terrillmoore
commented
5 years ago @lnlp I think the docs are confusing things, but the implementation doesn't do what you're worried about. In fact, the compliance sketch uses LMIC_registerEventCb() without defining LMIC_ENABLE_onEvent to 0, yet doesn't have an onEvent function. The intent of the code is that it uses a weak reference; if you don't provide an onEvent function, the "right thing" happens, but a few bytes of code are wasted on a runtime check.
Remove undesirable dependency '#define LMIC_ENABLE_onEvent 0' for LMIC_registerEventCb()
Documentation for
Advises ('in any case is better') not to use the legacy onEvent() event callback and dynamically register an event callback with LMIC_registerEventCb() instead.
But this always requires the following definition:
Having to '#define LMIC_ENABLE_onEvent 0' as requirement before LMIC_registerEventCb() can be used is not logical and not evident (therefore error prone). In fact current documentation for LMIC_registerEventCb() does not even mention it. This undesirable dependency can be removed by the following:
Make '#define LMIC_ENABLE_onEvent 0' the default behavior WITHOUT requiring any macro/symbol to be defined for that.
Only automatically register 'legacy' onEvent() as event callback when the following is explicitly defined: '#define LMIC_ENABLEonEvent' (without a value)_.
Add to file project_config/lmic_project_config.h the following:
And add to the documentation that above line shall be uncommented for existing ('legacy') applications (migrating from LMIC-Arduino).
Most people already need to adjust their region when switching from LMIC-Arduino so uncommenting this setting for existing applications will not be a big issue.
This solution removes an undesirable dependency and will free any future applications using the MCCI LoRaWAN LMIC library from being required to add '#define LMIC_ENABLE_onEvent 0' before LMIC_registerEventCb() can be used.