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From "Arun Thomas" <arun.tho...@paybytouch.com>
Subject RE: [collections] Primitive-value maps
Date Thu, 04 Dec 2003 17:54:06 GMT
Ash, 

Classes for this purpose which previously existed in COLLECTIONS were moved to the Sandbox
project - PRIMITIVES.  Please take a look there.  There's apparently a lot of work going on
with these classes, so check it out.  

-AMT

-----Original Message-----
From: Ash .. [mailto:equinus100@hotmail.com] 
Sent: Thursday, December 04, 2003 9:51 AM
To: commons-dev@jakarta.apache.org
Cc: equinus100@hotmail.com
Subject: [collections] Primitive-value maps


While waiting for a +1 on the MapUtils.getPrimxxxValue() methods, I have 
been wondering why the commons collections framework does not have Maps that 
store and help retrieve primitive values.

Stuff like IntMap with put(Object key, int value), etc.

I mean, when there are primitive-value collections (lists and sets), why not 
map? Maybe this was discussed before. In any case, perhaps we can have them. 
Comments.

Ash



Reposting this, so that if we are decided on the method signatures, I can work on the implementation
this weekend. Ash


[Stephen]
>I would only add the
>full signature version (with default). That way the method name can 
>just be getDouble().

But that would provoke the question "if I want to retrieve a primitive without specifying
a default, why should I have to mention a default (even
0) everytime??"

I would propose we inlclude both variants (with and sans default), and have a uniform naming
for them. Even if we add only the default-taking method today, what if we decide tomorrow
that the defaultless one can be useful.

And then, I think it is ok if we cannot preserve the same method names.

so, I propose the following:

public static double getIntValue(Map map, Object key)
public static double getIntValue(Map map, Object key, int defaultValue)

etc for each prim (and String)

Waiting for feedback from others.

I can implement these methods after I am done with the subarray(prim[]) ones.


>This is a very old class in [collections] and pre-dates me. I would
>probably
>oppose adding these methods now.

But why??


Ash



>
>-----Original Message-----
>From: Stephen Colebourne [mailto:scolebourne@btopenworld.com]
>
>
>This is a very old class in [collections] and pre-dates me. I would
>probably
>oppose adding these methods now. However, now that we have them, I would
>support having the primitive methods as you propose. I would only add the
>full signature version (with default). That way the method name can just be
>getDouble().
>Stephen
>
>----- Original Message -----
>From: "Ash .." <equinus100@hotmail.com>
> > I am curious to know why MapUtils does not have getters that return 
> > primitive types. Perhaps there was a discussion on whether it was 
> > needed
>or
> > not, you could point me to such discussion that took place in the 
> > past
>when
> > this class was conceived.
> > In any case, I think that getters that return primitives could be 
> > very useful, much more than those that return wrapper objects. Thus, 
> > I think
>we
> > could do with methods like:
> >
> > MapUtils.getDoubleValue(Map map, Object key [,defaultValue]);
> >
> > If the answer to my question is "you can do a 
> > MapUtils.getDouble(map,
> > key).doubleValue() and so on",
> > I would say, having a built-in method enhances the use of this class 
>than
> > having a programmer resort to such multiple method call. Of course, 
> > the internal implementation would do the same, but in the end, 
> > client code
>would
> > look far neater.
> >
> > Let me know,
> > Ash
> >

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