[Interest] porting to Qt 5.4 - MOC very slow on Windows
Hamish Moffatt
hamish at risingsoftware.com
Fri Jan 16 01:53:34 CET 2015
On 16/01/15 09:35, Henry Skoglund wrote:
> > I'm trying to port our app from Qt 4.8 to 5.4.
> > Currently working in MSVC 2013,
> > and using the pre-built Qt binaries for that environment.
> >
> > We have about 440 files being MOCed during build. On 5.4, each file
> > is taking 2-3 seconds meaning the overall build is significantly
> > longer than in 4.8.
> >
> > I found a reference to a similar problem here -
> > http://qt-project.org/forums/viewthread/47901 - which was due to using
> > MOC on a network drive. In my case everything is on local SSD.
> >
> > Any suggestions?
>
> One trick I've used for speedup; since MOC ignores your .cpp files, is
> to move #includes of external .h files, for example
> windows.h, from myclass.h to myclass.cpp.
>
Thanks Henry. That's good practice anyway - your .h is your interface to
other source modules, so if you don't need <windows.h> for example as
part of your interface, you shouldn't include it from your .h. This
applies to your own headers too (not just system/Qt headers), else you
end up waiting on long rebuilds if you change those headers.
Unfortunately this means I've already done much of what I can and my MOC
times are still terrible :-)
Hamish
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