On Thu, 24 Jun 2010 16:21:37 -0400, Pelle <[email protected]> wrote:
As heard around these parts, a lot of people want property-style
function calls to require the function to be declared with @property,
like this:
@property foo(); //getter
@property foo(int); //setter
foo; //getter
foo = 13; //setter
While this seems quite reasonable, in practice I and others feel this
leads to confusion, especially the getter part. Mostly when the getter
has no setter counterpart. D also lets us call no-argument functions
without parentheses today, so for this to happen a lot of code needs to
change.
How is this confusing? It's a read-only property. They are used in
countless design patterns.
Furthermore, how will allowing any no-arg function to be called without
parentheses *not* lead to confusion?
e.g.
struct File
{
bool open() {...}
}
File f;
if(f.open) // looks to me like a property saying whether f is open
if(f.open()) // looks to me like a function opening f.
Like it or not, the parentheses are part of the name of the
function/property, and to not be able to control whether parens are used
as an author of said function/property leaves me to answer unending
requests for changes to the API, such as "why don't you change open to
openFile to make it clear that it's a function." Hey, look, we're back
to Java's getX and setX, but in reverse! Wheeee!
With @property, I don't have to do that, because it's very obvious that
since open requires parentheses, it is effecting an action on f.
My suggestion is as follows; require @property for single-argument
setters *only*. Make the silly writeln = 13; go away, but keep the "a b
c".split;. This way, there can be no confusion about @property, and most
code will go unchanged.
@property is much better than the current situation, even for getters.
C#, python, I'm sure other languages, have worked fine for years with
explicit properties, this debate is non-existent there.
In a couple months after @property has been enforcing the parens rule,
nobody will think about this debate any more. The only pain is in undoing
the hack that is D's current properties.
-Steve
