[solved] C++ direct access a class mber variable vs getValue

[whisp]

Is there a difference in speed when accessing a classes member variable directly, compared to getting the value of the variable via a getValue method (that does nothing else than return value)?

If it would be an interpreted language i would say yes, due to the additional lines that had to be processed from the function call. But i have no clue how the compiler compiles such a method. So, again, is there a speed difference between accessing the value directly compared to a getValue function call?

Thanks for any answers!

[CuteAlien]

When you compile with optimization the function-call will usually be removed, so there is no difference then. Without optimization the function-call itself will slow this down.

[whisp]

Thanks CuteAlien. That's good to know, even though the "usually" makes me a bit wary. Depending on the compiler? Or are there some special situations where no compiler would translate that method to direct access? I guess i have to read a bit about compilers some time.

[Sylence]

Optimization at this level is senseless. Modern compilers optimize better than most of us could do in years.

[CuteAlien]

I said usually because I also don't know if there are situations where it might keep the function. Well, it would do so for virtual functions, but those are special anyway. But aside from that I guess this is rather one of the most typcial cases and will likely be optimized away by every modern compiler.

[whisp]

Thanks. This makes the decission to implement a public getValue() method instead a public value variable for own classes an easier one, also for values that are needed very often.

[randomMesh]

Thanks. This makes the decission to implement a public getValue() method instead a public value variable for own classes an easier one, also for values that are needed very often.

Make it inline and const-correct:

Code: Select all

inline int getValue() const { return mValue; }

If you return other types than POD, you should return a constant reference.

Code: Select all

inline const Object& getObject() const { return mObject; }