Re: [Boost-build] Leave target on failure?

Subject: Re: [Boost-build] Leave target on failure?
From: Vladimir Prus (ghost_at_[hidden])
Date: 2010-03-05 10:59:55

Johan Nilsson wrote:

>> I've tried to address this in small steps, and checked in a new
>> builtin,
>> PRECIOUS, that prevents removal of a target when update fails.
>> See:
>>
>> https://svn.boost.org/trac/boost/changeset/60157
>>
>> Does this help at least half-way? If it mostly works, I'll implement
>> an indirection to decide if to retain target based on exit code.
> 
> I think so (assuming that "clean" removes even PRECIOUS targets, which 
> it should do). Need to have the indirection implemented and be able to 
> test it before I can tell for sure. Also, I hope that there will be a 
> Boost.Build rule that allows this to be used more easily with 
> Boost.Build level targets (or am I just assuming this will make things 
> easier)?

I was hoping no other change would be required. E.g. if you have a custom
rule/action pair to run your testing tool, you can adjust the rule as follows:

rule run-tests ( targets * : sources * : properties * )
{
        PRECIOUS $(targets) ;
}

which seems just as good as introducing virtual-target.precious and calling it
from the generator. What do you think? This is basically up to you, adding
new rule in virtual-generator is low effort.

> 
> As for actually keeping the target based on the exit code, please 
> consider (such in this case) that the possible exit codes might not be 
> possible to determine in advance with reasonable effort. It should be 
> possible to set the exit code as a range, set, or logical/special 
> expression (such as e.g. NEGATIVE or "< 0"). I guess this could be 
> implemented by allowing the user to specify a rule used for determining 
> the PRECIOUS-ness of the target.

I am thinking that rule is indeed the best way -- as opposed to inventing
funny syntax.

- Volodya