I was thinking this is a little different because the Keyword data
type is unique to Clojure. So once in the Java land, you are never
going to want to use Keywords. In Clojure, I agree, the difference
between Keyword and String should be explicit, but in Java, I feel
like it's just pragmatic to be able to pass in a String and get the
value with the matching Keyword.
I think this might be possible to do because many of the methods that
implement java.util.Map are wrappers on the clojure methods. For
example, in APersistentMap, you could change get from:
public Object get(Object key){
return valAt(key);
}
To something like:
public Object get(Object key){
if(key instanceof String) {
if(contains(key)) {
return valAt(key);
} else {
return valAt(stringToKeyword(key));
}
} else {
return valAt(key);
}
}
I'd have to look at all the other methods that implement
java.util.Map, but if they are all separate from the actual methods
that make clojure maps work like they do, you could get the best of
both words. But if everyone thinks this is a bad idea, then I'll just
write my function to convert all Keywords in a Map to a String before
passing them to Java.
> Hi Paul,
>
> I think that I would rather see things remain explicit, i.e. if you
> need to interoperate with Java you convert manually before throwing
> the map over.
>
> In the Rails world they tried to solve a similar problem (string vs.
> symbol keys) by wrappering Hash to be indifferent between string and
> symbol keys, and it is still confusing. Now you have to remember
> whether you have the wrappered kind or not...
>
> Stuart
>
> > Now that clojure maps are Java Maps, it is easier to inter-operate
> > with Java code that has methods that take a Map as one of its
> > arguments, because you can just pass the Map right into the Java
> > code. The problem is that often times, the Java method is expecting
> > the Map to have String values in the keys, definitely not clojure's
> > Keywords. So if you have a {:foo 1} clojure map that you pass to a
> > Java method, which then calls map.get("foo"), you won't find that
> > value.
>
> > Does anyone have any suggestions for how to handle this? You could
> > just use Strings for the keys in the clojure map, but then that map
> > might not work with other clojure functions that expect the keys to be
> > Keywords, not Strings. You could pass the map through a function that
> > converts the Keywords to Strings before using it in Java, but I
> > thought that was the whole point of making clojure maps implement Map,
> > so I wouldn't have to do (jmap {:foo 1}) everytime I want to pass a
> > Map to Java.
>
> > I'm wondering if there is some way to make a clojure Map be smart
> > enough to return the value even if you give it string. Probably not,
> > because then what do you do with {:foo 1 "foo" 2}. Anyway, just
> > wondering if anyone else has run into this Keyword/String mismatch
> > problem and if you have an elegant solution.
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