sub craziness_lurks_here{
# do not count } me, I'm in a comment, not a '-ed string
warn "a parens }?\n";
print <<EOF;
}
EOF
}

##</code><code>##

while(s/\{/\}/gio){$b=~//;some-more-code-here}
# vs
s/\{/do{some-other-regexes+some-more-code-here;"}"}/egi
# (don't use delimeters like s{}{}ige, that way you'd
#  loose the construct's intended capriciousness :> )