[plt-scheme] About "interface" in MzScheme

For now, they are "stamps" on a class that "bless" it as "it implements 
this interface." You can then test it with is-a and validate that nobody
has given you a bad thing. It's like predicates on numbers, booleans, 
structures, and other things. 

We may also add contracts to interfaces one day. Don't hold your breath
however. 

-- Matthias



At Wed, 19 Jun 2002 15:01:51 +0800 (CST), =?big5?q?Oscar?= wrote:
> [Please handle PLT Scheme list administrative tasks through the Web:
>    http://list.cs.brown.edu/mailman/listinfo/plt-scheme]
> 
> Hi All,
>   I'm new to MzScheme and feel exciting 
> about the OO system =). 
>   However, I wonder what's the "interface" 
> for? In Java/C++ interfaces or classes with 
> pure abstract methods are used as place holder 
> for real implementation of methods. However, 
> in Scheme you do not even need to worry about 
> types when you create variables to hold the 
> object. 
> 
>   e.g. 
>    In Java:
>     public interface MyInterface {
>       public void doIt();
>       ...
>     }
>     public class MyClass implement MyInterface {
>       public void doIt();
>       ...
>     }
> 
>     public class OtherClass {
>       public void go(MyInterface mi) {
>         // so we are sure "mi" have "doIt()"
>         mi.doIt();
>       }
>     }
> 
> 
>    In Scheme:
>     // no need to declare type for "obj"
>     (define obj (make-object MyClass%))
> 
> So why do you need interfaces?
> Are there any more detailed tutorial to
> OO system of MzScheme besides the Manual?
> 
> Regards,
> Oscar
> 
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