Inheritance- Sub class instance variables

snra_perl has asked for the wisdom of the Perl Monks concerning the following question:

Hello PerlMonks,
I have a quick question on inheritance. Here is the my super class.

Package EventHandler;

sub new {
    my $class = shift;
    my $self  = {
        EVENT_ID            => $event_count,
        EVENT_CAT            => shift,
        EVENT_STATUS        => "current",
        EVENT_COMPONENT     => undef,
        EVENT_START_TIME    => undef,
        EVENT_END_TIME        => undef,
        EVENT_STATE            => "Unknown",
        EVENT_START_LOCATION=> undef,
        EVENT_END_LOCATION  => undef,
        EVENT_RECOVERED_BY    => undef,
    };
    bless( $self, $class );
    $event_count++ ;
    return $self;
}
[download]

I have a sub class DeviceEventHandler which inherits the above EventHandler module.
I create object using DeviceEventHandler ->new() which will call the super class method.
Now my question is how do i add some sub class specific attributes say "DeviceReset" in DeviceEventHandler and instantiate it during object creation.
For that purpose I need to define a "new" method in DeviceEventHandler module which will in turn call the "new" method of the super class.

Please help me out on this..

Thanks.

Comment on Inheritance- Sub class instance variables Download Code

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Re: Inheritance- Sub class instance variables by creamygoodness (Curate) on Aug 27, 2009 at 15:36 UTC
`package DeviceEventHandler; use base qw( EventHandler ); sub new { my $self = shift->SUPER::new(@_); $self->{DeviceReset} = undef; return $self; }` [download] You have to worry about parent and child classes stomping on each other's instance vars, but that's the basic idiom for hash-based objects.	[reply] [d/l]
Re: Inheritance- Sub class instance variables by NetWallah (Canon) on Aug 27, 2009 at 18:15 UTC
Hopefully, you have noticed by now that "Package EventHandler;" is incorrect - it should have a lower-case "p" for "package". Potentia vobiscum ! (Si hoc legere scis nimium eruditionis habes)	[reply]


No such thing as a small change
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