[fpc-pascal] generic class helper and class references

[Sven Barth]

On 29.09.2013 05:30, Xiangrong Fang wrote:
> type
>    generic TTree<T> = class
>      ... ...
>    end;
>    TTreeType = class of TTree;

This is illegal code and compiled by pre-2.7.1 FPC only because of bugs 
in the generic implementation. "TTree" is not a legal type outside of 
the generic's declaration or implementation (and no, TTree<T> is neither).

> 1) is it possible to define class helper for generic classes?

No. I recently had the thought to allow this as well, but not now.

> 2) why class helper require a class and we cannot use a class reference?

A class helper always work on variables (or return values) of the type 
you specified. So if you'd be able to define a class helper for 
TTreeType you'd only be able to use it on variables of type TTreeType or 
e.g. TTreeType(Self.ClassType), but not on instances of TTree<>.

Regards,
Sven