How about m/\S+=\S+/ instead of alteration?

while (<DATA>) {
    print if /\S+=\S+/;
}

__DATA__
$foo = 'hello';
$bar= 'hello';
$baz ='hello';
$qux='hello';
[download]

UPDATE:
Hope i am not second guessing myself, but i believe i am wrong here. You want only the bar, baz, and qux lines - correct? Looks like your answer is the right way. Sorry, that's what i get for posting before morning coffee. ;)

jeffa

L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)