Hi Ken,
> Shoundn't be too hard. Something like
[snip]
Thanks, looks good. I haven't had a chance to play with the code yet
but it looks like a very good start.
>
> You probably want it to omit bmi from the argument lists and compute
> it -- that will complicate things, something like:
>
[snip]
> used with something like
>
> (defentity person
> {:name {:type String}
> :id-number {:type Integer}
> :height {:type Double :default 100.0}
> :weight {:type Double :default 100.0}
> :bmi {:type Double :computer (/ weight height)}})
>
> Note that both the :default and the :computer can be s-expressions
> that just get inserted verbatim as code. The two differences are:
>
> 1. A field with :computer will not ever be a constructor parameter.
>
> 2. The :computer s-expression can refer to any of the fields; the
> :default can only refer to earlier ones and non-optional ones.
>
> I hope this shows how one might go about constructing a macro to take
> a definition similar to your original person-entity map and turn it
> into a record, constructor function, and possibly other structures.
> For example it could put code in the constructor function to run a
> :validator, if present, on that field, where the :validator throws an
> exception; or to turn a :validator field into a test and throw
> exception clause where the :validator is a boolean expression; etc.
Yes, that is great thanks!
Cheers,
David
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