Tangential to your main question (which I still don't understand), but the prototype of  measureFieldLength($$$) { ... } is declared too late to be effective.

c:\@Work\Perl\monks>perl -e
"package main;
 ;;
 use warnings;
 use strict;
 ;;
 sub foos () { foo(); }
 foos();
 ;;
 sub foo ($$$) { print qq{hi from foo() singular \n}; }
"
hi from foo() singular
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