Best way to overload a function based on argument type being pointer | reference?

Question

I have a function like so:

void myFunction(MyObject& obj)
{
    //lots of code to operate on obj
}

My issue is that sometimes obj will be a pointer to an instance of the type MyObject

void myFunction(MyObject* obj)
{
    //...
}

My question is how can I achieve having both function definitions, while not having to repeat any code?

I am not sure. Personally I would settle for one or other. Then, if needed, pass in &rObject or *pObject. That has worked for me. — Andrew Truckle
– Andrew Truckle, Commented May 23, 2016 at 17:47
You can always call one function from the other, but I don't think you really need two, the caller can provide either easily. — Retired Ninja
– Retired Ninja, Commented May 23, 2016 at 17:49

NathanOliver · Accepted Answer · 2016-05-23 18:02:30Z

5

You can simply forward the instance on from the pointer function.

void myFunction(MyObject* obj)
{
    if (obj != nullptr) // do not want to dereference a null pointer
        myFunction(*obj);
}

Will call the reference version of myFunction allowing you to only maintain one function.

This assumes that you only need to work with the value of the object and using a pointer or reference is to just save having to copy the object.

edited May 23, 2016 at 18:02

answered May 23, 2016 at 17:47

NathanOliver

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7 Comments

Andrew Truckle Over a year ago

Cool. I was not sure that would compile. But my comment implies something similar. But you did better. 😀

PaulMcKenzie Over a year ago

I would check for nullptr first before forwarding to the reference version of myFunction.

NathanOliver Over a year ago

@PaulMcKenzie Good suggestion. I added a check into the code.

LoPiTaL Over a year ago

Wouldn't it be easier to do it the other way around? From the reference function to the pointer function, since a reference cannot be ever null, no checkings would be required...

NathanOliver Over a year ago

@LoPiTaL You would still need the null check in the pointer version as the OP has values and pointers so I don't think it matters. Plus the OP already has the code in the reference version so I did not want to change that.

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