Game classification

[alexhroom]

Following up from #1413, to ensure strategies and algorithms are being used with compatible games there should be a method of classifying and organising games.

Some ideas:

• a 'games' directory in the package, which contains a sort of 'mini-package' for a specific game. For example, the import path axelrod.games.rockpaperscissors would contain a Game, Actions and Strategy objects for rock-paper-scissors.
• Maybe for convenience, the axelrod.games directory could contain a function where a user enters a game name and it returns a dict with the various components of the game, e.g.:

>>> from axelrod.games import get_game
>>> get_game("rock_paper_scissors")
{"game": axl.AsymmetricGame([RPS MATRICES HERE]),
 "actions": [R, P, S],
 "strategies": [[RPS STRATEGIES HERE]]
}

• Strategies themselves should have classifications for what action set size they're for, and raise an error or warning if used on an inappropriate game size.
• If we're worried about the package getting too big with more games/strategies it may be a good idea to use namespace packages so that other games can be installed separately but used from the axelrod namespace - particularly if a few games are added before the release of 5.0.0 this would be a good way to "generalise" the library completely.

[drvinceknight]

This is all awesome @alexhroom, I think #1413 really unblocks a bunch of stuff going forwards towards 5.0.0.

• a 'games' directory in the package, which contains a sort of 'mini-package' for a specific game. For example, the import path axelrod.games.rockpaperscissors would contain a Game, Actions and Strategy objects for rock-paper-scissors.

So this would imply moving a lot of the "current" functionality of the library to axelrod.games.ipd right?

• Maybe for convenience, the axelrod.games directory could contain a function where a user enters a game name and it returns a dict with the various components of the game, e.g.:

>>> from axelrod.games import get_game
>>> get_game("rock_paper_scissors")
{"game": axl.AsymmetricGame([RPS MATRICES HERE]),
 "actions": [R, P, S],
 "strategies": [[RPS STRATEGIES HERE]]
}

Not sure if we need something like this (for example the strategies for axelrod.gams.ipd would be huge). It feels like get_game would be trying to do the job of good documentation. So I think 🤔 I'd prefer us to ensure the documentation structures evolves/improves with the changes.

• Strategies themselves should have classifications for what action set size they're for, and raise an error or warning if used on an inappropriate game size.

:+1:

• If we're worried about the package getting too big with more games/strategies it may be a good idea to use namespace packages so that other games can be installed separately but used from the axelrod namespace - particularly if a few games are added before the release of 5.0.0 this would be a good way to "generalise" the library completely.

I suggest not worrying about this until it becomes a problem (but I like the suggestion of namespace packages as a solution).

[alexhroom]

if we're thinking towards 5.0.0 (i.e. being willing to make breaking changes) then yeah axelrod.games.ipd would contain a lot of the specific IPD functionality. in general I was trying to point towards the idea of having Axelrod "main" be the library classes and algorithms, and then each game as a "game box" with an easy way for users to load that game into their Python session - you're right that for IPD a strategy list would get huge

[drvinceknight]

if we're thinking towards 5.0.0 (i.e. being willing to make breaking changes) then yeah axelrod.games.ipd would contain a lot of the specific IPD functionality.

Yeah I feel like we're certainly going towards 5.0.0 here with breaking changes.

[marcharper]

@gaffney2010 worked on this for the ultimatum game, see this branch for some ideas and implementation details.