Morning Nikita, That's pretty persuasive ...
Dmitry, what are your thoughts on those points ? Cheers Joe On Wed, May 25, 2016 at 2:03 PM, Nikita Popov <nikita....@gmail.com> wrote: > On Wed, May 25, 2016 at 10:30 AM, Joe Watkins <pthre...@pthreads.org> > wrote: > >> Morning Dmitry, >> >> > I made this check(s) to be invariant. You may like to do this >> differently... >> >> I think this is what everyone expects, isn't it ? >> >> I did omit to mention that part ... >> >> > RFC doesn't define how uninitialized nullable typed properties should >> behave. >> >> It does: >> >> > *Nullable typed properties will not raise an exception when accessed >> before initialization.* >> > > I don't agree with this choice, for three reasons: > > a) This unnecessarily restricts what can be expressed in the type system. > With these semantics it will no longer be possible to express that a > property should be nullable, but have no default value. This situation is > not uncommon in practice, in particular anytime you have a nullable > constructor argument, you will want the corresponding property to be > nullable without a default, to ensure that it is explicitly initialized. > > b) This directly contradicts the meaning of ?Type for parameters. For > parameters ?Type means that it's a nullable parameter **without a default > value**. That's the very thing that distinguishes it from the Type $prop = > null syntax. And now ?Type for properties should mean the exact opposite? > > c) If you view this in a larger scope of union types, this *special case* > becomes even more weird. Why does the particular union Type|null get > special treatment, while all other unions don't? Or is it actually not > specific to "null", but to single value types? E.g. if we also allowed > Type|false, would that also receive an implicit false default value? What > about the type null|false? Does that get an implicit default, and if so, > which? I realize this is not quite in scope for type properties, but the > further evolution of the type system should be kept in mind. > > Please keep things consistent: If there is not default, there is no > default. > > Nikita >