Situation:
I have modules with such structure:
A.pm 
package A;

sub new {
    bless {}, shift;
}

sub doit {
    my $self = shift;
    warn 'A::doit';
}

1;

[download]
B.pm 
package B;

use base 'A';

sub doit {
    my $self = shift;
    
    warn 'B::doit';
    $self->SUPER::doit();
}

1;

[download]
C.pm 
package C;

use base 'B';

1;

[download]
D.pm 
package D;

sub new {
    bless {}, shift;
}

sub doit {
    my $self = shift;
    warn 'D::doit';
}

1;

[download]
And script: 
use C;

my $c = new C;
$c->doit();

[download]
So, when I'll execute this script I'll get
B::doit
A::doit
Now I need to modify this script to get
B::doit
D::doit
But by the condition I can't modify sub's or @ISA of B.pm, I can only dinamically modify C.pm from my script.
Here is my attempt: 
use C;
use D;

unshift @C::ISA, 'D';
*C::doit = \&B::doit;

my $c = new C;
$c->doit();

[download]
But it still prints
B::doit
A::doit
Because C::doit is only alias to B::doit and SUPER::doit() executes doit() from parent class of B.pm, not of C.pm.
So, is there a way to dynamically copy subroutine from one module to another or other way to solve my problem?

In reply to Is there a way to dynamically copy subroutine from one module to another? by OlegG

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.