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doc: move enum methods to enum section from sum types (#13843)

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Nick Treleaven 2022-03-27 15:46:20 +01:00 committed by GitHub
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@ -3095,6 +3095,50 @@ Output: `Grocery IDs: 0, 5, 6`.
Operations are not allowed on enum variables; they must be explicitly cast to `int`. Operations are not allowed on enum variables; they must be explicitly cast to `int`.
Enums can have methods, just like structs.
```v
enum Cycle {
one
two
three
}
fn (c Cycle) next() Cycle {
match c {
.one {
return .two
}
.two {
return .three
}
.three {
return .one
}
}
}
mut c := Cycle.one
for _ in 0 .. 10 {
println(c)
c = c.next()
}
```
Output:
```
one
two
three
one
two
three
one
two
three
one
```
### Sum types ### Sum types
A sum type instance can hold a value of several different types. Use the `type` A sum type instance can hold a value of several different types. Use the `type`
@ -3145,50 +3189,6 @@ fn main() {
} }
``` ```
Enums can have methods, just like structs
```v
enum Cycle {
one
two
three
}
fn (c Cycle) next() Cycle {
match c {
.one {
return .two
}
.two {
return .three
}
.three {
return .one
}
}
}
mut c := Cycle.one
for _ in 0 .. 10 {
println(c)
c = c.next()
}
```
Output:
```
one
two
three
one
two
three
one
two
three
one
```
#### Dynamic casts #### Dynamic casts
To check whether a sum type instance holds a certain type, use `sum is Type`. To check whether a sum type instance holds a certain type, use `sum is Type`.