iox2::legacy::PolymorphicHandler< Interface, Default, Hooks > Class Template Reference

Implements a singleton handler that has a default instance and can be changed to another instance at runtime. All instances have to derive from the same interface. The singleton handler owns the default instance but all other instances are created externally. More...

#include <polymorphic_handler.hpp>

Static Public Member Functions
static Interface &	get () noexcept
	obtain the current singleton instance
template<typename Handler >
static bool	set (StaticLifetimeGuard< Handler > handlerGuard) noexcept
	set the current singleton instance
static bool	reset () noexcept
	reset the current singleton instance to the default instance
static void	finalize () noexcept
	finalizes the instance, afterwards Hooks::onSetAfterFinalize will be called during the remaining program lifetime when attempting to set or reset the handler
static StaticLifetimeGuard< Self >	guard () noexcept
	returns a lifetime guard whose existence guarantees the created PolymorphicHandler singleton instance will exist at least as long as the guard.

Friends
class	StaticLifetimeGuard< Self >

Detailed Description

template<typename Interface, typename Default, typename Hooks = detail::DefaultHooks<Interface>>
class iox2::legacy::PolymorphicHandler< Interface, Default, Hooks >

Implements a singleton handler that has a default instance and can be changed to another instance at runtime. All instances have to derive from the same interface. The singleton handler owns the default instance but all other instances are created externally.

Template Parameters

Interface	The interface of the handler instances.
Default	The type of the default instance. Must be equal to or derive from Interface.
Hooks	A struct that implements onSetAfterFinalize which is called when attempting to set or reset the handler after finalize was called.

Note

In the special case where Default equals Interface, no polymorphism is required.

The lifetime of external non-default instances must exceed the lifetime of the PolymorphicHandler.

The PolymorphicHandler is guaranteed to provide a valid handler during the whole program lifetime (static). It is hence not advisable to have other static variables depend on the PolymorphicHandler. It must be ensured that they are destroyed before the PolymorphicHandler.

Hooks must implement static void onSetAfterFinalize(Interface& /*currentInstance*‍/, Interface& /*newInstance*‍/).

DefaultHooks call abort if the handler is set or reset after finalize

Definition at line 57 of file polymorphic_handler.hpp.

Member Function Documentation

finalize()

template<typename Interface , typename Default , typename Hooks = detail::DefaultHooks<Interface>>

static void iox2::legacy::PolymorphicHandler< Interface, Default, Hooks >::finalize ( )

staticnoexcept

finalizes the instance, afterwards Hooks::onSetAfterFinalize will be called during the remaining program lifetime when attempting to set or reset the handler

get()

template<typename Interface , typename Default , typename Hooks = detail::DefaultHooks<Interface>>

static Interface & iox2::legacy::PolymorphicHandler< Interface, Default, Hooks >::get ( )

staticnoexcept

obtain the current singleton instance

Returns

the current instance

Note

we cannot be sure to use the current handler unless we call get, i.e. a reference obtained from get may reference a previous handler (that is still functional)

Referenced by iox2::legacy::er::panic(), iox2::legacy::er::report(), iox2::legacy::er::detail::report(), iox2::legacy::er::detail::report(), and iox2::legacy::er::report().

guard()

template<typename Interface , typename Default , typename Hooks = detail::DefaultHooks<Interface>>

static StaticLifetimeGuard< Self > iox2::legacy::PolymorphicHandler< Interface, Default, Hooks >::guard ( )

staticnoexcept

returns a lifetime guard whose existence guarantees the created PolymorphicHandler singleton instance will exist at least as long as the guard.

Returns

opaque lifetime guard object for the (implicit) PolymorphicHandler instance

Note

the PolymorphicHandler will exist once any of the static methods (get, set etc.) are called

reset()

template<typename Interface , typename Default , typename Hooks = detail::DefaultHooks<Interface>>

static bool iox2::legacy::PolymorphicHandler< Interface, Default, Hooks >::reset ( )

staticnoexcept

reset the current singleton instance to the default instance

Returns

true if handler was reset to default, false otherwise

Note

the handler cannot be reset if it was finalized

set()

template<typename Interface , typename Default , typename Hooks = detail::DefaultHooks<Interface>>

template<typename Handler >

static bool iox2::legacy::PolymorphicHandler< Interface, Default, Hooks >::set ( StaticLifetimeGuard< Handler >  handlerGuard )

staticnoexcept

set the current singleton instance

Parameters

handlerGuard

a guard to the handler instance to be set

Returns

true if handler was set, false otherwise

Note

the handler cannot be replaced if it was finalized

using a guard in the interface prevents the handler to be destroyed while it is used, passing the guard by value is necessary (it has no state anyway)

If finalization takes effect here, setHandler will still change the handler This is still correct concurrent behavior in the sense that it maps to a sequential execution where the handler is set before finalization.

Friends And Related Symbol Documentation

StaticLifetimeGuard< Self >

template<typename Interface , typename Default , typename Hooks = detail::DefaultHooks<Interface>>

friend class StaticLifetimeGuard< Self >

friend

Definition at line 58 of file polymorphic_handler.hpp.

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

• iox2/legacy/polymorphic_handler.hpp