On Fri, 16 May 2014 16:28:41 -0400, Joshua Niehus <[email protected]>
wrote:
trying to follow:
http://ddili.org/ders/d.en/class.html
//--- OSX 10.9 DMD 2.065
module test;
class Foo {
int num;
this(int num) {
this.num = num;
}
Foo dup() const {
return new Foo(this.num);
}
immutable(Foo) idup() const {
return new immutable(Foo)(this.num);
}
}
void main() {
auto foo = new Foo(1);
auto mfoo = foo.dup();
auto ifoo = foo.idup();
}
* test.d(15): Error: mutable method test.Foo.this is not callable
using a immutable object
* test.d(15): Error: no constructor for Foo
* Failed: ["dmd", "-v", "-o-", "test.d", "-I."]
//---
What am i missing?
your constructor needs the immutable tag.
this(int num) immutable ...
However, you can avoid much of this by tagging things as pure:
(untested, but just keep the internals the same)
class Foo
{
int num;
this(int num) pure {...}
Foo dup() const pure {...}
immutable(Foo) idup() const pure {...}
}
void main()
{
... // same implementation
}
Note that doing this, you do not need to have an idup, this should work:
immutable ifoo = foo.dup();
-Steve
