Re: [jamboost] How to define additional transformations?

From: Vladimir Prus (ghost_at_[hidden])
Date: 2003-10-15 02:40:47

Hi Peter,

> Does that mean, that for BBv2 Vladimir is the man to ask?
>
> From superficially looking at the sources I guess I'd have to do
> something like:
> - declaring a type (where?) like it is done in builtin.jam
> - write a rule like register-c-compiler (where?)
> - write a rule (and register it) that strips my executables (in my
> toolset-file?)
>
> Am I on the right track?

Almost. The first caveat is that you don't need to write a rule like 
register-c-compiler. If you want to add new transformation, you have to 
declare new generator. The 'register-c-compiler' is just a convenience 
wrapper which declares new generator with some predefined properties.

The process of declaring a new generator is documented at 

http://boost.sourceforge.net/boost-build2/doc/extending.html

and it fact, stripping a binary is a simple transformation, so the process is 
just as described. I attach a working example.

How for the second caveat. The Jamfile looks like:

exe a : a.cpp ;
stripped-exe stripped_a : a ;

As you see, the name of stripped executable is different. That's because V2 
assumes that a single Jamfile cannot generate two targets with the same 
filename and the same properties --- naturally, it's not clear where to put 
them. 
Rene, could you tell how this problem is solved in V1? Will stripped "a" end 
in "bin/stipped_a/.....". And won't the code that you've posted create 
executable with name "stripped_a"?

There's another solution for your problem: make the feature that determines if 
the target is stripped or not.

First, the feature:

feature.feature strip : off on : composite ;
feature.compose <strip>on : <linkflags>-s ;

This will cause Boost.Build to pass "-s" flag for linker if <strip> if "on" -- 
that flag causes gcc to strip the binary.

Next, the main target:

exe a : a.cpp : : : <strip>off <strip>on ;

This will cause Boost.Build to build "a" both with <strip>off and <strip>on, 
unless specific value of <strip> is explicitly requested.

I attach the working example of this as well. It would be interesting to know 
this approach you find better. 

I actually have a third variant which works just like first, only places 
stripped "a" to a different location, without changing the name. I uses a 
kluge in one place, however, so I'd prefer some discussion about the right 
way.

- Volodya
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