On 11/19/2016 11:10 AM, Nicolas Gurrola via Digitalmars-d-learn wrote:
On Saturday, 19 November 2016 at 18:51:05 UTC, Charles Hixson wrote:
ubyte[] header() @property { return fHead[4..$]; }
This method should do what you want. You are only returning a slice of
the fHead array, so if the caller modifies the length it will only
affect of the return value, and not the length of fHead itself.
It's worse than that, if they modify the length the array may be
reallocated in RAM so that the pointers held by the containing class do
not point to the changed values. (Read the header comments...it's not
nice at all.)
More, the class explicitly requires the array to be a particular length
as it needs to fit into a spot in a binary file, so I really want to
forbid any replacement of the array for any reason. The first four
bytes are managed by the class and returned via alternate routines which
do not allow the original values to be altered, and this is necessary.
I could make them immutable, but actually what I do is return, e.g., an
int of 256 * fHead[0] + fHead[1], which is the length of the header.
It's an int to allow negative values to be returned in case of error.
So what I'll probably eventually decide on is some variation of
saveToHead, e.g.:
bool saveToHeader (ubyte[] rec)
{ if (rec.length + 4 > dheader) return false;
fHead[4..recLen + 4] = rec[0..$];
return true;
}
unless I can think of something better. Actually for this particular
case that's not a bad approach, but for the larger problem it's a lousy
kludge.
