Re: [Boost-build] Can I use other rules and variables that they are in different scope?

From: Vladimir Prus (ghost_at_[hidden])
Date: 2007-10-17 03:14:33

On Wednesday 17 October 2007 05:01:53 김영현 wrote:
> Hello.
> 
> Please, look at that code below.
> 
> # Jamroot
> 
> import xxx ;
> 
> # in xxx.jam file
> 
> SOME_DIR_PATH1 = /home/user/test ;
> 
> rule path-constants ( name )
> {
>     SOME_DIR_PATH2 = /home/user/test ;
> 
>     return $($(name)) ;
> }
> 
> class Test
> {

You need

        import xxx ;

here.

>    rule __init__ ( )
>    {
>       echo "[" $(SOME_DIR_PATH1) "]" ;

I don't think you can get at variable line this. [ modules.peek xxx : SOME_DIR_PATH1 ]
might work.

>       echo "[" [ path-constants SOME_DIR_PATH2 ] "]" ;

and here, with import in place, xxx.path-constants should work.

> import "class" : new ;
> 
> t = [ new Test ] ;
> 
> 
> # outputs
> $> bjam
> [ ] *"echo $(SOME_DIR_PATH1) - value is empty"
> */home/user/test/test.jam:16: in object(Test)@15.__init__
> rule *path-constants unknown* in module object(Test)@15.
> ...
> ...
> 
> 
> I can't access variables and rules that are in different scope, I mean not
> in class scope. why?

Because there's no scoping in jam. There are modules, and each module has
its own namespace. class, actually, is a module in disguise. Inside
module, you can access variables of that module, only. The fact that
class is defined inside some other module does not help.

- Volodya