On Thu, 24 Jan 2013 13:00:35 -0800, Jonathan M Davis <[email protected]>
wrote:
On Thursday, January 24, 2013 21:47:38 mist wrote:
On Thursday, 24 January 2013 at 20:44:33 UTC, eles wrote:
> On Thursday, 24 January 2013 at 20:26:50 UTC, mist wrote:
>> On Thursday, 24 January 2013 at 20:20:42 UTC, Adam Wilson
>
>> wrote:
> I think the widest spread use case of a property is:
>
> you start with a variable as memeber of a class, you write a lot
> of assignment code, then you decide that you need to do some
> more
> extensive processing instead of simple assignment, and all that
> without breaking existing code.
>
> so, you transform the variable into a property.
>
> of course, it could happen the other way around (converting a
> function into a property/variable).
It is a wrong use case for a property. Necessity to change data
assignment/access to call of function with side-effect is design
error and should be fixed with programmers experience, not
property hacks.
Being able to swap out a public variable with a function without having
to
change any code using it is arguably the primary reasons that property
functions exist in the first place. Yes, making it so that the property
function has a _side-effect_ is a bug, but replacing variables with
property
functions is not. A classic example of why it's useful is when you
refactor a
class such that a public variable becomes a calculated value such that it
doesn't make sense to have a variable for it anymore. Instead of
breaking all
of the code that uses the variable by changing it a function, you change
it to
be a property function, and all of the code which used it continues to
compile
and work just fine.
D's properties need some work before that will really work properly (e.g.
http://d.puremagic.com/issues/show_bug.cgi?id=8006 ), but it works just
fine
with property implementations in other languages (e.g. C#).
- Jonathan M Davis
++ to Mr. Davis!
This is much more concise way of stating what I was trying to say. And it
is an argument that should NOT be lightly dismissed, it is a very real,
very common problem.
--
Adam Wilson
IRC: LightBender
Project Coordinator
The Horizon Project
http://www.thehorizonproject.org/
