On Monday, 12 December 2011 at 21:57:36 UTC, Jonathan M Davis
wrote:
There has been discussion of UFCS (universal function call
syntax), which would then expand that beyond arrays to _all_
types - int, float, any user-
defined type, etc. However, there are a number of issues with
that (particularly with user-defined types; e.g. what if a
member function and a free function have the same name?), and
it has yet to be implemented. It may never be implemented.
C# easily avoids member confusion with pseudo methods by using
the 'this' keyword as a parameter attribute in the pseudo method
(http://msdn.microsoft.com/en-us/library/bb383977.aspx). Any
function(this a, b) can be invoked as: a.function(b) in C#. I
understand using the 'this' keyword as a parameter attribute
already serves a different purpose in D, but I'm sure another
keyword ('pseudo' perhaps?) or equivalent syntax could be
reached. At which point, any external pseudo method conflicting
with an objects internal members could simply result in a
compiler error (or, member functions could take priority over
pseudo methods).
I understand this isn't exactly a priority, but IMO it could
really help the overall syntax feel more consistent in some areas.
import std.conv;
void main()
{
string encoded = "1324.03";
double actual = encoded.to!string; // similar to
Object.toString()
}
More importantly, pseudo methods could be used to bend the rules
of member access, and to implement module-specific functionality
for imported objects without breaking OOP syntax.
module a;
class A {
int data;
}
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
module b;
pseudo void foo(A a, B b) {
// A can access B's private members
a.data = b._data;
}
class B {
private int _data;
}
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
import a, b;
void main() {
auto a = new A();
auto b = new B();
a.foo(b); // cool!
}
So, I think that there's a decent chance that you just
misunderstood what that section in TDPL was really saying (it
really should be clearer on whether it meant just arrays or all
types), but there are definitely folks who want it to be
extended to all types, so it may be eventually, but we'll have
to wait and see.
Undoubtedly a misunderstanding on my end. Still, +1 for seeing
Pseudo Members for all types.
- Philip
