inlining and copy constructors

if I have a templated inline function that takes an object by value
i.e.

Code:

---

template <typename T>
void DoSomething(T someT)
{
    // assume << is defined!!
    cout << someT;
}

---

if this function is called and inlined will T's copy ctor still get called?
i.e.

Code:

---

ExpseniveToCopy etc;
DoSomething(etc);

//becomes either
ExpseniveToCopy etc;
cout <<etc;

// or

ExpseniveToCopy etc;
ExpseniveToCopy someT(etc);
cout << someT;

---

I presume it's the latter, but can't find anything definite (and I can't use a reference, as DoSomething sometimes accepts a reference and reference to a reference is illegal)

Quote:

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(and I can't use a reference, as DoSomething sometimes accepts a reference and reference to a reference is illegal)

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Hmm, is that so? I thought it should work. Do you mean something like this?

Code:

---

#include <cstdlib>
#include <iostream>
using namespace std;

template <typename T>
void DoSomething(T& someT){
  cout << someT;
}

int main(int argc, char *argv[])
{
  int a = 2;
  int& b = a ;
  DoSomething( b );
  cin.get();
  return 0 ;
}

---

allow me to rephrase. ref to ref may or may not be illegal but VS.net2k3 spits out the following error

error C2529 : reference to reference is illegal

Yes a reference to a reference would be illegal and it makes no sense. However you can initalize a reference with an object that is a reference.

Code:

---

int a = 5;
int& b = a;
int&& c = b; // not legal

---

Code:

---

int a = 5;
int& b = a;
int& c = b; // legal

---

Quote:

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Originally Posted by Thantos

Yes a reference to a reference would be illegal and it makes no sense. However you can initalize a reference with an object that is a reference.

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the problem is that sometimes the type can't be deduced so you have to specify it (this happens specifically with mem_fun and bind2nd)

check out this thread on gamedev.net for more info.

Ok I'm still not seeing your problem. Can you show me some actual code that invokes this behavior?

You might consider asking this question on comp.lang.c++(.moderated) or the CodeGuru forums. They have a lot more active advanced users than there are here.

Quote:

---

Originally Posted by ChaosEngine

if this function is called and inlined will T's copy ctor still get called?

---

It's simple enough to try yourself.

Code:

---

#include <iostream>

class A
{
public:
  A() {}
  A(const A& obj) {std::cout
    << "Copy Constructor" << std::endl;}
};

template <typename T>
inline void DoSomething(T someT) {}

int main()
{
  A a;
  DoSomething( a );
  return 0 ;
}

---

Quote:

---

Originally Posted by ChaosEngine

allow me to rephrase. ref to ref may or may not be illegal but VS.net2k3 spits out the following error

error C2529 : reference to reference is illegal

---

Good, you gave us half of it. Now, let's see the code that generates this error.