On Fri, 07 Jan 2011 11:30:17 -0500, Adam Conner-Sax
<adam_conner_...@yahoo.com> wrote:
Thanks!
It's not really about correctness as much as trying to understand how
these
different storage classes work. I understand that there is only one foo
object.
I wanted to see which parts are thread-local and which are shared and
how the
constructors work.
A class instance can be shared or unshared. Either way, changing the data
on the same instance updates the same instance, there is not a copy of the
whole world in each thread, just a copy of the thread local storage block.
So you are sort of conflating 'per instance' with 'per thread.'
int x -- per instance (shared or not)
static int x -- per thread (in the TLS block)
shared static int x -- per process, not in any instance.
I'm working (way over my head) on a more complex threading issue and I
realized
that I didn't quite understand the storage classes and constructors. Now
I get it
a bit more.
By "untagged sharing" do you mean the "a" variable which is shared in
the sense
that all threads see the same copy but does not have storage class
"shared"? Yes,
that confuses me too. Should it be an error?
Yes, if you have a piece of data that shared and not marked with __gshared
or shared, then we have a problem. The problem is that a lot of code
assumes that situation cannot happen without casts (you can always cast
and override the type system), so you can make assumptions based on that.
For example, a lot of C++/java code is written *just in case* an object is
shared. With D, the hope is that you are *guaranteed* that it is shared
or not, so you can optimize your code that way (i.e. use a lock or not).
As long as the possibility exists that code not marked as shared can be
easily shared without a cast, we cannot make those assumptions.
I think it should be filed as a bug, but I'm not sure if someone's already
reported it.
I have never dealt with bugzilla but I will try to figure out how to do
what you
ask :)
Go to http://d.puremagic.com/issues/enter_bug.cgi
You will have to create a user before filing a bug, but bugzilla is
relatively straightforward to use.
-Steve
