I'm still a bit fuzzy on how to create immutable data and when said data is safe to share across threads.
To begin with, there is .idup, string literals and constructors of immutable objects. Those can be safely shared, no problem, right? But then, the spec mentions casting to immutable is ok if you do not have any mutable aliases left (http://www.digitalmars.com/d/2.0/const3.html): char[] s = ...; immutable(char)[] p = cast(immutable)s.dup; // ok, unique reference I do not understand how that works with sharing. Since immutable data is implicitly shared but the data that p refers to is allocated on the TLS, how can you share this? I always thought that threads do not have access to each others TLS at all? Finally a practical question: when you have a data structure that is too complex to create in a constructor, want to create it and then make it immutable, what is the current way to go about this? If it is created by one thread, would it be ok to type it as __gshared, cast to immutable and then send a message to other threads? Is __gshared required in this case?
