I recommend using strings as the base type for things like this, rather
than ints. There is no need to use ints, just because that's what C uses.
Thomas
On Fri, Sep 8, 2023 at 3:24 AM 'Mark' via golang-nuts <
golang-nuts@googlegroups.com> wrote:
> I often create small multi-value flag types, e.g.
> ```go
> type mode uint8
>
> const (
> argMode mode = iota
> baseMode
> cmdMode
> )
> ```
> The problem is that if I write, say, `m := baseMode`, although `m` has
> the correct type (`mode`), there is no way to constrain its values to the
> consts I've declared.
> In theory I could create a `NewMode(int) mode` function and have it panic
> if the given int isn't valid; but that won't prevent, say, `m += 99`. The
> next step would be to define a full type, e.g., something like:
> ```go
> type mode struct {
> m int
> }
> ```
> This would prevent `m++` and similar since all accesses would have to go
> through the public functions. However, this would still do all its checking
> at _runtime_; whereas for this kind of use it should surely be possible to
> check at compile time.
>
> In Pascal it is easy to declare a "subrange" type which might look like
> this in Go-like syntax:
>
> `type mode uint8 0..2`
>
> Is there a compile-time solution for this that I've missed?
>
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