On 5/1/12 8:02 PM, Brian Anderson wrote:
3) We can come up with a public API to create global, singleton tasks, possibly
with the following signatures:
unsafe fn register_named_service<T>(n: str, f: fn~(port<T>))
unsafe fn get_named_service<T>(n: str) -> chan<T>
This would, if the named service doesn't exist, create a new task and execute
the specified function. You would use this in each test to create or retrieve a
global service to manage your state. The big reservation I have about this is
that we can not currently make this interface type safe - we can't even check
the types at runtime.
So, brson and I were discussing this earlier. This was the most type
safe pattern I could come up with (it's still flawed):
enum named_service_key<T> = {
_named_service_key(str) // not exported
}
unsafe fn create_named_service_key<T>(n: str) -> named_service_key<T> {
_named_service_key(n)
}
fn register_named_service<T>(n: named_service_key<T>, f: fn~(port<T>))
fn get_named_service<T>(n: named_service_key<T>) -> chan<T>
then to create a named service you would do something like:
fn random_int_service_key() -> named_service_key<()> {
unsafe{create_named_service_key::<()>("random")}
}
Now at least the types are not provided anew at each call to
`get_named_service()` but rather they are specified when the named
service key is created. I use an unsafe fn to make the key itself since
that's the point where the type of channels is specified and that will
ultimately be unchecked.
But this all seems clumsy.
Niko
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