NFD » ndn-cxx

For one-liners (getters and setters mostly) I'd argue that the following is the most readable solution, in my opinion:

class C : noncopyable
{
public:
  int  getN() const { return m_n; }
  void setN(int n)  { m_n = n; }

private:
  int m_n;
};

Unfortunately it's incompatible with several other guidelines that we established some time ago.

Many setters are not one-liner.
They include return *this; to allow chaining.

I'm against any additional guidelines. All ways listed, including the one Davide mentioned and some others that are not mentioned, are acceptable and reasonable. Which one to use is up to the discretion and preference of the developer.

There should be one and only one way to do a thing. This ensures code is consistent and readable.

I'm with Alex on this one. All 3 proposed ways make sense depending on the circumstance and they're all readable, even if mixed together in the same file. The only recommendation we should make is to avoid writing long methods inline inside the class declaration (note that this recommendation mostly applies to templates, which require the method implementation in the header file, normal classes should not have long inline methods in the first place).

Without a new rule, the third style is not acceptable because it violates rule 1.5.