Singleton< T, Global > Class Template Reference

Basic support for the singleton pattern. More...

#include <ql/patterns/singleton.hpp>

Public Member Functions
	Singleton (const Singleton &)=delete
	Singleton (Singleton &&)=delete
Singleton &	operator= (const Singleton &)=delete
Singleton &	operator= (Singleton &&)=delete

Static Public Member Functions
static T &	instance ()
	access to the unique instance

Detailed Description

template<class T, class Global = std::integral_constant<bool, false>>
class QuantLib::Singleton< T, Global >

Basic support for the singleton pattern.

The typical use of this class is:

class Foo : public Singleton<Foo> {
    friend class Singleton<Foo>;
  private:
    Foo() {}
  public:
    ...
};

which, albeit sub-optimal, frees one from the concerns of creating and managing the unique instance and can serve later as a single implemementation point should synchronization features be added.

Global can be used to distinguish Singletons that are local to a session (Global = false) or that are global across all sessions (B = true). This is only relevant if QL_ENABLE_SESSIONS is enabled.

Notice that the creation and retrieval of (local or global) singleton instances through instance() is thread safe, but obviously subsequent operations on the singleton have to be synchronized within the singleton implementation itself.