[boost] Re: [build] relative vs absolute

From: David Abrahams (dave_at_[hidden])
Date: 2005-05-22 12:02:52

"Yuval Ronen" <ronen_yuval_at_[hidden]> writes:

>> > I'd like to ask one more question, if possible.
>> > How does it know how to expand $(BOOST_ROOT)?
>> > If I'm standing in C:\libraries\boost_1_32_0\libs\python\test, for
> example,
>> > how can it possibly know that "$(BOOST_ROOT)" is "../../.."? I can't
> think
>> > of any algorithm that can reliably determine this. What am I missing?
>>
>> BOOST_ROOT is registered as a "path global" in the top-level Jamrules
>> file:
>>
>>    path-global BOOST_ROOT : . ;
>>
>> Boost.Build simply adjusts its value appropriately before loading each
>> Jamfile.
>
> And how is this Jamrules file found? The only thing I can think of is this:
> Wherever (in terms of directory) I'm invoking the build, the algorithm is to
> go up the directory tree until a file by the name of "Jamrules" is found,
> and then do what it says.
> Is this correct?

Basically, yes.

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