A basic use_from implementation

usex-declare.pm

package UseX::Declare;

use strict;
use warnings;

use Carp;

use Devel::Declare ();

my $verbose = 0;

sub import {
  my $class = shift;
  my $opts = shift;

  $verbose = $opts->{verbose} || 0;

  my $caller = caller;

  Devel::Declare->setup_for(
      $caller,
      { 'use_from' => { const => \&rewrite_use_from } }
  );
  no strict 'refs';
  *{$caller.'::use_from'} = sub {};

}

sub rewrite_use_from {
  no strict 'refs';

  my $linestr = Devel::Declare::get_linestr;
  print STDERR "Got: $linestr" if $verbose;

  my $caller = Devel::Declare::get_curstash_name;

  $linestr =~ s/use_from\s+\$(\w+)/
    my $varname = $caller . '::' . $1;
    my $module = 
      (defined ${$varname}) 
      ? ${$varname}
      : croak "Cannot access variable \$$varname";
    "use_from; use $module"
  /e;
  
  print STDERR "Rewritten: $linestr" if $verbose;

  Devel::Declare::set_linestr($linestr);
}

1;