Cast to a new type

[Neil Vice]

"Tower Ty" <tytower at yahoo.com.au> wrote in message 
news:fsp4ft$7no$1 at digitalmars.com...
>I dont understand casting well. I see the following line in a program
>
> obj[0] = cast(Object) new ArrayWrapperString(data);
>
> Does ArrayWrapperString() exist in the Tango library  (I did not find it) 
> or does this automatically create an instance of new type and create the 
> type too. ?
> Where could I read up on this ?
>

The syntax "new Class(args)" constructs a new instance of a class on the 
heap. This will allocate memory for the instance and call the constructor 
that takes the arguments that are supplied in the parenthises.

The syntax "cast(type)" is a unary prefix operator that takes one argument 
(in this case the newly constructed ArrayWrapperString instance) and 
explicitly casts in to a reference of type Type (in this case Object).

Given that all classes in D inherit implicitly from class Object and I 
believe you should be able to implicitly cast an instance to a reference to 
any ancestor class I'd be surprised if the explicit cast was necessary.

The ArrayWrapperString class must be defined, no automatic type-creation 
occurs, and given this is from a DWT example I can only assume that it is 
declared as part of that library, though as it uses Tango it could also be 
in there - I'm personally familiar with neither.

If it was me I'd:

    grep -R "ArrayWrapperString" *

wherever I'd put my Tango/DWT source files to look for the declaration given 
that some quick google/digitalmars searching proved relatively fruitless.

Hope that puts you on the right track.