string <-> null/bool implicit conversion

[deadalnix via Digitalmars-d]

On Friday, 21 August 2015 at 11:34:42 UTC, Marc Schütz wrote:
> On Thursday, 20 August 2015 at 19:41:44 UTC, Jonathan M Davis 
> wrote:
>> On Thursday, 20 August 2015 at 17:50:11 UTC, Steven 
>> Schveighoffer wrote:
>>> if(arr != null)
>>
>> Definitely don't do that. IMHO, "== null and "!= null" should 
>> be illegal. If you really want to check for null, then you 
>> need to use "is null" or "!is null", whereas if you want to 
>> check that an array is empty, check its length or call empty. 
>> By using "== null" or "!= null", you tend to give the false 
>> impression that you're checking whether the object or array is 
>> null - which is not what you're actually doing.
>
> I disagree. `is null` is the one that should be illegal. `is` 
> is supposed to do a bitwise comparison, but `null` is usually 
> just a pointer/reference, while a slice consists of both a 
> reference and a length. Which of those are compared?

is, as its name says, is an identity check. It check that 2 thing 
ARE the same thing.

==, on the other hand, is a value check. It check if 2 thing have 
the same value, regardless if they are the same or not.