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From: Patrick Roemer <sangamon@netcologne.de>
Newsgroups: comp.lang.java.programmer
Subject: Re: double == double
Date: Mon, 17 Oct 2016 23:21:09 +0200
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Responding to 4ndre4:
> On 17/10/2016 17:58, Patrick Roemer wrote:
> 
> [...]
>> Passing an opaque string around to be interpreted as a version only
>> "when needed" feels fishy to me in any paradigm.
> 
> I agree that having a 'Version' class (as shown in my first example) is 
> generally better. However, I do not fully agree with not having opaque 
> information, in general.

Fundamentalism is always bad. ;)

> I believe that there has to be a certain "axiomatic" level with any data 
> structure. If you have the following:
> 
> Double speed = 1.5;
> Double height = 1.5;
> Double size = 1.5;
> 
> it is perfectly legit to have:
> 
> String version = "10.10.10"
> String name = "John"
> String email = "john@somedomain.com"
> 
> I might not always want to have a class for speed, a class for height, a 
> class for size, etc.. each with its own validation rules. Schools of 
> thought, maybe :)

The limits of our language are the limits of our world. :)

Most languages, including Java, simply don't allow the introduction of
cheap, ad hoc derived data types. If there were a way to declare a
Distance type derived from double that inherits the full double algebra
and incurs no runtime (Un-)Boxing overhead and minimal coding overhead,
there'd be every reason to do so. This is a limitation of our tools, not
a conceptually unreasonable thing.

Your argument holds as long as the overhead of a dedicated type
outweighs its benefits. If you never take an email address apart and
only use it as a string, by all means stick with String as the type. But
in the Version case everything, even performance considerations
(re-parsing!), seems to speak for the dedicated type.

Best regards,
Patrick