Re: Free feature problem

From: David Abrahams (dave_at_[hidden])
Date: 2004-07-03 10:15:33

Vladimir Prus <ghost_at_[hidden]> writes:

> David Abrahams wrote:
>
>> > But then you lose the ability to do some sanity checking.
>> > You can type
>> > <toolset>msvc
>> > <toolset>mvsc
>> >
>> > in some condition (maybe even deeply nested)
>>
>> This makes no sense to me. Nothing you're showing looks like a
>> conditional property.
>
> As I've mentioned in another post, requirements in alternatives can be used to 
> implement effect similiar to conditional properties:
>
> lib a : msvc.cpp : <toolset>mvsc ;
> lib a : gcc.cpp : <toolset>gcc ;
>
> The first line has a typo, and the first alternative will never be selected, 
> which would probably take some time to diagnose.

Understood. You would get a message, though, wouldn't you?
Something like "skipping lib a build due to incompatible
requirements"?

Another thought I'm having is that this "no checking" attribute might
really say, "just require that there be an appropriate loadable
module". So you could issue an error when it turned out that there
was no "mvsc.jam" toolset.

-- 
Dave Abrahams
Boost Consulting
http://www.boost-consulting.com