On 6/16/16 9:54 AM, MMJones wrote:
Suppose one has something like
class foo
{
int[] x;
void bar()
{
x = [];
}
}
Does the GC trash the "cache" when calling bar or does it realize that
it can use the same memory for x and essentially just shortens the array?
If you reassign x, the compiler does not know enough context to assume
nothing else has a reference to x's old data. So no, it would not re-use
that same data.
Is it equivalent to setting length = 0?
Even this is not going to overwrite the data. You'd need to do:
x.length = 0;
x.assumeSafeAppend;
I'm a bit worried that setting a managed array to [] might cause a
completely new reallocation, which is unnecessary and undesirable.
Use assumeSafeAppend when you need to do this.
BTW, x = [] is equivalent to x = null. So this is most certainly going
to cause a new allocation on the next append.
-Steve
