Just like other hashes, use exists. 
use Win32::TieRegistry qw( $Registry );

warn "No association exists for Perl files\n"
   if not exists $Registry->{'Classes\\.pl'};

[download]

In reply to Re: In Win32::TieRegistry, what is the best way to tell if a registry variable exists? by ikegami
in thread In Win32::TieRegistry, what is the best way to tell if a registry variable exists? by DrWhy

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