enum from/to string

[radare]

V version: V 0.1.25 876b73f
OS: macOS 10.15

What did you do?

enum foo {bar}�
eprintln(foo.bar.str)

What did you expect to see?

all enum types should provide a compiler helper to resolve an enum type by string or get the string representation of the enum type. it is so tedious to do that in GLIB programs for example, as well as in C, and i think V should provide such helpers otu of the box to avoid the ugly spaguetti in vlib/compiler/main.v - os_from_string(os string) pref.OS

What did you see instead?

[medvednikov]

Yes, this will be implemented.

[RiordanIX]

#4180 implemented this, did it not? If so, this can be closed.

[medvednikov]

This issue is also about the opposite: string to enum.

[Hayao0819]

I arrived at this discussion from Google. Haven't enums been implemented from strings yet?

[xqliang]

yes, you can use the from_string and str method:

enum Lang {
  en
}
assert Lang.from_string('en')? == Lang.en
assert Lang.en.str() == 'en'

BTW, the generic from is on the way too:

enum Lang {
  en
}
assert Lang.from('en')? == Lang.en
assert Lang.from(0)? == Lang.en

[mac-hel]

Behavior is inconsistent in my opinion
.from_string() returns Option while .from() returns Result

I think Option is better, I want operation to have `?Operation' type:

enum Operation {
	get_area
	get_sector
}

fn main() {
	operation_name := ''

        // Option
	operation := ?Operation(Operation.from_string(operation_name))

        // Result - less concise
	mut operation2 := ?Operation(none)
	if r := Operation.from(operation_name) {
		operation2 = r
	}

        // Impossible
	operation3 := Operation.from(operation_name) or { ?Operation(none) }
}

[JalonSolov]

.from gives a Result because Operation.from('fizzle'), for example, is an error, not none.

If it was a query, then yes, an Option would be appropriate. It is not, it is "create an enum from this string", but there is no such enum with that name. Since it cannot succeed that way, it is an error.