The following are meanderings.  They would be nice to have in ColdC, but
probably wont exist (perhaps ColdC 2.0).

----- Better error handling:

'retry' will direct it to rewind and retry the block of code in the
catch body.  For example:

mode = 'read_write;
catch any {
    obj.do_something(mode);
    return "Yipee, we did it!";
} with {
    if (error() == ~locked) {
        mode = 'read_only;
        retry;
    }
    return "Ack, error: " + error();
}

------ procedures:

Procedures are simply methods, which are not bound to objects, and which can
be passed around as data.  Furthermore, they can access 'external' local
variables (not object variables), within their scope.

public method .test(): nooverrides {
    arg threshold, list;
    var target, obj, add;
   
    add = closure {
        arg elem;
        import threshold;
        var total;
  
        target.add(elem);
        if (++total > threshold)
            throw(~max, "Maximum threshold breached.");
    };
   
    for x in (list)
       (> exec add(second) <);
};

-------
Miro created some pseudo code which may be used to implement ancestor
caching for is_ancestor:

typedef struct {
    int a,b;
    int result;
} ancestor_cache;

#define CACHE_SIZE 1257

ancestor_cache c[CACHE_SIZE];

int is_ancestor (object a, object b)
{

    int i;
    int hash;
    int res;

    if (a==b) return 1;
    hash=(a*1293112123+b*1723812128)%CACHE_SIZE;
    if (c[hash].a==a && c[hash].b=b) return c[hash].result;
    res=0;
    for i in parents(b) {
        if (is_ancestor(a,i)) {
            res=1;
            break;
        }
    }
    c[hash].a=a;
    c[hash].b=b;
    c[hash].result=res;
    return res;
}