|
De : Michael Stahl <mst@xxxxxxxxxxxxxxx>
Envoyé : lundi 8 juillet 2019 13:15 À : Tomaž Vajngerl; Adrien Ollier Cc : libreoffice@xxxxxxxxxxxxxxxxxxxxx Objet : Re: tdf#74702 2/2 On 08.07.19 13:06, Tomaž Vajngerl wrote:
> Hi, > > On 06.07.19 19:59, Adrien Ollier wrote: > .... > > > Well IMHO the problem that you even have to think about this is that > OutputDevice is a enormous class, and then you have to deal with another > even more enormous subclass vcl::Window, which should never be a > subclass of OutputDevice in the first place. However the work to change > that is quite big and non-trivial. i rarely work with VCL's implementation so i can't really have an informed opinion but if you say that delegation instead of inheritance would be an improvement here i'm all for it. Hello Michael,
thank you for your answer.
Can you explain what delegation means for you? I don't understand what you mean.
Also, I quite disagree with you.
First, C++ allows an overriding function to have a return type that is a subclass of the return type of the overridden function. You can ensure this by running the following example program:
#include <iostream>
struct A
{
A() = default;
A(const A&) = default;
A(A&&) = default;
virtual ~A() = default;
};
struct B : A {};
struct C
{
virtual A* getNewInstance() const { return new A{}; }
};
struct D : C
{
B* getNewInstance() const override { return new B{}; }
};
int main(int argc, char* argv[])
{
D d;
A* a = d.getNewInstance();
delete a;
return 0;
}Also, let's take a concrete example:
void Edit::Draw(OutputDevice* pDev, const Point& rPos, const Size& rSize, DrawFlags nFlags)
see l.1771
Regards,
Adrien Ollier
|
_______________________________________________ LibreOffice mailing list LibreOffice@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/libreoffice
