declare ISR to be weak

Is there any way to make an ISR weak so that it can be overridden by user code?

The problem I have is that in the Energia core I have a set of timer ISR's that are used for PWM. I would like to make those weak so that a library can declare the same ISR which would then override the ISR in the core.

Without this I am getting the "multiple definition of `__isr_XX'" as one would expect.

 

Thanks a bunch!

 

Robert