Prototype checking has been disabled in both the following examples...

my $coderef = sub {shift;};
my $val=$coderef->("Hello from down under");
sub doit{
       print shift, $/;
       }

&doit($val);
[download]

my $coderef = sub {shift;};
sub doit{
       print shift, $/;
       }
&doit($coderef->("Hello from down under"));
[download]

suppose I don't want the constructor to be directly modified from outside the package namespace of a class, so I return a reference to a closure from the constructor which can be indirectly accessed via an instance method of the class.

#Closured.pm
#!/usr/local/bin/perl        -cw
use strict;
use warnings;
package Closured;

sub new{
    our $self;
    my $closure = sub {
       shift;
       if(@_){
              $self = shift;
              }
       return $self;
       };
    bless $closure;
    return $closure; #returning a codeRef instead
    }
    
sub name{
    &{$_[0]};
    }
1;
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#using the Closured class...
use strict;
use warnings;

use Closured;
my $object = Closured->new("Hisham"); #try to feed a constructor direc
+tly.
print $object,$/;   #the constructor retruns a code ref.
print $object->name("BioHisham"), "\n";  #Feed via an instance method
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#Output 
Closured=CODE(0x18449ac)
BioHisham
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I'm not sure what you mean, BUK needs the (&) prototype as syntactic sugar to avoid writing the sub statement to get a coderef like in doit sub {...code ...}

But "disabling prototype checking" leads to another solution of his problem 8)

  DB<8> sub doit (&) { $_[0]->("para") }
 
  DB<9> $codeRef= sub { print @_ }
 
  DB<10> doit {print @_}
para
  DB<11> &doit($codeRef)  # disable checking
para
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Cheers Rolf