Re: [Webmacro-devel] RE: Binary accessor "set" problem

[Lane S. <la...@op...>]

Keats wrote:

> An update on a cold thread ...
>
> In playing around with the XmlDemo, I thought I had re-encountered 
> this elusive bug.  But then I realized the reason ...
>
> I tried to do something like:
>
>   #set $jdomElement.AttributeValue.Thinga = "mabob"
>
> and I got a NullPointerException.  After looking at the 
> PropertyOperator code, the problem was suddenly obvious.  WM will 
> always look for a "unary accessor" before a "binary mutator".  In this 
> case, it finds a getAttribute() method, which happens to return null, 
> hence the NPE. 

did you mean getAttributeValue() and not getAttribute() relative to your 
code?

>
>
> Perhaps this is the problem Marc was seeing?
>
> Anyway, it's not clear to me how to "fix" this.
>
> We could catch the exception and then look for a binary mutator before 
> throwing.  But this could result in inconsistent behavior.  For 
> example, in the above case, if the attribute "Thinga" did exist, you 
> would get an error, since you can't assign a String to a JDOM 
> Attribute field.
>
> Alternatively, we could always check for the "binary mutator" first. 
> This makes some sense, but there are issues here as well.  It would 
> break backwards compatability for anyone relying on the unary-first 
> behavior.  This probably wouldn't effect many templates, but if it did 
> it could be a puzzling error.  It also might have performance 
> implications.
>
> My feeling is that we should just document the behavior and live with 
> it.  But if anyone feels strongly that this is bad, I'm open to 
> persuasion.
>
> Keats
>
>
>
>
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