Go Enumerations
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External
Internal
Overview
Go does not have formal enums, but the language allows for sets of related, yet distinct int
constants. They represent a property that has several distinct possible int
values, like the days of the weeks or the months of the year. They are declared using the pre-declared constant iota
:
type DayOfTheWeek int
const (
MON DayOfTheWeek = iota
TUE
WED
THU
FRI
SAT
SUN
)
To make the enumeration constants visible outside the package, they need to start with a capital letter.
The enumeration constants can be rendered as strings by making the enum type implement a Stringer interface:
func (dotw DayOfTheWeek) String() string {
return []string{"Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday"}[dotw]
}
The inverse conversion can be done with a map:
var stringToDayOfTheWeek = map[string]DayOfTheWeek{
"Monday": MON,
"Tuesday": TUE,
"Wednesday": WED,
"Thursday": THU,
"Friday": FRI,
"Saturday": SAT,
"Sunday": SUN,
}
func StringToDayOfTheWeek(s string) DayOfTheWeek {
c, exists := stringToDayOfTheWeek[s]
if exists {
return c
}
return DayOfTheWeek(-1)
}