[Q] prebuild package deps and Boost-Build V2

From: Chris Drexler (CKolumbus_at_[hidden])
Date: 2003-08-23 08:48:50

Dear Listmembers,

since a few weeks I'm using boost within a development system
which should be changed towards operating system independence. 
As boost-buil V2 has a lot of nice features I wanted to base
the build process on it. Unfortunatly it's very confusing 
to get all the information I need and sometimes it is not clear
to which boost-build version (v1 or v2) some documentation 
belongs to. I hope this list is the right place to ask some
questions about this.

I'm going to describe the my current setup first (which is
a little bit longish in order to cover all important points,
hopefully) and afterwards I'll explain the problems.

The scenario: We have some self-made class libraries which
depend on downloaded packages (one is boost). So I thought 
of using the (usage-)dependency features of boost-build v2 
for automatically using the right include paths and the 
according libraries. (I'm using milestone 6 of boost-build)

root
| 
+ pkgs + boost_1_30_0
| |
| + log4cpp_0.3.4b + include
| + lib
|
+ mylib + include
| + src
| 
+ myapps + testapp + src

The idea was to separate the information of which package versions to 
use and where libraries and include files reside. 

For this I put a Jamfile into 'pkgs' which consist of the following entries
(OS independence not included right now)

-------------------------------------------------------------------

project pkgs ;

BOOST = boost_1_30_0 ;
LOG4CPP = log4cpp-0.3.4b ;

# system libraries
lib winsock : : <name>Ws2_32.lib ;
lib advapi : : <name>Advapi32.lib ;

alias all : log4cpp boost ;
alias boost : : <include>$(BOOST) ;

lib log4cpp
:
: <file>$(LOG4CPP)/msvc6/log4cpp/Release/log4cpp.lib <variant>release
:
: <library>winsock <library>advapi
;
lib log4cpp
:
: <file>$(LOG4CPP)/msvc6/log4cpp/Debug/log4cpp.lib <variant>debug
:
: <library>winsock <library>advapi
;
-------------------------------------------------------------------

and the Jamfile in 'root' (where project-root.jam and boost-build.jam 
resides) contains 

-------------------------------------------------------------------

project MyProject
: default-build debug <link>static
;

use-project /pkgs : ./pkgs ;
use-project /MyLib: ./mylib ;

-------------------------------------------------------------------

The Jamfile in 'mylib' uses several of the libraries defined in 
'pkgs' 

-------------------------------------------------------------------
project MyLib
: usage-requirements <include>./include
: requirements <include>./include
: source-location ./src
;

LIBSRC =
[ .. whatever ..]
;

lib MyLib : $(LIBSRC) : : : <library>/pkgs//log4cpp ;
lib MyLib2 : $(LIBSRC) : : : <library>/pkgs//all ;

-------------------------------------------------------------------

and the application 'testapp' depends on 'mylib'
-------------------------------------------------------------------
project testapp
: requirements <library>/MyLib//MyLib
: source-location ./src
;

exe test 
: testapp.cpp
;

exe test2
: testapp.cpp
: 
: <library>/MyLib//MyLib2
;
-------------------------------------------------------------------

Problems/Questions
==================
- I already know from this list that "include-only" libraries are
not supported right now. The line 

alias boost : : <include>$(BOOST) ;

hasn't been removed just to demonstrate the final idea.

- I had to put a (empty) 'project-root.jam' file into 'pkgs'.
Otherwise I get the error message:

error: default build can be specified only in first alternative
main target is ../../../pkgs/log4cpp

Any ideas why this happens?
I get the same error message if I put the prebuild declarations,
e.g. of log4cpp release/debug, into the main Jamfile in root.

- If I put the prebuild declarations, again c.f. log4cpp, into
the Jamfile in root (after having solved the problem described 
in the last paragraph ), how can I access the entries as depencies
as the reference via the package name ('/pkgs//log4cpp') 
is not possible any more as the something similar to the line
'use-project /pkgs : ./pkgs ;' is missing.

- the library dependcies for 'log4cpp' are correct and the 
appropriate library is linked BUT the include depencies 
are not used (neither for boost nor for log4cpp).
I had to add the paths once more into the Jamfile in 'root'
to make them available. After the changes the Jamfile looks 
like this

-------------------------------------------------------------------
BOOST = pkgs/boost_1_30_0 ;
LOG4CPP = pkgs/log4cpp-0.3.4b ;

project MyProject
: default-build debug <link>static
: requirements
<include>$(BOOST)
<include>$(LOG4CPP)/include
;

use-project /pkgs : ./pkgs ;
use-project /MyLib: ./mylib ;

-------------------------------------------------------------------

This is not what I want because now the paths to the 
package directories appear twice, once in root/Jamfile and once in
root/pkgs/Jamfile.

Thanks you very much !

Best Regards,
Chris Drexler