Re: function "exists" ?

I will add such a predicate - should be pretty trivial.
 
However, the way we normally handle this is to add the optional
attribute as a simple null value into the base template, for example
    swapsize;
 
then any link to it will succeed, but have a null value if not set by
override. Note that the ifThenElse will give exactly the same result as
such a link.
 
Patrick
 

________________________________

From: smartfrog-developer-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org
[mailto:smartfrog-developer-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org] On Behalf Of
Xavier Grehant
Sent: 19 July 2006 18:47
To: smartfrog-developer
Subject: Re: [Smartfrog-developer] function "exists" ?


Julio -

I think it checks if sfSchema is true, not if it exists because when it
does not exist the parser fails at link resolution...

sfSchema true;

//Prim with any schema
Prim extends NULL {
    sfPrimSchema extends ifThenElse { 
        if sfSchema;
        then extends PrimSchema;
        else NULL;
    }

Indeed It would be nice to use ifThenElse but with something like this:

LoopBackDomain extends Compound {
   backend extends LoopbackStorageBackend { 
       //...
       swapSize extends ifThenElse {
            if DEF PARENT:PARENT:swapSize;
            then PARENT:PARENT:swapSize;
            else NULL;
        }
    }
    //...
}

LoopbackDomainSchema extends Schema { 
   swapSize extends OptionalInteger;
}
sfConfig extends LoopbackDomain {
        //swapSize not here because it's optional
}

So I was wondering if there was such a DEF function?



Thank you,
Xavier

On 7/19/06, Guijarro, Julio <[email protected]> wrote: 

	An example used in  prim.sf

	 

	    sfPrimSchema extends ifThenElse {

	        if sfSchema;

	        then extends PrimSchema;

	        else NULL;

	    }

	 

	This creates an attribute called sfPrimSchema if sfSchema is
exists if not, it makes it NULL.

	 

	Julio

	 

	
________________________________


	From: smartfrog-developer-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org
[mailto:smartfrog-developer-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org ] On Behalf Of
Xavier Grehant
	Sent: 19 July 2006 15:38
	To: smartfrog-developer
	Subject: [Smartfrog-developer] function "exists" ?

	 

	
	Hi -
	
	Is there a way to check if an attribute exists in a smartfrog
description?
	The idea is to be able to have an optional attribute
	attr2 PARENT:attr1
	when attr1 is optional in the parent.
	
	Thank you, 
	Xavier

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