Re: [Boost-users] [bcp]minimal option

From: David Abrahams (dave_at_[hidden])
Date: 2005-08-07 08:21:02

"John Maddock" <john_at_[hidden]> writes:

> * It searches for library names first, so using "regex" as a name will give 
> you everything in the libs/regex directory and everything that depends on, 
> but that's not the case here.
> * If you include the header of a library with separate source, then you get 
> that libraries source and all it's dependencies, but that's not the case 
> here.
> * When you include a header, bcp doesn't know what compiler you're using, so 
> it follows all possible preprocessor paths.  If you're distributing a subset 
> of Boost with you're application then that is what you want to have happen 
> in general.  This is the case here, and it does bloat things, but not by as 
> much as you think:
>
> Running:
>
> g++ -x c++ -E -I. boost/shared_ptr.hpp | grep -c 'boost/'
>
> Gives an answer of 83, so that's the smallest number of headers you could 
> have got away with for that one compiler, then running bcp in report mode, 
> we can see what all the "extra" headers are:
>
> * All of the config system *headers* (52 headers, would be about 6 for one 
> compiler only).
> * All of the shared pointer synchronisation code (24 headers, would be about 
> 4 for one compiler/platform).
> * A lot of MPL and type traits code that includes workarounds for broken 
> compilers that you may or may not need (in fact gcc appears not include any 
> of these headers at all).
> * A lot of preprocessor lib headers, that are only really needed for type 
> traits and MPL maintenance, some of these could be trimmed out, but it's not 
> clear how many: MPL in particular cannot be used at all without the 
> preprocessor lib.
>
> To conclude: the only "minimal" version would be to extract the headers used 
> by a *specific compiler*, but you can already do that by preprocessing the 
> header and grepping for the filenames to copy.

John,

This description and the example would make a great addition to the
bcp documentation.
-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com