Thanks for that recommendation, I definitely like that proposal!
I guess the drawback is then that destructuring will not be safe.
I have to think some more time about it.
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Creating your own Closed Map type would be the object-oriented approach. One
downside is that a closed-map feels like a normal map, but can't be safely
substituted for most maps because of the booby-trap when using assoc (etc.)
with a new key. It doesn't really fulfill the map contract
On Tue, Apr 26, 2011 at 1:06 PM, Steve Miner stevemi...@gmail.com wrote:
Creating your own Closed Map type would be the object-oriented approach.
One downside is that a closed-map feels like a normal map, but can't be
safely substituted for most maps because of the booby-trap when using
Thanks for all of your answers, but I think for my use cases the
approach proposed by Justin looks most promising. I'll implement my
own closed map.
Another idea that come to my mind was that a closed map is actually a
Java Bean without behaviour. Perhaps the closed map could be
implemented by
I should be straightforward to implement a closed map (or record)
yourself using deftype. It could implement all the same interfaces as
Clojure's built-in maps, ensuring compatibility with assoc and such.
Here's an example of a map variant implemented using deftype:
With regard to mistyped keys in general, a simple option is to use
named keys; then the compiler will flag undefined ones.
(def k :key)
...
(k m)
On Apr 21, 10:44 pm, Christian Schuhegger
christian.schuheg...@gmail.com wrote:
I am taking up a discussion from
This defrecord2 implementation has key checks on construction but
still allows you to forcibly insert other keys after the fact. I
believe the proposed defrecord enhancements for 1.3 may have some
similar opportunities. You could use your own assoc that checked the
known record keys too.
I am taking up a discussion from 2010:
https://groups.google.com/group/clojure/browse_frm/thread/60dff89149c3d2e6/
I would prefer if it would be possible to define closed maps, e.g.
maps that allow only a certain set of keywords, both for get and
set (like in assoc, assoc-in, update-in, ...). It
Hi!
In general, what to give greater attention if I'm getting lots of
runtime errors due to mistyped keywords? (eg. I'm referencing a map
where the keyword is non-existent and this nil value goes deep down into
my code where it is very hard to see that this was caused by a
non-existing map
Hi Istvan,
I've run into this a fair bit too. To catch such problems (at
runtime), I sprinkle my code with (safe-get m :key) in key places,
rather than (:key m) or (m :key) or (get m :key). safe-get:
(defmacro lazy-get
Like get but lazy about evaluating default
[m k d]
`(if-let [pair#
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