C++ - passing references to boost::shared_ptr
- by abigagli
If I have a function that needs to work with a shared_ptr, wouldn't it be more efficient to pass it a reference to it (so to avoid copying the shared_ptr object)?
What are the possible bad side effects?
I envision two possible cases:
1) inside the function a copy is made of the argument, like in
ClassA::take_copy_of_sp(boost::shared_ptr<foo> &sp)
{
...
m_sp_member=sp; //This will copy the object, incrementing refcount
...
}
2) inside the function the argument is only used, like in
Class::only_work_with_sp(boost::shared_ptr<foo> &sp) //Again, no copy here
{
...
sp->do_something();
...
}
I can't see in both cases a good reason to pass the boost::shared_ptr by value instead of by reference. Passing by value would only "temporarily" increment the reference count due to the copying, and then decrement it when exiting the function scope.
Am I overlooking something?
Andrea.
EDIT:
Just to clarify, after reading several answers : I perfectly agree on the premature-optimization concerns, and I alwasy try to first-profile-then-work-on-the-hotspots. My question was more from a purely technical code-point-of-view, if you know what I mean.
