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goenumsiota

ENUMs for custom types in GO


I am trying to generate an enum for a type I defined

type FeeStage int

From this I learned that I can use iota to create an enum based on this type

const(
     Stage1 FeeStage = iota
     Stage2 
     Stage3
)

However, manipulating the actual values of the enum is rather cumbersome and error prone

const(
     Stage1 FeeStage = iota           // 0
     Stage2          = iota + 6       // 7
     Stage3          = (iota - 3) * 5 // -5
)

Is there a way to automatically convert a list of ENUMs with custom values to a certain type. This is what I was using before but only converts the first member of the constant to the custom type.

const(
     Stage1 FeeStage = 1
     Stage2          = 2
     Stage3          = 2
)

Here is a playground with a similar result


Solution

  • There's no way beyond either using iota and automatic enums, or doing the most straightforward thing:

    const(
         Stage1 FeeStage = 1
         Stage2 FeeStage = 2
    
         // or another syntax with same results
         Stage3 = FeeStage(2)
    )
    

    which IMHO is less cumbersome than doing stuff like iota + 5 which as you said is really bad.

    I usually either use iota if the value is not important beyond the context of the program, or explicit typing if I need the values to be used in a protocol or something.

    Though I have to say sometimes just using ints or strings is good enough, it depends on the context. See for example the http status codes in the standard library. They don't have a special type.