#!/usr/bin/perl
use strict;
use warnings;

{   package OnlyAString;
    use overload fallback=>0,     '""'=>sub { ${shift()} }  }
{   package ICanStringify;
    use overload fallback=>undef, '0+'=>sub { ${shift()} }  }
{   package OnlyANumber;
    use overload fallback=>0,     '0+'=>sub { ${shift()} }  }

print "  OnlyAString: ",strify(bless \do {my $x=111}, 'OnlyAString'  ),"\n";
print "ICanStringify: ",strify(bless \do {my $x=222}, 'ICanStringify'),"\n";
print "  OnlyANumber: ",strify(bless \do {my $x=333}, 'OnlyANumber'  ),"\n";

use Scalar::Util 'blessed';
use overload ();
use Carp;
sub strify {
    my ($x) = @_;
    if (!defined $x) {
        warnings::warnif('uninitialized','Use of uninitialized value in argument list');
        return "" }
    elsif (blessed($x) && overload::Overloaded($x)) {
        if (overload::Method($x,'""'))  # we can assume stringify will work
            { return "$x" }
        elsif (defined(my $rv = eval { "$x" }))
            { return $rv }
        elsif ($@=~/\bno method found\b/)  # throw custom error message
            { croak "Package ".ref($x)." doesn't overload stringification: $@" }
        else { die $@ }
    }
    else {
        ref($x) and warnings::warnif("Argument list contains references/objects");
        return "$x" }
}

##</code><code>##

  OnlyAString: 111
ICanStringify: 222
Package OnlyANumber doesn't overload stringification: Operation """": no method found, argument in overloaded package OnlyANumber at ...