[news.eclipse.modeling.m2m] Re: [QVTO] Nullable enumerations

["radek dvorak" <dvorak.radek@xxxxxxxxx>]

Hi Alex,

At the moment there is no direct support for this in QVTO.
Could you please raise bugzilla so we can track this down
https://bugs.eclipse.org/bugs/enter_bug.cgi?product=M2M&component=QVT_OML-Engine

Regards,
/Radek


On Tue, 25 Aug 2009 00:02:26 +0200, Alex <alex.leites@xxxxxxxxx> wrote:

> Is there any way QVT could directly support EMF/Ecore nullable  
> enumerations pattern? Currently assigning to an attribute using this  
> pattern in QVT requires additional cast of the EnumLiteral being  
> assinged to the "wrapper" EDataType ...
>
> Some background: There appears to be a standard EMF/Ecore pattern for  
> nullable enumerations (enumerations that can have a null value in  
> addition to their null values) - using an additional "wrapper" EDataType  
> as a type for an attribute, linked to the appropriate EEnum via  
> ExtendedMetadata annotation. This patterns is used by XSD-derived Ecore  
> models, and is frequently referred to as pattern of choice for this kind  
> of thing on EMF forums.  (The only alternative is to introduce a special  
> NULL EnumLiteral into each nullable enum.)
>
> This should only take a check for relationship between EDataType and  
> enumeration literal for the assignment. Admittedly, this would have to  
> reach into Ecore annotations, which is somewhat unusual I assume for QVT  
> compiler, but the pattern appears to be common enough and important  
> enough to justify supporting it directly...
>
> Thank you,
> Alex