Another "Silly use for Perl" entry.

Anonymous Monk asked for a method for incrementing mixed letters and numbers recently, which particular need is satisfied with Math::Base36. Can we do better? I guess, yes.

`use 5.10.0;
use Math::Base;
my $begin = Math::Base->new(36, 1009, 1); # base, number, is_encoded
my $end = Math::Base->new(36, 1020, 1);
my $c = Math::Base->new(36, 42);
say $c->encode($_) for $begin .. $end;
# 1009
# 100A
# 100B
# 100C
# ...
# 101X
# 101Y
# 101Z
# 1020
# also (with updated code below)
# my $x = Math::Base->new(36, 46664); # 1008 in base36
# say ++$x for 0..63; # output same as above
# Arithmetics with different encodings:
$p = Math::Base->new(8,777,1); # decimal 511
$z = Math::Base->new(36, 35); # 'Z' as base36
say $z * $p; # 42735 (octal)
say $p * $z; # 'DST' (base36)
# Changing the string representation:
$s = Math::Base->new(16,18);
say $s; # 12
$s->rebase(18);
say $s; # 10
$s += 3; # 13
$s->rebase(2);
say $s; # 10101
# Get decimal value:
$xyz = Math::Base->new(64, 'XYZabc', 1);
say $xyz->num; # 36013230438
`

Far from complete, but fun enough yet. For me, that is... ;-)

`package Math::Base;
use strict; use warnings;
use overload (
'""' => \&encode,
'0+' => \&num,
'-' => \&minus,
'+' => \&add,
'*' => \&mul,
'/' => \&div,
);
my %hash;
my @chars = (0..9,'A'..'Z','a'..'z',map{chr$_}32..47,58..64,91..96
+);
@hash{@chars} = 0..$#chars;
sub new {
my ($class, $base, $value, $encoded) = @_;
my $self = bless [$base, $value], $class;
$self->decode if $encoded;
$self;
}
sub rebase { $_[0]->[0] = $_[1] }
sub num { shift->[1] }
sub minus {
my ($self, $other, $swap) = @_;
my $result = $self->[1] - $other;
$result = -$result if $swap;
ref $result ? $result : bless [$self->[0],$result];
}
sub add {
my ($self, $other, $swap) = @_;
my $result = $self->[1] + $other;
ref $result ? $result : bless [$self->[0],$result];
}
sub mul {
my ($self, $other, $swap) = @_;
my $result = $self->[1] * $other;
ref $result ? $result : bless [$self->[0],$result];
}
sub div {
my ($self, $other, $swap) = @_;
my $result = $swap ? $other / $self->[1] : $self->[1] / $other;
int(ref $result ? $result : bless [$self->[0],$result]);
}
sub encode {
my $self = shift;
my ($base,$num) = @$self;
$num = shift if $_[0];
my ($rem,@ret);
while ($num) {
push @ret, $chars[($rem = $num % $base)];
$num -= $rem;
$num /= $base;
}
return join '', reverse @ret;
}
sub decode {
my $self = shift;
my ($base, $str) = @$self;
$str = shift if $_[0];
my $num = 0;
$num = $num * $base + $hash{$_} for $str =~ /./g;
$self->[1] = $num;
}
1;
__END__
`

**Update:** Below is an updated version which handles negative numbers, implements missing operators and lets you define your own charset for baseX conversion, e.g. to calculate base3 with `qw(a b c)`. Also, a method `integer()` is added which emulates `use integer` globally for all calculations, and some utility methods/functions.

Update: fixed some bugs

I'll eventually make it into a CPAN package proper.

perl -le'print map{pack c,($-++?1:13)+ord}split//,ESEL'

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