On Tuesday, 17 May 2022 at 14:40:48 UTC, Kevin Bailey wrote:
Foo foo;
is undefined behavior waiting to happen, that I can't detect at
a glance.
It is actually perfectly well defined - for the class, it will be
null, and this will kill the program if you use it.
You might not like that definition, but that's how it is defined.
- A *secondary* goal would be for class objects to be able to
have deterministic destructors like structs.
they can with the `scope` keyword.
The first looks trivial: Just have it allocate a Foo by default.
Worth noting that D *never* calls a user defined function on
variable declaration; there are no default constructors.
Even if it is a struct, it never actually calls a constructor, it
just copies over the default init value.
This is different than classes, which have some kind of
constructor call any time you make one.
I think it is probably this default constructor stance that the
rest flows from: a class is assumed to encapsulate some
non-trivial state so it has a constructor, interfaces, object
identities, etc. A struct is more of a plain collection of data.
Of course, in practice the lines are more blurred than that, but
I think that's where it comes from. Especially if you look at the
older D versions when structs didn't support constructors at all.
