Passing template objects to regular functions

[tonton81]

This has come up before in the past and many people asked how to do it. I will put it here for reference. This will allow you to pass the template object directly into your own functions.

Now, we can't create and use a pointer to a template object, we can only do it's base class. So this will never work:

void configure_CAN(FlexCAN_T4* bus, uint32_t bitrate) {
  // DoSomething();
}

This is because the runtime function has no idea what the template parameters are to be passed in with the template object.
But with the base class, this is valid:

void configure_CAN(FlexCAN_T4_Base* bus, uint32_t bitrate) {
  // DoSomething();
}

Although this works for a base class pointer, you can still pass a template object of that base in, however the problem here is when you call functions that exist in the main class (FlexCAN_T4) that do not exist in the base class (FlexCAN_T4_Base), you'll get an error. So you are limited by the base class function accesses for both base and template objects.

[COLOR="#FF0000"]error: 'class FlexCAN_T4_Base' has no member named 'setTX'
   bus->setTX(DEF);
error: 'class FlexCAN_T4_Base' has no member named 'setTX'
   bus->setTX(DEF);
[/COLOR]

Now the solution is very simple actually to have a template object being passed into a regular function that is capable of access all of the main class's function calls. Simply change to this:

[COLOR="#008000"]template <class T>[/COLOR]
void configure_CAN([COLOR="#008000"]T bus[/COLOR], uint32_t bitrate) {
  bus->setRX(DEF);
  bus->setTX(DEF);
}

Now the actual template object will be able to fully run within your function without the limits of the base class!

configure_CAN(&Can0, 500000);

template <class T>
void configure_CAN(T bus, uint32_t bitrate) {
  bus->onReceive(onReceive) ;
  bus->setRX(26);
  bus->setTX(25);
  bus->begin();
  bus->setBaudRate(bitrate);
}