On 8/8/17 2:34 PM, Johan Engelen wrote:
Hi all,
How would you express the function interface intent that a reference
to a class may not be null?
For a function "void foo(Klass)", calling "foo(null)" is valid. How do I
express that that is invalid? (let's leave erroring with a compile error
aside for now)
There isn't a way to do this in the type itself.
One can always create a null class instance via:
MyObj obj;
There is no way to disallow this somehow in the definition of MyObj.
With structs, you can @disable this(), and it's still possible but
harder to do so.
I would say, however, that if you wanted to express the *intent*, even
without a compile-time error, you could use a contract:
void foo(Klass k) in {assert(k !is null);};
Since the contract is part of the signature, this should be symantically
what you want.
However, this has to be done on every function that would accept a
Klass, there's no way to bake it into the type itself.
-Steve
