On Sun, Jan 31, 2010 at 10:33 PM, Barry Dahlberg
<barry.dahlb...@gmail.com> wrote:
> Perhaps I'll write up my findings once the language stops intimidating
> me.
>
> At the moment I'm writing an account "object". I have some standard
> CRUD type functions which operate on a map behind the scenes. I would
> like to add some metadata to start specifying rules for validation, UI
> generation and so on. The trouble is I can't really figure out where
> to attach this metadata as I don't have a type definition as such,
> e.g. I would do this in C#:
>
> [Required, MaxLength(50)]
> public string Name { get; set; }
>
> defstruct seems promising though I can't find an example with
> metadata.
>
> Any pointers of where to start looking?
You can attach metadata to Clojure constructs using the with-meta function:
user=> (def x {:name "Frank"})
#'user/x
user=> (def x-with-metadata (with-meta x {:RequiredParameter true,
:MaxLength 50}))
#'user/x-with-metadata
user=> (:MaxLength (meta x-with-metadata))
50
As for whether you want to define the metadata directly on your map,
or on functions that construct/operate on your map, or somewhere else,
that's your design decision.
e
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