qt weak points and disadvantages?

[wysota]

On Qt, yes, but if you use native OS widgets the OS can take that duty away from you.

But processing still takes place. It doesn't matter (like you said before) if it is the OS responsibility or the application's. And Qt uses native rendering on recent Windows platforms so I'm assuming that happens the same way as for MFC apps (if they conform to the style at all).

Some of the OS widgets I do feel are more efficient than Qt widgets however (for example, a QTableView or QTreeView with several million items where the native widget takes 9% to keep updated, whilst Qt takes 30%+). This is typically because the Qt variant is far more complex and flexible.

Yes, the last part is the thing that makes a difference

QT_USE_NATIVE_WINDOWS=1 certainly seems to work, but I can't help but think it's not really native - it seems to use different windows for each widget,

But that's what is called native.

but doesn't use any of the widgets built into the OS.

No, that wouldn't make sense as APIs are not compatible. But you can use native controls in Qt apps if you want. Of course your software will stop being portable...

[squidge]

But you can use native controls in Qt apps if you want. Of course your software will stop being portable...

Hmmm, I have the choice of using powerful open source portable widgets or closed source proprietary widgets. I know which I'm going to continue using

[wysota]

But you have a choice Many people don't have that choice.

[kokonech]

Thanks for this discussion )
I just would like to comment some points:

0) I think, when we discuss Qt disadvantages, we have to remember about C++ disadvantages too. There are such projects as QtJambi and PyQt, but still most people use C++ for writing Qt based applications. This is important point if we compare Qt with Java or .NET

1) The amount of disk space required for compilation could be critical aspect. We use a single server for unit-testing and night builds with several virtual machines. We had to improve our hardware significantly to handle such builds. Also the compilation time is larger comparing to pure C++ (moc, uic takes it's time), though I don't have any numbers.

And, yes, Qt is growing. It's becoming really huge, but it's not becoming "clumsy". I suppose that as long as Qt is flexible, easy to use and to understand, the size of the library won't cause many problems.

[wysota]

0) I think, when we discuss Qt disadvantages, we have to remember about C++ disadvantages too. There are such projects as QtJambi and PyQt, but still most people use C++ for writing Qt based applications. This is important point if we compare Qt with Java or .NET

In my opinion you can't compare Qt to pure Java simply because of the reason you already mentioned - there is a C++ layer beneath Qt so if you compared languages, you'd have to compare Java to C++, not to Qt.

1) The amount of disk space required for compilation could be critical aspect. We use a single server for unit-testing and night builds with several virtual machines. We had to improve our hardware significantly to handle such builds.

Do you build Qt on those machines every night? Because the space consumption would be significant only in that case.

Also the compilation time is larger comparing to pure C++ (moc, uic takes it's time), though I don't have any numbers.

I wouldn't agree here. If you want to compare compilation time to pure C++, you'd have to take into consideration also compilation time for code you would have to write (in the "pure C++" version) to implement functionality provided by Qt that doesn't exist in ANSI C++.

[kokonech]

Do you build Qt on those machines every night? Because the space consumption would be significant only in that case.

We don't build Qt every night, but we have "pre-commit builds" of our project. Sometimes there could be several simultaneous builds, which requires large amount of disk space.

I wouldn't agree here. If you want to compare compilation time to pure C++, you'd have to take into consideration also compilation time for code you would have to write (in the "pure C++" version) to implement functionality provided by Qt that doesn't exist in ANSI C++.

That's a good point

[wysota]

We don't build Qt every night, but we have "pre-commit builds" of our project. Sometimes there could be several simultaneous builds, which requires large amount of disk space.

So size of Qt is irrelevant in this case.