any news on const/invariant?

[Derek Parnell]

On Tue, 27 Nov 2007 06:54:40 +0000, Janice Caron wrote:

> On 11/27/07, Derek Parnell <derek at nomail.afraid.org> wrote:
>> On Mon, 26 Nov 2007 21:24:13 -0800, Walter Bright wrote:
>>
>>> I'm not sure why one would need protection against changing the bitmap
>>> pointer. GammaAdjust should just take a byte[], not a ref byte[].
>>
>>  byte[] bitmap;
>>  bitmap = LoadBitMapFromFile("worldroadmap.bmp");
>>  GammaAdjust(bitmap, 0.20);
>>  Render(device, bitmap);
>>
>> If the 'GammaAdjust' routine changed the pointer then 'Render' routine
>> would not display the adjusted bitmap.
> 
> The GammaAdjust routine /cannot/ change the pointer, because it is
> passed in by value, not by reference.
> 
> I guess it could change its own local copy of the pointer, but that
> would just be a bug local to the function.

I'm sorry I'm not getting my request out clear enough.

I *know* that at run time the GammaAdjust routine cannot effectively change
the pointer. But that is not what I'm saying. 

I would like the compiler to tell me at /compile/ time that I've
incorrectly attempted to change a pointer that has been designed to remain
unchanged. I would like to avoid waiting for this to only become apparent
at /run/ time.

-- 
Derek
(skype: derek.j.parnell)
Melbourne, Australia
27/11/2007 6:24:56 PM