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perlcheat

by Juerd (Abbot)
on Feb 23, 2003 at 17:33 UTC ( #237910=perlmeditation: print w/ replies, xml ) Need Help??

Update (20061211)
It has been with Perl since 5.8.1. The current official version can be found at http://perldoc.perl.org/perlcheat.html.

re consideration: I am strongly against changing the title. This title was chosen because it most concisely states the point: the cheat sheet as a perldoc, under the name perlcheat. This title was very carefully chosen, years ago. Vote as you wish, and change the title if you must, but you should at least know my opinion.

Update (20030812)
perlcheat was accepted and will very probably be part of perl-5.8.1.

A few months ago, I posted my Perl Cheat Sheet here, and today it's at its seventh version. I'm only updating the one on my website, because I'm too lazy to copy and paste it every time. But neither the new version nor me being lazy is the reason for posting another meditation.

Some people suggested to me that it I should ask if the cheat sheet should be included in the Perl documentation as perlcheat. I'm not sure though. It's worth the try, but before I try, I'd like to know what you think.

I'd like to thank everyone who e-mailed or messaged me about this thing. And of course all people who link to it and all people who upvoted the node; it's the most popular Perl-related page on my website, and it's my best node (reputation-wise) ever.

So - perlcheat shipped with Perl - good or bad idea?

Juerd
- http://juerd.nl/
- spamcollector_perlmonks@juerd.nl (do not use).

Comment on perlcheat
Re: perlcheat
by Zero_Flop (Pilgrim) on Feb 23, 2003 at 18:54 UTC
    Juerd-
    I like Cheat sheets. They help with the everyday stuff until it become routine. I would submitt the idea, any good SW book has a summery of commands in the appendix. Worst case let them say no and keep the page up for those in need.

    One comment on your Cheat Sheet. It would be nice if you did something in addition to making the titles Bold to make them stand out. Maybe Underline too.

      One comment on your Cheat Sheet. It would be nice if you did something in addition to making the titles Bold to make them stand out. Maybe Underline too.

      Can't do that, since I want it to be plain ASCII. That's also why there are no borders around the sections, and why I didn't just use a table to format the thing.

      Besides, bold characters are wider in most fonts, so it'd ruin the lay-out. Underline would be possible, but still the ASCII thing holds.

      If this ever becomes a perldoc, markup like this is not possible at all, since in POD you can't have fixed formatting and markup at the same time.

      Juerd
      - http://juerd.nl/
      - spamcollector_perlmonks@juerd.nl (do not use).
      

        =pod C<You B<certainly> can.> =cut
        See perlpod.

        Makeshifts last the longest.

Re: perlcheat
by webfiend (Vicar) on Feb 23, 2003 at 19:00 UTC

    I'm really surprised that something like this doesn't already ship with Perl. If not, then it's about time they started. ++ from me to that idea.


    I just realized that I was using the same sig for nearly three years.

Re: perlcheat
by Mr_Person (Hermit) on Feb 23, 2003 at 19:49 UTC
    I think it looks great, hadn't seen it before. A lot of useful information in a small space. I vote for including it as it would be handy to just be able to say perldoc perlcheat whenever I wanted to see it again.
Re: perlcheat
by Ctrl-z (Friar) on Feb 23, 2003 at 20:37 UTC
    I like it - but how about a "Cheat fold-out Poster"? - A4 is just not enough :D


    time was, I could move my arms like a bird and...
Re: perlcheat
by logan (Curate) on Feb 23, 2003 at 22:03 UTC
    I like cheatsheets. A lot. For one reason or another, I have a lousy memory, and often need a quick refresh to key into the knowledge that has been lost somewhere in my brain. For this reason, I have a large list of aliases in my .tcshrc file, and I am never without my PDA.

    As a matter of fact, I don't think "cheatsheet" is a fair name. As long as you're not taking a closed-book test, who cares if you need a quick refresh on pack? Isn't that what documentation is for in the first place?

    Adding a cheatsheet to perl would be a godsend. We've already got perldoc. Why not include a quickie version? It's not like we're adding a 100 meg PDF to the binary. For what it's worth, I say go for it, and I'll look forward to seeing perlcheat in Perl 6.

    -Logan
    "What do I want? I'm an American. I want more."

      and I'll look forward to seeing perlcheat in Perl 6.

