Re: Why do no targets depend on the Jamfiles?

From: David Abrahams (dave_at_[hidden])
Date: 2005-04-05 09:26:11

Zbynek Winkler <zw-bjam_at_[hidden]> writes:

>>
>>Right. It was requested once, IIRC, but overall there was little demand.
>> 
>>
> I believe it was me. And I still consider it to be a major problem but I 
> was alone and I did not manage to convice anybody about it
> seriousness. 

I've been convinced of it for years.

> See my comment at
> http://www.scons.org/cgi-bin/wiki/SconsVsOtherBuildTools
>
>> Another problem is that the built files depend only on the source 
>> files and not on the command to build them (like in scons). That means 
>> that when you alter your Jamfile you either have to find and delete 
>> the executable by yourself or rebuild the whole target. That is 
>> another problem since it does not rebuild only the target you specify 
>> but also all depending libraries (aka rebuilding the world) without 
>> the option not to.
>
>
>> [snip]
>>
>>However, it's a question if it should be enabled by default, or via
>>some explicit options. I'm sure some of your users will disagree to
>>have everything rebuilt on every Jamfile change.
>> 
>>
> Well, I agree that it is not a good idea to rebuild everything on
> every Jamfile change. IMHO the built files should depend on the
> commands used to build them...

Right. We should write the contents of the commands out to some files
as part of the build process and then make inequality a precondition
of outdating new targets. Or we could wait for the Python integration
to be finished and let Scons' mechanisms take care of it...

...which we can't do until BBv1 is retired. How's that project coming
along, Volodya?

-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com