Is it valid to assume that a reference is passed as a pointer
arguments, c++, reference, visual-studio-2010
Solution
Is it valid to assume that a reference is passed as a pointer?
No, it is not. The standard does not mandate that the reference should be implemented in terms of pointer.
How to actually implement a reference is an implementation detail which the standard leaves out for implementations to decide on. It only describes the expected behavior from an Reference and one of them is a reference can never be `NULL` in a standard conformant program.
If your function parameter is expected to be `NULL` sometimes then you should pass it as an pointer.
Problem
I have a function defined like this: ``` void doSomethingWithCustomer (const Customer &customer); ``` One of my fellow developers called it like this: ``` Customer *customer = order.getCustomer(); doSomethingWithCustomer (*customer); ``` Unfortunately, the `getCustomer` method can return a nullptr, if the order is not tied to a customer. If `getCustomer` returns a nullptr, then the application does not crash at the time of the call to `doSomethingWithCustomer` but rather within the function, where the customer reference is used. Of course the correct way to write this is to check for customer not being a nullptr first, then call the function if we have a valid customer. Normally we expect that if a function/method has a reference argument, that the caller checks the validity of it (which wasn't the case here), instead of the function itself checking the argument. I know that Visual Studio 2010 (and earlier versions) passes references by actually passing the pointer, but I wonder if this is indicated somewhere in the C++ standard. Can we assume that a reference is always passed as a pointer (personally, I wouldn't rely on this, but it's interesting to know it)? Is it possible to tell Visual Studio that when passing a reference, it should automatically dereference it first and crash at the time of the call rather then somewhere much deeper (doing this in a debug version might be sufficient)?