Can someone please clarify for me which of these is the "preferred" syntax?

alias that this;
alias this : that;

The documentation here (http://dlang.org/class.html#AliasThis) doesn't mention the latter.  I'll do the unrewarding work of updating the docs if someone could just please tell me which syntax the core language folks prefer.

Thanks.
Mike

For context:
https://github.com/D-Programming-Language/dmd/pull/1413
https://github.com/D-Programming-Language/dmd/pull/1685

On Friday, 7 February 2014 at 07:36:57 UTC, Mike wrote:
> Can someone please clarify for me which of these is the "preferred" syntax?
>
> alias that this;
> alias this : that;
>
> The documentation here (http://dlang.org/class.html#AliasThis) doesn't mention the latter.  I'll do the unrewarding work of updating the docs if someone could just please tell me which syntax the core language folks prefer.
>
> Thanks.
> Mike
>
> For context:
> https://github.com/D-Programming-Language/dmd/pull/1413
> https://github.com/D-Programming-Language/dmd/pull/1685

`alias this : that` was discussed but has never been implemented, so currently the only way to do it is `alias that this`.

On Friday, 7 February 2014 at 07:52:22 UTC, Meta wrote:
> On Friday, 7 February 2014 at 07:36:57 UTC, Mike wrote:
>> Can someone please clarify for me which of these is the "preferred" syntax?
>>
>> alias that this;
>> alias this : that;
>>
>> The documentation here (http://dlang.org/class.html#AliasThis) doesn't mention the latter.  I'll do the unrewarding work of updating the docs if someone could just please tell me which syntax the core language folks prefer.
>>
>> Thanks.
>> Mike
>>
>> For context:
>> https://github.com/D-Programming-Language/dmd/pull/1413
>> https://github.com/D-Programming-Language/dmd/pull/1685
>
> `alias this : that` was discussed but has never been implemented, so currently the only way to do it is `alias that this`.

Is alias this = that not a thing? If not, why?

On Friday, 7 February 2014 at 20:48:37 UTC, Tofu Ninja wrote:
> On Friday, 7 February 2014 at 07:52:22 UTC, Meta wrote:
>> On Friday, 7 February 2014 at 07:36:57 UTC, Mike wrote:
>>> Can someone please clarify for me which of these is the "preferred" syntax?
>>>
>>> alias that this;
>>> alias this : that;
>>>
>>> The documentation here (http://dlang.org/class.html#AliasThis) doesn't mention the latter.  I'll do the unrewarding work of updating the docs if someone could just please tell me which syntax the core language folks prefer.
>>>
>>> Thanks.
>>> Mike
>>>
>>> For context:
>>> https://github.com/D-Programming-Language/dmd/pull/1413
>>> https://github.com/D-Programming-Language/dmd/pull/1685
>>
>> `alias this : that` was discussed but has never been implemented, so currently the only way to do it is `alias that this`.
>
> Is alias this = that not a thing? If not, why?
Because
alias this = that;
alias this = anotherThat;

is wierd

On 02/07/2014 10:02 PM, Daniel Kozak wrote:
> On Friday, 7 February 2014 at 20:48:37 UTC, Tofu Ninja wrote:
>> On Friday, 7 February 2014 at 07:52:22 UTC, Meta wrote:
>>> ...
>>
>> Is alias this = that not a thing? If not, why?
> Because
> alias this = that;
> alias this = anotherThat;
>
> is wierd

Even if we assume for now that this is somehow bad, it is no reason to have syntax inconsistent with alias.

int baz(int x){ return x; }
double bar(double x){ return x; }

alias foo = bar;
alias foo = baz;

On Friday, 7 February 2014 at 21:30:46 UTC, Timon Gehr wrote:
> On 02/07/2014 10:02 PM, Daniel Kozak wrote:
>> On Friday, 7 February 2014 at 20:48:37 UTC, Tofu Ninja wrote:
>>> On Friday, 7 February 2014 at 07:52:22 UTC, Meta wrote:
>>>> ...
>>>
>>> Is alias this = that not a thing? If not, why?
>> Because
>> alias this = that;
>> alias this = anotherThat;
>>
>> is wierd
>
> Even if we assume for now that this is somehow bad, it is no reason to have syntax inconsistent with alias.
>
> int baz(int x){ return x; }
> double bar(double x){ return x; }
>
> alias foo = bar;
> alias foo = baz;

+1

On Friday, 7 February 2014 at 07:36:57 UTC, Mike wrote:
> Can someone please clarify for me which of these is the "preferred" syntax?
>
> alias that this;
> alias this : that;
>
> The documentation here (http://dlang.org/class.html#AliasThis) doesn't mention the latter.  I'll do the unrewarding work of updating the docs if someone could just please tell me which syntax the core language folks prefer.
>
> Thanks.
> Mike
>
> For context:
> https://github.com/D-Programming-Language/dmd/pull/1413
> https://github.com/D-Programming-Language/dmd/pull/1685

I'd like for 'alias that this' to go away.

I'm fine with 'alias this = that'

If we must 'alias this : that' or "this implicitly casts to that" is also reasonable to me.

Yes 'alias that this' can stay for backwards compatibility.

No 'alias this : that' has not been implemented (that I'm aware of).

On Friday, 7 February 2014 at 21:30:46 UTC, Timon Gehr wrote:
> On 02/07/2014 10:02 PM, Daniel Kozak wrote:
>> On Friday, 7 February 2014 at 20:48:37 UTC, Tofu Ninja wrote:
>>> On Friday, 7 February 2014 at 07:52:22 UTC, Meta wrote:
>>>> ...
>>>
>>> Is alias this = that not a thing? If not, why?
>> Because
>> alias this = that;
>> alias this = anotherThat;
>>
>> is wierd
>
> Even if we assume for now that this is somehow bad, it is no reason to have syntax inconsistent with alias.
>
> int baz(int x){ return x; }
> double bar(double x){ return x; }
>
> alias foo = bar;
> alias foo = baz;

Reserving `alias this = ...;` allows adding aliasing of constructors in the future, assuming it can be meaningfully defined.

On 02/07/2014 11:23 PM, Jakob Ovrum wrote:
>>
>
> Reserving `alias this = ...;` allows adding aliasing of constructors in
> the future, assuming it can be meaningfully defined.

What a mess that would be. If the consensus is that alias this syntax was a mistake then _both_ forms should be removed and the concept should be re-introduced as specially named member instead.

On Friday, 7 February 2014 at 22:55:05 UTC, Timon Gehr wrote:
> On 02/07/2014 11:23 PM, Jakob Ovrum wrote:
>>>
>>
>> Reserving `alias this = ...;` allows adding aliasing of constructors in
>> the future, assuming it can be meaningfully defined.
>
> What a mess that would be. If the consensus is that alias this syntax was a mistake then _both_ forms should be removed and the concept should be re-introduced as specially named member instead.

Timon, this makes a lot of sense.  Would you mind elaborating with a simple syntax sample?