On Tuesday, 19 September 2017 at 13:59:27 UTC, Jonathan M Davis
wrote:
On Tuesday, September 19, 2017 13:11:03 Craig Black via
Digitalmars-d wrote:
I've recently tried coding in D again after some years. One
of my earlier concerns was the ability to code without the GC,
which seemed difficult to pull off. To be clear, I want my
programs to be garbage collected, but I want to use the GC
sparingly so that the mark and sweep collections will be fast.
So I want guarantees that certain sections of code and
certain structs will not require the GC in any way.
I realize that you can allocate on the non-GC heap using
malloc and free and emplace, but I find it troubling that you
still need to tell the GC to scan your allocation. What I
would like is, for example, to be able to write a @nogc
templated struct that guarantees that none of its members
require GC scanning. Thus:
@nogc struct Array(T)
{
...
}
class GarbageCollectedClass
{
}
void main()
{
Array!int intArray; // fine
}
@nogc is a function attribute. It has no effect on types except
on their member functions. All it does is guarantee that a
function marked with @nogc cannot call any function which is
not @nogc and cannot do any operation which is not considered
@nogc. It's to guarantee that a function does not use the GC
and has nothing more to do with types than attributes like
@safe or nothrow do.
- Jonathan M Davis
Thank you for your response. The @nogc attribute is good, but in
my opinion it is incomplete if all types still require scanning.
The purpose of not employing GC in certain sections of code is
performance, and we are sacrificing performance with every
allocation unit that is needlessly scanned.
-Craig
