#!/usr/bin/perl

use strict; # https://perlmonks.org/?node_id=11164860
use warnings;

sub divertSTDERR
  {
  my ($sub) = @_;
  my $buffer;
  local *STDERR;
  open STDERR, '>', \$buffer or die "open failed $!";
  $sub->();
  chomp $buffer;
  return $buffer;
  }

my $buf = divertSTDERR( \&handleInner );
warn "output from handleInner:\n>>$buf<<\n";
warn "\n##################################################\n\n";
$buf = divertSTDERR( \&handleOuter );
warn "output from handleOuter:\n>>$buf<<\n";

sub handleInner
  {
  warn "inside handleInner\n";
  }

sub handleOuter
  {
  warn "before inner divert\n";
  my $buf = divertSTDERR( \&handleInner );
  warn "after inner divert\n";
  warn "handleOuter returns >>$buf<< from handleInner\n";
  }