in reply to using 'use' conditionally

If I'm not mistaken, you want to require instead of use in your eval block.   Here's how I did similarly a while back:
my $have_SWE; BEGIN { $have_SWE = 0; eval { require Spreadsheet::WriteExcel }; unless ($@) { Spreadsheet::WriteExcel->import(); $have_SWE = 1; } } if ($have_SWE == 1) { ... }
If memory serves, I picked that up from something merlyn once said or posted.
    striving toward Perl Adept
    (it's pronounced "why-bick")

Super Search for "module installed" is what lead me to this thread, where I learnt of BEGIN, eval, and require.

After discussing with brother BUU, the lone advantage I can see of BEGIN... eval is that it allows you to include a more user-friendly message in the event that Tk isn't installed.   As always, Wiser Monks Than I may very well rightly say that I'm fullabeans.   {grin}

Untested, but perhaps a wee bit cleaner than my original code example:

my $have_Tk; BEGIN { $have_Tk = 0; eval { require Tk }; $have_Tk = 1 unless ($@); } if ($have_Tk == 1) { ... }