V: Allow method on types definition inside structs

[mp81ss]

It would be very nice to allow something like this:

struct Abc {
    name string
    // all other fields

    fn (a Abc) is_empty() bool {
        return a.name.len == 0
    }
    // all other funcs
}

This imply the use of type Abc before its complete definition.
I would add method definition inside structs AFTER all fields have been declared, as shown above.
This would greatly simulate OOP without changing the language

[bashery]

In this case, (a Abc) will not be required. like this:

struct Abc {
    name string

    fn  is_empty() bool {
        return this.name.len == 0
    }
}

When I was learning Go and Rust, I was wondering about the benefit of separating the method from the body struct.
Their merging into one body struct seemed more friendly and clear in reading. I do not know.

But I got used to this. I don't think it is so important

[mp81ss]

Yes, merging methods inside parent data-structure is more friendly and clear in reading.
That's why I asked for it.
Your synthax with this keyword is equivalent and shorter, but requires changing the actual parser.
Both ways would be good

[StunxFS]

I like the idea, I'm used to that way of writing methods (from C#, C++, etc ...), it would be great if you could do that in V.
BTW, in addition to this you could use self like in Rust/Python.

struct Abc {
    name string

    // like in Python (without `self` parameter)
    fn is_empty() bool {
        return self.name.len == 0
    }

    // or like in Rust
    fn is_empty(self) bool {
        return self.name.len == 0
    }

    fn is_empty_mut(mut self) bool {
        return self.name.len == 0
    }

    fn is_empty_ref(&self) bool {
        return self.name.len == 0
    }
}

[JalonSolov]

Why do you need to declare the functions inside the struct? This already works:

struct Abc {
    name string
    // all other fields
}

fn (a Abc) is_empty() bool {
    return a.name.len == 0
}
// all other funcs

Since it references a, it will be a per-instance reference. No need for self or other placeholders.

[ntrel]

In this case, (a Abc) will not be required.

But sometimes we need a receiver of type &Abc or a mutable receiver.

[bashery]

@ntrel You are right