new DIP5: Properties 2

[Sergey Gromov]

Fri, 31 Jul 2009 21:37:06 -0500, Andrei Alexandrescu wrote:

> To clarify: if there was any extra checking by the compiler, any 
> guarantee that the feature would provide at all, I'd be glad to pay the 
> price of thinking more when putting together a design. But you want to 
> define a language feature that allows people to require "()" or not as 
> they please, and that's all. It's a frivolous detail to be spending time 
> on when designing an API. I simply don't believe that's good language 
> design.

That's not "all."  To me it's mostly maintainability.

If there is a property 'foo' and you allow to set it both as 'foo = 5'
and 'foo(5)' then somebody *will* use the foo(5) form.  Making it hard,
or even impossible for you, the maintainer, to switch from a property
back to a regular field for 'foo'.

If you allow to call function 'bar()' both with and without parentheses,
and a project is maintained by more than one person, they *will* call it
differently making the source look inconsistent.

Dropping the 'omittable parentheses' thing happens to solve these, and
the delegate return problem, and helps to disambiguate words with
overloaded meanings.