removing an item from a dynamic array

[Graham Fawcett]

On Wed, 26 Oct 2011 07:38:06 -0400, Steven Schveighoffer wrote:

> 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.

Yes, it works with null, although you have to cast it to typeof(arr).

Graham