如何向播放器对象添加属性？

I don't quite know if those are the correct words, but in my plugin, the players have to choose a class and I don't quite know how to separate the classes. Each class gets unique spells/abilities. If I could add a property (e.g. a boolean for each class; true if they are that class, false otherwise) to a player and return the value, that would solve my problem. How would I do this?I don't quite know if those are the correct wor