Walter: extend existing classes with new methods?

[Ivan Senji]

Marcio wrote:
> 
>    If I understood your argument correctly, you are saying that you 
> can't have a compiler compile code for a class if the source is split 
> across multiple source files? Because, after all, that's all we're 
> talking about here. Class foo has some code in foo.d, some code in bar.d 
> (it added methods to foo) and so on.
> 
>   Well, if we are going to use that argument, we might as well move back 
> in time to the old days of Turbo Pascal 3.0. If you wanted to use a 
> procedure Foo, it had to have already appeared in the source. So, for 
> cases like recursive descendent parsers or recursive tree traversal you 
> had to declare the function, and later have it appear again, with the 
> body itself. This allowed you to have mutually recursive procedures. 
> This was because the compiler couldn't do any look-ahead or 2-pass. Way 
> to go, put the burden on the developer because of a compiler limitation. 
> Fina when you have 64KB of RAM like the MSX I guess...
> 
>   I think compilers should serve developers, not the other way around.
> 
>   By the way, the reason Java source has so many "instanceof" is because 
> it doesn't allow this type of extension. If the language allows 
> extensions, you can easily code things with polymorphism by adding say 
> isFoo to Object (return false) and overriding it in your Foo class 
> (return true). No need for instanceof. You want to know if the object 
> isFoo? Damn, just ask it. Use OO. This is a very common pattern of 
> coding in systems like Smalltalk.

Now I know I misunderstood you. Extension methods I was thinking of are 
like the ones in C#3.0 and they can only be static. I don't see how 
adding a nonstatic method should work. Static extension methods might 
not be as useful as nonstatic ones but it can be a nice feature.