On request by Maxim Fomin I ask an opinion here. This is a very small enhancement request, that for me is borderline bug report (so originally I didn't plan in showing it in the main D newsgroup):

http://d.puremagic.com/issues/show_bug.cgi?id=9857



Maybe this should be valid:


struct Foo {
    int opCall(bool b) {
        return 0;
    }
}
void main() {
   Foo foo;
   auto b1 = foo(true); // OK
   auto b2 = true.foo;  // Error
}


dmd 2.063alpha gives:

temp.d(9): Error: no property 'foo' for type 'bool'


Explanation:

1) I am using UFCS often in D, for functions, higher order functions, etc. A struct with an opCall method is usable like a function with state. So for uniformity with the other functions I'd like to use it with UFCS. When you have a long UFCS chain you don't want to break it, if it's possible.


2) Both struct constructors, struct implicit constructors and struct static opCall support UFCS, so I don't see a good reason for just the normal struct opCall to not support it:


struct Foo {
    static int opCall(int x) {
        return x * 2;
    }
}
struct Bar {
    int x;
    this(int y) {
        x = y * 2;
    }
}
struct Spam {
    int x;
}
void main() {
    assert(10.Foo == 20);
    assert(10.Bar.x == 20);
    assert(10.Spam.x == 10);
}


Jonathan Davis doesn't like this. For more information I suggest to take a look at the thread in Bugzilla.

- - - - - - - - - - -

Regarding UFCS, currently this doesn't work, I don't know if this should be considered a bug or not (I think the answer is positive):


struct Node {}
void foo(Node* p) {}
void main() {
    auto p = new Node();
    foo(p); // OK
    p.foo;  // Error: no property 'foo' for type 'Node'
}


Bye,
bearophile