array depth template

[Jarrett Billingsley]

On Thu, Jun 11, 2009 at 11:45 PM, Saaa<empty at needmail.com> wrote:

>> I'm.. not sure, in this case anyway.  Normally == does strict type
>> comparison while : does implicit type conversion, but in this case,
>> is() is being (ab)used to pick apart a type rather than test one.  I
>> think it'll always return 'true' in either case if T is an array, so I
>> don't think there's a functional difference.
>
> Implicit convertion sounds a bit dangerous, might start using == instead

Um, there's no "one's better than the other."  Don't overgeneralize on
things you don't understand.  Implicit conversion is necessary in some
cases, and in others, exact comparison is needed.

>>> Also, what's the advantage of explicitly defining it as a template?
>>
>> As opposed to what, implicitly defining it as a template?  This
>> question doesn't really make sense.
>
> I mean, I was using a function template.

A function template is just a function in a template.  Templates can
work just fine on their own.  If you're manipulating types, there's
really no need to get functions involved.

>> template ArrayDepth(T: T[]) { const ArrayDepth = 1 + ArrayDepth!(T); }
>> template ArrayDepth(T)       { const ArrayDepth = 0; }
>
> The code looks a bit strange to me:
> ArrayDepth is both a (const) value and template name and where is the return
> value ?

See "Implicit Template Properties" here:
http://www.digitalmars.com/d/1.0/template.html

When you create a member in a template with the same name as the
template, you can access it from the template without explicitly
writing ArrayDepth!(int[]).ArrayDepth.