This is slower but is a bit clearer.
(defn get-with-exception [map key]
(if (contains? map key)
(get map key)
(throw (Exception. "oops"))))
Curious, why do you want to do this? Are you working with Java interop?
Ambrose
On Sun, Mar 20, 2011 at 5:50 PM, Andreas Kostler <
andreas.koestler.le...@gmail.com> wrote:
> Hi all,
> I would like to throw an exception when I'm trying to retrieve a value in a
> map for a key that doesn't exist.
> The obvious first shot was:
> (get {:foo "bar"} :foo (throw (new Exception "Oh no!")))
> However, this doesn't work because the exception always throws since get
> apparently eagerly evaluates it's arguments.
> One way to work around this could be:
>
> (defn get-with-exception [map key]
> (let [res (get map key (new Exception "my-exception"))]
> (if (= (class res) java.lang.Exception)
> (throw res)
> res)))
>
> I was wondering, is there another more concise/idiomatic way?
>
> Cheers
> Andreas
>
> --
> "Test-driven Dentistry (TDD!) - Not everything should be test driven"
> - Michael Fogus
> --
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> Leica Geosystems Pty Ltd
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