Re: overriding keyword behavior?
On Mar 10, 5:31 pm, kurtharriger wrote: > That was basically my question, protocols are designed for this but > ILookup isn't a protocol. Is it possible to make ILookup into a > protocol? I haven't looked at the java code much at all, but I might > take a stab at creating a patch it that seems possible. > > Converting java.util.Properties into a map isn't hard, but converting > java objects to native maps is extreamly common (bean, reflect, ring, > etc...) and perhaps unnecessary in many situations if one could just > extend an existing java type with ILookup so that if it looks like a > duck, its a duck. I've had the same idea a couple of day ago; specifically, looking up public members of an object. In the end, I think the actual use cases generally are more involved than just :keyword lookup, so I wrote some code to automatically do the conversion to map: https://github.com/joodie/clj-java-fields -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: overriding keyword behavior?
It is not possible to turn an interface into a protocol. When protocols first appeared, the idea was floated to replace the low-level interfaces like ILookup with equivalent protocols, but this idea has not received substantial attention since. -Stuart Sierra clojure.com -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: overriding keyword behavior?
That was basically my question, protocols are designed for this but ILookup isn't a protocol. Is it possible to make ILookup into a protocol? I haven't looked at the java code much at all, but I might take a stab at creating a patch it that seems possible. Converting java.util.Properties into a map isn't hard, but converting java objects to native maps is extreamly common (bean, reflect, ring, etc...) and perhaps unnecessary in many situations if one could just extend an existing java type with ILookup so that if it looks like a duck, its a duck. - Kurt On Mar 8, 3:34 pm, Stuart Sierra wrote: > Oh yeah, you can't extend an interface to a new class. So it won't work. > This is why protocols exist, in fact. Silly me. > > -S -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: overriding keyword behavior?
Oh yeah, you can't extend an interface to a new class. So it won't work. This is why protocols exist, in fact. Silly me. -S -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: overriding keyword behavior?
On Mon, Mar 7, 2011 at 9:34 PM, Stuart Sierra wrote: > Yes, something like tonyl's code will work. OH RLY? # -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: overriding keyword behavior?
Yes, something like tonyl's code will work. -S -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: overriding keyword behavior?
I little redundant but looking now at the source code in Keyword.java
the Keyword class extends IFn, Comparable, Named, and Serializable;
they are all java that you could extend.
But I am not sure how the keyword lookup system works, haven't look
into it.
Just something that might help.
On Mar 6, 9:27 pm, kurtharriger wrote:
> I was curious if it was possible to extend keyword lookup behavior to
> additional types, such as java.util.Properties.
>
> Currently I just convert java.util.properties into a keyword map with
> something such as the following.
> (defn as-keyword-map [prop]
> (into {} (for [[k v] prop] [(keyword k) v])))
>
> This works well enough but I thought this might be possible to extend
> keywords or java.util.Properties via protocols or something to change
> the implementation of (:access-key prop) to (.get "access-key" prop).
> Its easy enough to redefine get using multimethods so that (get
> prop :access-key) would work on any type I wanted but I couldn't
> figure out how to do the same with keywords. Looking at keyword.java
> it expects that object implements ILookup so I tried using (extend-
> type java.util.Properties Lookup ...) however ILookup isn't a protocol
> so this doesn't seem to work.
>
> I'm beginning to think that implementation of keywords being
> implemented in java doesn't support clojures more advanced
> extensibility features. This makes me wonder if using the more
> idiomatic (:access-key obj) instead of (get obj :access-key) also
> limits my future extensibility options. Is there a way to do this
> that I haven't thought of? and would it be possible to make ILookup
> into a protocol to enable this type of extensibility?
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Re: overriding keyword behavior?
I haven't tested it or anything, but you can use:
(extend-type java.util.Properties
ILookup
(valAt [this key] ...)
(valAt [this key not-found] ...))
AFAIK you can extend on Interfaces but not Abstracts or Classes.
On Mar 6, 9:27 pm, kurtharriger wrote:
> I was curious if it was possible to extend keyword lookup behavior to
> additional types, such as java.util.Properties.
>
> Currently I just convert java.util.properties into a keyword map with
> something such as the following.
> (defn as-keyword-map [prop]
> (into {} (for [[k v] prop] [(keyword k) v])))
>
> This works well enough but I thought this might be possible to extend
> keywords or java.util.Properties via protocols or something to change
> the implementation of (:access-key prop) to (.get "access-key" prop).
> Its easy enough to redefine get using multimethods so that (get
> prop :access-key) would work on any type I wanted but I couldn't
> figure out how to do the same with keywords. Looking at keyword.java
> it expects that object implements ILookup so I tried using (extend-
> type java.util.Properties Lookup ...) however ILookup isn't a protocol
> so this doesn't seem to work.
>
> I'm beginning to think that implementation of keywords being
> implemented in java doesn't support clojures more advanced
> extensibility features. This makes me wonder if using the more
> idiomatic (:access-key obj) instead of (get obj :access-key) also
> limits my future extensibility options. Is there a way to do this
> that I haven't thought of? and would it be possible to make ILookup
> into a protocol to enable this type of extensibility?
--
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