• Joshua Niehus (27/27) May 16 2014 trying to follow:
• Steven Schveighoffer (20/47) May 16 2014 your constructor needs the immutable tag.
• =?UTF-8?B?QWxpIMOHZWhyZWxp?= (7/34) May 16 2014 My apologies. The code was written for an older version of dmd. The
• Steven Schveighoffer (3/4) May 16 2014 Beat you by 8 seconds :)
• =?UTF-8?B?QWxpIMOHZWhyZWxp?= (3/6) May 16 2014 I am happy to be within one minute. :)
• Joshua Niehus (3/9) May 16 2014 Ahh great thanks guys.

"Joshua Niehus" <jm.niehus gmail.com> writes:

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?

"Steven Schveighoffer" <schveiguy yahoo.com> writes:

On Fri, 16 May 2014 16:28:41 -0400, Joshua Niehus <jm.niehus gmail.com>  
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

=?UTF-8?B?QWxpIMOHZWhyZWxp?= <acehreli yahoo.com> writes:

On 05/16/2014 01:28 PM, Joshua Niehus 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?

My apologies. The code was written for an older version of dmd. The 
simplest fix is to define the constructor as pure:

      pure this(int num) {
          this.num = num;
      }

Ali

"Steven Schveighoffer" <schveiguy yahoo.com> writes:

On Fri, 16 May 2014 16:36:36 -0400, Ali =C3=87ehreli <acehreli yahoo.com=
 wrote:

Beat you by 8 seconds :)

-Steve

=?UTF-8?B?QWxpIMOHZWhyZWxp?= <acehreli yahoo.com> writes:

On 05/16/2014 01:37 PM, Steven Schveighoffer wrote:
 On Fri, 16 May 2014 16:36:36 -0400, Ali Çehreli <acehreli yahoo.com> wrote:

 Beat you by 8 seconds :)

 -Steve

I am happy to be within one minute. :)

Ali

"Joshua Niehus" <jm.niehus gmail.com> writes:

On Friday, 16 May 2014 at 20:36:37 UTC, Ali Çehreli wrote:
 My apologies. The code was written for an older version of dmd. 
 The simplest fix is to define the constructor as pure:

      pure this(int num) {
          this.num = num;
      }

 Ali

Ahh great thanks guys.
No worries Ali, great book, i refer to it all the time :)