the actual problem aside, my first thought is to use a different delimiter to make a little more legible (avoid having to escape the slashes): 
s#(.*\s*)(.*)\b\s*//\s*(.*)\b#$1defined($2) ? $2 : $3#gm;

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Second thought is that at least some (if not most) of the * (0 or more) should be + (1 or more). Without them, the regex will match just the string "//".

also, should "$1defined" be "$1 defined" ?

In reply to Re: regex for Err operator. by davidrw
in thread regex for Err operator. by Anonymous Monk

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