Feature request: Deploying a class instance in the default data segment

[Weed]

Weed пишет:
> Feature request: Deploying a class instance in the default data segment 
> and creation of a class instance at compile time.
> 
> In this post I'll try to prove the necessity of this feature.
> 
> I have found that in D it is impossible to create a polymorphic object 
> (class or struct) which can be created at compile-time.
> 
> Good specific example of such an object is a matrix class.
> 
> For some matrices it is good to create and initialize them at compile
> time, not dynamically at run time.
> 
> Also for matrices of predefined size it is wrong to duplicate their
> dimensions (their width and height should be declared invariant and,
> consequently occupy memory only once)
> 
> At the same time dynamically created matrices of arbitrary size which
> can be changed at run time are also needed. For example to make a slice 
> of giant matrix it's more efficient to modify it in-place than to copy 
> it. These matrices have variable width and height.
> 
> So we have minimum two types of matrices: dynamic and constant sized 
> with ability of compile time initialization. It is necessary to provide
> interaction between them (for example overload arithmetic operators
> for them). For this purpose it is necessary for them to be inherited
> from common parent. So it can not be structures, only classes.
> 
> But classes can not be created at compile time.
> 
> So I propose to add possibility of deployment of class instance in the 
> default data segment and creation of class instance at compile time.


In more general terms:
Structures and classes must be identical except that the structure can 
not have inheritance, and classes can not be assigned by value (to 
prevent slicing). Everything else, including constructors, and static 
initialization they must match.

(Yes, of course structures have alignment control and other pieces for 
the Plain Old Data)