On Tuesday, 4 February 2014 at 22:30:39 UTC, Walter Bright wrote:
That's just what I wish to avoid. Consider adding more pointer
types - the combinatorics quickly explode. Heck, just have two
pointer parameters, and you already have 4 cases.
I wonder how Rust deals with this.
Rust does not have null pointers.
In cases where you want to mark an object of some type as having
"no value", or being "null", you use a stdlib type Option<T>,
which is basically a tagged union plus some static compiler
guarantees:
enum Option<T> {
Some(T),
None
}
An Option<T> either contains a T (tagged 'Some' then) or nothing
(tagged 'None').
If you have a function that takes an Option<T> you can also pass
it a (pure, non-nullable) T by specifying Some(myT) as the
parameter.
