Static disptach OR dynamic dispatch

[Fresenius_Medical_Care]

In object-oriented programming, when you have a class hierarchy like "Square" inheriting from "Rectangle," Is it better to use dynamic dispatch (polymorphism) or static dispatch (method hiding or shadowing) for the "WriteHeight" and "WriteWidth" functions?

[raphschru · Accepted solution]

Hi Fresenius,

If you want to allow (or force) redefinition of these methods in the child class, you must use dynamic dispatch (for both base and child methods). Static dispatch is used when a method should not be redefined by a child class.

Also, the concept of method hiding like in java does not exist with LabVIEW Objects.

If, in a child class, you try to name a static method the same as a static method in one of its ancestor classes, your method will be broken with the error: "This VI attempts to override a static VI in an ancestor class". So you'll either have to make the methods dynamic or choose another name for the method in the child class.

Also, your example is a bit particular because mathematically speaking, the width and height of a "Square" should not be set independently. So you would have to override methods "WriteWidth" and "WriteHeight" to make them write both width and height to the same value.

Regards,

Raphaël.