LCleanedupHandle Class Reference

Detailed Description

A class template for the creation and CleanupStack-based local-scope automatic management of resource handles (typically instances of R-classes).

By default, the cleanup action is to call the Close() member function of the managed handle. An alternative cleanup strategy may be selected by specifying a cleanup strategy template class in the optional second template parameter position. The most common alternative cleanup strategies are predefined. It is also possible to specialize the default cleanup action for a given class using the DEFINE_CLEANUP_FUNCTION macro.

The constructors of this class may leave.

Any arguments supplied when initializing an instance of this class are automatically passed through to T's constructors.

As a convenience, the methods of the managed handle may be accessed via "->" notation directly on the management object, while "." notation is used to access the interface of the management object itself. Using "*" to dereference the management object yields a T&, and is often useful when passing the managed object as an argument.

Automatic cleanup may be disabled at any time by calling Unmanage(), while cleanup may be forced at any time by calling ReleaseResource().

	// block scope example
	{
	LCleanedupHandle<RClosable> obj;
	obj->DoSomethingL(); // leave-safe
	if (obj->Finished())
		return; // RClosable::Close is invoked automatically
	obj->DoSomethingElseL(); // leave-safe
	// RClosable::Close is invoked automatically
	}

Behind the scenes, this class template is implemented in terms of the thread-local CleanupStack, restricting its use to locals on the stack. This use of the CleanupStack ensures a consistent cleanup order between functions that call one another, even if they use different cleanup idioms.

This class template together with the cleanup strategy class templates provide a template-based implementation of the Strategy design pattern (See also: Policy-based design).

See also: TClose which implements the default Close() calling cleanup strategy TResetAndDestroy which implements an alternative ResetAndDestroy() calling cleanup strategy TFree which implements an alternative Free() calling cleanup strategy TDestroy which implements an alternative Destroy() calling cleanup strategy TRelease which implements an alternative Release() calling cleanup strategy LManagedHandle which has the same interface, but does not use the cleanup stack and is suitable for protecting the data members of classes