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digitalmars.D - Own type for null?

reply Benjamin Thaut <code benjamin-thaut.de> writes:
I recently tried to replace the deprecated overloading of new and delete 
and came across a serious issue. You can not use std.conv.emplace with 
null. If you pass null to it, null loses it's implicit casting 
cabablities and just becomes a void*.
This issue pretty much exists with every template. As soon as you pass 
null to a template (compile time) information gets lost.

Besides fixing std.conv.emplace it could be really handy to be able to 
check for a null-type at compile time for example with non-nullable types.

There is already a enhancement reqeust in bugzilla since January but it 
didn't get much attention yet: 
http://d.puremagic.com/issues/show_bug.cgi?id=5416

Would this be a worthwile improvement for the langauge?
-- 
Kind Regards
Benjamin Thaut
Oct 25 2011
next sibling parent reply Gor Gyolchanyan <gor.f.gyolchanyan gmail.com> writes:
I agree. Null is a very common special-case value and overloading may
be necessary based on that special-case value. Currently doing so
means accepting any kind of typeless pointer (which is certainly not
desirable).

On Wed, Oct 26, 2011 at 9:49 AM, Benjamin Thaut <code benjamin-thaut.de> wrote:

 I recently tried to replace the deprecated overloading of new and delete and
 came across a serious issue. You can not use std.conv.emplace with null. If
 you pass null to it, null loses it's implicit casting cabablities and just
 becomes a void*.
 This issue pretty much exists with every template. As soon as you pass null
 to a template (compile time) information gets lost.

 Besides fixing std.conv.emplace it could be really handy to be able to check
 for a null-type at compile time for example with non-nullable types.

 There is already a enhancement reqeust in bugzilla since January but it
 didn't get much attention yet:
 http://d.puremagic.com/issues/show_bug.cgi?id=5416

 Would this be a worthwile improvement for the langauge?
 --
 Kind Regards
 Benjamin Thaut
Oct 26 2011
parent deadalnix <deadalnix gmail.com> writes:
Le 26/10/2011 09:20, Gor Gyolchanyan a écrit :

 I agree. Null is a very common special-case value and overloading may
 be necessary based on that special-case value. Currently doing so
 means accepting any kind of typeless pointer (which is certainly not
 desirable).



+1 for me ! And +1 for non nullable types.
Oct 26 2011
prev sibling next sibling parent reply Timon Gehr <timon.gehr gmx.ch> writes:
On 10/26/2011 07:49 AM, Benjamin Thaut wrote:

 I recently tried to replace the deprecated overloading of new and delete
 and came across a serious issue. You can not use std.conv.emplace with
 null. If you pass null to it, null loses it's implicit casting
 cabablities and just becomes a void*.
 This issue pretty much exists with every template. As soon as you pass
 null to a template (compile time) information gets lost.

 Besides fixing std.conv.emplace it could be really handy to be able to
 check for a null-type at compile time for example with non-nullable types.

 There is already a enhancement reqeust in bugzilla since January but it
 didn't get much attention yet:
 http://d.puremagic.com/issues/show_bug.cgi?id=5416

 Would this be a worthwile improvement for the langauge?



++vote.

We also need an own type for the empty array literal '[]' btw.
Oct 26 2011
next sibling parent reply Benjamin Thaut <code benjamin-thaut.de> writes:
Am 26.10.2011 10:56, schrieb Timon Gehr:

 On 10/26/2011 07:49 AM, Benjamin Thaut wrote:

 I recently tried to replace the deprecated overloading of new and delete
 and came across a serious issue. You can not use std.conv.emplace with
 null. If you pass null to it, null loses it's implicit casting
 cabablities and just becomes a void*.
 This issue pretty much exists with every template. As soon as you pass
 null to a template (compile time) information gets lost.

 Besides fixing std.conv.emplace it could be really handy to be able to
 check for a null-type at compile time for example with non-nullable
 types.

