did you mean like this when you say ref/deref :

sub resp { $a="abcdefg";\$a }

while (${&resp} =~ /(.)/g) {
  print $1;
}
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however that goes to an infinitely loop too and for the first time on windows I crash perl interpreter so fast (when i hit Ctrl^C).

sub resp { "abcdefg" }

while (&resp =~ /(.)/g) { # you forgot the &,didn't you?
  print $1;
}
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in the above code, I expect that &resp returns the 'value' of the subroutine and becomes

while ("abcdefg" =~ /(.)/g) {
  print $1;
}
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it would work if it were the case.

so return by ref doesn't work either. what happens in while( &resp =~ /(.)/g ) ??