[snip]This bit comes from the p6i list, and I just thought I'd ask those in-the-know if my suggested "returntype" role/property would make sense here, or if there's another way to do it that makes more sense?
For that matter, does MMD on return type map into Perl6's gestalt at all, or would it be tumorous?
To sum up:
Dan: return continuations and MMD calling means we can dispatch return via MMD
Aaron: suggested an implementation in Perl and Python. In Perl, it would be a role/propery called "returntype" that would take some sort of list or hash of types and closures. The difference between this and a given/when block being that the MMD internals of parrot handle which closure is invoked based on the return type. Thus, very low overhead.
My example in the attached message is mostly error handling, but that's obviously not the only way it could be used....
$sock.peername()
does returntype(
Net::Address::IP -> $ip {
die "Remote host unresolvable: '$ip'";
}, Net::Address -> $addr {
die "Non IP unresolvable address: '$addr'";
}, Str -> $_ {
print "Seemingly valid hostname: '$_'\n";
});
Could this just work with the switch statement somehow? If not, could 'when' be extended to take a signature that is matched against the return 'arguments'?
given $sock.peername() {
when(Net::Address::IP){
die "Remote host unresolvable: '$_'"
}
when(Net::Address){
die "Non IP unresolvable address: '$_'"
}
when(Str){
print "Seemingly valid hostname: '$_'\n"
}
}or more complexly
sub foo {
return time if time % 2;
return (time,
() = gmtime)# ya, I know p6 has a better way,
# but I can't remember it right now
}
given foo(){
when(Int){
say $_, " ", join " ", gmtime $_
}
when(Int $t, Array @gmt){
say $t, " ", join " ", @gmt
}
}Dan
