[SR-Users] Syntax of xavp

[Olle E. Johansson]

12 dec 2012 kl. 10:44 skrev Daniel-Constantin Mierla <miconda at gmail.com>:

> Hello,
> 
> On 10/9/12 3:59 PM, Andreas Granig wrote:
>> Hi,
>> 
>> I'm playing around with xavp, but there are some things I can't wrap my
>> head around.
>> 
>> What basically works is this:
>> 
>> $xavp(a=>foo) = 'foo';
>> $xavp(a[0]=>bar) = 'bar';
>> 
>> Getting the value like this:
>> 
>> xlog("L_INFO", "a-foo='$xavp(a=>foo)' and a-bar='$xavp(a=>bar)'");
>> as well as
>> xlog("L_INFO", "a-foo='$xavp(a[0]=>foo)' and a-bar='$xavp(a[0]=>bar)'");
>> 
>> ... works, because when omitting the index, it assumes [0]. I really
>> like to avoid such implicit assumptions though, to make the config
>> really clear, so I prefer the second approach.
>> 
>> What doesn't work for me then is explicit assignment of the very first
>> value, like this:
>> 
>> $xavp(a[0]=>foo) = 'foo';
>> $xavp(a[0]=>bar) = 'bar';
>> 
>> If I do this, the "a" xavp is never created. Wouldn't it be good
>> practice to create the xavp on first assignment? That way, I don't have
>> to take care in the config file whether the xavp is used for the first
>> time, where I have to omit the index.
> 
> xavps are reusing the avps architecture in regards of working as a stack. So last added is first in the list.
> 
> The problem of creating the structure when providing the index is also related to it. What should happen if one does:
> 
> $xavp(a[5]=>foo) = 'foo';
> 
> Create other 5 xavps named 'a' (indexes 0 to 4)?
> 
> It seemed the right approach not to create new structures at invalid position, by simply not providing the position. For overwriting a value, the index has to be provided.
> 
> The xavps system was under rfc at some point:
> http://lists.sip-router.org/pipermail/users/2009-July/024180.html
> 
> Of course, it can be adjusted when something can be better, for the moment I don't see a solution to this case, unless a new operator is introduced.
> 
>> 
>> What I'm also wondering is whether it's possible to directly access
>> nested xavps, like this:
>> 
>> $xavp(a=>foo) = 'afoo';
>> $xavp(b=>foo) = 'bfoo';
>> $xavp(c=>a) = $xavp(a);
>> $xavp(c=>b) = $xavp(b);
>> xlog("L_INFO", "a-foo='$xavp(c=>a[0]=>foo)'");
>> or
>> xlog("L_INFO", "a-foo='$xavp(c=>a=>foo)'");
>> 
>> Both ways give me "a-foo='<<xavp:0x7f0d387fe178>>'". Is this even
>> intended? Would be really cool if that's possible!
> Internally it is possible to have as many nested xavps (the value for an xavp can be a list of xavps). At this moment, the config file syntax has support only for two levels, your example is returning the value of c=>a, which is a pointer to another xavp list.

A question I came up with yesterday evening:

I have an AVP with five values (0-4) called "jultomte".

Is there a way to assign the FULL avp - all five values - to an xavp value?

Like:
xavp(xmas=>tree) = $avp(jultomte)[*];

/O
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