On Nov 19, 2:35 pm, Stuart Halloway <[EMAIL PROTECTED]> wrote:
> Rich,
>
> Very helpful, as always. Alias + the ability to pull in symbols names
> via refer was exactly what I was looking for.
>
> One scenario still worries me:
>
> 1. I create a multimethod that dispatches around a tag whose value is
> an unresolved keyword (:Foo instead of ::Foo). Everything works fine.
>
> 2. If at some later point I want the dispatch to depend on (derive),
> it is breaking change for clients to switch to from :Foo to ::Foo.
>
> I am tempted to conclude that you should never use unqualified
> keywords as type tags, because you are exposing an implementation
> detail. That is, the implementation promises not to rely on derive.
>
Agreed. Qualified keywords or symbols as :tag values makes sense,
independent of derive, as many people will be using :tag, you can't
assert that you alone own the tag :Foo.
Rich
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