[fpc-pascal] Implementing Factory Method with Pascal

[Graeme Geldenhuys]

Hi Anthony,

On 2015-11-28 00:16, Anthony Walter wrote:
> type
>   IBarkable = interface(IInterface)
>   ['{B241068F-2ED9-43C7-066B-778B94CB58F9}']
>     procedure Bark;
>   end;
> ...snip...

That is a much better solution for what Luciano wants to accomplish.


> and later ...
> 
> if Animal is IBarkable then (Animal as IBarkable).Bark;

This is not good usage of Interfaces. Use the interface variable instead.

var
  intf: IBarkable
begin
  if Supports(Animal, IBarbable, intf) then
  begin
    intf.Bark;
    // you can continue here using intf further without casting
  end;



Regards,
  - Graeme -

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