assert(obj) is an atrocity

[dsimcha]

On 11/8/2011 7:05 PM, Timon Gehr wrote:
> On 11/08/2011 11:35 PM, Alex Rønne Petersen wrote:
>> Hi,
>>
>> As the title suggests, I'm going to be rather blunt about this.
>> assert(obj) testing the invariant *without* doing a null check is insane
>> for the following reasons:
>>
>> 1) It is not what a user expects. It is *unintuitive*.
>> 2) assert(!obj) does an is-null check. assert(obj) is a completely
>> broken opposite of this.
>> 3) No AssertError is thrown, which is the entire point of the built-in
>> assert().
>> 4) The few added instructions for the null check hardly matter in a
>> *debug* build of all things.
>>
>> I don't mind assert(obj) testing the invariant of obj. In fact, that
>> very much makes sense. But please, please, *please* check the object for
>> null first.
>
> +1.

+1.  **AND** in debug mode all pointers should be checked for null. 
Conceptually, I fail to see how a null pointer dereference is different 
from an array bounds error.  A null pointer is effectively an array with 
length zero.