Why not to write instead of a doubtful construction

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DGIO_setDiscrete(RedLED, ON); //your example 
a simple expression 
RedLED = ON;

It's called encapsulation. Imagine you found the LED flickering occasionally. With the RedLED = ON construct, you could not set a break point and do a stack back trace to see who the caller was. Only use direct hardware access like this when performance is critical and you are very careful.