Re: Building the dependency graph

From: Markus Schöpflin (markus.schoepflin_at_[hidden])
Date: 2002-08-01 08:37:32

Vladimir Prus wrote:
> 
> (brining this to the list)
> 
> Hi Markus,
> 
> Markus Schöpflin wrote
> 
> >sorry for the long delay, I have been on holiday...
> >
> Hope you had a good time :-)

Yes, thanks.

[snip]

> So if we generate one *bsc file for each exe/lib target this will be
> perfectly OK?

I think so, yes.

> 

[snip question about pch]

> 
> >3. How files compiled with and without precompiled headers are separated? Can
> >we assume that sources for each main target all either use PCH or don't use
> >them. That would allow to write
> >
> > lib a : a.cpp ;
> > lib b : b.cpp my_project_pch ;
> >
> >Or is finer granularity required?
> >
> >
> >
> >Yes, I think so.
> >
> >MSVC dev studio allows you to to specify three options (off, auto, manual)
> >for the PCH on a project level but each setting can be overwritten on a
> >per file basis and this is occasionally needed.
> >
> >Jam should support the first and the last option. The auto option
> >is completely useless IMHO
> >
> Oh... I already thought we'll have no problem with your use case, but
> there are problems :-(
> Suppose we can specify pch file in sources for every exe. In that case
> it will be used by default
> for each compiled file. It would be possible to turn PCH for a specific
------------------------------------------------------^ off(?)

> file using the syntax we use
> for source properties, i.e.
> 
> exe a : a.cpp b.cpp/<pch>off my_project_pch ;
> 
> Here, a.cpp will be compiled with pch, and b.cpp without. Would such
> arrangement be OK?

I think so. The way I usually use PCH is to enable it for the whole
project and disable it for some individual files.

> (I actually don't know yet how that <pch>off will really be implemented,
> but seems the right way
> from UI point of view)
> 
> - Volodya

Would it be possible to use the same PCH for more than one main target?

precompiled_headers my_project_pch : stdafx.cpp ;
exe a : a.cpp my_project_pch ;
exe b : b.cpp my_project_pch ;

The compiler does support it but I have to admit I never used it so far.

Markus