in reply to Re: Tiny Perl puzzle
in thread Tiny Perl puzzle

I wasn't even trying to guess what it would really parse as so I just Deparse and run it

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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:

    This is confirmed by the more low-level output of B::Concise:

    $ perl -MO=Concise,-exec, -e 'print ( two + two == five ? "true" : "fa +lse" )' 1 <0> enter 2 <;> nextstate(main 1 -e:1) v:{ 3 <0> pushmark s 4 <$> gv(*two) s 5 <1> rv2gv sKR/1 6 <$> const(PV "two") s/BARE 7 <$> const(PV "five") s/BARE 8 <2> eq sK/2 9 <|> cond_expr(other->a) lK/1 a <$> const(PV "true") s goto b d <$> const(PV "false") s b <@> print vKS c <@> leave[1 ref] vKP/REFC -e syntax OK

    It's easy to see from this output that the first two is treated as a typeglob; a filehandle. The second two and the five are treated as barewords; constants in this case, which are then compared to one another. They evaluate to the same constant defined value, which is probably an empty string, equating to 0 for the purpose of numeric equality. So "true" will result, but it's printed to a filehandle that hasn't been attached to anything.


    Dave

        I can't test ATM

        You gotta stop saying that :)

        Contrary to AnoMonk I doubt space matters.

        Sure it does, it matters how Deparse places the space, because it matters to perl

        That is exactly as deparsed with -p, behaves exactly like the original