asterisk users - Jan 2009 - AEL question: testing channel variables

Hi!

I use the following condition:

if (${FOOBAR}=YES) {
   ...
}

The problem is, that if FOOBAR is not defined at all Asterisk generates 
a warning:

WARNING[11982]: ast_expr2.fl:407 ast_yyerror: ast_yyerror():  syntax 
error: syntax error, unexpected '=', expecting $end; Input:
=YES


Of course I could use the following code, but this bloats up the code:


if (${EXISTS(${FOOBAR})}) {
   if (${FOOBAR}=YES) {
     ...
   }
}


Is there another syntax to have nice looking code but avoid the warning?

thanks
klaus

Klaus Darilion wrote:
> Hi!
>
> I use the following condition:
>
> if (${FOOBAR}=YES) {
>    ...
> }
>
> The problem is, that if FOOBAR is not defined at all Asterisk generates 
> a warning:
>
> WARNING[11982]: ast_expr2.fl:407 ast_yyerror: ast_yyerror():  syntax 
> error: syntax error, unexpected '=', expecting $end; Input:
> =YES
>
>
> Of course I could use the following code, but this bloats up the code:
>
>
> if (${EXISTS(${FOOBAR})}) {
>    if (${FOOBAR}=YES) {
>      ...
>    }
> }
>
>
> Is there another syntax to have nice looking code but avoid the warning?
>   
How about

if ("${FOOBAR}"="YES") {

Julian
> thanks
> klaus
>
> _______________________________________________
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>
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> To UNSUBSCRIBE or update options visit:
>    http://lists.digium.com/mailman/listinfo/asterisk-users
>
>   

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On Thu, 2009-01-08 at 19:24 +0100, Klaus Darilion wrote:
> Hi!
> 
> I use the following condition:
> 
> if (${FOOBAR}=YES) {
>    ...
> }
> 
> The problem is, that if FOOBAR is not defined at all Asterisk generates 
> a warning:
> 
> WARNING[11982]: ast_expr2.fl:407 ast_yyerror: ast_yyerror():  syntax 
> error: syntax error, unexpected '=', expecting $end; Input:
> =YES
> 
> 
> Of course I could use the following code, but this bloats up the code:
> 
> 
> if (${EXISTS(${FOOBAR})}) {
>    if (${FOOBAR}=YES) {
>      ...
>    }
> }
> 
> 
> Is there another syntax to have nice looking code but avoid the warning?
Klaus--

The simplest I can think of is:

if ("${FOOBAR}"="YES") {
   ...
}

adding the quotes just makes it so if ${FOOBAR} evaluates to nothing,
then it will still end being a token, and you avoid the syntax error.

You have to keep in mind that by the time the $[ ... ] exprs are evaluated,
all ${..} constructs have been recursively evaluated away.

the wiki is a good reference for AEL2...
(http://voip-info.org/wiki/view/Asterisk+AEL2
and there is a page of example snippets.

murf

> 
> thanks
> klaus
-- 
Steve Murphy <murf at digium.com>
Digium
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Initialize FOOBAR to some know value (ie NO) and change it when you need 
to.  Then it will always be defined.

Klaus Darilion wrote:
> Hi!
>
> I use the following condition:
>
> if (${FOOBAR}=YES) {
>    ...
> }
>
> The problem is, that if FOOBAR is not defined at all Asterisk generates 
> a warning:
>
> WARNING[11982]: ast_expr2.fl:407 ast_yyerror: ast_yyerror():  syntax 
> error: syntax error, unexpected '=', expecting $end; Input:
> =YES
>
>
> Of course I could use the following code, but this bloats up the code:
>
>
> if (${EXISTS(${FOOBAR})}) {
>    if (${FOOBAR}=YES) {
>      ...
>    }
> }
>
>
> Is there another syntax to have nice looking code but avoid the warning?
>
> thanks
> klaus
>
> _______________________________________________
> -- Bandwidth and Colocation Provided by http://www.api-digital.com --
>
> asterisk-users mailing list
> To UNSUBSCRIBE or update options visit:
>    http://lists.digium.com/mailman/listinfo/asterisk-users
>
>
>

Klaus Darilion schrieb:
> I use the following condition:
> 
> if (${FOOBAR}=YES) {
>    ...
> }
> 
> The problem is, that if FOOBAR is not defined at all Asterisk generates 
> a warning:
> 
> WARNING[11982]: ast_expr2.fl:407 ast_yyerror: ast_yyerror():  syntax 
> error: syntax error, unexpected '=', expecting $end; Input:
> =YES
> 
> 
> Of course I could use the following code, but this bloats up the code:
> 
> 
> if (${EXISTS(${FOOBAR})}) {
>    if (${FOOBAR}=YES) {
>      ...
>    }
> }
> 
> 
> Is there another syntax to have nice looking code but avoid the warning?
if ("${FOOBAR}"="YES") {
   ...
}

or

if (x${FOOBAR}=xYES) {
   ...
}


   Philipp Kempgen

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