• Sobaya (18/18) Jan 29 2018 I found a strange behavior.
• Jonathan M Davis (5/23) Jan 29 2018 I don't think so. The first "assignment" is actually initialization, not
• Simen =?UTF-8?B?S2rDpnLDpXM=?= (11/28) Jan 29 2018 The first assignment in the constructor isn't actually a call to
• Sobaya (6/37) Jan 29 2018 I have not read https://dlang.org/spec/class.html

Sobaya <sobaya007 gmail.com> writes:

I found a strange behavior.

class A {
     void opAssign(int v) {}
}

class Test {
     A a;
     this() {
         a = new A(); // removing this causes compile error.
         a = 3; // cannot implicitly convert expression `3` of 
`int` to `A`
     }
}

void main() {
     // this is allowed.
     A a;
     a = 3;
}

Is it a compiiler's bug?

Jonathan M Davis <newsgroup.d jmdavisprog.com> writes:

On Monday, January 29, 2018 09:23:55 Sobaya via Digitalmars-d-learn wrote:
 I found a strange behavior.

 class A {
      void opAssign(int v) {}
 }

 class Test {
      A a;
      this() {
          a = new A(); // removing this causes compile error.
          a = 3; // cannot implicitly convert expression `3` of
 `int` to `A`
      }
 }

 void main() {
      // this is allowed.
      A a;
      a = 3;
 }

 Is it a compiiler's bug?

I don't think so. The first "assignment" is actually initialization, not
assignment. opAssign is for assigning to a value that was already
initialized.

- Jonathan M Davis

Simen =?UTF-8?B?S2rDpnLDpXM=?= <simen.kjaras gmail.com> writes:

On Monday, 29 January 2018 at 09:23:55 UTC, Sobaya wrote:
 I found a strange behavior.

 class A {
     void opAssign(int v) {}
 }

 class Test {
     A a;
     this() {
         a = new A(); // removing this causes compile error.
         a = 3; // cannot implicitly convert expression `3` of 
 `int` to `A`
     }
 }

 void main() {
     // this is allowed.
     A a;
     a = 3;
 }

The first assignment in the constructor isn't actually a call to 
opAssign, it's a constructor call. In the same way, this will not 
compile:

A a = 3;

Also, since classes are reference types, you will need to 
construct an instance before assigning an int to it. The code in 
your main() will crash at runtime because the 'this' reference is 
null inside opAssign.

--
   Simen

Sobaya <sobaya007 gmail.com> writes:

On Monday, 29 January 2018 at 10:06:23 UTC, Simen Kjærås wrote:
 On Monday, 29 January 2018 at 09:23:55 UTC, Sobaya wrote:
 I found a strange behavior.

 class A {
     void opAssign(int v) {}
 }

 class Test {
     A a;
     this() {
         a = new A(); // removing this causes compile error.
         a = 3; // cannot implicitly convert expression `3` of 
 `int` to `A`
     }
 }

 void main() {
     // this is allowed.
     A a;
     a = 3;
 }

 The first assignment in the constructor isn't actually a call 
 to opAssign, it's a constructor call. In the same way, this 
 will not compile:

 A a = 3;

 Also, since classes are reference types, you will need to 
 construct an instance before assigning an int to it. The code 
 in your main() will crash at runtime because the 'this' 
 reference is null inside opAssign.

 --
   Simen

I have not read https://dlang.org/spec/class.html
In 15.9, there is an explanation about it.
Sorry.

--
   Sobaya