| java as language for constraints validation [message #57213] |
Thu, 28 September 2006 16:12  |
Eclipse User |
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Originally posted by: john.watson.yahoo.com
Hi,
where can I get more info how I can use java as language for constraints
validation in Audit Rule in gmfmap file? (How can I get all object for any
EClass, how to get the desired attribute, how to validate; any limitations
if exists, etc)
Thanks in advance!
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| Re: java as language for constraints validation [message #57506 is a reply to message #57213] |
Fri, 29 September 2006 12:14  |
 Radomil Dvorak
Messages: 249
Registered: July 2009 |
Senior Member |
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Hi John,
It's on my TODO list to provide such info
(https://bugs.eclipse.org/bugs/show_bug.cgi?id=159255).
For now, see comments bellow:
Java should be usually the option, when the expression logic represents
excessive complexity or requires direct access to complete ecore reflective
API,
which is impossible with the rest of supported languages (like OCL).
While the other language alternatives can be validated at modeling time and
interpreted at runtime, a concrete java implementation
is to be provided by the user as a post code-generation step. In other
words, a java expression body attribute is not to contain the actual java
source code.
Instead, the body holds a java identifier, which becomes the basis for
deriving a name for the corresponding java element in the generated code.
The common convention of EMF code-generation has been adopted and an
operation skeleton for every java expression is generated.
This skeleton has appropriate context (eventually environment variables, for
instance in case of LinkCreationConstraints) as arguments and its default
implementation only throws an exception reporting 'Missing user
implementation!'.
As soon as the user provides a custom implementation, the operation should
be marked as @generated NOT in order to preserve it across generation
sessions.
Which class will be the owner of the skeleton operation is dependent on the
type of the expression based construct in GMF models.
As an example:
AuditRule {
Constraint {
lang : 'java'
body : 'checkEClass_NonEmptyName'
}
DomainElementTarget{
element: ecore::EClass
}
}
results in generation of the following code in the GMF diagram
....ValidationProvider class.
/**
* @generated
*/
static class JavaAudits {
/**
* @generated
*/
private static Boolean checkEClass_NonEmptyName(EClass self) {
// TODO: implement this method
// Ensure that you remove @generated or mark it @generated NOT
throw new EcoreAbstractExpression.NoImplException(
"No user java implementation provided in 'checkEClass_NonEmptyName'
operation"); //$NON-NLS-1$
}
} //JavaAudits
It's worth mentioning, that there are also other options.
You can implement your own org.eclipse.emf.ecore.EValidator (see
http://dev.eclipse.org/viewcvs/indextools.cgi/*checkout*/org .eclipse.emf/doc/org.eclipse.emf.doc/references/overview/EMF .Validation.html).
If registered, it gets involved in GMF diagram validation automatically.
As GMF diagram validation uses EMFT Validation framework, you can also
create EMFT constraintProvider extension (see
http://help.eclipse.org/help31/index.jsp?topic=/org.eclipse. gmf.doc/tutorials/msl/validationTutorial.html).
It will be included in GMF diagram validation as well.
Regards,
/Radek
"John Watson" <john.watson@yahoo.com> wrote in message
news:ac37f348421836751a4e7a1959cee894$1@www.eclipse.org...
> Hi,
>
> where can I get more info how I can use java as language for constraints
> validation in Audit Rule in gmfmap file? (How can I get all object for any
> EClass, how to get the desired attribute, how to validate; any limitations
> if exists, etc)
>
> Thanks in advance!
>
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