new DIP5: Properties 2

[Andrei Alexandrescu]

Chad J wrote:
> Andrei Alexandrescu wrote:
>> My perception is that there are a few vocal people. The protests have
>> been historically against the stupid "writeln = 42" which we must get
>> rid of.
>>
> 
> Seems odd to me.  I thought the unpopular bit was the lack of
> lvalue-ness and how "array.length++;" did not work.  No idiot would
> write "writefln = 42;" in serious code.  It's easy to avoid since you
> have be rather intentional about it.

Oh, yes. That needs fixing too!

>> I have a dream.
>>
> 
> I feel like ranting ;)
> 
>> * Parameterless functions still can be called without "()". People will
>> realize that it's a prejudice to believe that this impedes code
>> understanding, and their eyes and wrists will thank them.
>>
> 
> Earlier I was thinking yeah ok w/e that's fine.  Now I'm thinking these
> are just evil.  But only when the function returns a value-type.  void
> functions are alright.  Ref returns may or may not be alright.
> 
> It's not because of "writefln = 42;".
> 
> It's because of this:
> 
> // Library code
> struct Rectangle
> {
> 	float x,y,w,h;
> 	// etc blah blah
> }
> 
> class Widget
> {
> 	Rectangle _rect; // eww no optional backing storage
> 	Rectangle rect() { return _rect; }
> 	//...
> }
> 
> // User code (probably test code in this case...)
> auto widget = new Widget(...);
> widget.rect.w = 200;
> widget.rect.h = 100;
> 
> // End
> A few hours later this poor library developer takes a break from the
> debugger and writes a small experiment.  The conclusion is
> "AARRGGGHHH!".  He runs to the news group to bitch and moan, and someone
> responds, "yeesh use ref return and RTFM already".  Bad day.

This serious problem has already been mentioned once. Incidentally I 
think it was Steve who mentioned it. It is big and relates to the fact 
that you could call member functions against rvalues. Could you please 
add it to bugzilla?

> This is only the example that pops to mind.  I am sure there are cases
> where the library writer may intentionally NOT ref return, and the user
> will miss this and get bitten.  When the library writer and user are the
> same, things only goes downhill.
> 
>> * The syntax "foo = bar" is rewritten into "foo(bar)" IF AND ONLY IF the
>> expression "auto __x = foo, __x = bar" is compilable.
>>
> 
> I seem to know exactly what you said with great mathematical precision
> and certainty.  I have no idea what this actually DOES though :/
> 
> (In another post you mentioned this being a guarantee of a getter, but
> there seems to be more to it, such as type equality between foo and bar.)
> 
>> * The non-uniformity regarding parameterless functions returning
>> parameterless functions is acknowledged but considered minor.
>>
> 
> O.O
> 
> R-R-Really?!
> 
> So you're just going to give up?

Well that kind of sucks. I agree.



Andrei