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reply "Jonas Drewsen" <nospam4321 hotmail.com > writes:
Isn't it a bug that the assertion is triggered for this:

class Test3 {}

void main()
{
	assert( (new Test3()) == (new Test3()) );
}

Tried it on http://dpaste.dzfl.pl/ as well.

/Jonas
Nov 26 2013
parent reply "Namespace" <rswhite4 googlemail.com> writes:
On Tuesday, 26 November 2013 at 21:37:49 UTC, Jonas Drewsen wrote:

 Isn't it a bug that the assertion is triggered for this:

 class Test3 {}

 void main()
 {
 	assert( (new Test3()) == (new Test3()) );
 }

 Tried it on http://dpaste.dzfl.pl/ as well.

 /Jonas


Because your Test3 class has probably no own opEquals method, 
your comparison is the same as
assert( (new Test3()) is (new Test3()) );
which is obviously wrong.

See: 
https://github.com/D-Programming-Language/druntime/blob/master/src/object_.d#L116
Nov 26 2013
parent reply Ary Borenszweig <ary esperanto.org.ar> writes:
On 11/26/13 7:00 PM, Namespace wrote:

 On Tuesday, 26 November 2013 at 21:37:49 UTC, Jonas Drewsen wrote:

 Isn't it a bug that the assertion is triggered for this:

 class Test3 {}

 void main()
 {
     assert( (new Test3()) == (new Test3()) );
 }

 Tried it on http://dpaste.dzfl.pl/ as well.

 /Jonas


 Because your Test3 class has probably no own opEquals method, your
 comparison is the same as
 assert( (new Test3()) is (new Test3()) );
 which is obviously wrong.

 See:
 https://github.com/D-Programming-Language/druntime/blob/master/src/object_.d#L116


The ddoc for the method is wrong. It should say something like:

returns != 0 if this object has the same memory address as obj. 
Subclasses may override this method to provide custom equality comparison.

Because for the OP, Test3 has the same contents as the other Test3 (both 
empty).
Nov 26 2013
parent reply "Jonas Drewsen" <nospam4321 hotmail.com > writes:
On Wednesday, 27 November 2013 at 00:46:30 UTC, Ary Borenszweig 
wrote:

 On 11/26/13 7:00 PM, Namespace wrote:

 On Tuesday, 26 November 2013 at 21:37:49 UTC, Jonas Drewsen 
 wrote:

 Isn't it a bug that the assertion is triggered for this:

 class Test3 {}

 void main()
 {
    assert( (new Test3()) == (new Test3()) );
 }

 Tried it on http://dpaste.dzfl.pl/ as well.

 /Jonas


 Because your Test3 class has probably no own opEquals method, 
 your
 comparison is the same as
 assert( (new Test3()) is (new Test3()) );
 which is obviously wrong.

 See:
 https://github.com/D-Programming-Language/druntime/blob/master/src/object_.d#L116


 The ddoc for the method is wrong. It should say something like:

 returns != 0 if this object has the same memory address as obj. 
 Subclasses may override this method to provide custom equality 
 comparison.

 Because for the OP, Test3 has the same contents as the other 
 Test3 (both empty).


"does have the same contents as obj"

yes this is what confused me... and actually, it is a bit wierd 
coming from a c++ background that obj1 == obj2 is the same as 
(obj1 is obj2) and not per field comparison as expected (and 
documented). What is the reasoning behind this... principle of 
most astonishment? :)
Nov 28 2013
parent "Meta" <jared771 gmail.com> writes:
On Thursday, 28 November 2013 at 13:23:22 UTC, Jonas Drewsen 
wrote:

 On Wednesday, 27 November 2013 at 00:46:30 UTC, Ary Borenszweig 
 wrote:

 On 11/26/13 7:00 PM, Namespace wrote:

 On Tuesday, 26 November 2013 at 21:37:49 UTC, Jonas Drewsen 
 wrote:

 Isn't it a bug that the assertion is triggered for this:

 class Test3 {}

 void main()
 {
   assert( (new Test3()) == (new Test3()) );
 }

 Tried it on http://dpaste.dzfl.pl/ as well.

 /Jonas


 Because your Test3 class has probably no own opEquals method, 
 your
 comparison is the same as
 assert( (new Test3()) is (new Test3()) );
 which is obviously wrong.

 See:
 https://github.com/D-Programming-Language/druntime/blob/master/src/object_.d#L116


 The ddoc for the method is wrong. It should say something like:

 returns != 0 if this object has the same memory address as 
 obj. Subclasses may override this method to provide custom 
 equality comparison.

 Because for the OP, Test3 has the same contents as the other 
 Test3 (both empty).


 "does have the same contents as obj"

 yes this is what confused me... and actually, it is a bit wierd 
 coming from a c++ background that obj1 == obj2 is the same as 
 (obj1 is obj2) and not per field comparison as expected (and 
 documented). What is the reasoning behind this... principle of 
 most astonishment? :)


C++ is the odd one out here, I believe. Most OO languages compare 
addresses by default.
Nov 29 2013