Re: Getting a bundle to load symbols from the main app bundle

FROM : Damien Sorresso
DATE : Mon Jul 10 20:11:49 2006

On 8 Jul, 2006, at 10:53 AM, Michael Ash wrote:
> On 7/7/06, Damien Sorresso <<email_removed>> wrote:
>

>> I've got a program that dynamically loads bundles, and I'd like those
>> bundles to load a symbol from the main application bundle.
>> Specifically, I'd like them to get a hold of the value of a global
>> debug variable.
>>
>> I'm currently doing this from the loadable bundle.
>>
>> __debug_level = (int *)CFBundleGetDataPointerForName(mainBundle, 
>> CFSTR
>> ("__debug_level"));
>>
>> But `CFBundleGetDataPointerForName()' returns NULL in this case. When
>> I do this call from the main application bundle, I get garbage. So
>> I'm wondering if my main app's symbols aren't getting exported 
>> properly.
>>

>
> If "__debug_level" is the actual variable name then the symbol name
> will have an extra underscore prepended and so should be
> "___debug_level". Otherwise if the name is actually "_debug_level"
> then it sounds like it's not getting exported properly. You could
> check using /usr/bin/nm which will save you from speculating.
>


I've verified that the symbol is being exported correctly. The CF 
calls just don't want to grab it. Would it be because the main bundle 
is an executable and not dynamically loadable?


> Once you get the symbol to export properly, or verify that it is
> exported properly already, you can bypass the whole manual symbol
> lookup by setting your bundle's Bundle Loader. This will effectively
> link the bundle against your application, allowing you to refer to
> __debug_level directly using an extern, as well as access any other
> symbols the application provides in a simpler fashion.
>


I'm trying that, but `ld' keeps coming back saying that the 
executable cannot be found. I'm pretty sure it's because the main 
executable gets built after the bundle. Is there any way I can tell 
the target to link against the executable at the very end rather than 
immediately after the object code is generated?
--

Damien Sorresso
Macintosh Developer
Computer Infrastructure Support Services
Illinois State University
damien.<email_removed>