On Sunday, 15 December 2013 at 00:21:37 UTC, Ali Çehreli wrote:
On 12/14/2013 10:48 AM, Gary Willoughby wrote:
> On Friday, 13 December 2013 at 17:35:27 UTC, John Colvin
wrote:
>>> public void opAssign(uint value)
>>> {
>>> this._octets = value.nativeToBigEndian();
>>> assert(this._octets == [1, 2, 3, 4]);
>>> }
>>> }
>> opAssign is escaping a reference to its stack by assigning
the static
>> array to the slice _octets. Therefore, garbage.
>
> I'm not going to lie that has gone over my head a little.
Could you
> explain it more simply please? I just want to totally
understand the
> issue here. Thanks.
According to documentation, nativeToBigEndian returns a static
array (fixed-length array):
http://dlang.org/phobos/std_bitmanip.html#.nativeToBigEndian
It says "returns it as a ubyte[n] where n is the size of the
given type."
Since static arrays normally live on the stack, the returned
array is a local array.
As with any slice assignment, the assignment to this._octets in
opAssign makes _octets a slice to the elements of that local
array. Upon leaving opAssign that array is no more. So, _octets
is left referring to elements that are long gone. :(
Ali
Ah right, that now makes perfect sense. Thanks all! :)
