title: How do you override the default value of a field in a class?
body: <p>This is the best way I've found so far to override default field values in a class:</p>
  
  <pre><code>(define sa-canvas%
    (class canvas%
      . . .
      (init-field [min-width 600]
                  [min-height 300]
                  [stretchable-width #f]
                  [stretchable-height #f])
      (super-new [min-width min-width]
                 [min-height min-height]
                 [stretchable-width stretchable-width]
                 [stretchable-height stretchable-height])
      . . .))
  </code></pre>
  
  <p>This seems way too verbose for Racket. What is the intended way that Racket's class system is designed to support?</p>