On 09/09/2014 04:04, Marvin Humphrey wrote:
However, we have a problem with C implementation code: how can we get the C
compiler to tell us whether invoking an interface method on a given value is
safe?
In Go, the compiler detects invalid assignment to an interface variable
(<http://play.golang.org/p/mT743SWoxu>):
package main
type Futzer interface {
Futz()
}
func main() {
var futzer Futzer = "I am not a Futzer" // fails to compile.
futzer.Futz()
}
In Clownfish-flavored C, we can perform a runtime check:
You can also perform a runtime check in Go
(http://play.golang.org/p/8irDzxASe4):
futzer, ok := any.(Futzer)
if ok {
futzer.Futz()
} else {
fmt.Println("Not a Futzer")
}
I think we can make that check redundant using DSO-style lazy loading
techniques: have each class start off with a dummy interface table populated
with stubs which lazily build the interface table, replacing themselves and
reinvoking on success or throwing an exception on failure.
I can't see how this would work. The interfaces a class could implement aren't
known at compile time.
Nick
