hg: lambda/lambda/jdk: Cleanup in Optional

[Ricky Clarkson]

Actually I can think of plenty of times when that is exactly what I wanted.
On Nov 23, 2012 9:09 AM, "Gernot Neppert" <mcnepp02 at googlemail.com> wrote:

> I don't think it's realistic to be "thinking you do not have null and
> you'd rather have an exception".
> Either I know the value is null, then I may call empty(), or I don't know,
> in which case I wouldn't want to invoke a method that might throw an
> Exception. I'd rather get a valid 'Optional' instance, be it empty or not.
>
> Note that everything would be different if 'Optional' were allowed to have
> 'null' values. Then of course we'd need to be able to discriminate between
> 'No value at all' and 'The value null'. But since that has been voted down,
> the reason for having distinct factory methods has (IMO) gone away.
>
>
> > You might be calling .of(T) thinking you do not have null and you'd
> rather have an exception than an empty Optional as the result.
>
>
> 2012/11/23 Ricky Clarkson <ricky.clarkson at gmail.com>
>
>> That's a useful method but I'd suggest calling it 'option' or
>> 'fromNullable'.  You might be calling .of(T) thinking you do not have null
>> and you'd rather have an exception than an empty Optional as the result.
>>  For reference, Scala calls it option, Guava calls it fromNullable,
>> Functional Java calls it fromNull and all 3 make that a distinct method
>> from the one that throws an exception if it's null (Some(t) in Scala, of in
>> Guava, some(t) in Functional Java).
>>
>>
>> On Fri, Nov 23, 2012 at 5:36 AM, Gernot Neppert <mcnepp02 at googlemail.com>wrote:
>>
>>> Hi Brian,
>>>
>>> I do think that having factory methods 'empy()' and 'of(T)' and no public
>>> constructor is a good thing, I wonder whether it's necessary to make
>>> 'of(T)' is so restrictive: it throws NullPointerException if the supplied
>>> value is null.
>>> So why place the burdon of picking the correct factory method upon the
>>> user?
>>> Why not simply have:
>>>
>>> public static <T> Optional<T> of(T value) {
>>>   return value == null ? empty() : new Optional<T>(value);
>>> }
>>>
>>>
>>>
>>>
>>> 2012/11/15 <brian.goetz at oracle.com>
>>>
>>> > Changeset: ab258565c0c9
>>> > Author:    briangoetz
>>> > Date:      2012-11-15 17:19 -0500
>>> > URL:
>>> http://hg.openjdk.java.net/lambda/lambda/jdk/rev/ab258565c0c9
>>> >
>>> > Cleanup in Optional
>>> >
>>> > ! src/share/classes/java/util/Optional.java
>>> > ! src/share/classes/java/util/streams/ops/FindAnyOp.java
>>> > ! src/share/classes/java/util/streams/ops/FindFirstOp.java
>>> > ! src/share/classes/java/util/streams/ops/SeedlessFoldOp.java
>>> >
>>> >
>>> >
>>>
>>>
>>
>