Question

I have a Perl project were I just had a problem by making a circular package call. The code below demonstrates the problem.

When this is executed, each package will call the other until all of the memory of the computer is consumed and it locks up. I agree that this is a bad design and that circular calls like this should not be made in the design, but my project is sufficiently big that I would like to detect this at run time.

I have read about the weaken function and Data::Structure::Util, but I have not figured out a way to detect if there is a circular package load (I am assume, because a new copy is being made at each iteration and stored in each copy of the $this hash). Any ideas?

use system::one;  my $one = new system::one();   package system::one;  use strict;  use system::two;  sub new {   my ($class) = @_;    my $this = {};     bless($this,$class);    # attributes   $this->{two} = new system::two();   return $this;  }   package system::two;  use strict;  use system::one;  sub new {   my ($class) = @_;    my $this = {};     bless($this,$class);    # attributes   $this->{one} = new system::one();   return $this;  }  

Answer 1

Here, have some code too. 🙂

sub break_recursion(;$) {     my $allowed = @_ ? shift : 1;     my @caller = caller(1);     my $call = $caller[3];     my $count = 1;     for(my $ix = 2; @caller = caller($ix); $ix++) {         croak 'found $count levels of recursion into $call'             if $caller[3] eq $call && ++$count > $allowed;     } }  sub check_recursion(;$) {     my $allowed = @_ ? shift : 1;     my @caller = caller(1);     my $call = $caller[3];     my $count = 1;     for(my $ix = 2; @caller = caller($ix); $ix++) {         return 1             if $caller[3] eq $call && ++$count > $allowed;     }     return 0; } 

These are called like:

break_recursion(); # to die on any recursion break_recursion(5); # to allow up to 5 levels of recursion my $recursing = check_recursion(); # to check for any recursion my $recursing = check_recursion(10); # to check to see if we have more than 10 levels of recursion. 

Might CPAN these, I think. If anyone has any thoughts about that, please share.