Pattern: Non-const reference
Issue: -
Within function parameter lists all references must be const:
void Foo(const string &in, string *out);
In fact it is a very strong convention in Google code that input arguments are values or const references while output arguments are pointers. Input parameters may be const pointers, but we never allow non-const reference parameters except when required by convention, e.g., swap().
However, there are some instances where using const T* is preferable to const T& for input parameters. For example:
- You want to pass in a null pointer.
- The function saves a pointer or reference to the input.
Remember that most of the time input parameters are going to be specified as const T&. Using const T* instead communicates to the reader that the input is somehow treated differently. So if you choose const T* rather than const T&, do so for a concrete reason; otherwise it will likely confuse readers by making them look for an explanation that doesn't exist.