pollen.rkt

#lang racket/base
(require racket/class pollen/setup)

(define tags% (class object%
                (super-new) 
                (define/public (strong) 'default-strong)
                (define/public (em) 'default-em)))

(define pdf-tags% (class tags%
                    (super-new)
                    (define/override (em) 'pdf-em)))

(define text-tags% (class tags%
                     (super-new)
                     (define/override (strong) 'text-strong)))

(define current-tag-object (make-parameter (new tags%)))

(define (strong) (send (current-tag-object) strong))
(define (em) (send (current-tag-object) em))

(parameterize ([current-tag-object (new tags%)])
  (println (strong))
  (println (em)))

(parameterize ([current-tag-object (new pdf-tags%)])
  (println (strong))
  (println (em)))

(parameterize ([current-tag-object (new text-tags%)])
  (println (strong))
  (println (em)))