I doubt because keyword will use its internal Symbol object to compare with
each other (or other objects), it means it's Symbol's interned strings(ns &
name) make the comparison fast but not this caching stuff. I found a
"find()" method in source code but not sure if the cache is relevant to
this method.....
在 2012年7月18日星期三UTC+8下午4时52分25秒，dennis写道：
>
> Compare keywords can be very fast.
> 在 2012-7-18 PM4:51，"jaime" <xiejianm...@gmail.com>写道：
>
>> Hello,
>>
>> When I read the source code keyword, say, Keyword.java (V1.3), I found
>> that when we "intern" a keyword, (if I understand it correctly) it uses
>> a cache for keywords:
>> =============================================
>> public static Keyword intern(Symbol sym) {
>> if (sym.meta() != null)
>> sym = (Symbol) sym.withMeta(null);
>> *Util.clearCache(rq, table);*
>> Keyword k = new Keyword(sym);
>> Reference<Keyword> existingRef = table.putIfAbsent(sym,
>> new WeakReference<Keyword>(k, rq));
>> if (existingRef == null)
>> return k;
>> Keyword existingk = existingRef.get();
>> if (existingk != null)
>> return existingk;
>> // entry died in the interim, do over
>> table.remove(sym, existingRef);
>> return intern(sym);
>> }
>> ==============================================
>>
>> well, I just don't understand why we need caching for keywords. Anyone
>> could give me a hint?
>>
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>
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