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# $Id: Compare.pm 846 2002-10-25 15:46:01Z richardc $
package Number::Compare;
use strict;
use Carp qw(croak);
use vars qw/$VERSION/;
$VERSION = '0.01';
sub new {
my $referent = shift;
my $class = ref $referent || $referent;
my $expr = $class->parse_to_perl( shift );
bless eval "sub { \$_[0] $expr }", $class;
}
sub parse_to_perl {
shift;
my $test = shift;
$test =~ m{^
([<>]=?)? # comparison
(.*?) # value
([kmg]i?)? # magnitude
$}ix
or croak "don't understand '$test' as a test";
my $comparison = $1 || '==';
my $target = $2;
my $magnitude = $3;
$target *= 1000 if lc $magnitude eq 'k';
$target *= 1024 if lc $magnitude eq 'ki';
$target *= 1000000 if lc $magnitude eq 'm';
$target *= 1024*1024 if lc $magnitude eq 'mi';
$target *= 1000000000 if lc $magnitude eq 'g';
$target *= 1024*1024*1024 if lc $magnitude eq 'gi';
return "$comparison $target";
}
sub test { $_[0]->( $_[1] ) }
1;
__END__
=head1 NAME
Number::Compare - numeric comparisons
=head1 SYNOPSIS
Number::Compare->new(">1Ki")->test(1025); # is 1025 > 1024
my $c = Number::Compare->new(">1M");
$c->(1_200_000); # slightly terser invocation
=head1 DESCRIPTION
Number::Compare compiles a simple comparison to an anonymous
subroutine, which you can call with a value to be tested again.
Now this would be very pointless, if Number::Compare didn't understand
magnitudes.
The target value may use magnitudes of kilobytes (C<k>, C<ki>),
megabytes (C<m>, C<mi>), or gigabytes (C<g>, C<gi>). Those suffixed
with an C<i> use the appropriate 2**n version in accordance with the
IEC standard: http://physics.nist.gov/cuu/Units/binary.html
=head1 METHODS
=head2 ->new( $test )
Returns a new object that compares the specified test.
=head2 ->test( $value )
A longhanded version of $compare->( $value ). Predates blessed
subroutine reference implementation.
=head2 ->parse_to_perl( $test )
Returns a perl code fragment equivalent to the test.
=head1 AUTHOR
Richard Clamp <richardc@unixbeard.net>
=head1 COPYRIGHT
Copyright (C) 2002 Richard Clamp. All Rights Reserved.
This module is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
=head1 SEE ALSO
http://physics.nist.gov/cuu/Units/binary.html
=cut
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