On Tue, 12 Apr 2016 11:17:31 -0500,
Héctor Mc wrote:
>
> Thanks,
>
> This start because I need a syntax like the next:
>
> (define u (make-s user (nom ape sexo))
> (set-s u ((nom "nom" ) (ape "ape")))
> (get-s u 'nom)
> u ; --> '((nom "nom") (ape "ape") (sexo ""))
>
> And I start using lists but I can't hidden. From there I changed to a struct
> but now I get this problem.
>
> set-usuario-key!: unbound identifier in module in: set-usuario-key!
>
> How I can solve that?
Structs are not collections of key-value pairs, so there are no
accessors that can take the name of a field and access it.
They will, however, have accessors for individual fields, like
`set-usuario-nom!`. Those should work fine.
If you do want to have such a function, I would write it something like
this:
(define (set-usuario-key! usuario key val)
(cond [(equal? key 'nom) (set-usuario-nom! usuario val)]
...))
Or, if you really want key-value pairs, use hashes. Possibly wrapped in
a struct, to get the hiding you want.
Vincent
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