>
> type Y struct {
> //some fields
> }
>
> This rather depends on what those some fields ARE, and whether type Y is
conceptually mutable or immutable.
For example, I might make a lightweight struct just to group a pair of
values; X/Y coordinates, or Latitude and Longitude:
type LatLon struct {
Latitude, Longitude float64
}
or the like, and in that case, I might treat it as immutable, and just make
a new one if I needed changes, in which case doing a map[string]LatLon
would be fine.
If the struct is larger or is mutable, then a pointer makes more sense.
BUT! There is one *critical* case to consider.
type Something struct {
guard sync.Mutex
... guarded things
}
This one MUST be done as a pointer, otherwise you are copying the mutex
when you assign to the map, or assign from the map to a variable. As the
docs say, "A Mutex must not be copied after first use."
So if you have mutexes or mutable values in the struct, best to use *.
"Only use the non-pointer map when your structs are simple, small, and
immutable" is probably a reasonable rule of thumb.
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