CODEWITHSUNDEEP
delphirtti
Ulisses Caon
Ulisses Caon

Reputation: 470

How to call a Generic procedure recursively with delphi and RTTI?

I'm working on Delphi 10.2 Tokyo and facing the following situation:

Assuming I have the following procedure, to verify the properties of an object:

procedure TGenericUnit.VerifyProps<T>(_AObj: T);
var
   AContext: TRttiContext;
   AType: TRttiType;
   AProp: TRttiProperty;
begin
   AType := AContext.GetType(T);
   for AProp in AType.GetProperties do
      if AProp.PropertyType is TObject then
         // VerifyProps<?>(?);  
end;

If I don't know which type of object it will be and it won't necessarily be the same as T, how could I call this procedure recursively?

Upvotes: 0

Views: 498

Answers (2)

Stefan Glienke
Stefan Glienke

Reputation: 21758

Do all your work in a non generic method working with TObject. You can get the type from AObj.ClassType or AObj.ClassInfo passing that to AContext.GetType.

By the way your check if AProp.PropertyType is TObject then is wrong because yes of course PropertType is a TObject (it is an TRttiType object). What you probably mean is if AProp.PropertyType.IsInstance then (is the type of the property a class type)

Upvotes: 5

David Heffernan
David Heffernan

Reputation: 613461

Generics are a compile time construct. The type parameters must be resolved at compile time. Since you don't know the type at compile time you can't call the generic method.

Instead of using a generic method, you will have to implement this using RTTI. Instead of using a generic parameter to specify the type, use a standard parameter of type TRttiType.

Upvotes: 3

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