blob: 25bd6450f15522936e2e8d2cf65b04dc98a1926f (
plain) (
blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
|
#!/usr/bin/env perl
#
# Write a script that allows you to capture/display historical data. It could be
# an object or a scalar. For example
#
# my $x = 10; $x = 20; $x -= 5;
#
# After the above operations, it should list $x historical value in order.
################################################################################
use strict;
use warnings;
{
package Hist;
require Tie::Scalar;
our @ISA = qw<Tie::Scalar>;
sub TIESCALAR {
return bless \my @histogram, shift;
}
sub FETCH {
my @self = @{shift()};
printf STDERR "History of values: %s\n", join(", ", @self);
return @self[@self-1]
}
sub STORE {
my $self = shift;
my $value = shift;
push @$self, $value;
}
}
tie my $x, 'Hist';
$x = 10;
$x = 20;
$x = -5;
my $y = $x;
print "y=$y\n";
$x = 200;
print "x=$x\n";
|
