Hello, $var(...) cannot be deleted. Its implementation relies on startup replacement of the name with a pointer in memory, at runtime being used only the pointer (for speed considerations). You should use $avp() if you want to deal with $null.
For the second, it depends on transformation, afaik, most transformations don't return null, but empty string (at least the string transformations). If you implement a new one and want to return $null, the value must have the flag PV_VAL_NULL set, like: val->flags |= PV_VAL_NULL Cheers, Daniel On 05/01/15 13:36, Luis Azedo wrote: > HI Daniel, > > thanks, so in the first case instead of assigning the value to the > $var(x) can i delete the $var(x) so that comparison works ? > > in the second case (returned value from transform) what value should i > compare against to check if returned value was null ? > > ------------------------------------------------------------------------ > *From:* sr-dev [[email protected]] on behalf of > Daniel-Constantin Mierla [[email protected]] > *Sent:* Monday, January 05, 2015 3:51 AM > *To:* Kamailio (SER) - Development Mailing List > *Subject:* Re: [sr-dev] need help understanding $null > > Hello, > > $var(...) cannot be null by design, setting it to $null makes it 0. > > $null is more for variables that don't exist, e.g., you don't have the > $avp(x), then it is null if you compare it. > > Cheers, > Daniel > > On 04/01/15 12:35, Luis Azedo wrote: >> Hi Daniel, >> >> can you help on this ? >> >> Thank you >> ------------------------------------------------------------------------ >> *From:* sr-dev [[email protected]] on behalf of >> Luis Azedo [[email protected]] >> *Sent:* Wednesday, December 31, 2014 4:19 AM >> *To:* [email protected] >> *Subject:* [sr-dev] need help understanding $null >> >> Hi, >> >> if we return val.flags = PV_VAL_NULL, does the == $null comparison work ? >> >> script example >> >> my_function("some param","$var(result)"); >> if( $var(result) == $null { >> do something >> } >> in code => dst_pv->setf(msg, &dst_pv->pvp, (int)EQ_T, &dst_val); >> should the comparison work if we set dst_val.flags = PV_VAL_NULL ? >> >> >> if( $(myPvar{my.mytransform,transformParameter}) == $null) { >> .... >> } >> should this work if the transform returns val.flags = PV_VAL_NULL ? >> >> >> thank you >> >> >> >> >> >> >> >> _______________________________________________ >> sr-dev mailing list >> [email protected] >> http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-dev > > -- > Daniel-Constantin Mierla > http://twitter.com/#!/miconda - http://www.linkedin.com/in/miconda -- Daniel-Constantin Mierla http://twitter.com/#!/miconda - http://www.linkedin.com/in/miconda
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