On 03/07/2012 04:41 AM, Timon Gehr wrote:
On 03/07/2012 02:40 AM, Chad J wrote:
But to initialize non-null fields, I suspect we would need to be able to
do stuff like this:
class Foo
{
int dummy;
}
class Bar
{
Foo foo = new Foo();
this() { foo.dummy = 5; }
}
Which would be lowered by the compiler into this:
class Bar
{
// Assume we've already checked for bogus assignments.
// It is now safe to make this nullable.
Nullable!(Foo) foo;
this()
{
// Member initialization is done first.
foo = new Foo();
// Then programmer-supplied ctor code runs after.
foo.dummy = 5;
}
}
I remember C# being able to do this. I never understood why D doesn't
allow this. Without it, I have to repeat myself a lot, and that is just
wrong ;).]
It is not sufficient.
class Bar{
Foo foo = new Foo(this);
void method(){...}
}
class Foo{
this(Bar bar){bar.foo.method();}
}
Lowered it a bit to try to compile, because it seems Foo doesn't have a
method() :
import std.stdio;
class Bar{
Foo foo;
this()
{
foo = new Foo(this);
}
void method(){ writefln("poo"); }
}
class Foo{
this(Bar bar){bar.foo.method();}
}
void main()
{
}
And, it doesn't:
main.d(12): Error: no property 'method' for type 'main.Foo'
Though, more to the point:
I would probably forbid "Foo foo = new Foo(this);". The design that
leads to this is creating circular dependencies, which is usually bad to
begin with. Would we lose much of value?
