Question

What’s the thoughts on allowing simple constructor/method definitions in header files in C++. Some classes I am creating are simple data objects that compose another object say, so they need there own constructor and get/set methods. However these are usually < 3-4 lines each with the constructors using init lists. Is it OK to just have .h for these classes.?

UPDATE::
What about where to store .h files, in a seperate directory from the cpp files?

Answer 1

I’d vote for only putting declarations in your header file. This will make the header file more clean (no implementation cluttering your view). The user can look upon the header file to view the interface, without being confronted with irrelevant implementation details.

Putting definitions (as opposed to declarations) in your header file can also cause linker errors (as mentioned by Captain Comic). Maybe not currently, but surely when you expand your code.

Besides, explicitly separating declaration from definition (lets forget templates and inline functions here) also works towards a more “perfect” model. The code will be completely modularized in separate source files. From my personal experiences this takes time and care, but is consistent and avoids linker errors etc.

Surely, if you’re writing a quick application nobody else is going to see…nobody is there to criticize 😉