[OpenSIPS-Users] Question about script variables

Liviu Chircu liviu at opensips.org
Thu Nov 23 08:34:51 EST 2017

Hi Denys,

The book is doing the correct thing - educating the script writer that 
he must not rely on any $var() holders once an instance of script 
execution ends for a given message.

You, on the other hand, have the additional knowledge of an underlying 
optimization: the $var() values are not reset (actually, they are rarely 
touched at all beyond the script manipulations). The fact that you 
occasionally find the value that you left in the previous message is 
just a coincidence, and you cannot reliably use their initial values. 
Since this is just a "nice to know" developer quirk, I think it would 
cause confusion if the authors were to include it in the book.

If you talk C, you can think of $vars as "uninitialized stack variables".


Liviu Chircu
OpenSIPS Developer

On 23.11.2017 14:13, Denys Pozniak wrote:
> Hello!
> I am newbie in OpenSIPS and probably my question is stupid, but I 
> could not sleep without correct answer :)
> In the book *Building Telephony Systems with OpenSIPS Second Edition* 
> I found next part (p. 97):
> /The script variables/
> /As the name indicates, these variables are strictly bound to the 
> scripting routes. The/
> /variables are visible only in the routing blocks and they have no 
> persistency—when/
> /the route (with all its subroutes) ends, the variables are discarded./
> Is it correct explanation?According to this, variable lives on SIP 
> message level when script are executing, but I think something is not 
> correct as variable lives on proccess level.
> Please help me to sort out this!
> BR
> Denys
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