Re: return value of "if" (documentation?)

AFAIK are if and and opcode-wise identical

lanx@nc10-ubuntu:~$ perl -MO=Deparse -e  ' print if $a '
print $_ if $a;
-e syntax OK
lanx@nc10-ubuntu:~$ perl -MO=Deparse,-p -e  ' print if $a '
($a and print($_));
-e syntax OK
[download]

This and short-circuiting should explain the returned values.

Cheers Rolf

( addicted to the Perl Programming Language)

Comment on Re: return value of "if" (documentation?) Select or Download Code

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Re^2: return value of "if" (documentation?) by ikegami (Patriarch) on Jan 08, 2014 at 15:17 UTC
Deparse tries to reproduce code, while Concise shows what's actually there. A more accurate demonstration: `$ perl -MO=Concise,-exec -e'print if $a' 1 <0> enter 2 <;> nextstate(main 1 -e:1) v:{ 3 <#> gvsv[a] s 4 <\|> and(other->5) vK/1 5 <0> pushmark s 6 <#> gvsv[_] s 7 <@> print vK 8 <@> leave[1 ref] vKP/REFC -e syntax OK $ perl -MO=Concise,-exec -e'$a and print' 1 <0> enter 2 <;> nextstate(main 1 -e:1) v:{ 3 <#> gvsv[a] s 4 <\|> and(other->5) vK/1 5 <0> pushmark s 6 <#> gvsv[_] s 7 <@> print vK 8 <@> leave[1 ref] vKP/REFC -e syntax OK` [download] But the question is about the `if` statement. `$ perl -MO=Concise,-exec -e'if ($a) { print }' 1 <0> enter 2 <;> nextstate(main 3 -e:1) v:{ 3 <#> gvsv[a] s 4 <\|> and(other->5) vK/1 5 <0> pushmark s 6 <#> gvsv[_] s 7 <@> print vK 8 <@> leave[1 ref] vKP/REFC -e syntax OK` [download]	[reply] [d/l] [select]
Re^3: return value of "if" (documentation?) by LanX (Saint) on Jan 08, 2014 at 15:32 UTC
> Deparse tries to reproduce code, True but B::Deparse has documented options to switch of the reconstruction of `if` from `and-op`. I chose one of the waysš... I also checked it with B::Terse before posting, just wanted to keep the post short. Thanks for supporting my point. :) > But the question is about the if statement. Do you imply that a post-fix `if` is not a "statement" like pre-fix `if` ? Cheers Rolf ( addicted to the Perl Programming Language) š) `-xLEVEL Expand conventional syntax constructions into equivalent ones that exp +ose their internal operation. ... If LEVEL is at least 7, "if" statements will be translated into equivalent expressions using "&&", "?:" and "do {}"; for instance` [download] `lanx@nc10-ubuntu:~$ perl -MO=Deparse,-x7 -e 'if($a){print $b}' $a and do { print $b }; -e syntax OK` [download]	[reply] [d/l] [select]
Re^4: return value of "if" (documentation?) by ikegami (Patriarch) on Jan 08, 2014 at 20:33 UTC
B::Deparse has documented options to switch of the reconstruction of if from and-op. I chose one of the waysš... Maybe I wasn't clear enough: B::Deparse can show they're similar as long as you assume the output is correct. B::Concise can show they're the same, and the output will be correct. Do you imply that a post-fix if is not a "statement" like pre-fix if ? No. The statement with the post-fix if is not an if statement, but I was not implying it's not a statement. I was implying it's not an if statement.	[reply]


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