removing an item from a dynamic array

[Steven Schveighoffer]

On Tue, 25 Oct 2011 14:52:57 -0400, Timon Gehr <timon.gehr at gmx.ch> wrote:

> On 10/25/2011 08:38 PM, Graham Fawcett wrote:
>> On Tue, 25 Oct 2011 13:11:20 -0400, bearophile wrote:
>>
>>> Dmitry Olshansky:
>>>
>>>> No, it's not a bug. It's the same as c++ STL remove - it operates on
>>>> range but not on container. To shrink container, update it's length.
>>>
>>> Thank you for your answer, I didn't know this, and I didn't think about
>>> this possibility because it's weird, it's an in-place operation that
>>> modifies the data only partially, leaving it in a wrong state. It looks
>>> like a bad design, bug prone-too. The design of Python del is better.
>>> (Maybe I'll have to bring this in the main D newsgroup too, because
>>> Phobos bug reports often get unnoticed). In the meantime I'll add a
>>> wrapper function to dlibs2.
>>
>> I think I'd like to see std.array.replaceInPlace grow a three-parameter
>> version, so you could write:
>>
>>    replaceInPlace(arr, f, t);	// del arr[f:t]
>>
>> ...instead of:
>>
>>    replaceInPlace(arr, f, t, cast(typeof(arr)) []);
>>
>> ...and skip the pointless allocation of the empty array.
>>
>> Graham
>>
>
> There is no allocation, so no significant runtime overhead ( assert([]  
> is null); )

Note that there *is* overhead, even if it's not significant.  I highly  
recommend never to use [] and use null instead.

Does replaceInPlace(arr, f, t, null) work?  Perhaps replaceInPlace could  
just default the fourth argument to null.

-Steve