Hints and tips

Hints and tips

Overloading

In many cases you will want to add more parameters to MisterHouse objects, e.g.

$Dining_room_radiator->{room_name} = "Dining room";

Unfortunately these parameters become undefined each time that MisterHouse starts, so need to be initialised each time. There is a number of ways to do this.

If they are static, then you can do it in your items.mht file e.g.

GENERIC, 	 Back_hall_detector,				variable
CODE, $Back_hall_detector->{room_name} = "Dining room";

Or in an initialising perl script e.g.

if ( $Startup or $Reload ) {
$Back_hall_detector->{room_name} = "Dining room";
}

If they are volatile, then each time they change you will have to save this away in a file, then on startup add the routine that reloads the values from this file to your initialisation script above.

Dynamic overloading

If you have a lot of dynamically overloaded items, you can save a huge amount of code by implementing dynamic overloading.

The first line of a vsDB data file contains the names of the columns e.g.

ID      name    room    on_off  timeHHMI
1       Main_bedroom_radiator     Main bedroom    on      08:00   

It is then possible to create a generic, extensible overloading routine that for each row of the file overloads the MisterHouse Item that matches the `name' then sets the values for each column e.g. in this case it would set

$Main_bedroom_radiator->{room} = "Main bedroom";
$Main_bedroom_radiator->{on_off} = "on";
$Main_bedroom_radiator->{timeHHMI} = "08:00";

By using the column names this way you can add extra overloads by just adding them to the datafile e.g changing the datafile to;

ID      Name    Room    on_off  timeHHMI        days   
1       Main bed on morning     Main bedroom    on      08:00   SMTWTFS

Would also set

$Main_bedroom_radiator->{days} = "SMTWTFS";

Without any change to your overloading code.

It looks like this in Pseudocode;

Read in the first line of the datafile
Split it to get a list of column names
For each subsequent row
    split it to get the values
    $this_object = get_object_by_name(<name value>)
    for each of the subsequent columns
       $this_object->{<column_name>} = <column value>
    next column
next row

Logging

Ìn order to be able to turn logging on and off without restarting MisterHouse, define a generic item GENERIC, logging_level, Variable in items.mht and create a new logger e.g.

#-----------------------------------------------------------------------
# write_log (text)
# writes a log message when logging_level > 0
#-----------------------------------------------------------------------
sub write_log {
	my $message = $_[0];
	if ( $logging_level->{state} > 0 ) {
		print_log($message);
	}
	return;
}

Then use write_log(zzz) instead of print_log(zzz) and it will only fill your log when logging_level > 0