On Fri, 08 Oct 2010 17:26:41 +0400, Stanislav Blinov <bli...@loniir.ru>
wrote:
08.10.2010 16:55, Steven Schveighoffer пишет:
Someone was asking about UFC syntax for properties on d.learn, and I
realized, we have a huge ambiguity here.
Given a function:
@property int foo(int x)
Is this a global setter or a getter on an int?
i.e.
int y = foo = 3;
or
int y = (3).foo;
???
I know arrays have an issue with property setters, see a bug report I
filed a while back:
http://d.puremagic.com/issues/show_bug.cgi?id=3857
But that seems like a totally unambiguous case (a global property
function with two parameters is obviously a setter on the first
parameter in UFC).
The getter seems much more problematic. Does anyone have a solution
besides adding more syntax? Should we disallow global properties to
avoid ambiguity?
What if we make @properties have first parameter as ref/ref const if
it's meant to be part of UFC? This way we can keep module-scope
properties and easily make UFC properties for existing types:
@property int foo(int x) { /*...*/ } // module-scope setter
@property int foo() { /*...*/ } // module-scope getter
@property int foo(ref int x, int v) { /*...*/ } // UFC 'setter' for int
@property int foo(ref int x) { /*...*/ } // or int foo(ref const int x)
- UFS 'getter' for int
There's a caveat, though, as having ref/ref const would disallow doing
thigs like 3.foo() (which makes perfect sense for 'setters', but not for
getters.
C# uses 'this' keyword for that purpose:
@property int set(this int x, int y)
{
x = y;
}
@property int get(this const(int) x)
{
return x;
}
int a = 1;
a.set(42); // a is 42 now
3.set(42); // fails to compile, 3 is of type const(int)
