Stripping away const/invariant in D 2.0

[Bruno Medeiros]

Daniel Keep wrote:
> I've been trying to work this out for a few hours now, and I'm drawing a
> blank.  In D 2.0, there doesn't appear to be any way of deriving the
> type of T given either (const T) or (invariant T).
> 
> This came up because of my templated join function which takes an array
> of arrays, a separator, and joins all the arrays together.  For instance:
> 
>   ["foo","bar","baz"].join(", ") == "foo, bar, baz"
> 
> The problem is when the arguments are some combination of const and/or
> invariant.  In order to efficiently do the join, it allocates a result
> array large enough for the full result, then fills it in using slicing.
>  Problem is, what type does it use?
> 
> Given:
> 
>   T[] join(T,U)(in T[][] parts, in U[] sep=null)
> 
> There doesn't appear to be any way to derive a mutable version of T or
> U.  I've tried is( T V : const V ) and is( T V == const V ) as well as
> various array tricks, but nothing seems to be working.  In the two "is"
> cases, V is *always* the same type as T.
> 

Use "typeof(T)". For example if T is invariant char , then typeof(T) == 
char. typeof() kinda works like a declaration, so it removes the top 
level const/invariant.



-- 
Bruno Medeiros - MSc in CS/E student
http://www.prowiki.org/wiki4d/wiki.cgi?BrunoMedeiros#D