      The next version of Perl will not be Perl 6, and this cheat sheet is a Perl 5 cheat sheet.

      Perl 6 is a new language. Most of this cheat sheet does not apply to Perl 6. Heck, most of Perl as we know it does not apply to Perl 6. I think the difference between Perl 5 and 6 will much greater than the difference between C and C++ :)

      Juerd
      - http://juerd.nl/
      - spamcollector_perlmonks@juerd.nl (do not use).
      

        Perl 6 is a new language.

        Err. No. Perl 6 is a new version of the same language: Perl. Just as Perl 5 was. Just as Perl 4 was.

        Most of this cheat sheet does not apply to Perl 6.

        Au contraire! The vast majority of it is unchanged for Perl 6. See my other node on this topic.

        Heck, most of Perl as we know it does not apply to Perl 6.

        Just not true. My guess is that about 80% of your existing Perl knowledge will map usefully over to Perl 6.

        I think the difference between Perl 5 and 6 will much greater than the difference between C and C++ :)

        I very much doubt it. More like the difference between pre-ANSI C++ and post-ANSI C++.

        Except, of course, that Perl 6 won't suck. ;-)

Re: perlcheat
by toma (Vicar) on Feb 24, 2003 at 04:19 UTC
    I like the cheat sheet. As far as adding it to the distribution, I think it is a good idea. I think a better name for it is 'quick reference guide'.

    I was unable to get a clean text formatted version of the sheet from your web site. Cut-and-paste brought weird characters in, and the 'view source' version has escaped characters.

    For content, I would like more about exists, defined, keys, values, and ref.

    For typography, I think a PDF would be a great addition! A PDF could hold more information. I would like a PDF that could be rendered into a little four-page booklet, created by folding a double-sided printout. Those of us without young eyes could print on two double-sided sheets, or use bigger paper. A narrow version suitable for taping to the side of a monitor would be a true 'cheat sheet'.

    A PDF version with various page layouts would make a great addition to the test suite of the PDF generation modules.

    It should work perfectly the first time! - toma

Re: perlcheat
by TheDamian (Priest) on Feb 24, 2003 at 04:55 UTC
    A couple of small suggestions. Change:
    | ^ REGEX METACHARS REGEX MODIFIERS && ^ string begin /i case insens. || $ str. end (before \n) /m line based ^$ .. ... + one or more /s . includes \n ?: * any amount /x ign. wh.space = += -= *= etc. ? zero or one /g global</b> , => () capture list ops (?:) no capture REGEX CHARCLASSES not [] character class . == [^\n] and | alternation \s == [\x20\f\t\r\n] or xor {1,2} amount \w == [A-Za-z0-9_] \b word boundary \d == [0-9] \z string end \S, \W and \D negate
    to:
    | ^ REGEX METACHARS REGEX MODIFIERS && ^ string begin /i case insens. || $ str. end (before \n) /m line based ^$ .. ... + one or more /s . includes \n ?: * zero or more /x ign. wh.space = += -= *= etc. ? zero or one /g global , => {3,7} repeat in range list ops () capture REGEX CHARCLASSES not (?:) no capture . == [^\n] and [] character clas \s == [\x20\f\t\r\n] or xor | alternation \w == [A-Za-z0-9_] \b word boundary \d == [0-9] \z string end \S, \W and \D negate
Perl 6 version of cheatsheet
by TheDamian (Priest) on Feb 24, 2003 at 05:34 UTC
    Here's a first draft of the equivalent Perl 6 cheatsheet. I have deliberately restricted it to the same topics. Notice how similar to the Perl 5 version most of it is?
    Perl 6 cheat sheet v1 Based on the Perl 5 cheetsheet by Juerd Waalboer . CONTEXTS SIGILS ARRAYS HASHES void $scalar whole: @array %hash scalar @array slice: @array[0, 2] %hash{'a', 'b'} list %hash element: @array[0] %hash{'a'} &sub SCALAR VALUES number, string, reference, undef REFERENCES \ references @{$foo}[1] aka $foo.[1] $@%& dereference %{$foo}{bar} aka $foo.{bar} [] anon. arrayref @{@{$foo}[1]}[2] aka $foo.[1].[2] {} anon. hashref @{@{$foo}[1]}[2] aka $foo[1][2] \() list of refs NUMBERS vs STRINGS LINKS OPERATOR PRECEDENCE = = perl.plover.com + ~ search.cpan.org ++ -- == != eq ne cpan.org ** < > <= >= lt gt le ge pm.org ! u^ \ u+ u- ? u~ <=> cmp tpj.com ~~ !~ perldoc.com * / % x xx SYNTAX + - ~ for LIST { }, loop (a;b;c) { } .<< .>> +<< ~<< etc. while EXPR { }, until ( ) { } named uops if EXPR { } elsif EXPR { } else { } & unless EXPR { } elsif EXPR { } else { } |^ < > <= >= lt gt le ge == != <=> eq ne cmp && REGEX METACHARS REGEX MODIFIERS || ^^ // ^ string begin :i case insens. $ string end :w skip w/space .. + one or more :e each ?? :: * zero or more = += -= *= etc. ? zero or one , () capture list ops [] no capture REGEX CHARCLASSES not <[]> character class . == any char and | alternation \s == [\x20\f\t\r\n] or xor err <1,2> repeat in range \w == [A-Za-z0-9_] \b word boundary \d == [0-9] \S, \W and \D negate DO use strict; DON'T LINKS use warnings; "$foo" perl.com my $var; $$variable_name perlmonks.org open() err die $!; `$userinput` use.perl.org use Modules; /$userinput/ perl.apache.org parrotcode.org FUNCTION RETURN OBJECT ELEMENTS stat localtime caller SPECIAL VARIABLES 0 dev 0 second 0 package $_ current topic 1 ino 1 minute 1 filename $0 regex result 2 mode 2 hour 2 line 3 nlink 3 day 3 subroutine 4 uid 4 month-1 4 hasargs 5 gid 5 year-1900 5 want $! error object 6 rdev 6 weekday 6 evaltext 7 size 7 yearday 7 is_require 8 atime 8 is_dst 8 hints 9 mtime 9 bitmask @ARGS command line args 10 ctime @INC include paths 11 blksz @_ subroutine args 12 blcks %ENV environment

