Storing arrays as Variant types.

[ketmar via Digitalmars-d-learn]

On Tue, 23 Dec 2014 22:57:07 +0000
"Winter M. via Digitalmars-d-learn" <digitalmars-d-learn at puremagic.com>
wrote:

> I've run into a problem while trying to coerce array values from 
> a variant; specifically,
> 
> char[] a = aVariant.coerce!(char[]); // This works just fine.
> 
> byte[] b = bVariant.coerce!(byte[]); // This causes a static 
> assertion to fail.
> 
> I'm not really sure why a byte[] would be an unsupported type, 
> since memory-wise the reference should take up as much space as 
> for the char[] (as I understand it).
> Perhaps I'm missing something, but I'm lost as to why this is the 
> case.

heh. this is due to how `.coerce!` written. it doesn't really checks
for arrays, what it checks for is:

1. static if (isNumeric!T || isBoolean!T)
2. static if (is(T : Object))
3. static if (isSomeString!(T))

see the gotcha? ;-) both types you requested are not numeric, not
boolean and not objects. but `char[]` satisfies `isSomeString!`, and
`byte[]` doesn't.

i don't sure that coercing is designed to work this way, it seems that
`isSomeString!` is just a hack for coercing to strings.

i.e. with `char[]` variant tries to build some textual representation
of it's value, and with `byte[]` variant simply don't know what to do.

maybe we should allow coercing to `byte[]` and `ubyte[]` with the
defined meaning: "get raw binary representation of variant contents".
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