Warning W60: require not met for a call to a virtual method

Elements Oxygene
1

Hello,
compile the following class library:

namespace ClassLibrary1;

interface

  type
    Class1 = public abstract class
    assembly

      method Load;
      begin
        Load (Nil)
      end;

    public

      method Load (Data : Object); virtual;
      require
        assigned (Data);
      begin
      end;

    end;

implementation

end.

Warning:

C:\Temp\ClassLibrary1\ClassLibrary1\Class1.pas(11,14): warning W60: Requirement (assigned(Data)) for method “method Class1.Load(Data: Object)” not met

As the Load (Object) is virtual, it could be overridden in a descending class.
What I would like to test in the base method is that a descending class calling the base method should provide a value.

2

One could argue that the contract is that data is assigned though? And that subclasses should meet that too?

3

In my case, the parameter is a database table.
The base method needs it to load the data, but an overloaded method knows the database table(s) to use.
In some cases, an overloaded method calls the base method twice, with different tables.
That’s what I would like to define here.

4

Well, really your abstract class just should not call Load(nil) then, because IF that code ever ran, it’d ostensibly crash?