Re: [Boost-build] How to select a source file by <target-os>

From: Jonathan Biggar (jon_at_[hidden])
Date: 2008-07-22 12:02:55

Jurko Gospodnetić wrote:
>> Seems to me there ought to be a better way, but I haven't found one yet.
>>
> 
>   Well your solution seems quick good to me :-) and could be trimmed 
> down to (also avoids a typo in the original example):
> 
>> for local os in [ modules.peek builtin : .os-names ]
>> {
>>     alias target-os-source : foo-$(os).cpp : <target-os>$(os) ;
>> }

Yup.

>   But IME most often you do not have the same files on different OS's 
> and then it is more useful to actually have a separate alias alternative 
> for each OS.

It depends. :)  Sometimes managing the alternatives by hand is ok, 
sometimes it's not.

>   There is also the option of providing the source file names lazily 
> using indirect conditional requirements (see 
> http://www.boost.org/doc/tools/build/doc/html/bbv2/advanced/targets.html#bbv2.advanced.targets.requirements) 
> and the <source> property. Something like (warning: untested code):
> 
>> rule add-os-specific-sources ( properties * )
>> {
>>     local target-os = [ MATCH "^<target-os>(.*)$" : $(properties) ] ;
 >>     return
>>     $(target-os)-specific-source-1
>>     $(target-os)-specific-source-2
>>     $(target-os)-specific-source-3
>>     $(target-os)-specific-source-4
>>     $(target-os)-specific-source-5 ;
>> }

Hmmm.  Should that be:

rule add-os-specific-sources ( properties * )
{
     local target-os = [ MATCH "^<target-os>(.*)$" : $(properties) ]  ;
     return
       <source>$(target-os)-specific-source-1
       <source>$(target-os)-specific-source-2
       <source>$(target-os)-specific-source-3
       <source>$(target-os)-specific-source-4
       <source>$(target-os)-specific-source-5 ;
}

Or am I misunderstanding something?

>> exe my-exe
>>     :
>>         some-fixed-source-1
>>         some-fixed-source-2
>>         some-fixed-source-3
>>     :
>>         <conditional>@add-os-specific-sources ;
> 
> 
>   I guess what you would really like would be something like:
> 
> exe my-exe
>     :
>         some-fixed-source-1
>         some-fixed-source-2
>         some-fixed-source-3
>     {target-os}-specific-source-1
>     {target-os}-specific-source-2
>     {target-os}-specific-source-3
>     {target-os}-specific-source-4
>     {target-os}-specific-source-5 ;
> 
>   and have Boost Build dynamically construct the source file names fotr 
> you, but I don't think that is possible with the current Boost Build. 
> But if you can define a clear and robust syntax for achieving this 
> effect feel free to suggest it on the list.

Actually, I think <conditional> handles it pretty well.  Thanks!

-- 
Jon Biggar
Floorboard Software
jon_at_[hidden]
jon_at_[hidden]