On 13.05.2012 02:49, Leonardo M. Ramé wrote:
On 2012-05-12 13:07:18 -0300, Leonardo M. Ramé wrote:
Thanks Sven and Michalis. Using the suggestion by Michalis, I got a
solution mixing Generics and regular objects.
What I'm pursuing is to replace my TCollection based ORM, with a
Generics based one, this allow users to write less code, in a clearer
way.
The way the ORM works, is to create a TCollection instance, then execute
an ORM's method to load/save data into/from it, example:
var
lCustomers: TCustomers; // this is a TCollection descendant
begin
lCustomers := TCustomers.Create;
FConnector.LoadData(lCustomers, []);
... do something with lCustomers ...
lCustomers.Free;
end;
As you can see, FConnector.LoadData receives a TCollection as parameter,
and using RTTI, it fills each TCustomer published property.
With Michalis's solution, I can turn my ORM from TCollections to
Generics with very little changes, see how small is the unit customer
now, instead of a complete TCollection/TCollectionItem definition:
Following the same subject, inside a method receiving an TFPSList, how
can I know the type of items it will contain, even if the list is
empty?.
In a TCollection, I can use myCollection.ItemClass to know it, but in a
specialized Generic type, how can I know, in an abstract way the type of
a TFPGList<T>?. I mean, what type is T?.
You can't. That's why the method with the "parent class" might be
considered less powerful than the one with generic methods/procedures.
Regards,
Sven
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