Re: [rust-dev] "Virtual fn" is a bad idea

[Tommi]

I'm sorry for being kind of off-topic here, but whatever you decide on this 
matter, I'd still like to be able to emulate multiple-inheritance using the 
following idiom (which requires being able to say that a trait method is 
private or, preferably, why don't we make trait methods private by default):

trait Inflate {
    priv fn get_radius<'s>(&'s mut self) -> &'s mut int;

    fn inflate_by(&mut self, amount: int) {
        *self.get_radius() += amount;
    }
    // ... rest of the implementation ...
}

trait Flatten {
    priv fn getRadius<'s>(&'s mut self) -> &'s mut int;

    fn release_all_air(&mut self) {
        *self.getRadius() = 0;
    }
    // ... rest of the implementation ...
}

struct Balloon {
    radius: int
}

impl Inflate for Balloon {
    priv fn get_radius<'s>(&'s mut self) -> &'s mut int {
        &mut self.radius
    }
}

impl Flatten for Balloon {
    priv fn getRadius<'s>(&'s mut self) -> &'s mut int {
        &mut self.radius
    }
}

fn main() {
    let mut b = Balloon { radius: 123 };
    b.inflate_by(10);
    b.release_all_air();
    // b.get_radius(); // ERROR: get_radius is private
    // b.getRadius();  // ERROR: getRadius is private
}


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