On 2/21/21 9:29 PM, Preetpal wrote:
I want to restrict a D application to a single instance. Is there a way
to do this using the D standard library?
When you say "application", you mean a class or type?
If so, you can do this:
class C
{
private this() { /*ctor code for single instance */ }
private static C _instance = new C();
public C instance() { return _instance; }
}
You can also do it with a struct, but it's not as bullet-proof:
struct S
{
@disable this();
private static S _instance;
ref S instance() { return _instance; }
}
But one can always do this, and the compiler will never prevent it:
S s = S.init;
All these have an instance per thread.
If you want a global singleton that is initialized on first use, use the
D singleton pattern: https://wiki.dlang.org/Low-Lock_Singleton_Pattern
-Steve
