Re^2: Avoiding circular references

I would have someting like this working

use strict;
use warnings;

use Devel::Cycle;

package A;

sub new {
    my ( $class, $href ) = @_;
    my $self = { dbi => $$href{dbi} }; 
    $self->{helper} =
        Helper->new( helper_function => sub {
                      my $dbi = $$href{dbi}; 
                     return  $self->this_is_from_A(@_);
            } );
    bless $self, $class;
}

sub do_something {
    my $self = shift;
    $self->{helper}->called_from_helper();
}

sub this_is_from_A {
    my ($self, $arg) = @_;
    print "$arg\nthis_is_from_A using $dbi\n";
}

package Helper;

sub new {
    my $class = shift;
    my %def = ( a => "something");
    my %arg   = ( ref $_[0] eq "HASH" ? ( %def, %{ $_[0] } ) : ( %def,
+ @_ ) );
    my $self  = \%arg;
    bless $self, $class;
}

sub called_from_helper {
    my $self = shift;
    print "called_from_helper\n";
    my $coderef = $self->{helper_function}->();
    $coderef->("param from Helper");
}

package main;
my $a = A->new( { dbi => "some dbi object" } );
$a->do_something();
$a->do_something();
find_cycle($a);
[download]

But this does not even compile since $dbi in this_is_from_A is not declared.

Comment on Re^2: Avoiding circular references Select or Download Code

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Re^3: Avoiding circular references by tobyink (Canon) on Dec 06, 2019 at 14:48 UTC
So you pass `$dbi` as an argument. `package A; sub new { my ( $class, $href ) = @_; my $self = { dbi => $$href{dbi} }; $self->{helper} = Helper->new( helper_function => sub { my $dbi = $$href{dbi}; return $self->this_is_from_A($dbi, @_); # p +ass $dbi } ); bless $self, $class; } sub do_something { my $self = shift; $self->{helper}->called_from_helper(); } sub this_is_from_A { my ($self, $dbi, $arg) = @_; # r +eceive $dbi print "$arg\nthis_is_from_A using $dbi\n"; }` [download] toby döt ink	[reply] [d/l] [select]
Re^4: Avoiding circular references by frazap (Monk) on Dec 06, 2019 at 15:16 UTC
Thanks ! but that still make a circular reference because of `$self` This works use strict; use warnings; use Devel::Cycle; package A; sub new { my ( $class, $href ) = @_; my $self = { dbi => $$href{dbi} }; $self->{helper} = Helper->new( helper_function => sub { &this_is_from_A( $$href{dbi}, @_) } ); bless $self, $class; } sub do_something { my $self = shift; $self->{helper}->called_from_helper(); } sub this_is_from_A { my ($dbi, $arg) = @_; print "$arg\nthis_is_from_A using $dbi\n"; } package Helper; sub new { my $class = shift; my %def = ( a => "something"); my %arg = ( ref $_[0] eq "HASH" ? ( %def, %{ $_[0] } ) : ( %def, + @_ ) ); my $self = \%arg; bless $self, $class; } sub called_from_helper { my $self = shift; print "called_from_helper\n"; $self->{helper_function}->("param from Helper"); } package main; my $a = A->new( { dbi => "some dbi object" } ); $a->do_something(); $a->do_something(); find_cycle($a); [download]	[reply] [d/l] [select]
Re^5: Avoiding circular references by haj (Vicar) on Dec 06, 2019 at 19:27 UTC
but that still make a circular reference because of `$self` You could stick close to your original solution with a method call if you pass a weakened copy of `$self` to the subroutine reference: `use strict; use warnings; use Devel::Cycle; package A; use Scalar::Util qw/weaken/; sub new { my ( $class, $href ) = @_; my $self = { dbi => $$href{dbi} }; my $weak_self = $self; weaken $weak_self; $self->{helper} = Helper->new( helper_function => sub { $weak_self->this_is_from +_A(@_) } ); bless $self, $class; } # ....the rest remains unchanged.` [download] That way, `this_is_from_A` has full access to the `$self` object (which isn't needed in your example so far).	[reply] [d/l]