# use 4 spaces indents and automatic line ending
use indent indent_size => 4, indent_eol => 1;
indent::new;
indent::printf "Hello, world!";
indent::new;
indent::printf "Hello, world!";
indent::back;
indent::printf "Hello, world!";
indent::back;

##</code><code>##

    Hello, world!
        Hello, world!
    Hello, world!

##</code><code>##

package indent;

use strict;
use warnings;

our $INDENT = " " x 4;
our $EOL = $\;

sub import {
	shift;
	goto &config;
}

sub config {
	my %opts = @_;

	if ( $opts{indent_tab} ) {
		$INDENT = "\t";
	} elsif ( 
		defined $opts{indent_size} 
		&& $opts{indent_size} =~ /^\d+$/ 
	) {
		$INDENT = " " x $opts{indent_size};
	}

	if ( defined $opts{indent_eol} ) {
		$EOL = $opts{indent_eol} ? "\n" : $\;
	}
}

my @indent = ( "" );

sub reset {
	@indent = $indent[0];
}

sub current {
	$indent[-1];
}

sub new {
	push @indent, current . $INDENT;
}

sub back {
	pop @indent if @indent > 1;
}

sub print {
	local $\ = $EOL;
	CORE::print current, @_;
}

sub vprint {
	local $\ = $EOL;
	CORE::print current, $_ for ( @_ );
}

sub printf {
	indent::print sprintf(( shift || "" ), @_);
}

1;