Re: What is the point of project-root.jam/Jamroot?

From: David Abrahams (dave_at_[hidden])
Date: 2004-12-29 11:33:40

Vladimir Prus wrote:

> So, the net result of your conversation is that to eliminate Jamroot, it's 
> needed to require every Jamfile to call some rule (maybe different for 
> top-level and child project) right at the top? 

No. I must've failed to be clear.
There are lots of options. For example:

#1: a Jamfile doesn't label a subproject unless it declares itself to be
a subproject with a rule invocation. Result: top-level jamfiles need no
such call.

#2: a Jamfile is assumed to label a subproject unless it declares itself
to be a top-level project with a rule invocation. Result: subproject
jamfiles need no such call.

#3: Just like #2 except that if the search upward from an unlabeled
Jamfile finds no parent Jamfile, the Jamfile is treated as a top-level
Jamfile. Warnings are optional and tunable.

I rather like #3 because it makes writing subprojects easy and it makes
the simplest "getting started" project easy. I have some concern about
what happens when unintentional hierarchies are created, but the cases
actually seem non-problematic when I think them through.

> The problem is that I still not sure what this requirements is less 
> problematic than having two filenames. Moreover, requiring every Jamfile to 
> call some rule might break existing projects. So I think we better retain the 
> current scheme, at least for now. I'll try to update the tutorial to refer to 
> Jamroot when needed, and we'll see how that looks.
> 
> What do you think?

You might be right. If Scons does it and hasn't changed the practice
due to pressure from users, there may not be a need to do better. I
just have a strong feeling that in real projects there's enough
information to do this stuff with one filename and the
project/subproject declarations that are already there.

-- 
Dave Abrahams
Boost Consulting
http://www.boost-consulting.com