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

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
>

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.

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.
>

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

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
>

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
}

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.

+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
>>
>

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
>>>
>>
>