Beefy Boxes and Bandwidth Generously Provided by pair Networks
Your skill will accomplish
what the force of many cannot
 
PerlMonks  

Re^4: self-feeding infinite loop

by syphilis (Canon)
on Aug 18, 2007 at 14:33 UTC ( #633486=note: print w/ replies, xml ) Need Help??


in reply to Re^3: self-feeding infinite loop
in thread self-feeding infinite loop

But you're definitely in the territory of "unpredictable behaviour"

I may be being somewhat picky (or I may even be downright wrong), but I don't see any "unpredictable behaviour" there. I agree that one needs to be careful when modifying an array by iterating over the same array, but the following does behave predictably:

use strict; use warnings; my @array = ('a'); foreach (@array) { push @array,'a'; print"@array\n"; sleep(1); # so we can absorb what's happening }
Cheers,
Rob


Comment on Re^4: self-feeding infinite loop
Download Code
Re^5: self-feeding infinite loop
by Errto (Vicar) on Aug 18, 2007 at 18:03 UTC
    It's not "unpredictable" in the sense of being random but it is undefined in the sense that it is not specified in the documentation and could potentially change in a future release. Quoting perlsyn:
    If any part of LIST is an array, foreach will get very confused if you add or remove elements within the loop body, for example with splice. So don't do that.
    I should add for the record that I once asked the same question myself.

Log In?
Username:
Password:

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://633486]
help
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others drinking their drinks and smoking their pipes about the Monastery: (2)
As of 2014-11-29 10:15 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    My preferred Perl binaries come from:














    Results (204 votes), past polls