Thanks Danny. There's also something I recall for validation, as in the docs for (define/override...) where usage outside of a (class...) form is a syntax error. I'll hunt...:)
On Sat, Feb 23, 2013 at 12:19 PM, Danny Yoo <d...@hashcollision.org> wrote: > On Sat, Feb 23, 2013 at 12:22 PM, Scott Klarenbach <sc...@pointyhat.ca> > wrote: > > What is the best approach for creating a macro that parses sub-forms in > any > > order, similar to the way (class ...) works in Racket? > > > I believe that there's support in the syntax-parse library to parse > these sub-forms in any order. Let me see if I can find the > appropriate documentation... Ah, here: > > http://docs.racket-lang.org/syntax/Optional_Keyword_Arguments.html > > > The documentation here focuses on parsing optional keyword arguments > that can be consumed in any order. The underlying mechanism should > work with non-keywords as well. > > > For example: > > > ;;;;;;;;;;;;;;;;;;;;;;;;; > #lang racket > > (require (for-syntax syntax/parse)) > > (struct person (name age) #:transparent) > > ;; Accept name and age in any order, or even omit them: > (define-syntax (new-person stx) > (syntax-parse stx > [(_ (~or (~optional ((~datum name) name) #:defaults ([name #'"Jane > Doe"])) > (~optional ((~datum age) age) #:defaults ([age #'#f]))) > ...) > #'(person name age)])) > > (new-person) > > (new-person (name "Pen Pen")) > > (new-person (age 48) (name "Gendo Ikari")) > ;;;;;;;;;;;;;;;;;;;;;;;;; > -- Talk to you soon, Scott Klarenbach PointyHat Software Corp. www.pointyhat.ca p 604-568-4280 e sc...@pointyhat.ca 200-1575 W. Georgia Vancouver, BC V6G2V3 _______________________________________ To iterate is human; to recur, divine
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