      Even though not much of this is new to me, seeing it on a single A4 piece of paper next to the Perl 5 cheat sheet is very comforting. Thank you again for translating perl 5 stuff.

      Juerd
      - http://juerd.nl/
      - spamcollector_perlmonks@juerd.nl (do not use).
      

      I may just be 'not getting it' as usual, but shouldn't the line:
      element: @array[0] %hash{'a'}
      instead be:
      element: $array[0] $hash{'a'}
      Or is that a Perl 6 change?

      Thanks,
      xenchu

        It's a Perl 6 change :-)

      Here's an updated version of the Perl 6 cheat sheet;
      Perl 6 cheat sheet v2 SIGILS MAJOR/MINOR CONTEXTS ACCESS ARRAYS HASHES $scalar item list sink whole: @array[] %hash{} @array Str flat/slice element: @array[0] %hash{'a'} %hash Num lazy/eager/hyper (or) %hash<a> &code Bool slice: @array[0,2] %hash{'a','b +'} COMPOSERS (or) %hash<a b> TWIGILS [ ] array $normal-lexical { } block/hash AUTOMATIC DEREFERENCE $?compiler-constant < > quotewords &($foo)(1,2) == $foo(1,2 +) $*dynamic-or-global (,) parcel @($foo)[1] == $foo[1] $.public-accessor :() signature %($foo){'bar'} == $foo<bar +> $!private-attribute \() capture @(@($foo)[1])[2] == $foo[1][ +2] $^positional-param $:named-parameter CONTROL SYNTAX $=pod-info for LIST { } # implicit $_ ar +g $<named-match-capture> for LIST -> $a, $b { } # explicit args $~slang-variable while/until EXPR { } repeat while/until EXPR { } # do at least on +ce OPERATOR PRECEDENCE loop { } loop (a;b;c) { } # parens require +d! .method .[] i if EXPR { } elsif EXPR { } else { } ++ -- unless EXPR { } # no else allowe +d! ** given EXPR { when EXPR { } default { } } unary + - ~ ! ? ^ EXPR if EXPR for LIST; # list comprehensi +on * / % %% div next, last, redo # loop controls + - proceed, succeed # switch control +s x xx TYPES ~ Bool Bit Int Rat FatRat UInt Num Complex int32, complex64 e +tc. & Str Cat Blob Char Byte Codepoint Grapheme Buf buf8 buf32 ut +f8 | ^ IO Mu Any Cool Junction Whatever Mat +ch sleep abs sin temp Parcel Capture Signatu +re <=> leg cmp .. but SCOPE DECLARATORS Pair Range Set B +ag ~~ > == gt eq === eqv !op my lexical scope KeyHash KeySet KeyB +ag && our package scope Scalar Array Hash Co +de || ^^ // min max has instance scope Enum Order TrigBa +se ??!! ff anon no scope at all Block Routine S +ub = := op= => state persistent lexical Method Reg +ex so not augment benign parasitic Failure Excepti +on , : supersede deadly parasitic Instant Durati +on X Xop Z Zop ... Date DateTi +me say die map etc OPERATOR DOMAINS and Numeric: == !==(!=) + < > <=> <= >= or xor Stringy: eq !eq(ne) ~ lt gt leg le ge <== ==> Value: eqv !eqv before after cmp !after !befo +re ObjectID: === !=== METAOPERATORS LINKS IRC [op] reduce listop to A op B op C... perl6.org #perl6 irc.freenode.n +et op= A = A op B rakudo.org #parrot irc.perl.org !op !