How should I use the "my" keyword in Perl? - Stack Overflow

my restricts the scope of a variable. The scope of a variable is where it can be seen. Reducing a variable's scope to where the variable is ... Home Public Questions Tags Users Companies Collectives ExploreCollectives Teams StackOverflowforTeams –Startcollaboratingandsharingorganizationalknowledge. CreateafreeTeam WhyTeams? Teams CreatefreeTeam StackOverflowforTeamsismovingtoitsowndomain!Whenthemigrationiscomplete,youwillaccessyourTeamsatstackoverflowteams.com,andtheywillnolongerappearintheleftsidebaronstackoverflow.com. Checkyouremailforupdates. Collectives™onStackOverflow Findcentralized,trustedcontentandcollaboratearoundthetechnologiesyouusemost. LearnmoreaboutCollectives Teams Q&Aforwork Connectandshareknowledgewithinasinglelocationthatisstructuredandeasytosearch. LearnmoreaboutTeams HowshouldIusethe"my"keywordinPerl? AskQuestion Asked 8years,9monthsago Modified 7years,9monthsago Viewed 93ktimes 101 New!Savequestionsoranswersandorganizeyourfavoritecontent.Learnmore. Ikeepseeingthe"my"keywordinfrontofvariablenamesinexamplePerlscriptsonlinebutIhavenoideawhatitmeans.ItriedreadingthemanualpagesandothersitesonlinebutI'mhavingdifficultydiscerningwhatitisforgiventhedifferencebetweenhowIseeitusedandthemanual. Forexample,itsusedtogetthelengthofthearrayinthispost: FindsizeofanarrayinPerl Butthemanualsays: Amydeclaresthelistedvariablestobelocal(lexically)tothe enclosingblock,file,oreval.Ifmorethanonevalueislisted,the listmustbeplacedinparentheses. Whatdoesitdoandhowisitused? perlscopedeclaration Share Follow editedMay23,2017at11:47 CommunityBot 111silverbadge askedJan2,2014at18:43 FistOfFuryFistOfFury 6,38777goldbadges4545silverbadges5757bronzebadges 2 3 Re"itsusedtogetthelengthofthearrayinthispost",Notatall.mydidnotfactorintoitintheleast.It'sthescalarassignmentoperator(=)thatenforcedthescalarcontexton@arr. – ikegami Jan2,2014at20:03 Ifit'snotreally"yours",youshouldnotuseit. – icenac Jan23,2017at14:26 Addacomment  |  3Answers 3 Sortedby: Resettodefault Highestscore(default) Trending(recentvotescountmore) Datemodified(newestfirst) Datecreated(oldestfirst) 153 myrestrictsthescopeofavariable.Thescopeofavariableiswhereitcanbeseen.Reducingavariable'sscopetowherethevariableisneededisafundamentalaspectofgoodprogramming.Itmakesthecodemorereadableandlesserror-prone,andresultsinaslewofderivedbenefits. Ifyoudon'tdeclareavariableusingmy,aglobalvariablewillbecreatedinstead.Thisistobeavoided.Usingusestrict;tellsPerlyouwanttobepreventedfromimplicitlycreatingglobalvariables,whichiswhyyoushouldalwaysuseusestrict;(andusewarnings;)inyourprograms. Relatedreading:Whyuseusestrict;andusewarnings;? Share Follow editedMay23,2017at12:10 CommunityBot 111silverbadge answeredJan2,2014at20:00 ikegamiikegami 352k1515goldbadges254254silverbadges499499bronzebadges 5 13 Finallyananswerthatexplainswhy. – ThisSuitIsBlackNot Jan2,2014at21:18 ForpeoplecomingherefromJS:It'sessentiallylikevarandletinJavaScript.Without'usestrict';JSwillletyoudeclarenewglobalvariableswithouteitherkeyword,whichisn'tconsideredthebestofpractices. – ElectricCoffee Aug10,2020at7:25 @ElectricCoffee,InJSterms,thequestionwouldbe"Whatdoesletandvardoandhowshouldtheybeused?"Andyes,theanswerwouldberoughlythesame.