized (perl) because Unix-like file systems are case-sensitive. Before the release of the first edition of Programming Perl, it was common to refer to the language as perl; Randal L. Schwartz, however, capitalised the language's name in the book to make it stand out better when typeset. This case distinction was subsequently documented as canonical.[10]

There is some contention about the all-caps spelling "PERL," which the documentation declares incorrect[10] and which some core community members even consider a sign of outsiders.[11] Although the name is occasionally taken as an acronym for Practical Extraction and Report Language (which appears at the top of the documentation[12]), this expansion actually came after the name; several others have been suggested as equally canonical, including Wall's own humorous Pathologically Eclectic Rubbish Lister.[13] Indeed, Wall claims that the name was intended to inspire many different expansions.[14]

[edit] The camel symbol

Programming Perl, published by O'Reilly Media, features a picture of a camel on the cover and is commonly referred to as The Camel Book.[6] This image of a camel has become a general symbol of Perl. It is also a hacker emblem, appearing on some T-shirts and other clothing items.

O'Reilly owns the image as a trademark but claims to use their legal rights only to protect the "integrity and impact of that symbol".[15] O'Reilly allows non-commercial use of the symbol and provides Programming Republic of Perl logos and Powered by Perl buttons.[16] However, the Camel has never been meant to be an official Perl symbol, and if one is to be considered instead, it's an onion.[17]

[edit] Overview

Perl is a general-purpose programming language originally developed for text manipulation and now used for a wide range of tasks including system administration, web development, network programming, and GUI development.

The language is intended to be practical (easy to use, efficient, complete) rather than beautiful (tiny, elegant, minimal).[18] Its major features include support for multiple programming paradigms (procedural, object-oriented, and functional styles), reference counting memory management (without a cycle-detecting garbage collector), built-in support for text processing, and a large collection of third-party modules.

According to Larry Wall, Perl has two slogans. The first is "There's more than one way to do it," commonly known as TMTOWTDI. The second slogan is "Easy things should be easy and hard things should be possible."

[edit] Features

The overall structure of Perl derives broadly from C. Perl is procedural in nature, with variables, expressions, assignment statements, brace-delimited code blocks, control structures, and subroutines.

Perl also takes features from shell programming. All variables are marked with leading sigils, which unambiguously identify the data type (for example, scalar, array, hash) of the variable in context. Importantly, sigils allow variables to be interpolated directly into strings. Perl has many built-in functions that provide tools often used in shell programming (although many of these tools are implemented by programs external to the shell) such as sorting, and calling on system facilities.

Perl takes lists from Lisp, associative arrays (hashes) from AWK, and regular expressions from sed. These simplify and facilitate many parsing, text-handling, and data-management tasks.

In Perl 5, features were added that support complex data structures, first-class functions (that is, closures as values), and an object-oriented programming model. These include references, packages, class-based method dispatch, and lexically scoped variables, along with compiler directives (for example, the strict pragma). A major additional feature introduced with Perl 5 was the ability to package code as reusable modules. Larry Wall later stated that "The whole intent of Perl 5's module system was to encourage the growth of Perl culture rather than the Perl core."[19]

All versions of Perl do automatic data typing and memory management. The interpreter knows the type and storage requirements of every data object in the program; it allocates and frees storage for them as necessary using reference counting (so it cannot de-allocate circular data structures without manual intervention). Legal type conversions—for example, conversions from number to string—are done automatically at run time; illegal type conversions are fatal errors.