Tiny Perl puzzle

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Re: Tiny Perl puzzle by tobyink (Canon) on Jun 05, 2014 at 22:19 UTC
I realised fairly quickly that the plus would be treated as a unary operator, and thus assumed the whole thing would be effectively: `print two( 0==0 ? "true" : "false" );` [download] ... and thus Perl would die because there's no function `two()` defined. But how foolish of me!! The first `two` becomes a file handle of course, albeit an unopened one. So the whole line ends up printing to nowhere. Good puzzle. This sort of thing is precisely the reason various best practices have arisen. `use Moops; class Cow :rw { has name => (default => 'Ermintrude') }; say Cow->new->name`	[reply] [d/l] [select]
Re: Tiny Perl puzzle (duh) by tye (Sage) on Jun 06, 2014 at 00:22 UTC
This surprises any even moderately experienced Perl programmer? Update: It appears that my test didn't sufficiently accurately replicate the original program text. Though I admit this particular quirk didn't and doesn't bother me much as I avoid barewords exactly because they lead to lots of ambiguities. - tye	[reply]
Re: Tiny Perl puzzle by LanX (Saint) on Jun 06, 2014 at 00:35 UTC
<Reveal this spoiler or all spoilers in this node or all in this thread> Can't test ATM :) Cheers Rolf (addicted to the Perl Programming Language) update tobyinc's analysis is correct! :) one more reason to enforce `use strict` and 'warnings'...	[reply] [d/l]
Re^2: Tiny Perl puzzle by Anonymous Monk on Jun 06, 2014 at 01:16 UTC
I wasn't even trying to guess what it would really parse as so I just Deparse and run it $ perl -MO=Deparse print (two + two == five ? "true" : "false") ^Z print two 'two' == 'five' ? 'true' : 'false'; - syntax OK $ perl -MO=Deparse,-p print (two + two == five ? "true" : "false") ^Z print(two (('two' == 'five') ? 'true' : 'false')); - syntax OK $ perl -w print (two + two == five ? "true" : "false") print (...) interpreted as function at - line 1. Unquoted string "two" may clash with future reserved word at - line 1. Unquoted string "two" may clash with future reserved word at - line 1. Unquoted string "five" may clash with future reserved word at - line 1 +. ^Z Name "main::two" used only once: possible typo at - line 1. Argument "five" isn't numeric in numeric eq (==) at - line 1. Argument "two" isn't numeric in numeric eq (==) at - line 1. print() on unopened filehandle two at - line 1. [download]	[reply] [d/l]
Re^3: Tiny Perl puzzle by davido (Cardinal) on Jun 06, 2014 at 18:43 UTC
I think B::Deparse gets it wrong -- as it sometimes does -- when you add `-p`: <Reveal this spoiler or all spoilers in this node or all in this thread> This is confirmed by the more low-level output of B::Concise: <Reveal this spoiler> Dave	[reply] [d/l] [select]
Re^4: Tiny Perl puzzle by Anonymous Monk on Jun 07, 2014 at 07:25 UTC
Re^4: Tiny Perl puzzle by LanX (Saint) on Jun 07, 2014 at 15:38 UTC
Re^5: Tiny Perl puzzle by Anonymous Monk on Jun 08, 2014 at 09:17 UTC
Some notes below your chosen depth have not been shown here
Re: Tiny Perl puzzle by locked_user sundialsvc4 (Abbot) on Jun 06, 2014 at 12:09 UTC
`print (two + two == five) ? ( user == politician) ? "Re-elect me and I will fix it." : "It's not a bug, it's a feature!" : (user == accountant) ? "What do you -want- the answer to be?" : "Don't worry, sonny, no child will be left behind.™" ;` [download]
Re^2: Tiny Perl puzzle by LanX (Saint) on Jun 06, 2014 at 13:31 UTC
Another incorrect Perl puzzle? (hint: `print` greedily loves brackets! :) Cheers Rolf (addicted to the Perl Programming Language)	[reply]
Re^2: Tiny Perl puzzle by Anonymous Monk on Jun 07, 2014 at 07:27 UTC
(Please mark spoilers accordingly.) sundialsvc4, why not honor the OPs request and use spoiler tags?	[reply]

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