Should accessors be Inlined?

Question

This is the declaration in the header file:

class PrimeSieve  
{
    populate(int lim);
    vector<int> sieve;
    long long limit;

    public:
        unsigned int limit();
};

Should I define the accessor method in the .cpp file or in the .h, inline?

I'm new to C++, but I'd like to follow best practices. I've seen this around in some of the books—is this considered standard?

unsigned int limit() { return limit; };

Answer 1

Definitely write the accessor inline in the header file. It makes better optimizations possible, and doesn't reduce encapsulation (since changes to the format of private data require recompiling all units that include the header anyway).

In the case of a complicated algorithm, you might want to hide the definition in an implementation file. Or when the implementation requires some types/header files not otherwise required by the class definition. Neither of those cases applies to simple accessors.

For one-liners, put it inside the class definition. Slightly longer member functions should still be in the header file, but might be declared explicitly inline, following the class definition.

Answer 2

Most newer compilers are smart enough to inline what is necessary and leave everything else alone. So let the compiler do what its good at and don't try to second guess it.

Put all your code in the .cpp and the code declarations in the .h.