#!/usr/bin/env perl

use v5.14;

package The::Package {
	use Carp;
	use base "Exporter";
	BEGIN { our @EXPORT = qw( my_generator foo takes_coderef ) };
	
	my $scratchpad;
	sub my_generator (&) {
		$scratchpad = {};
		shift->();
		my $tmp = $scratchpad;
		undef $scratchpad;
		return $tmp;
	}
	
	sub foo ($) {
		croak "foo must be called within my_generator" unless $scratchpad;
		$scratchpad->{foo} = shift;
	}
	
	sub takes_coderef (&) {
		croak "takes_coderef must be called within my_generator" unless $scratchpad;
		$scratchpad->{coderef} = shift;
	}
	
	BEGIN { $INC{"The/Package.pm"} = __FILE__ };
};

use The::Package;
use Data::Dumper;

my $complex_result = my_generator {
	foo 'bar';
	takes_coderef { ... };
};

print Dumper($complex_result);

foo 'baz'; # Should not affect $complex_result.
           # Ideally, should croak, or not even compile.