A C++ template library for embedded applications
MIT licensed
Designed and
maintained by
John Wellbelove
Support the development
of the ETL
Delegate Service
This template class allows easier integration of 'C' style events (such as interrupt vectors) and C++ handlers.
It can allow abstraction between low level events such as interrupts and their application dependent handlers.
The handlers may be any combination of global, static, member functions, lambdas and functors.
It utilises the templated function wrapper. See here.

The delegate callbacks are identified by an id. The values of the ids must range from zero or a specified offset, up to the
maximum range of specified delegates. Calling an unused delegate id will either do nothing or, if the user has specified a
handler, call this with the id of the delegate.

There are functions that use both runtime and compile time checks of the delegate id.
Compile time is preferable.

template <size_t Range, size_t Offset = 0U, const etl::delegate<void(size_t)>* Delegates = nullptr>
etl::delegate_service

Range     The id range of the delegates (last - first + 1).
Offset    The starting id for the range. Default 0.
Delegates An optional pointer to an array of delegate pointers.

If the pointer to a delegate array is supplied as a template parameter then the delegate service may be declared
constexpr, otherwise the service is runtime only.
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Member functions
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delegate_service()
Runtime only
Sets all of the delegates to route to the unhandled delegate.
Sets the unhandled delegate to default (do nothing).
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template <const size_t ID>
void register_delegate(etl::delegate<void(size_t)>& callback)
Runtime only
Registers delegate with the id specified in the template parameter.
A compile time error will occur if the id is out of range.
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void register_delegate(size_t id, etl::delegate<void(size_t)>& callback)
Runtime only
Registers delegate with the id specified in the template parameter.
The registration will be ignored if the id is out of range.
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void register_unhandled_delegate(etl::delegate<void(size_t)>& callback)
Runtime only
Registers the delegate to be used for unhandled ids.
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template <const size_t ID>
void call()
Calls the delegate associated with the id.
Calls the unhandled delegate if the id has not been registered.
A compile time error will occur if the id is out of range.
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void call(const size_t id)
Calls the delegate associated with the id.
Calls the unhandled delegate if the id has not been registered or if is out of range.
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Example

Tutorial

See the example project in etl\examples\FunctionInterruptSimulation-Delegates
delegate_service.h