[plt-scheme] for-each on a collection object members

I'd gather experience with concrete examples and implementations  
before I'd try my hands on generalizing. -- Matthias


On Jan 8, 2008, at 9:51 AM, Stephen De Gabrielle wrote:

> Should I, (hypothetically);
>
> Extend class.ss macros with a way to specify a class may be
> - a 'collection', with matching;
>   + the data-structure to use, (List or BST)
>   + and a implementation of fold(for list, or the appropriate  
> equivalent for BST's) (thanks Noel, very sensible advice)
>
> I'm comfortable with extending classes, using class.ss, but I'm  
> unsure with extending macros, am I right in guessing that I would  
> define a new macro that referred to the class macro.
>
> Would it be cheating to make a class class? (class%) then use the  
> class system to extend the class% class instead.
>
> thanks,
>
> Stephen
>
>
>
> On Jan 8, 2008 1:00 PM, Matthias Felleisen <matthias at ccs.neu.edu>  
> wrote:
> That looks perfectly fine to me, if it is otherwise acceptable to use
> lists for storing the collection. (If you needed random access or
> fast search, you might consider BST's instead. In that case, you'd
> have to write your own for-each.)
>
> The reason class.ss is a macro is so that people can evolve the
> design of the class system and match it to their needs.
>
> -- Matthias
>
>
>
>
> On Jan 8, 2008, at 6:53 AM, Stephen De Gabrielle wrote:
>
> > Hi,
> >
> > [Please excuse me if this is a silly question]
> >
> > I want to 'map' or 'for-each' of a collection object which is a
> > collection of other objects, in the same way as I would over a  
> regular
> > list (also filter from the list.ss List Utilities)
> >
> > I can just turn the collection of objects into a list of objects,  
> but
> > it seems there might be a better way? 'for-each-object-on-collection
> > object
> >
> >   ;; collection of tuples
> >   (define TupleSet% (class object%
> >                       (define collection '())
> >                       (super-new)
> >                       ;; insert : alist -> void
> >                       (define/public (addTuple alist)
> >                         (set! collection (cons (new Tuple%
> > [initial-fields alist] ); tuple
> >                                                collection))
> >                         )
> >
> >
> >                       ;; getTupleCount : -> number
> >                       (define/public (getTupleCount)
> >                         (length collection)
> >                         )
> >  ... and so on ...
> >
> >
> > Should I just make up the smalltalk iterator equivalents as needed?
> > eg; 'do:' from smalltalk
> >
> >                       ;; do : tupleMethod -> result
> >                       (define/public (do tupleMethod)
> >                         (for-each
> >                            (lambda (tuple) (send tuple  
> tupleMethod) )
> >                             collection)
> >                         )
> >
> > I'm searching for the 'right' way, or is this a silly question?
> >
> > Cheers,
> >
> > Stephen
> >
> >
> >
> > --
> > Stephen De Gabrielle
> > _________________________________________________
> >   For list-related administrative tasks:
> >   http://list.cs.brown.edu/mailman/listinfo/plt-scheme
>
>
>
>
> -- 
> Cheers,
>
> Stephen
>
>
>
> --
> Stephen De Gabrielle
> s.degabrielle at ucl.ac.uk
> Telephone +44 (0)20 7679 5242 (x45242)
> Mobile                  079 851 890 45
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