Alok Bhatt wrote:
Hi All,
Can someone please tell me how do we keep track of a
variable. ie Whenever a particular variable is
accessed (printed, incremented .... etc.), a counter
should increase, so that we can know how many times it
has been accesssed.
The mechanism is tie, see `perldoc tie`
Here is an example: (See CPAN for others)
#!/usr/bin/perl
package Traced::Var;
use strict;
require Tie::Scalar;
our @ISA = qw(Tie::StdScalar);
sub FETCH {
my $self = shift;
print "FETCH: value is " . ${$self} . "\n";
return ${$self};
}
sub STORE {
my $self = shift;
my $val = shift;
print "STORE: old value is " . ${$self} . "\n";
${$self} = $val;
print "STORE: new value is " . ${$self} . "\n";
return ${$self};
}
package main;
my $var;
tie $var, 'Traced::Var';
$var = 42;
print "$var\n";
$var = "The answer";
print "$var\n";
__END__
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