(A op B) »op« hyper/vectorize REGEX METACHARS REGEX MODIFIERS Zop zip with op ^ $ string begin/end :i ignore case Xop cross with op ^^ $$ line begin/end :m ignore marks Rop reverse args + one or more :g global Sop sequentialize * zero or more :r ratchet ? zero or one :s sigspace SPECIAL VARIABLES **1..3 repeat in range :4th nth occurrence $_ current topic () capture to $0,$1 :4x n times $/ regex result [] no capture $! error object <foo> subrule REGEX CHARCLASSES @*ARGS command line <[]> character class . == anychar, \N non +\n @*INC include path | parallel or \s == <space>, \S non %*ENV environment || serial or \d == <digit>, \D non $*PID process id « » word boundary \w == <+alpha+digit+[_ +]>

        I love it!

        Could you please change the <code> to a <pre>, though? This wraps around, which is ugly. I think a tag change may fix it. screenshot.

        Juerd # { site => 'juerd.nl', do_not_use => 'spamtrap', perl6_server => 'feather' }

Re: perlcheat
by Aristotle (Chancellor) on Feb 24, 2003 at 14:38 UTC
    I like the idea of perldoc perlcheat.

    Makeshifts last the longest.

Re: perlcheat
by ghenry (Vicar) on May 06, 2005 at 14:09 UTC

    Could we add http://perldoc.perl.org to the list of urls?

    Thanks.

    Walking the road to enlightenment... I found a penguin and a camel on the way.....
    Fancy a yourname@perl.me.uk? Just ask!!!

      Could we add http://perldoc.perl.org to the list of urls?

      No, there's no room for a very long URL like that. The only URLs that are unimportant enough to go are tpj.com and perldoc.com, both too short to be replaced with perldoc.perl.org. It should be perl.org/doc or doc.perl.org anyway, and not have "perl" twice in the URL. (The reason for using perldoc in full was Google ranking. I don't agree with optimizing for search engines either.)

      Juerd # { site => 'juerd.nl', plp_site => 'plp.juerd.nl', do_not_use => 'spamtrap' }

        Well, OK. But I don't think it's that long a url.

        I also think the reason it's perldoc.perl.org and not doc.perl.org, is that the previous url was perldoc.perldrunks.org and nothing to do with Google ranking. I may be wrong however.

        Gavin.

        Walking the road to enlightenment... I found a penguin and a camel on the way.....
        Fancy a yourname@perl.me.uk? Just ask!!!
        It should be perl.org/doc or doc.perl.org anyway, and not have "perl" twice in the URL.
        Does it also bother you that every perldoc about perl has perl in it's name? For example, perlreftut, perlfunc, perlsec... That is to say, that the perldoc already says that we're looking at the documentation for perl, why prefix the subject with perl again?

        thor

        Feel the white light, the light within
        Be your own disciple, fan the sparks of will
        For all of us waiting, your kingdom will come

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