Walter Bright wrote:
Denis Koroskin wrote:
If an object may or may not have a valid value, you mark it as
nullable. All the difference is that it's a non-default behavior,
that's it. And a user is now warned, that an object may be not
initialized.
He isn't warned, that's just the problem. The null object happily says
"I succeeded" for all input and returns more default values and null
objects.
This is not the proposal. The proposal was to codify in the type system
whether a particular object has "null" as a valid value. If a variable
that cannot be null is not initialized to a non-null value before use,
that is an error.
It's entirely equivalent to using the current type system with a ton of
manual contracts requiring that variables not be null. Except the
contracts are enforced at compile time, not runtime.
A similar concept would be range-bounded integer types, or floating
point types that cannot be NaN or infinity.
