ch09.022_best

来自「Perl Best Practices the source code」· 022_BEST 代码 · 共 56 行

##############################################################################
##   Code fragment (Recommended) from Chapter 9 of "Perl Best Practices"    ##
##     Copyright (c) O'Reilly & Associates, 2005. All Rights Reserved.      ##
##  See: http://www.oreilly.com/pub/a/oreilly/ask_tim/2001/codepolicy.html  ##
##############################################################################


# Standard modules...
use strict;
use warnings;
use IO::Prompt;
use Carp;
use English qw( -no_match_vars );
use Data::Alias;
use Readonly;

use Readonly;

Readonly my $SPACE => q{ };

use List::Util qw( max );

sub _check_non_empty {
    my ($str) = @_;
    croak "Empty string" 
        if !defined $str || !length $str;
}

sub _limit_to_positive {
    my ($len) = @_;
    return max($len, 0);
}

sub padded {
    my $text           = _check_non_empty(shift);
    my $cols_count     = _limit_to_positive(shift);
    my $want_centering = shift;
 
    # Compute the left and right indents required...
    my $gap   = $cols_count - length $text;
    my $left  = $want_centering ? int($gap/2) : 0;
    my $right = $gap - $left;

 
    # Insert that many spaces fore and aft...
    return $SPACE x $left 
         . $text 
         . $SPACE x $right;
}


package Elsewhere;

print '[', main::padded( 'hi there', -40, 1 ), "]\n";
print '[', main::padded( '', 40, 0 ), "]\n";