bug in assigning to dynamic array element

[Iain Buclaw via Digitalmars-d]

On 1 November 2014 12:39, ketmar via Digitalmars-d
<digitalmars-d at puremagic.com> wrote:
> On Sat, 1 Nov 2014 12:34:50 +0000
> Iain Buclaw via Digitalmars-d <digitalmars-d at puremagic.com> wrote:
>
>> On 1 November 2014 09:03, ketmar via Digitalmars-d
>> <digitalmars-d at puremagic.com> wrote:
>> > Hello.
>> >
>> > let's run this code:
>> >
>> >       info.list[idx] = saveIt(info, count-1); //!!!
>>
>> You could use:
>>
>> emplace(&info.list[idx], saveIt(info, count-1));
> i know some workarounds, i just want to know how can i explain this
> nonsense to newcomers. "please, remember that you can't safely assign
> values to array elements"?

Or how about: Every side effect is evaluated LTR.  So whatever you do,
don't have LHS-altering side-effects on the RHS.  It may be over the
top to explain simply that it is questionable and potentially wrong to
assume that things happen in a given order.  But you may not be too
far off the mark to explain that when the need for an explicit order
is required, do it yourself.  Avoid surprises.