[news.eclipse.modeling.mdt.ocl] Re: New to EMF and OCL

[Ed Willink <ed@xxxxxxxxxxxxx>]

Hi Richard

I don't really understand what you're asking.

A pre-condition is a side-effect free expression that can be used to 
determine whether the invocation context is suitable to invoke a function.

The function can the do whatever it likes.

A post-condition is a side-effect free expression that can be used to 
determine whether the function behaved as expected.

Sometimes the post-condition may be sufficiently simple to be able to 
reinterpret its is-it-so query into a make-it-so operation. That is not 
what OCL does, although a specific form of OCL code synthesizer might.

	Regards

		Ed Willink


Richard Catlin wrote:
> All,
>
> I am using the EMF Framework Validation Plug-in: "OCL Example".  It 
> allows me to write OCL expressions in a text file.
>
> Is it possible to set properties in the model based on OCL expressions? 
>  The OCL 2.0 Spec says that expressions are guaranteed to be without 
> side effects, but then goes on to say that OCL expressio can be used to 
> specify a state change (eg. in a post-condition).
>
> Pardon me if this is an obvious question.  I am new to EMF and OCL.
>
> Thank you,
> Richard Catlin