✅ Enum and generics
Hello there!
In our current code, we use structs to represent a packet;
Packet<Data>.
This packet (struct) has a ushort Identifier and a Codec<Data> Codec.
This Identifier should be unique, but currently we assign these manually:
This isn't ideal, so I considered using an Enum to represent the packet Id's, however that would mean that the packets would be in 2 places, the enum and the Packet instance holding the codec.
Is there a way to combine this? The ideal solution would be an enum with generic <Data> to allow enforcing the codec used:
But that is obviously not supported.19 Replies
So I'm either looking for
- A way to enforce unique Identifiers (incrementing)
- A way to use an enum while enforcing a generic type
what you want is a discriminated union
as you can see, right now it takes a lot of manual work to get something like that
adding a way to express such things more naturally in C# is a hot design issue that the language team is investigating https://github.com/dotnet/csharplang/discussions/7010
GitHub
[LDM] - Union Types · dotnet csharplang · Discussion #7010
The following is a summary of discussions held on discriminated unions in C# by members of the C# language design team. It is not a proposal, and it is not the actual meeting notes. Union Types Uni...
Ah, interesting
The
tag union is probably the closest to what I want
Well, I guess I'll just use the enum + instance method for now@Tim the libraries dotVariant or OneOf can do this for you
You can just use a Guid for your identifier. It should be globally unique on generation; no need to do discriminations in the database.
Could you elaborate on your usecase of using an enum in a generic type? It's possible but I'm not sure what you're trying to achieve.
Now the packet has 112 extra bits for no reason
An enum is a good choice here
I mean, it's a tradeoff 😄
Could you explain where the enum is used and how? I'm not understanding it from the text so far.
@jcotton42
No enum right now
Defining packet Id's manually, given to the
Packet struct instances
An enum works
But it will duplicate with the Packet struct
e.g.I don't see any advantage to using an enum in this scenario
You just want a unique Id, inside the ushort scope?
basically yes
shouldn't all send message instances have a different Id?
they should
if you use that enum, they'll all have the same value.
1 enum entry per packet
so incrementing Id
enum is not a good choice here. Enums represent a collection of bussiness-sensible labeled values
Yes- packet type Id's
Ok, so lets say you have this enum:
you make one packet, which uses PacketIds.SEND_MESSAGE value
which value will the next packet use for its Id?
an enum does not generate values.
It's simply a dictionary/map between labels and values:
By default, this
is actually
Whenever you use PacketIds.SEND_MESSAGE, you're just using
0Yeah ofc
.
I got that
I don't want 'generating' enums
that'd be useless since it's mostly a compile time thing
It's solved tho. Seems C# doesn't solve it itself, so I can choose between
- using an enum and having repeating packet names (enum entry
SEND_MESSAGE and packet instance SendMessage etc etc.)
- manually assigning Identifiers
- using a library (bit over the top for me tho)
It just seemed logical to make use of the enum property that it creates unique incrementing Id's
But the redundancy that creates in my case made me look for another alternative