[OCL] How to handle accessing protentially non-existing properties

Question

I am a beginner in ocl so there are things that I don't know how to handle yet.

I am building a dynamic constraint which does a coherence check based on a "user_level" profile property (Profiling/System Design/Element).

The check is basically the "user_level" of an element has to be higher than the "user_level" of it's parent.

Context: sysml::SysMLElement

inv:
let
	level:Integer = self.getProfilePropertyValue('user_level'),
	parentLevel:Interger = self.mediniGetContainer().oclAsType(sysml::SysMLElement).getProfilePropertyValue('user_level'),
in
	parentLevel < level

The principal issue I have is that mediniGetContainer() can return something that does not have the "user_level" property (e.g. System Model). OCL has strict access rules during the coding so I though I was being clever with "oclAsType(sysml::SysMLElement)" but it obviously does not work. I don't know what's the cleanest way to handle this.

The other issue I have is that sysml::SysMLElement seems to contain ports and defining user_level in Profiling/System Design/Element does not impact ports. Can you tell me which context in dynamic constraints is strictly equivalent to Profiling/System Design/Element ?

Have a nice day,

Adrien Gerard

medini_1024169437 · Answer

Gerard,

I assume parentLevel is undefined in case the object does not have that property? I wonder how hat OCL works at all, I mean, getProfilePropertyValue does not return an Integer typically. One way is to write an OCL constraint that explicitely checks the type of the parent before actually getting the level, something ike (pseudo code):

in

parent.oclIsTypeOf(...)

and

parent.getProfilePropertyValue(...) > otherValue

medini_1050701002 · Answer

I solved it (it was sysml::SysMLPart and that gave other errors which preventede the code from functionning correctly).

Apparently getProfilePropertyValue() does not mind if I'm trying to get something that doesn't exist but I don't know what is the best practice.