Beefy Boxes and Bandwidth Generously Provided by pair Networks
Perl: the Markov chain saw

Re: How does next label work?

by moritz (Cardinal)
on Jan 06, 2013 at 10:04 UTC ( #1011869=note: print w/replies, xml ) Need Help??

in reply to How does next label work?

I thought next is just another way to say goto

Well, it's not. You can see that next and goto compile to different ops internally:

$ perl -MO=Concise -e 'X: next X' 4 <@> leave[1 ref] vKP/REFC ->(end) 1 <0> enter ->2 2 <;> nextstate(X: main 1 -e:1) v:{ ->3 3 <"> next("X") v ->4 -e syntax OK $ perl -MO=Concise -e 'X: goto X' 4 <@> leave[1 ref] vKP/REFC ->(end) 1 <0> enter ->2 2 <;> nextstate(X: main 1 -e:1) v:{ ->3 3 <"> goto("X") v ->4 -e syntax OK

Another difference is this warning here:

$ perl -wE 'sub f() { next X }; X: for (1) { f }' Exiting subroutine via next at -e line 1.

which you don't get with goto. And of course the fact that the code above terminates, but doesn't if you replace 'next' with 'goto'.

Log In?

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://1011869]
[Discipulus]: someone can explain last faq by jdporter? if humor i missed it

How do I use this? | Other CB clients
Other Users?
Others examining the Monastery: (8)
As of 2018-06-22 07:40 GMT
Find Nodes?
    Voting Booth?
    Should cpanminus be part of the standard Perl release?

    Results (122 votes). Check out past polls.