[asterisk-users] AEL: how to check if variable is defined

[Richard Lyman]

Philipp Kempgen wrote:
> Richard Lyman schrieb:
>   
>> Philipp Kempgen wrote:
>>     
>
>   
>>> But I guess it wouldn't hurt to add a DEFINED() function to
>>> Asterisk.
>>>
>>> if (DEFINED(myvariable)) {
>>>     // ...
>>> }
>>>   
>>>       
>> Isn't that what ISNULL is for?
>>     
>
> No. ISNULL() works on values not on variables.
>
> But Dave Fullerton found EXISTS():
> http://lists.digium.com/pipermail/asterisk-users/2008-December/224059.html
>
>
>    Philipp Kempgen
>
>   
                if (${ISNULL(${CAMPAIGN})}) {
                        Set(CAMPAIGN=INBOUND);
                };

This is how i use it.