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Object Inheritance

One way to potentially save yourself some time, when building objects that have some relationship to each other, is to build a parent object for some or all of them. For instance if you're building a large number of sun-drenched rooms in an outdoor labyrinth somewhere then an awfully large number of them are likely to have grass, sunlight, a hedge, a view of a tower and so on. You can put all those various details into a single parent object and make your tens or hundreds of labyrinth rooms all implement them automatically. This tutorial can show you how.

At the moment, inheritance is primarily a way to inherit object details. That's a useful thing, but it doesn't do everything. We hope that object nouns and adjectives will also be inheritable soon. Things like weights, heights, etc should already be. We're considering object descriptions, but it's not entirely clear how that should work.

So, back to that sun-drenched labyrinth. You're going to need a parent room, which should be clearly marked as such and not connected (via exits) to any other room anywhere, to avoid people randomly walking into it and changing stuff. So use @make_room to make just such a thing. Your parent rooms are allowed to have their own parents, but in this example there's probably no reason to bother. Take note of the parent room's object number, when you find out what it is.

For your brief and glance descriptions you should put something like "labyrinth parent room", and for your look description you should put something like "this room contains details for other labyrinth rooms. You should never, never be able to enter it."

You'll also want an ordinary labyrinth test room to try out the nifty inheritance tricks. Go ahead and create one with @make_room. Up to this point, when @make_room asks you for a parent object, you've probably just been hitting enter to leave it blank. And that's been the right thing to do. But when you make the labyrinth test room, you should instead type the number of the labyrinth parent room -- the one we told you to take note of awhile back. You did, right?

The description can be whatever you like, but for the full example experience, I recommend mentioning sunshine and a distant tower in the desc.

Now, go ahead and make a new detail with @make_detail. Make it a part of the labyrinth parent room, not the labyrinth test room. Describe the sunshine playing on the grass and hedges, and how you can see the dust motes playing in it. Give it nouns like sun, sunshine, dust and motes, and adjectives like bright, shiny and dust (so that you can look at the dust motes and get the same desc).

To test it out, go to the labyrinth parent room and look at the dust motes. Now go back to the labyrinth test room and do the same. If you want, go ahead and add more details to the labyrinth parent rooms for things like grass, the tower, the hedges and the other stuff you can see. In a Skotos room you'd be spending two or three hours at least on all the descriptions, so don't be shy about taking ten or fifteen minutes on this. Players eat this stuff up. And remember, every minute you spend on the details in the parent room is that much more detail in every child room.

So test it out. Make another child room. That's another room like the labyrinth test room, one that also inherits from the labyrinth parent room (whose number you still remember, yeah?). After making this fresh-minted room with @make_room and giving it the labyrinth parent room as a parent, go ahead and look around at the grass, the dust motes, and everything else you made details for. And there they are!

Note how just by making a room with a cool parent, you've suddenly gotten a lot of details for free. This is inheritance, but it's not the kind you're used to in an Object Oriented programming language (just in case you're a programmer). That kind of inheritance is also called code inheritance because it's code being inherited. Those languages almost never allow data inheritance, which is what you're seeing here in Phantasmal. That's because these details are object data, not methods or any other kind of code. MUDs tend to be better served by data inheritance, at least for "physical" objects.

The only other thing you should know about inheritance is the way to change or remove object parents. The @set_obj_parent command is your friend here (check its online help!). You can set an object #1124's parent to object #375 by saying "@set_obj_parent #1124 #375". You can then make it parentless again by saying "@set_obj_parent #1124 #-1" or (in recent versions of Phantasmal) "@set_obj_parent #1124 none".

Now go build some more stuff by following the tutorials.