[Laszlo-dev] Is this the idiom people use to set the initial value of an attribute in a class declaration?

[P T Withington]

The bug we have is that we don't treat every instance initializer as  
an expression, so you can't say `value="new Array"` to get around the  
sharing, you have to say `value="${new Array}"`.  I think this is an  
FAQ that Antun covers.

And yes, you are right.  This would be solved by moving attribute  
initializers into the class initializer.

But if we fix this bug, we'll need to provide a way to share in the  
cases where you _do_ want to share, perhaps by providing an LZX way  
to declare a static attribute?

On 2007-07-08, at 22:25 EDT, Henry Minsky wrote:

> I've been hacking on an app this week, and realizing it's been  
> awhile since
> I tried
> to actually program anything in Laszlo.
>
> There's this huge "gotcha" when setting the initial value of  
> attributes to
> an object in a class
> declaration, like this
>
>
> <class name="foo">
>  <attribute name="pets" value="[]"/>
>
> Which screws you since that object will now be shared among all  
> instances.
>
> The idiom I think I remember people using is
>
> <class name="foo">
>  <attribute name="pets" value="$once{[]}"/>
>
> Or more readably
>
> <class name="foo">
>  <attribute name="pets" value="$once{new Array()}"/>
>
> Is that what we recommend to do now? I guess we going to quietly  
> fix this
> issue if and when we get
> our node initialization rewritten as a compile-time-generated  
> initializer
> function?
>
>
> -- 
> Henry Minsky
> Software Architect
> hminsky at laszlosystems.com