Clear deletes all instances stored.

Get returns the instance by given name.

GetOrSet returns the instance by name, or set instance to the instance manager if it does not exist and returns this instance.

GetOrSetFunc returns the instance by name, or sets instance with returned value of callback function `f` if it does not exist and then returns this instance.

GetOrSetFuncLock returns the instance by name, or sets instance with returned value of callback function `f` if it does not exist and then returns this instance.

Set sets an instance to the instance manager with given name.

SetIfNotExist sets `instance` to the map if the `name` does not exist, then returns true.