 There is already a enhancement reqeust in bugzilla since January but it
 didn't get much attention yet:
 http://d.puremagic.com/issues/show_bug.cgi?id=5416

 Would this be a worthwile improvement for the langauge?



 ++vote.

 We also need an own type for the empty array literal '[]' btw.



Do you have an example where a own type for [] would be usefull?

-- 
Kind Regards
Benjamin Thaut
Oct 26 2011
parent Timon Gehr <timon.gehr gmx.ch> writes:
On 10/26/2011 05:55 PM, Benjamin Thaut wrote:

 Am 26.10.2011 10:56, schrieb Timon Gehr:

 On 10/26/2011 07:49 AM, Benjamin Thaut wrote:

 I recently tried to replace the deprecated overloading of new and delete
 and came across a serious issue. You can not use std.conv.emplace with
 null. If you pass null to it, null loses it's implicit casting
 cabablities and just becomes a void*.
 This issue pretty much exists with every template. As soon as you pass
 null to a template (compile time) information gets lost.

 Besides fixing std.conv.emplace it could be really handy to be able to
 check for a null-type at compile time for example with non-nullable
 types.

 There is already a enhancement reqeust in bugzilla since January but it
 didn't get much attention yet:
 http://d.puremagic.com/issues/show_bug.cgi?id=5416

 Would this be a worthwile improvement for the langauge?



 ++vote.

 We also need an own type for the empty array literal '[]' btw.



 Do you have an example where a own type for [] would be usefull?



It is the same rationale as the one for null

Eg:

class Class{
     this(int,string,double[]) {}
}

auto New(T,A...)(A args) {
     return new T(args);
}

void main(){
     auto a = new Class(1,"hi",[]); // fine
     auto b = New!Class(1,"hi",[]); // would require an own type
}
Oct 26 2011
prev sibling parent Gor Gyolchanyan <gor.f.gyolchanyan gmail.com> writes:
Functions, overladed on different types of arrays will always fail
with empty arrays unless empty arrays have their own type.

On Wed, Oct 26, 2011 at 7:55 PM, Benjamin Thaut <code benjamin-thaut.de> wrote:

 Am 26.10.2011 10:56, schrieb Timon Gehr:

 On 10/26/2011 07:49 AM, Benjamin Thaut wrote:

 I recently tried to replace the deprecated overloading of new and delete
 and came across a serious issue. You can not use std.conv.emplace with
 null. If you pass null to it, null loses it's implicit casting
 cabablities and just becomes a void*.
 This issue pretty much exists with every template. As soon as you pass
 null to a template (compile time) information gets lost.

 Besides fixing std.conv.emplace it could be really handy to be able to
 check for a null-type at compile time for example with non-nullable
 types.

 There is already a enhancement reqeust in bugzilla since January but it
 didn't get much attention yet:
 http://d.puremagic.com/issues/show_bug.cgi?id=5416

 Would this be a worthwile improvement for the langauge?



 ++vote.

 We also need an own type for the empty array literal '[]' btw.



 Do you have an example where a own type for [] would be usefull?

 --
 Kind Regards
 Benjamin Thaut
Oct 26 2011
prev sibling next sibling parent Gor Gyolchanyan <gor.f.gyolchanyan gmail.com> writes:
Yes! Empty array is also a special-case value, which can be
interpreted in a special way, which is completely different from any
other array.

On Wed, Oct 26, 2011 at 12:56 PM, Timon Gehr <timon.gehr gmx.ch> wrote:

 On 10/26/2011 07:49 AM, Benjamin Thaut wrote:

 I recently tried to replace the deprecated overloading of new and delete
 and came across a serious issue. You can not use std.conv.emplace with
 null. If you pass null to it, null loses it's implicit casting
 cabablities and just becomes a void*.
 This issue pretty much exists with every template. As soon as you pass
 null to a template (compile time) information gets lost.

 Besides fixing std.conv.emplace it could be really handy to be able to
 check for a null-type at compile time for example with non-nullable types.

