wish for new nemerle feature: Java like anonymous classes

[jens]

example:

foo(i : int) : SomeType {
SomeType(i) /* syntax and semantic as constructor call but SomeType
may be abstract or interface (no arg for interface though) */
{
/* syntax as class body, semantic as local functions body */
public bar() : bool{
i > 0
}
}
}

=>

class UniqueName : SomeType{
UniqueName(i : int) : SomeType(i){
}
public bar() : bool{
i > 0
}
}
foo(i : int){
UniqueName(i)
}

[catbert]

Hmm, when I'm in need of anonymous classes, I always can get this
behaviour using local functions.

E. g., for your case you can write something like:

def foo = x => x > 0;

And you can for example sort a list:

List[string] x;
FillListWithRandomStrings(x);
x.Sort(foo);

[jens odborg]

Sure you can do the behaviour part with local functions but other net components expect you to fullfill an interface, unless that interface is enumerable (where you can use cofunctions and yield) you currently have to create some glue code to map the local functions to the interfacess, basically what you want is to return a class where your local functions fullfill an interface or overload methods in an existing class

[catbert]

Now I see. It would probably be interesting to implement such a
feature using Nemerle macros.

[jens odborg]

Yes, I guess so but for different reasons it seems that it cant be done as a pure syntax extension instead you probably have to rely on calling compiler internal parser functions.

 

e.g. the most elegan syntax would be

 

constructor_name (parameter_to_base) { new class members }

but (among other)

• syntax must start with a keyword
• "{" ... "}" is not supported in "syntax(...)"
• there is currently no hook for parsing class body members

 

 

 

On 2/23/09, catbert <catbe...@gmail.com> wrote: