I don't want to answer for Ovid but I especially dislike mixing the declaration with that kind of assignment. I'd prefer

my $foo; 
($foo = $bar) =~ s/baz/qux/;
[download]

but if you are going to separate them anyway, it makes perfect sense to do it in a way that makes all the steps blindingly obvious such as this:

my $foo = $bar; 
$bar =~ s/baz/qux/;
[download]

There's rarely a good reason to sacrifice clarity for brevity.

-sauoq
"My two cents aren't worth a dime.";