 There is already a enhancement reqeust in bugzilla since January but it
 didn't get much attention yet:
 http://d.puremagic.com/issues/show_bug.cgi?id=5416

 Would this be a worthwile improvement for the langauge?



 ++vote.

 We also need an own type for the empty array literal '[]' btw.
Oct 26 2011
prev sibling next sibling parent kenji hara <k.hara.pg gmail.com> writes:
+1
I think 5899 is related issue.

Kenji Hara

2011/10/26 Gor Gyolchanyan <gor.f.gyolchanyan gmail.com>:

 I agree. Null is a very common special-case value and overloading may
 be necessary based on that special-case value. Currently doing so
 means accepting any kind of typeless pointer (which is certainly not
 desirable).

 On Wed, Oct 26, 2011 at 9:49 AM, Benjamin Thaut <code benjamin-thaut.de> wrote:

 I recently tried to replace the deprecated overloading of new and delete and
 came across a serious issue. You can not use std.conv.emplace with null. If
 you pass null to it, null loses it's implicit casting cabablities and just
 becomes a void*.
 This issue pretty much exists with every template. As soon as you pass null
 to a template (compile time) information gets lost.

 Besides fixing std.conv.emplace it could be really handy to be able to check
 for a null-type at compile time for example with non-nullable types.

 There is already a enhancement reqeust in bugzilla since January but it
 didn't get much attention yet:
 http://d.puremagic.com/issues/show_bug.cgi?id=5416

 Would this be a worthwile improvement for the langauge?
 --
 Kind Regards
 Benjamin Thaut
Oct 27 2011
prev sibling parent reply kenji hara <k.hara.pg gmail.com> writes:
https://github.com/D-Programming-Language/dmd/pull/476
The pull request implementing that enhancement.

Kenji Hara

2011/10/27 kenji hara <k.hara.pg gmail.com>:

 +1
 I think 5899 is related issue.

 Kenji Hara

 2011/10/26 Gor Gyolchanyan <gor.f.gyolchanyan gmail.com>:

 I agree. Null is a very common special-case value and overloading may
 be necessary based on that special-case value. Currently doing so
 means accepting any kind of typeless pointer (which is certainly not
 desirable).

 On Wed, Oct 26, 2011 at 9:49 AM, Benjamin Thaut <code benjamin-thaut.de> wrote:

 I recently tried to replace the deprecated overloading of new and delete and
 came across a serious issue. You can not use std.conv.emplace with null. If
 you pass null to it, null loses it's implicit casting cabablities and just
 becomes a void*.
 This issue pretty much exists with every template. As soon as you pass null
 to a template (compile time) information gets lost.

 Besides fixing std.conv.emplace it could be really handy to be able to check
 for a null-type at compile time for example with non-nullable types.

 There is already a enhancement reqeust in bugzilla since January but it
 didn't get much attention yet:
 http://d.puremagic.com/issues/show_bug.cgi?id=5416

 Would this be a worthwile improvement for the langauge?
 --
 Kind Regards
 Benjamin Thaut
Oct 27 2011
parent reply Timon Gehr <timon.gehr gmx.ch> writes:
On 10/27/2011 02:12 PM, kenji hara wrote:

 https://github.com/D-Programming-Language/dmd/pull/476
 The pull request implementing that enhancement.

 Kenji Hara



Great! Thank you. I hope that is merged soon. What do you think about 
emptyarray_t?
Oct 27 2011
parent Benjamin Thaut <code benjamin-thaut.de> writes:
Am 27.10.2011 18:14, schrieb Timon Gehr:

 On 10/27/2011 02:12 PM, kenji hara wrote:

 https://github.com/D-Programming-Language/dmd/pull/476
 The pull request implementing that enhancement.

 Kenji Hara



 Great! Thank you. I hope that is merged soon. What do you think about
 emptyarray_t?




-- 
Kind Regards
Benjamin Thaut
Oct 27 2011