On Fri, 2 Feb 2018 13:20:21 +0000, Stephen Colebourne wrote:
Some of the classes you are talking about are what I call VALJOs.
Follow these guidelines and your class will be well placed for the
future.
http://blog.joda.org/2014/03/valjos-value-java-objects.html


Thanks.
In that post, you mention "final" in this sentence:
---CUT---
The class must be immutable, which implies the final keyword
and thread-safety.
---CUT---
Do you mean that the *class* must be declared "final"?
A class can be immutable without being "final", can't it?
Or is the requirement necessary for future optimization of
value objects?

Regards,
Gilles

Stephen

On 2 February 2018 at 12:45, Gilles <gil...@harfang.homelinux.org> wrote:
On Thu, 1 Feb 2018 08:30:00 -0700, Gary Gregory wrote:

Hi All:

I like the "of" prefix but I think it might be odd to force the convention
for ALL factories. It might be an English language thing for me.

For example, (picking a made up example) this reads really well to me:
Pair.of(foo, bar) because that what you'd use in spoken English.

OTOH, this does not read well to me: Fraction.of(num, denum); this would
be
better: Fraction.from(num, denum)

All of this to say that we should make sure that the factory method "reads
well" for that class. I know it might feel subjective.

I like the idea of a private ctor but it does not have to be unique in my
mind. Sure, it's nice if there is one.

I also like the idea of the ctor being private because we can open it up
later to protected if we want to allow for subclassing.

I would also consider making classes final, especially if the ctor is
private.


Any caveat on doing that?  Is this a final (!) decision or can one
change one's mind in a later release?
What are the benefits?

Thanks,
Gilles


Gary


On Thu, Feb 1, 2018 at 7:07 AM, Gilles <gil...@harfang.homelinux.org>
wrote:

On Thu, 01 Feb 2018 13:59:13 +0100, Gilles wrote:

Hi.

IMHO, there are too many accessor and factory methods.
We should strive for a lean and consistent API.

For the factory methods, I suggest the "of" convention:
 public static Complex ofCartesian(double re, double im)
 public static Complex ofPolar(double abs, double arg)
And, as syntactic sugar:
 public static Complex ofCis(double arg)


Those are useful too:
   public ofReal(double re)
   public ofImaginary(double im)


For the accessors:
 public double re() { return real }
 public double im() { return imaginary }

I'd have
  public double arg()
  public double abs()
in order to compute the polar coordinates.

I'm -0 to have others as syntactic sugar since they are
misleading (a.o. when "implying" the read of a field when
a computation is performed).

WDYT?


In addition to the above, I propose
* to have a single, "private", constructor:
    private Complex(double re, double im)
* to remove the "protected" method "createComplex" (
  unless there is a case for inheritance).

Regards,
Gilles


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