gistfile1.rs

extern mod extra;

use extra::treemap::TreeMap;
use extra::json::{Json,Object};

enum NestedSearchError {
        NoSuchAncestor(~str),
        NoSuchKey,
        TypeMismatch
}

trait NestableObject {
        fn find_nested(&self, key: &~str) -> Result<Json, NestedSearchError>;
}

impl NestableObject for Object {
        fn find_nested(&self, key: &~str) -> Result<Json, NestedSearchError> {
                Err(NoSuchKey)
        }
}

fn main(){
        let obj = Object(~TreeMap::<~str, Json>::new());

        match obj.find_nested(&~"dog") {
                NoSuchKey => println("Couldn't find that key."),
                _ => println("Unexpected result.")
        }
}

/* 

simplejson.rs:25:7: 25:33 error: type `extra::json::Json` does not implement any method in scope named `find_nested`
simplejson.rs:25        match obj.find_nested(&~"dog") {
                              ^~~~~~~~~~~~~~~~~~~~~~~~~~
error: aborting due to previous error
task 'rustc' failed at 'explicit failure', /home/zslayton/rust/src/libsyntax/diagnostic.rs:102
task '<main>' failed at 'explicit failure', /home/zslayton/rust/src/librustc/lib.rs:393

*/