Re: [jamboost] BB4

From: David Abrahams (dave_at_[hidden])
Date: 2003-01-05 10:06:26

Vladimir Prus <ghost_at_[hidden]> writes:

> David Abrahams wrote:
>> Hi Volodya,
>
> Hi Dave,
>
>> Every time I go to look at addressing BB4, I get confused.
>> 
>> Needd to implement new version of the "flags" rule. 
>> Generators ids 
>> 
>> Where can I read about "generator IDs"?
>
> Generator id is the first parameter to class generator constructors.
> The idea is that whenever you create a new generate, you give it
> an id via ctor. This was it's possible to refer to the generator
> using more convenient name than "object_at_....".

OK.

>> will be used to denote generator, to which flags apply. 
>> 
>> What does it mean that flags will apply to a generator? Is the idea
>> simply to limit the "on target" variable assignments to the products
>> of that generator?
>
> Kind of. Generator id has a second function. It names a rule which is
> used to actually set up build action. E.g. gcc.link generator has
> associated gcc.link rule. (In fact, gcc.link *rule* is empty, there's
> only gcc.link *action*, but that's detail).
>
> I meant that if you say that flags apply to gcc.link, that the variable
> assingment will be only done for that rule, but not for gcc.compile, for example.

What do you mean by saying a variable assignment will be done for a
rule?

I can't change the contents of the rule to add a variable assignment,
and we don't want to burden action writers with explicitly adding some
boilerplate code to do it. It seems possible to have the generator
base class perform the variable assignment before the generator
invokes the rule, which is what I was saying, and seems to correspond
to what you're saying below.

>> Before calling user-supplied rule, 
>> 
>> What user-supplied rule? The one which implements the generator's
>> action?
>
> Yes.
>
>> generator will set target variables accordingly.
>> 
>> Also, I don't know how to reach this link mentioned in BB4 anymore:
>> 
>> news://news.gmane.org:119/[e-mail] 
>
> Hmm... I get to it simply by clicking in Mozilla... Can Outlook open
> news article by URL?

I don't use Outlook.
Outlook Express says first,

"The server could not be found"

and second:

"Outlook express could not download the requested message. It is
likely that the message was removed or expired from the server"

I assume it's this one, though:

http://article.gmane.org/gmane.comp.lib.boost.build/1443

> HTH,
> Volodya
>
> P.S. BTW, there's now a long row of holidays in Russia. I had a week of them 
> already, and there will be two more: 6th and 7th. I'll be online as usual 
> after that (and will resume Boost.Build hacking as well).

Fabulous!

-- 
David Abrahams
dave_at_[hidden] * http://www.boost-consulting.com
Boost support, enhancements, training, and commercial distribution