Re: [Boost-build] What is _message_

Subject: Re: [Boost-build] What is _message_
From: Rene Rivera (grafikrobot_at_[hidden])
Date: 2016-06-03 09:55:13

On Fri, Jun 3, 2016 at 8:41 AM, Edward Diener <eldiener_at_[hidden]>
wrote:

> On 6/3/2016 9:18 AM, Rene Rivera wrote:
>
>> On Fri, Jun 3, 2016 at 7:17 AM, Edward Diener <eldiener_at_[hidden]
>> <mailto:eldiener_at_[hidden]>> wrote:
>>
>>     I am seeing in the predef.jam file a call to rule _message_ but I
>>     can find no information on it. Does this exist in some Boost Build
>>     jam file ?
>>
>>
>> That's not a rule.. It's a variable. Or rather, a group of variables.
>>
>
> How does the syntax:
>
> _message_(/check/predef//predef_check_cc_$(key))
>
> apply to a Boost Build variable ? I thought Boost Build variables ( which
> are list of strings ) had to use [n] to access a string in the list.

That's, literally, the name of the variable. Variables in bjam have almost
no limitations on characters allowed. In this case, because it has a
variable expansion in it, the name comes out to be something like:

  _message_(/check/predef//predef_check_cc_79054025255fb1a26e4bc422aef54eb4)

I.e. it's a variable that is specifically named for the target of a
specific predef check sub/expression. If you where indexing an element in
the variable's list value you would then end up with:

_message_(/check/predef//predef_check_cc_79054025255fb1a26e4bc422aef54eb4)[0]

For example.

-- 
-- Rene Rivera
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