The cost of passing by shared_ptr

Question

I use std::tr1::shared_ptr extensively throughout my application. This includes passing objects in as function arguments. Consider the following:

class Datas         


        

Answer 1

Always pass your shared_ptr by const reference:

void f(const shared_ptr& pds) {...} 
void g(const shared_ptr& pds) {...} 

Edit: Regarding the safety issues mentioned by others:

• When using shared_ptr heavily throughout an application, passing by value will take up a tremendous amount of time (I've seen it go 50+%).
• Use const T& instead of const shared_ptr& when the argument shall not be null.
• Using const shared_ptr& is safer than const T* when performance is an issue.