Re: [RFC] [DISCUSSION] Immutable/final/readonly properties

> > Avoiding that confusion will save the industry millions of dollars. > On the one hand, you are right, because currently it's not very useful to effectively provide two ways of declaring a constant. On the other hand however, if we also consider a longer term aim of adding support for object default values (just like what Marco mentioned): public read-only DateTimeImmutable $startupTime = new DateTimeImmutable(); then allowing default values for "write-once" properties seems much more sensible. At this point, the "million dollar mistake" label doesn't hold anymore since class constants and "write-once" properties with default values will actually be two different things. But we've just ended up at Marco's suggestion: > 1. Prevent the parser from accepting default values on write-once > properties (parser error) > 2. Re-introduce them once we know what we want to do with default values > (and it makes sense) > Yes, this scenario definitely makes sense. I'm just not yet sold that it will have any negative effects if we don't restrict the usage of default values now. I understand that it's usually advantageous to be conservative with adding new features - especially when groping in the dark - since we are the ones who have to support and fix them later. That's why I was hesitant to add property covariance to the proposal. But this case seems to be much more well-understood than let's say property covariance would be, it avoids another special rule while aligning nicely with our longer term goals, so I think all in all, it is still a better idea to allow default values than not. I think what will happen is that people will start requesting for read-only > properties with default values to be over-writable-once (a mess): better to remove them from the equation > completely, no? I can also imagine people to ask for default values if we disallow them now. :) After all, we always want what we don't have. ^^ Does anyone else have any more comments or objections? I wouldn't in the least want to be stubborn about this topic, so if anyone has any feelings for/against, it's the best time to reassure my point of view or change my mind. :) Thanks, Máté