Re: Problem with Singleton and auto_ptr

Soumen <>
Fri, 14 Mar 2008 07:25:26 -0700 (PDT)
On Mar 14, 7:18 pm, Soumen <> wrote:

On Mar 14, 6:57 pm, Goedson Paixao <> wrote:

On 14 mar, 10:35,Soumen<> wrote:

On Mar 12, 7:23 pm, ppi <> wrote:

On Mar 12, 10:02 am,Soumen<> wrote:


I've implemented singleton in one of my project. The way my command
works is user issues
the command and when the command finishes it object gets destroyed.
Singleton is required
to make sure when the command is running, user shouldn't be able to
invoke it again since
this is a GUI application. And my top level class uses auto_ptr. The
interesting part is it always
crashes in the 2nd invocation (after the 1st one is complete) - some
sort of pointer corruption.
 If I remove the static pointer for singleton implementation (i.e.
remove the singleton implementation)
itself or change the auto_ptr to normal pointers everything works
fine. I made sure that there's no
transfer of ownership for auto_ptr objects.

Any clue what could be going wrong?


maybe you should post some code, like the singleton code ...

-- paulo

Here it goes:

class MyTypeSTon {
    static MyTypeSTon* create();
    void addData(const std::string &data);

typedef std::vector<std::string > ContainerType;
auto_ptr<ContainerType > _container;
static MyTypeSTon* _instance;


   if (_instance == NULL) {
       _instance = new MyTypeSTon();

   return _instance;


: _container(new ContainerType)

MyTypeSTon::addData(const std::string &data)
   if (_container.get()) {


You should have:

MyTypeSTon::~MyTypeSTon() {
     _instance = NULL;


to make sure _instance never points to an invalid object.

Yes, I'd that in actual code. Here in the example I missed it.

Also, after first pass of my command, everything gets destroyed like

void myCommand() {
   auto_ptr<MyTypeSTon> obj(MyTypeSTon::create());

   if (obj.get()) {
       //Do processing using obj

But when code re-inters myCommand (not when any object of MyTypeSTon
is already alive)
in the 2nd pass, it crashes - debugging shows _container is corrupted.
If I remove
singleton implementation, everything works.

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