https://github.com/hipeta/cl-singleton-mixin.git
    git clone 'https://github.com/hipeta/cl-singleton-mixin.git'
      
      
(ql:quickload :cl-singleton-mixin)
    
  
  Cl-singleton-mixin simply provides singleton-mixin class by using metap (https://github.com/hipeta/metap).
(ql:quickload :cl-singleton-mixin)
(defclass some-singleton (singleton-mixin) ())
(eq (make-instance 'some-singleton)
    (make-instance 'some-singleton))  ; => T
(defclass some-child (some-singleton) ())
(eq (make-instance 'some-child)
    (make-instance 'some-child))  ; => T(ql:quickload :cl-singleton-mixin)Cl-singleton-mixin is released under the MIT License, see LICENSE file.