Overriding properties inline

Like discussed in #822 it should be possible to override some attributes inline in a functionblock/entity.

Here some examples: Example1:

namespace com.ipso.smartobjects

functionblock Distance {

   status {
       mandatory sensor_value as float
       optional sensor_units as string 
       ...    
   }
}

Information model using the IPSO model and overriding it:

using com.ipso.smartobjects.Distance;0.0.1

infomodel MyDistance100MeterDevice {

   functionblocks {
       distance as Distance with {
            mandatory sensor_value as float <max:100>
       }
   }
}

Example2:

entity EntityA {
	mandatory valueA as int
	optional valueB as int
}

using de.vorto.EntityA;0.0.1

functionblock FunctionblockA {
   status {
       mandatory entityA as EntityA
       optional unit as string 
   }
}

using de.vorto.FunctionblockA;0.0.1

infomodel DeviceA {
   functionblocks {
       distance as FunctionblockA with {
            mandatory entityA as EntityA with {
            	valueA as int <MAX 100>
            }
       }
   }
}

[e-grigorov]

My understanding on this topic is that there are:

• descriptions - that’s the data type description, function block description and info model description
• description consumers - function block uses the data type descriptions, the info model uses the function block descriptions etc.

If this feature is integrated, no such thing like “description” will exist any more. The application has to merge the info model with the function block to find the function block complete description. To me, it’ll break the main goal of Vorto: clear models.

To compare with OOP, the subsclass should not change the contract from the base class - Liskov substitution principle

[thjaeckle]

Do I understand correctly that by this I can no longer rely on that a functionblock always contains a well defined (and versioned) contract but that it depends on the context? And even worse I cannot rely on the defined entities because they may also be changed by the context (infomodel).

What is the point of a functionblock then if I cannot rely that it is the same when used in different infomodels?