On Tuesday, 6 October 2015 at 18:10:42 UTC, bitwise wrote:
On Tuesday, 6 October 2015 at 17:20:39 UTC, Jonathan M Davis
wrote:
I'm not sure what else I can say. The example I posted says it
all, and it can't be done properly in D (or C#, but why lower
the bar because of their mistakes? ;)
It's a side effect of having the lifetime of an object managed by
the GC. There's no way around that except to use something else
like manual memory management or reference counting. In D, it's a
good reason to use structs to manage resources like that, and
since most objects really have no need of inheritance and have no
business being classes, it's usually fine. But in the cases where
you do have to use a class, it can get annoying.
I'm not sure exactly how C# and Java handle destruction for
non-memory resources, but I'm guessing it's something like
calling GC.collect() manually every couple of seconds. If the
textures aren't released in the destructor, I don't really see
any other way to tell when they're referenced or not.
Of course though, mobile devices are the new PC, and battery
life is very much a concern, so this is a total
waste...especially if I'm doing very little GC allocation
anyways. Also, of course, there are the performance issues.
You simply do not rely on the GC or the destruction of the object
to free system resources. You manually call a function on the
object to free those resources when you're done with it. In the
case of C#, they have a construct to help with it that (IIRC) is
something like
using(myObj)
{
} // myObj.dispose() is called when exiting this scope
In Java, you'd have no choice but to call dispose manually. And
yes, that sucks, but it's life with a GC-managed object. The GC
has a number of benefits to it, but it does not come without its
costs.
Having the option to have properly ref-counted classes in
addition to classes managed by the GC would definitely be an
improvement, and I expect that we'll get there at some point, but
there _are_ ways to deal with the problem in the interim, even if
it's not ideal.
In most cases though, just don't use classes. In most cases,
inheritance is a horrible way to write programs anyway, because
it's _horrible_ for code reuse. It definitely has its uses, but
I've found that I rarely need classes in D. I suspect that far
too many folks new to D end up using classes instead of structs
just because they're used to using classes in C++ or Java or
whatever.
- Jonathan M Davis
