Re: [boost] Directory structure not quite right yet?

Subject: Re: [boost] Directory structure not quite right yet?
From: Bjørn Roald (bjorn_at_[hidden])
Date: 2015-01-05 18:10:37

On 04. jan. 2015 16:48, Peter Dimov wrote:
> Bjørn Roald wrote:
>
>> What is the end goal?
>
> That was, and remains, a very good question.
>
> The end goal is a tool 'bpm' that can do this:
>
> D:\tmp3>bpm install filesystem
> bpm: installing module 'filesystem'
> bpm: installing module 'assert'
> bpm: installing module 'config'
> bpm: installing module 'core'
> bpm: installing module 'detail'
> bpm: installing module 'functional'
> bpm: installing module 'io'
> bpm: installing module 'iterator'
> bpm: installing module 'range'
> bpm: installing module 'smart_ptr'
> bpm: installing module 'static_assert'
> bpm: installing module 'system'
> bpm: installing module 'type_traits'
> bpm: installing module 'mpl'
> bpm: installing module 'preprocessor'
> bpm: installing module 'function'
> bpm: installing module 'function_types'
> bpm: installing module 'integer'
> bpm: installing module 'optional'
> bpm: installing module 'typeof'
> bpm: installing module 'utility'
> bpm: installing module 'concept_check'
> bpm: installing module 'conversion'
> bpm: installing module 'tuple'
> bpm: installing module 'array'
> bpm: installing module 'regex'
> bpm: installing module 'align'
> bpm: installing module 'predef'
> bpm: installing module 'throw_exception'
> bpm: installing module 'bind'
> bpm: installing module 'move'
> bpm: installing module 'build'
> bpm: the following libraries need to be built:
>   filesystem regex system
> bpm: (use ./b2 to build)
> bpm: recreating header links
>
> which should be self-explanatory.
>
> When it says "installing module 'foo'", it means "downloading libs/foo"
> (except for build, where it downloads tools/build and a few other files.)

I like the intentions here.  I think having a platform agnostic tool for 
source level packet management is a good way to go.  I would be more 
skeptical if you intended make the next generic packet manager from 
scratch for binary distribution.  It is just too complex, and there are 
too much competition too have a reasonable chance of getting wide 
adaption.  That said, useful meta data from boosdep, bpm, b2, etc., with 
some HOWTOs, could make life better for boost packet maintainers trying 
to make good binary distributions of boost for various platforms.

A few opinions:

A source packet manager, like bpm, should copy headers from the 
installed modules' into the $BOOST/include/boost directory.  The bpm 
tool should not depend on headers in $BOOST/boost, nor depend on ./b2 
for staging headers in $BOOST/boost or $BOOST/include/boost.  Further 
bpm should avoid any symbolic link, junction, or hard link trickery like 
"b2 headers" attempts, it is just too tricky to do right for everyone, 
in particular automated symbolic link creation on Windows is hard and 
just not worth it. We are talking about an installation, so keep it simple.

For the b2 build I would suggest changing jam files so b2 is specifying 
a -I for each module the build depend on, rather than a single -I 
$BOOST/include to where bpm staged the headers.  That will keep the two 
tools independent of each other.

I would also like to suggest having bpm install all modules, including 
build in a "modules" folder together with a custom bootsstrap and set of 
Boost.Build project root files, and stage libraries in a "lib" folder 
rather than stage/lib.

--
Bjørn