Extending time and details

For the fun of it I added an "Extended Room" contrib to Evennia the other night.

("Contribs" are optional code snippets and systems that are not part of the actual codebase. They are intended for you to use or dissect as you like in your game development efforts).

The ExtendedRoom is a room typeclass meant to showcase some more advanced features than the default one. Its functionality is by all means nothing revolutionary in MUD-world, but it was fun and very simple to do using only Evennia's basic building blocks - the whole thing took me some two hours to code, document and clean up for a contrib push. The "ExtendedRoom" contribution has the following features:

• Season-based descriptions. The new Room typeclass will change its overall description based on the time of year (the contrib supports the four seasons, you can hack this as you please). It's interesting from an implementation point of view since it doesn't require any Script or ticker at all - it just checks on-demand, whenever it is being looked at, only updating if the season has actually changed. There is also a general description used as a fallback in case of a missing seasonal one.
• Time-of-day-based descriptions. Within each Season-based description you can embed time-of-day based ones with special tags. The contrib supports four time slots out of the box (morning, afternoon, evening, night). In the description, you just embed time-dependent text within tags, like <morning>Morning sunlight is shining through the windows</morning>. Only time-relevant tags will be shown. This is a simple regular expression substitution, should be easy to expand on if one wants more fine-grained time slots.
• Details. I took the inspiration of these from a MOO tutorial I read a long time ago. "Details" are "virtual" look-targets in the room. It allows you to add visual interest without having to add a bunch of actual objects for that purpose. Details are simply stored in a dictionary on the room. Details don't change with Season in this implementation, but they are parsed for time-of-day based tags!
• Custom commands. The room is supported by extending two of the custom commands. The Details require a slightly modified version of the look command. There is also a new @desc for setting/listing details and seasonal descriptions. The new time command, finally, simply shows the current game time and season in the room.

Installing and testing the snippet is simple - just add the new commands to the default cmdset (they will dynamically replace the same-named default ones), dig a few rooms of the new typeclass and play around! Especially the details do make building interesting rooms a lot more fun (I got hung up playing with them way too long last night).