Where there is a choice, prefer default arguments over overloading

Reason

Default arguments simply provide alternative interfaces to a single implementation. There is no guarantee that a set of overloaded functions all implement the same semantics. The use of default arguments can avoid code replication.

Note

There is a choice between using default argument and overloading when the alternatives are from a set of arguments of the same types. For example:

void print(const string& s, format f = {});

as opposed to

void print(const string& s);  // use default format
void print(const string& s, format f);

There is not a choice when a set of functions are used to do a semantically equivalent operation to a set of types. For example:

void print(const char&);
void print(int);
void print(zstring);

See also

Default arguments for virtual functions

Enforcement

• Warn on an overload set where the overloads have a common prefix of parameters (e.g., f(int), f(int, const string&), f(int, const string&, double)). (Note: Review this enforcement if it's too noisy in practice.)