From a google search:

#!/usr/bin/perl
use warnings;
use strict;

my $part_2 = "Not a good idea";
my $var1 = "part";
my $var2 = "2";
my $compound = eval "\$${var1}_$var2";

print "$compound\n";

__END__

There are three important things to note about this:
1. it is a really bad idea
2. the first $ must be escaped to avoid the first evaluation (the
interpolation into the string)
3. $var1 must be in the form of ${var1} because $var1_ is a valid vari
+able name
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#!/usr/bin/perl
use warnings;
use strict;
use Tk;
use Tk::Pane;
use Encode;

my $topdir= shift || '.';
my @subdirs = get_sub_dirs($topdir);

my $mw = tkinit();
$mw->geometry('400x400+100+100');

my $sp = $mw->Scrolled('Pane', -scrollbars=>'osoe', sticky=>'nwse')
     ->pack(-expand=>1, -fill=>'both' );

my @cbvalues;
my @cbnames;
my $count = 0;
foreach my $d( @subdirs){

  $cbnames[$count] = $d;

  $sp->Checkbutton(-text => $d,
        -font=>[arial => 12],
        -onvalue => 1,
        -offvalue => 0,
        -variable => \$cbvalues[$count],
        -font => 'big',
        -bg => 'white',
     )->pack(-anchor=>'w')->pack();

$count++;
}

my $showbutton= $mw->Button(-text=>'Show Selected',
-bg => 'lightyellow',
-command => sub{ 
       my @selected = ();
       foreach my $c( 0.. $count ){
            if ( $cbvalues[$c] ){
                push @selected, $cbnames[$c];
              }
         }
  
      print "@selected\n"; 
      } )->pack();

MainLoop();


sub get_sub_dirs {
 my $dir = shift;
 opendir my $dh, $dir or die "Error: $!";
 my @files = grep !/^\.\.?$/, readdir $dh;
 @files = map { decode( 'utf8', "$dir/".$_ ) } sort @files;
 closedir $dh;
 my @sdirs;

 for my $file ( @files ) {
   if(-d $file){push @sdirs,$file;}
  }

return @sdirs;
}
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