I think this cache is just the same with String.intern method in java,it
just want to reduce the cost (memory & cpu) of producing keywords
frequently especial when using them with map structure.
2012/7/18 jaime <xiejianm...@gmail.com>
> 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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