(JS'sletvarsarealotlikePerl'smyvars,exceptthatletvarscan'tbecaptured.) – ikegami Aug10,2020at7:52 1 IjustmeantthatifpeoplecametoPerlfromJS,itwouldbeaneasywaytoexplainthesameconcept – ElectricCoffee Aug10,2020at8:32 @ElectricCoffee1)Aprogrammerthatunderstandsscopingdoesn'tneedtohaveitexplainedtothemagainafterswitchinglanguages.2)Notsurethatyouactuallydidexplainscoping,intermsaJSprogrammerwouldunderstandorotherwise.Maybeyouweretryingtoexplainusestrict;?Butthatwasn'tthequestion,andusestrict;doesmorethanthat.Ormaybeyoumeanttocommunicatethatmylimitsthescopeofvarskindalikeletandvardo,butthat'sprettymuchthefirstsentenceoftheanswer.3)Ifyouwishtoansweraquestiondifferently,that'swhatAnswersarefor. – ikegami Aug10,2020at8:52 Addacomment  |  31 Quicksummary:mycreatesanewvariable,localtemporarilyamendsthevalueofavariable Intheexamplebelow,$::arefersto$ainthe'global'namespace. $a=3.14159; { my$a=3; print"Inblock,\$a=$a\n"; print"Inblock,\$::a=$::a\n"; } print"Outsideblock,\$a=$a\n"; print"Outsideblock,\$::a=$::a\n"; #Thisoutputs Inblock,$a=3 Inblock,$::a=3.14159 Outsideblock,$a=3.14159 Outsideblock,$::a=3.14159 ie,localtemporarilychangesthevalueofthevariable,butonlywithinthescopeitexistsin. Source:http://www.perlmonks.org/?node_id=94007 Update Aboutdifferencebetweenourandmypleasesee WhatisthedifferencebetweenmyandourinPerl? (ThankstoThisSuitIsBlackNot). Share Follow editedMay23,2017at12:34 CommunityBot 111silverbadge answeredJan2,2014at18:46 IgorChubinIgorChubin 58.7k1010goldbadges117117silverbadges139139bronzebadges 4 2 Ithinkthisanswerneedssomeadjusting.Youhaveacodeexampledemonstratingtheuseofmy,butthenfollowthatupwithasentencetalkingaboutlocalasifyouhadjustdemonstratedlocal'suse,despitethatlocalisnotdemonstratedanywhereinthisanswer.IthinkyoukindofmisquotedthesourceonPerlMonks,whichhastwocodeexamples.Thesentenceaboutlocalwasdescribingtheotherone,nottheoneyoutranscribedhere. – temporary_user_name May17,2017at8:01 1 Whyevenmentionlocalwhenyoudon'tuseitinthecodeexample? – Greenonline Dec16,2020at15:48 @Greenonline:Withthislogic,ifyouhavenocodeexampleatall,youshouldn'tmentionanything? – IgorChubin Dec16,2020at21:31 Wellyes.Asmentionedinthiscomment,thecodeexamplethatyougivedoesn'tshowtheuseoflocal.However,youthenexplainthescopeoflocal,butithasn'tbeendemonstrated.Theproblemisthatyou'vecopiedthewrongcodesnippetfromtheperlmonkspage.It'srathermisleading. – Greenonline Jan14,2021at9:35 Addacomment  |  6 PrivateVariablesviamy()istheprimarydocumentationformy. Inthearraysizeexampleyoumention,it'snotusedtofindthesizeofthearray.It'susedtocreateanewvariabletoholdthesizeofthearray. Share Follow answeredJan2,2014at18:47 cjmcjm 60.9k99goldbadges125125silverbadges173173bronzebadges Addacomment  |  YourAnswer ThanksforcontributingananswertoStackOverflow!Pleasebesuretoanswerthequestion.Providedetailsandshareyourresearch!Butavoid…Askingforhelp,clarification,orrespondingtootheranswers.Makingstatementsbasedonopinion;backthemupwithreferencesorpersonalexperience.Tolearnmore,seeourtipsonwritinggreatanswers. Draftsaved Draftdiscarded Signuporlogin SignupusingGoogle SignupusingFacebook SignupusingEmailandPassword Submit Postasaguest Name Email Required,butnevershown PostYourAnswer Discard Byclicking“PostYourAnswer”,youagreetoourtermsofservice,privacypolicyandcookiepolicy Nottheansweryou'relookingfor?Browseotherquestionstaggedperlscopedeclarationoraskyourownquestion. 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