Re: [Boost-build] language.html#jam.language.rules confusing about rules and actions

From: Rene Rivera (grafikrobot_at_[hidden])
Date: 2007-09-26 11:36:51

Larry Evans wrote:
> The description of "updating" rules and actions in:
> 
> http://www.boost.org/doc/html/jam/language.html#jam.language.rules
[...]
> All these lead, IMO, quite naturally to the conclusion that the
> following portion of a Jamfile:
> 
> <--- cut here ---
> rule my-update
> {
>      ECHO "in rule my-update" $(1) ":" $(2) ;
> }
> 
> actions my-update
> {
>      echo "in actions my-update" $(1) ":" $(2) ;
> }
> 
> my-update x : y ;
> 
> 
>  >--- cut here ---
> 
> together with the following command line:
> 
>    bjam x
> 
> could lead to the following output to the screen:
> 
>    in rule my-update x : y
>    ...
>    in actions my-update x : y
> 
> However, only the following relevant output appears:
> 
>    in rule my-update x : y
>    ...
>    don't know how to make <e>x

It will work as described, and assuming the above is the entire content 
of the Jamfile, if you do:

   bjam -f Jamfile

[...]
>    So, I guess, when rules and like-named actions are only connected,
>    automatically, the make rule; otherwise, they have to be explicitly
>    connected with the generators.register-standard rule.  Is that
>    right?

Volodya will have to answer that. But I believe all your observations 
here are based on the misunderstanding the difference between Boost.Jam 
and Boost.Build. Boost.Build is an abstraction on top of Boost.Jam, and 
hence the interface it presents to users is different than the one 
describe by the direct use of Boost.Jam.

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