On Monday, 14 October 2013 at 18:27:52 UTC, Kagamin wrote:
On Sunday, 13 October 2013 at 12:39:55 UTC, Abdulhaq wrote:
Anyway I treated it as an educational exercise and make QRect
et al. regular classes, and got it generally working again.
QRect as a class doesn't sound good: the class layouts are
incompatible between D and C++. If you want to mimic C++ data
layout, you should do it manually - use structs with pads or
translate the data at the border of languages.
In the binding my making QRect/QLine/QPoint bound as a class
means that data access is through methods and so always works
regardless of the way the compiler lays out the data - whereas it
was previously being treated as a struct, which didn't work on my
64bit machine. I want to keep the wrapper as simple as possible
(personally) so avoid padding data etc. I also wanted something
quick to do as I had no idea how much other work would be
required before anything worked at all.
I'm not a C++ developer (I read it a fair amount but write very
little) but my understanding of what was happening is that in the
developers' environment the C++ and D compilers laid out the
class the same, wheres on 64bit Linux I found that (after a lot
of time debugging) that while things compiled, they didn't work
due to corruption in QRect when passing through the wrapper.
I guess the original developers made QRect/QLine/QPoint structs
for performance reasons, but in my own Qt experience you don't
actually deal with that many instances of these types so
application performance is not sensitive to how they are wrapped
(of course YMMV).
Ultimately, it didn't work for me before whereas it does now :-)
