singleton & auto_ptr (destructor is protected)

From:

"joycemenger" <joycemenger@gmail.com>

Newsgroups:

comp.lang.c++.moderated

Date:

5 Jul 2006 19:23:10 -0400

Message-ID:

<1152094504.403892.251020@p79g2000cwp.googlegroups.com>

Hi, I was reading this online article

http://www.codeproject.com/cpp/singleton.asp

and tried to write some code to do something similar. Although when i
compile it i get the following message which seems logical to me. Any
idea how to make that work ? I suspect the author of the article knows
what he is talking about so it must something that i am missing.

Thank you, joyce

* code *

class Test {
protected:
  Test() {}
  ~Test() {}
public:
  static Test& Instance();
};

Test& Test::Instance() {
  static auto_ptr<Test> instance( new Test );
  return *instance;
}

int main() {
  // call Test::Instance() here
}

* error message *

test.cpp: In function `int main()':
test.cpp:120: error: 'Test::Test()' is protected
test.cpp:127: error: within this context
/usr/include/gcc/darwin/4.0/c++/memory: In destructor
`std::auto_ptr<_Tp>::~auto_ptr() [with _Tp = Test]':
test.cpp:127: instantiated from here
test.cpp:121: error: 'Test::~Test()' is protected
/usr/include/gcc/darwin/4.0/c++/memory:260: error: within this context
JMenger-Computer:~/singleton_test jmenger$ c++ -o test test.cpp
/usr/include/gcc/darwin/4.0/c++/memory: In destructor
`std::auto_ptr<_Tp>::~auto_ptr() [with _Tp = Test]':
test.cpp:127: instantiated from here
test.cpp:121: error: 'Test::~Test()' is protected
/usr/include/gcc/darwin/4.0/c++/memory:260: error: within this context

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