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From: Giovanni Azua <bravegag@hotmail.com>
Newsgroups: comp.lang.java.programmer
Subject: Re: Immutable Datastructures with good Sharing
Date: Mon, 07 Nov 2011 02:08:17 +0100
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On 11/7/11 12:02 AM, in article
alpine.DEB.2.00.1111062256510.4201@urchin.earth.li, "Tom Anderson"
<twic@urchin.earth.li> wrote:
> If you had read the whole thread, or indeed just the OP's initial post,
> you would understand that these classes are not helpful. They are
>
Indeed it was a lucky shot but read on ...

> To recap, Jan wants to be able to say:
> 
> ImmutableStack<String> a = new ImmutableStack<String>(); // empty
> ImmutableStack<String> b = a.push("foo");
> assert a.isEmpty();
> assert b.size() == 1;
> 
> That is, the quasi-mutation creates a new instance exhibiting the change,
> rather than changing an existing instance.
> 
> The Guava Immutable* classes do not have such methods.
> 
Would this check the box?

ImmutableMap<String, Integer> a = ImmutableMap.of("A", 1, "B", 2, "C", 3);
ImmutableMap<String, Integer> b =
     new ImmutableMap.Builder<String, Integer>().
          putAll(a).put("D", 4).build();


>> I really enjoy the improvement in code readability as well, it suits the
>> appropriate template types e.g.
>> 
>> // from
>> List<RequestData> requests = new ArrayList<RequestData>();
>> 
>> // to
>> List<RequestData> requests = Lists.newArrayList();
> 
> I see absolutely no improvement in the code here, only unhelpful
> obfuscation.
> 
When you say it like this, any function can be labeled as "unhelpful
obfuscation" :)

Giovanni