CLOS-ENCOUNTERS

A system including a few common OOP Patterns.

• abstract-class
• singleton-class

Example: Global DB

(defclass db ()
  ((person-table :initform (make-hash-table))
   (job-table :initform (make-hash-table)))
  (:metaclass singleton-class))
  
;; whenever you need to acces your DB you can instantiate the DB class:

(run-query (make-instance 'db) my-query) 

;; This works (though is perhaps a little goofy) because 

(eq (make-instance 'db) (make-instance 'db)) 

;; will always return T

Example: Platonic Forms

(defclass aristotelian-espresso ()
  ((grind :initarg :grind)
   (roast :initarg :roast))
  (:metaclass abstract-class))
  
(make-instance 'aristotelian-espresso
    :grind :moderate
    :roast :moderate)
    
;; Abstract class ARISTOTELIAN-ESPRESSO cannot be instantiated
;;      [Condition of type SIMPLE-ERROR]

Why?

This is a duplicate of a subset of of the functionality exposed in tfeb-lis-hax. We reimplement it here because tfeb's library makes a decision to lazy load the closer-mop system dependency in a way that does not agree with the build process of quilc and qvm. See this issue for context.