[fpc-pascal] corba interfaces - is/as not working properly

[David Emerson]

On 09/28/2016 12:40 PM, Lars wrote:

> Curious, where do corba interfaces come in handy ? When can you use them
> that object oriented code won't offer the same features?

For multiple inheritence, since fpc does not support multiple 
inheritence without interfaces. Interfaces are an addition to object 
oriented code, not separate from it.

In my particular case, in a project of mine in which I am drawing 
lattices, I have a concept of a node. Sometimes I want to draw that node 
myself using AGGPAS, and sometimes I want that node to itself be a 
Window/Widget, descending from fpGUI classes. If I'm using AGGPAS to 
draw the node, then I don't want the node to descend from fpGUI -- I use 
my own lighter-weight class hierarchy. So in order to be able to treat 
these two things the same, I define "enclosing node" as an interface. 
Now I can have classes descending from two (or more) different 
hierarchies, which both implement the enclosing node interface. I can 
write functions to do things with enclosing nodes, and get the benefits 
of polymorphism with multiple inheritence.

All that said, interfaces have their quirks and I wish we had more 
native support for multiple inheritence (also templates but that's 
another story) but anyway I'll take what I can get :-)

~David.