On Sunday, 8 February 2015 at 00:31:42 UTC, Mike wrote:
I'm elevating this from D.Learn [1] because I think it needs
some input from the language designers.
This code compiles and executes:
-----------------------------------
import std.stdio;
struct StaticRegister {
static private uint _value;
@property static uint value() { return _value; }
@property static void value(uint v) { _value = v; }
static alias value this;
static void test() {
writeln(this.stringof);
writeln(typeof(this).stringof);
writeln(this.value);
}
}
void main(string[] s) {
// works due to `alias value this`
StaticRegister = 1;
StaticRegister.test();
}
-----------------------------------
Output:
StaticRegister
StaticRegister
1
`this` should not exist within a static member function. The fact
that this code compiles is probably a bug. `StaticRegister = 1`
is almost definitely not intended behaviour, and I don't know
about `static alias value this`.
However, this code fails to compile:
-----------------------------------
struct StaticRegister {
static void test() {
assert(this is null);
}
}
void main(string[] s) {
StaticRegister.test();
}
-----------------------------------
Output:
test.d(5): Error: 'this' is only defined in non-static member
functions, not test
This is correct behaviour.
Is `this` overloaded to mean "this class" in a static context
or is `this` only valid in a non-static context. Please
clarify, and if it's a bug, help me understand so I can make an
accurate and actionable bug report.
`this` should only be valid in a non-static context, as far as I
know. That's pretty much what static means: "there is no `this`".
