ubyte array changing values between calls? Possible bug?

[Ali Çehreli]

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