...using text Template.

In case you mean Text::Template, you could do something like this:

use Text::Template;

my $tmpl = <<'EOTMPL';
{$Col1 ? "Col1:$Col1" : ''}
{$Col2 ? "Col2:$Col2" : ''}
{$Col3 ? "Col3:$Col3" : ''}
EOTMPL

my $template = Text::Template->new(
                   TYPE   => 'STRING',
                   SOURCE => $tmpl
               );
$Col1 = 12;
$Col2 = 4;
$Col3 = 0;

my $text = $template->fill_in();
print $text;

__END__
Col1:12
Col2:4
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