[news.eclipse.modeling.mdt.ocl] Re: OCLExpressions

[Ed Willink <ed@xxxxxxxxxxxxx>]

Hi Mary

You should ask this question on the M2M newsgroup with a [QVTo] subject 
prefix.

What you are doing does not seem to make sense. OCL is built-in to all 
the QVT languages so you do not have to construct OCL expressions from 
their AST elements. You appear to be working at what seems like two 
extra levels of encoding.

I would have thought that

if (self.name=Class1)  then 'true'.dump() else 'false'.dump() endif

would have met your requirements.

	Regards

		Ed Willink

mary wrote:
> Hello, I am new to OCL and I am trying to use it with QVT. I want to 
> create an OCL Expression from a string. I created a type 
> StringLiteralExp and in the stringSymbol attribute  i give it the OCL 
> string.
>
> var strExp:=object 
> OCL::expressions::StringLiteralExp{stringSymbol:='self.name=Class1'};
>     
> now i want to use this OCLExpression inside an if condition to evaluate 
> it and check if it is true or false. However, it seems that the if 
> condidtion always returns false. Which I guess because it is not 
> correctly evaluating the ocl expression.
>
> if(strExp=true) then 'true'.dump() else 'false'.dump() endif;
>
> So my questions are : 1. Am-I using the correct way to build an OCL 
> Expression from a string?
>
> 2. Is it possible to use the OCL expression inside an IF statement and 
> to evaluate it ?
>
> Thanks in advance.. Mary