TfSingleton< T > Class Template Reference

Manage a single instance of an object (see. More...

#include <singleton.h>

Public Member Functions
void	DeleteInstance ()=delete

Static Public Member Functions
static T &	GetInstance ()
	Return a reference to an object of type T, creating it if necessary.
static bool	CurrentlyExists ()
	Return whether or not the single object of type T is currently in existence.
static void	SetInstanceConstructed (T &instance)
	Indicate that the sole instance object has already been created.
static void	DeleteInstance ()
	Destroy the sole instance object of type T, if it exists.

Detailed Description

template<class T>
class TfSingleton< T >

Manage a single instance of an object (see.

Typical Use for a canonical example).

Definition at line 107 of file singleton.h.

Member Function Documentation

CurrentlyExists()

static bool CurrentlyExists ( )

inlinestatic

Return whether or not the single object of type T is currently in existence.

This call tests whether or not the singleton currently exists.

Definition at line 140 of file singleton.h.

DeleteInstance()

void DeleteInstance

inlinestatic

Destroy the sole instance object of type T, if it exists.

A singleton can be destroyed by a call to DeleteInstance. This call is threadsafe in the sense that competing simultaneous calls will not result in double deletion; however, it is up to the user to ensure that the instance is not being used in one thread during an attempt to delete the instance from another thread. After being destroyed, a call to GetInstance() will create a new instance.

Definition at line 142 of file instantiateSingleton.h.

GetInstance()

static T & GetInstance ( )

inlinestatic

Return a reference to an object of type T, creating it if necessary.

When GetInstance() is called for the first time, it creates an object of type T, and returns a reference to it. The type in question must have a default constructor (i.e. a constructor taking no arguments).

Subsequent calls to GetInstance() return a reference to the same object. This call is threadsafe; simultaneous attempts to create an object result in only one object being created; locking beyond this (for example, letting only one thread at a time call a member function) are the responsibility of the class author.

Definition at line 122 of file singleton.h.

SetInstanceConstructed()

void SetInstanceConstructed ( T &  instance )

inlinestatic

Indicate that the sole instance object has already been created.

This function is public, but should only be called by T 's constructor. It makes the instance available to the calling thread for initialization purposes during the remainder of T 's construction. In contrast, concurrent threads that call GetInstance() will continue to wait until construction is fully complete before returning the instance.

The need for this function occurs when T's constructor generates a call chain that calls back to TfSingleton<T>::GetInstance(). Normally calls to TfSingleton<T>::GetInstance() during T's construction will wait for construction to complete. Calling SetInstanceConstructed() lets future calls to TfSingleton<T>::GetInstance() by the same thread that called SetInstanceConstructed() to access the instance before T's constructor has finished. This is useful when the singleton's constuctor calls TfRegistryManager::SubscribeTo(), for example. The invoked TF_REGISTRY_FUNCTION()s can successfully call GetInstance() to access the singleton.

Be sure that T has been constructed (enough) before calling this function. Calling this function anywhere but within the call chain of T's constructor will generate a fatal coding error.

Definition at line 61 of file instantiateSingleton.h.

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The documentation for this class was generated from the following files:

• pxr/base/tf/singleton.h
• pxr/base/tf/instantiateSingleton.h