if ($0 =~ /\.pm$/i) {
 # execute stand alone
)
# fall thru for module.
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Of course, that's also the least robust solution of the four.

Makeshifts last the longest.

True and I agree
but
a working solution is all I needed, and it is simple and it works. No need to get too much robustness.
I guess my second choice would be the "caller EXPR", so I keep this in mind if the simple solution stops working.
thanks again for all replies.