[SR-Users] Accessing #!define "variables" from within lua

Daniel-Constantin Mierla miconda at gmail.com
Sat Mar 24 13:54:10 CET 2012


Hello,

On 3/24/12 1:25 PM, Alex Balashov wrote:
> I am not sure that exporting #defines to third-party language API modules makes much sense just because some user thought it would be neat.
>
> The #!... constructs are all intended as preprocessor directives, to make easier management of global constant values in the native Kamailio config environment and to allow easier management of conditionally-enabled chunks of code therein, right?
>
> Conceptually, it does not seem to me that they should have any representation outside of that evaluative context.  It would be like making preprocessor macro values in C available through the libdl/ELF dynamic shared object interface.  It doesn't make any sense.  If you really want to export preprocessor macro-dependent values, trouble yourself to use an intermediate variable--a real variable.
>
> In Kamailio, this would take the form:
>
> #!ifdef MYPROJECT
>
> #!define MYPROJECT_IP 1.2.3.4
>
> # Exportable symbol:
>
> myproject.ip = "MYPROJECT_IP" descr "..."
>
> #!endif
>
> Doesn't that make much more sense, in terms of what these directives were really intended for?
yes, the directives were added as switches for part of the config 
initially, next version added also values for defines. I thought of 
being able to detect in Lua and do switches there as well based on what 
was defined in kamailio config.

Your solution is good, exporting them to lua will just save some memory 
and make config smaller. So it is indeed more an optimization, not at 
all an implementation of a missing (impossible) feature.

Cheers,
Daniel
>
> --
> Alex Balashov - Principal
> Evariste Systems LLC
> 235 E Ponce de Leon Ave
> Suite 106
> Atlanta, GA 30030
> Tel: +1-678-954-0671
> Web: http://www.evaristesys.com/, http://www.alexbalashov.com
>
> Daniel-Constantin Mierla<miconda at gmail.com>  wrote:
>
>> Hello,
>>
>> On 3/23/12 2:00 PM, Asgaroth wrote:
>>> I'll check this option out, thanks for the tip Alex.
>> it is a good way to do, $sel(...) are available in Lua, @... format not,
>> but they are the same, just different access mechanism.
>>
>>> I guess the other option too, which I have not tried, is to possibly
>>> pass in the values as lua script parameters.
>> Yes, you can do that. You may need to use 'subst' instead of 'define' in
>> order to be able to replace the token inside another string.
>>
>> Exporting defines to Lua could be a good enhancement anyhow, I will
>> think about and maybe add it in the near future.
>>
>> Cheers,
>> Daniel
>>
>>> On 23/03/12 12:12, Alex Balashov wrote:
>>>> Have you considered using selectors/cfg_get variables instead?
>>>>
>>>> They are also a common way to store various types of "global"
>>>> values/constants, with the difference that they can be accessed at
>>>> run time using PV container functions instead of set at preprocessing.
>>>>
>>>> myproject.local_ip = "1.2.3.4" descr "IP address"
>>>>
>>>> $sel(cfg_get.my project.local_ip)
>>>> Or SER-style: @cfg_get.my project.local_ip
>>>>
>>>> You can evaluate those in Lua, right?
>>>>
>>>> -- 
>>>> Alex Balashov - Principal
>>>> Evariste Systems LLC
>>>> 235 E Ponce de Leon Ave
>>>> Suite 106
>>>> Atlanta, GA 30030
>>>> Tel: +1-678-954-0671
>>>> Web: http://www.evaristesys.com/, http://www.alexbalashov.com
>>>>
>>>> Asgaroth<00asgaroth00 at gmail.com>   wrote:
>>>>
>>>>> Hi All,
>>>>>
>>>>> I am looking at writing a lua function that would really benefit from
>>>>> accessing "variables" that I would have defined by using the #!define
>>>>> statement. Is this at all possible? I've tried looking at the
>>>>> documentation surrounding lua and kamailio, but I cannot see how I
>>>>> would
>>>>> access it. I thought I'd ask the list to see if anyone else may have
>>>>> attempted this.
>>>>>
>>>>> for example, I may have
>>>>>
>>>>> #!define INTERNAL_ADDRESS 1.2.3.4
>>>>>
>>>>> Which I subsequently use through the the routing script to refer to the
>>>>> internal address I am listening on. Now I would like to try and access
>>>>> this "variable" from a lua script. Any pointers/tips/workarounds would
>>>>> be greatly appreciated.
>>>>>
>>>>> Thanks
>>>>>
>>>>> _______________________________________________
>>>>> SIP Express Router (SER) and Kamailio (OpenSER) - sr-users mailing list
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>>>
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>> -- 
>> Daniel-Constantin Mierla
>> Kamailio Advanced Training, April 23-26, 2012, Berlin, Germany
>> http://www.asipto.com/index.php/kamailio-advanced-training/
>>
>>
>> _______________________________________________
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>> sr-users at lists.sip-router.org
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-- 
Daniel-Constantin Mierla
Kamailio Advanced Training, April 23-26, 2012, Berlin, Germany
http://www.asipto.com/index.php/kamailio-advanced-training/




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