Declaring methods with `in` parameters
If a I'm writing a synchronous method, should I always declare read-only value types with the
in keyword.
9 Replies
in is basically readonly ref
Only matters when passing some super large structs, to avoid copying
fwiw, I've seen in used in the wild maybe, like, twiceBut are there downsides to declaring it like this or is just overkill?
From what I understand the caller doesn't have to specify the
in keyword when calling the method, but still benefit from it.Overkill
And only really works with value types
For reference types, you're already passing a reference
Yeah I know it is just for value types, but was just curious what the general consensus was. Like at what point do I need to consider using it
There are downsides, yes. There's more overhead to ref parameters
Unless you have a struct over 16 bytes, you probably shouldn't use it
Okay now I'm curious, what is the overhead?
Refs are tracked by the gc
even for structs that contain no reference types?
Yes. The location of the struct could change
For example, if you passed a ref to a field of a reference type
Even if there's no chance the location can change, knowing that is a tiny bit of overhead