Array as an argument, ambiguous behaviour.

[Maxim Fomin]

On Wednesday, 29 January 2014 at 16:26:05 UTC, Cooler wrote:
> On Wednesday, 29 January 2014 at 16:15:36 UTC, Tobias Pankrath 
> wrote:
>> On Wednesday, 29 January 2014 at 16:01:08 UTC, Cooler wrote:
>>>
>>> Do you read my post? I am answering... why do I need fun3() 
>>> if I already have fun1() and fun2().
>>
>> fun3 guarantees that the argument has the same length for 
>> example.
>
> Where argument has the same length? After function call, or 
> inside function? I don't understand what my intention should be 
> to push me to use fun3()?

If you want to modify the slice and make changes visible in 
caller, you should use ref. If you don't care whether changes are 
visible in caller, you can omit any attributes and use plain 
array. This belongs to the case you are asking about. If you 
don't want to change array in callee, pass it as const qualified.

Now, after rethinking the issue I am inclining that "don't care 
whether changes are visible for caller" is not very wrong, but 
not very good design. Ideally it should be specified to avoid 
unexpected problems to pop up. So yes, it is better to qualify 
array.

Another point. This casino games of whether changes would be 
visible or not is direct consequence of how slices are 
implemented (and how runtime service them). Remember, that many 
features in D work in a strange way not because of wise design 
but as a consequence of not fully thought design (like array). As 
a result, some features work in not best way they should. 
Although many folks in newsgroups would eagerly say that you 
don't understand the lang, it wouldn't make a bad design a good 
one.