Hello,

I'm looking to use the Tuple type as a way of generating types to represent data in a send recieve connection pair. I created a template to try this:


template s_to_c(UDP packetType) {
         static if (packetType == UDP.ping) {
    alias Tuple!() s_to_c;
  } else static if (packetType == UDP.connect) {
    alias Tuple!(byte) s_to_c;
  } else static if (packetType == UDP.keep_alive) {
    alias Tuple!() s_to_c;
  }
}

(UDP is a enum with packet types.)

This works, but it also means that s_to_c(UDP.ping) is the same type as s_to_c(UDP.keep_alive). I want to be forced to distinguish between types, even if they contain the same fields, so that

recieve(
  (s_to_c!(UDP.ping) value) { },
  (s_to_c!(UDP.keep_alive) value) { }
)

isn't an error.

Any suggestions are welcome, and thanks for any help,

-Evan Davis

On Friday, 6 June 2014 at 23:44:04 UTC, Evan Davis wrote:
> Hello,
>
> I'm looking to use the Tuple type as a way of generating types to represent data in a send recieve connection pair. I created a template to try this:
>
>
> template s_to_c(UDP packetType) {
>          static if (packetType == UDP.ping) {
>     alias Tuple!() s_to_c;
>   } else static if (packetType == UDP.connect) {
>     alias Tuple!(byte) s_to_c;
>   } else static if (packetType == UDP.keep_alive) {
>     alias Tuple!() s_to_c;
>   }
> }
>
> (UDP is a enum with packet types.)
>
> This works, but it also means that s_to_c(UDP.ping) is the same type as s_to_c(UDP.keep_alive). I want to be forced to distinguish between types, even if they contain the same fields, so that
>
> recieve(
>   (s_to_c!(UDP.ping) value) { },
>   (s_to_c!(UDP.keep_alive) value) { }
> )
>
> isn't an error.
>
> Any suggestions are welcome, and thanks for any help,
>
> -Evan Davis


Is there any reason you couldn't (or would rather not) use structs rather than tuples?

On Saturday, 7 June 2014 at 03:14:52 UTC, Chris Nicholson-Sauls wrote:
> Is there any reason you couldn't (or would rather not) use structs rather than tuples?

That would work. What would be the best way to auto-generate the types? I have somewhere around 30 already, and the number will grow with this project.

Evan Davis

>> Is there any reason you couldn't (or would rather not) use structs rather
>> than tuples?
>
>
> That would work. What would be the best way to auto-generate the types? I have somewhere around 30 already, and the number will grow with this project.
>
> Evan Davis

Maybe you could use a struct template, with UDP as a template parameter. It'll instantiate a different type for each UDP value. If you add new possible values to the enum, the rest of the code will follow.

struct SendReceivePair(UDP udp)
{
    /// maybe here some different values, differentiated by static if,
if needed.
}

Then, use these types directly in 'receive':

receive(
  (SendReceivePair!(UDP.ping) value) { },
  (SendReceivePair!(UDP.keep_alive) value) { }
)

If you want to 'retrieve' the UDP template parameter, you can expose it through an alias:


struct SendReceivePair(UDP udp)
{
    alias packetType = udp;
}

So, given SendReceivePair!(xxx) srp, you can get 'xxx' by srp.packetType;