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POHidden features of Perl?
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161872
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7
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2008-10-02T19:48:08.200
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2008-10-02T11:49:22.907
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2017-09-25T20:53:06.747
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2017-09-25T20:53:06.747
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143
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57995
LastEditorDisplayName
Adam Bellaire
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What are some really useful but esoteric language features in Perl that you've actually been able to employ to do useful work? Guidelines: <ul> <li>Try to limit answers to the Perl core and not CPAN</li> <li>Please give an example and a short description</li> </ul> <hr> <h2>Hidden Features also found in other languages' Hidden Features:</h2> (These are all from <a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#162257">Corion's answer</a>) <ul> <li><a href="https://stackoverflow.com/questions/132241/hidden-features-of-c#">C</a> <ul> <li>Duff's Device</li> <li>Portability and Standardness</li> </ul></li> <li><a href="https://stackoverflow.com/questions/9033/hidden-features-of-c">C#</a> <ul> <li>Quotes for whitespace delimited lists and strings</li> <li>Aliasable namespaces</li> </ul></li> <li><a href="https://stackoverflow.com/questions/15496/hidden-features-of-java">Java</a> <ul> <li>Static Initalizers</li> </ul></li> <li><a href="https://stackoverflow.com/questions/61088/hidden-features-of-javascript">JavaScript</a> <ul> <li>Functions are First Class citizens</li> <li>Block scope and closure</li> <li>Calling methods and accessors indirectly through a variable</li> </ul></li> <li><a href="https://stackoverflow.com/questions/63998/hidden-features-of-ruby">Ruby</a> <ul> <li>Defining methods through code</li> </ul></li> <li><a href="https://stackoverflow.com/questions/61401/hidden-features-of-php">PHP</a> <ul> <li>Pervasive online documentation</li> <li>Magic methods</li> <li>Symbolic references</li> </ul></li> <li><a href="https://stackoverflow.com/questions/101268/hidden-features-of-python">Python</a> <ul> <li>One line value swapping</li> <li>Ability to replace even core functions with your own functionality</li> </ul></li> </ul> <h2>Other Hidden Features:</h2> Operators: <ul> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#162094">The bool quasi-operator</a></li> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#162058">The flip-flop operator</a> <ul> <li>Also used for <a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#205627">list construction</a></li> </ul></li> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#162004">The <code>++</code> and unary <code>-</code> operators work on strings</a></li> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#162075">The repetition operator</a></li> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#161943">The spaceship operator</a></li> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#162239">The || operator (and // operator) to select from a set of choices</a></li> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#162152">The diamond operator</a></li> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#162249">Special cases of the <code>m//</code> operator</a></li> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#162060">The tilde-tilde "operator"</a></li> </ul> Quoting constructs: <ul> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#163416">The qw operator</a></li> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#162094">Letters can be used as quote delimiters in q{}-like constructs</a></li> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#163374">Quoting mechanisms</a></li> </ul> Syntax and Names: <ul> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#162094">There can be a space after a sigil</a></li> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#162094">You can give subs numeric names with symbolic references</a></li> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#163416">Legal trailing commas</a></li> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#162601">Grouped Integer Literals</a></li> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#168925">hash slices</a></li> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#195254">Populating keys of a hash from an array</a></li> </ul> Modules, Pragmas, and command-line options: <ul> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#163440">use strict and use warnings</a></li> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#163440">Taint checking</a></li> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#162085">Esoteric use of -n and -p</a></li> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#163541">CPAN</a></li> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#162601"><code>overload::constant</code></a></li> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#164255">IO::Handle module</a></li> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#163725">Safe compartments</a></li> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#310083">Attributes</a></li> </ul> Variables: <ul> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#162357">Autovivification</a></li> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#161985">The <code>$[</code> variable</a></li> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#168947">tie</a></li> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#172118">Dynamic Scoping</a></li> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#205627">Variable swapping with a single statement</a></li> </ul> Loops and flow control: <ul> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#163440">Magic goto</a></li> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#163481"><code>for</code> on a single variable</a></li> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#169592">continue clause</a></li> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#205104">Desperation mode</a></li> </ul> Regular expressions: <ul> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#162565">The <code>\G</code> anchor</a></li> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#161976"><code>(?{})</code> and '(??{})` in regexes</a></li> </ul> Other features: <ul> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#163440">The debugger</a></li> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#162206">Special code blocks such as BEGIN, CHECK, and END</a></li> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#163700">The <code>DATA</code> block</a></li> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#162601">New Block Operations</a></li> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#162601">Source Filters</a></li> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#162601">Signal Hooks</a></li> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#167309">map</a> (<a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#167809">twice</a>)</li> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#162842">Wrapping built-in functions</a></li> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl/189883#189883">The <code>eof</code> function</a></li> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#194796">The <code>dbmopen</code> function</a></li> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#205104">Turning warnings into errors</a></li> </ul> Other tricks, and meta-answers: <ul> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#163532">cat files, decompressing gzips if needed</a></li> <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl#162271">Perl Tips</a></li> </ul> <hr> See Also: <ul> <li><a href="https://stackoverflow.com/questions/132241/hidden-features-of-c">Hidden features of C</a></li> <li><a href="https://stackoverflow.com/questions/9033/hidden-features-of-c">Hidden features of C#</a></li> <li><a href="https://stackoverflow.com/questions/75538/hidden-features-of-c">Hidden features of C++</a></li> <li><a href="https://stackoverflow.com/questions/15496/hidden-features-of-java">Hidden features of Java</a></li> <li><a href="https://stackoverflow.com/questions/61088/hidden-features-of-javascript">Hidden features of JavaScript</a></li> <li><a href="https://stackoverflow.com/questions/63998/hidden-features-of-ruby">Hidden features of Ruby</a></li> <li><a href="https://stackoverflow.com/questions/61401/hidden-features-of-php">Hidden features of PHP</a></li> <li><a href="https://stackoverflow.com/questions/101268/hidden-features-of-python">Hidden features of Python</a></li> <li><a href="https://stackoverflow.com/questions/2493996/hidden-features-of-clojure">Hidden features of Clojure</a></li> </ul>
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