[Chicken-users] Re: Updated objc-header.scm

[Zbigniew]

If you want to use your existing structure without the namespace
pollution, here is a possible solution, minus user-friendly error
messages.  Change the name munging as desired.

#;1> (use objc)

;; Add clause to prepend objc: to first element of list, throw this in
objc-header.scm
#;2>
(define (macro:type->encoding x)
 (cond ((symbol? x) (string->symbol
                     (string-append "objc:" (symbol->string x))))
       ((list? x)
        (cons (string->symbol
               (string-append "objc:" (symbol->string (car x))))
              (cdr x)))
       (else x)))

;; (gen-ID NSString) -> macro (objc:NSString*)
#;3>
(define-macro (gen-ID TYPE)
        `(define-macro (,(string->symbol (conc "objc:" TYPE "*")))
                'objc:ID))

#;4> (gen-ID NSString)
#;5> (objc:NSString*)
"@"
#;6> (define-objc-class ABCD NSObject () (+ (NSString*) hello (print
"hi") "booga"))
#;7> (@ ABCD hello)
hi
@"booga"


On 6/13/06, Kon Lovett <address@hidden> wrote:
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> On Jun 13, 2006, at 12:31 PM, Zbigniew wrote:
>
> > Kon,
> >
> > I've been away for a bit and am just now catching up on my email
> > backlog.  It looks like a interesting idea.  However, I'm curious why
> > you made NSString* and so on into macros that generate 'objc:ID etc.,
> > instead of using variables.  In other words:
> >
> > #;2> (define objc:NSString* objc:ID)
> > #;3> (define-objc-class ABCD NSObject ()
> >              (+ NSString* hello
> >                  (print "hi")
> >                  "ooga"))
> > #;4> (@ ABCD hello)
> > hi
> > @"ooga"
> > #;5>
> >
> > Is this approach workable?  Do you want the extra parens to emulate
> > the look of Objective C, or find the macros are necessary?
>
> Emulate the look of obj-c. Variables are fine too.
>
>    (- NSData* ((#:dataOfType NSString* aType) (#:error NSError**
> outerr))
>
> >
> > As an aside, the function macro:type->encoding provides some control
> > over this conversion; the default behaviour---prepend objc: to
> > symbols, pass the rest through---allows you to evaluate functions or
> > pass encoded typestrings directly.  It is possible to augment this to
> > provide alternate syntax, for example when you pass a list; your
> > macros do effectively the same job, with just a bit of namespace
> > pollution.
>
> In practice, a lot of namespace pollution. The set I defined is
> popular but a real app would have lots of these things. Some other
> method is preferable.
>
> >
> > The only qualm I have about allowing type-like symbols instead of
> > plain ID and PTR is that it gives the erroneous impression of
> > typechecking, whereas ID and PTR spell this out.  I guess it comes
> > down to user preference and, ultimately, can be loaded if the user so
> > desires.
>
> I wanted them to remind me what was coming in & going out,
> documentation really.