Re: [Boost-build] How can I pass the property-set as a parameter toa rule call from source section of target?

From: Daniel Einspanjer (deinspanjer_at_[hidden])
Date: 2006-03-01 10:43:12

I'd like to ask a follow-up question for my further education if I may.  An 
answer simply pointing to relevant documentation is just fine if I've 
overlooked it.

"Vladimir Prus" <ghost_at_[hidden]> wrote in message 
news:200603011057.33931.ghost_at_cs.msu.su...
> On Wednesday 01 March 2006 02:22, Daniel Einspanjer wrote:
>> rule get_extra_source ( properties )
>> {
>>     local cust_name = [ $(properties).get <customer> ] ;
>>     return [ glob fubar-$(cust_name).cpp ] ;
>> }
>
>    rule get_extra_source ( properties * )
>    {
>       local cust_name = [ feature.get-values <customer> : $(properties) ] 
> ;
>       local s = [ glob fubar-$(cust_name).cpp ] ;
>       return <source>$(s) ;
>    }

Why do some rules need ( properties * ) as a parameter instead of ( 
properties ) ?
I assume that if the parameter is ( properties * ) then the [ 
feature.get-values <customer> : $(properties) ] form must be used to extract 
something from it whereas if the parameter is just ( properties ) then [ 
$(properties).get <customer> ] is the right way to extract a value.  Is this 
a correct understanding?

I wrote this rule to be used in a <tag> call and I based it almost exactly 
off of the test in tag.py.
rule make_customer_branded_name ( base_name : type ? : properties )
{
    local cust_name = [ $(properties).get <customer> ] ;
        return [ virtual-target.add-prefix-and-suffix 
$(base_name)-$(cust_name) : $(type) : $(properties) ] ;
}

Both this rule and the conditional rule are invoked in the same manner, in 
the same requirements section of a target.  What controls the parameters 
passed in to them?