How should I handle none?

[hellolio]

module main

fn main() {
	a, b := foo()
	println(a)
	println(b)

}

fn foo() ?(int, string) {
	return none, 'eee'
}

I know there is an issue with this code, but I'm not sure how to fix it. Please tell me what to do.
The functionality I want to achieve is that when the return value a is none, a default value should be assigned, while b, because it is not none, should retain its original value

[hellolio]

forgive me, this is a very basic question. i am learning it

[jorgeluismireles]

Something like this?:

fn main() {
	a, b := foo()
	if a == none {
		println('a: default')
	} else {
		println('a: ${a}')
	}
	println('b: ${b}')
}

fn foo() (?int, string) {
	return none, 'eee'
}

a: default
b: eee

A good place to practice is here: https://play.vlang.io/p/296a95059b

[jorgeluismireles]

Another way: a is still what V language call, an Option. And a1 is a real integer after using or:

fn main() {
	a, b := foo()
	a1 := a or { -1 } // -1 means default
	println('a: ${a1} b:${b}')
}

fn foo() (?int, string) {
	return none, 'eee'
}

a: -1 b:eee

See https://docs.vlang.io/type-declarations.html#optionresult-types-and-error-handling

[hellolio]

@jorgeluismireles
Thank you very much for your help, I get it

[hellolio]

@jorgeluismireles
i have a new question, if I do it(if a is immutable), I would have to add an extra variable,
which will take up more memory. Why not like Rust unpack a?

[jorgeluismireles]

I read once a Rust book, and though should be my next language after Go, but then I met V and forget everything about Rust. I have no idea the memory usage for mutable/immutable things. Lets wait a seasoned V user explain it.