auto_ptr

>> but that does not work

define "does not work".

does get_select_folder() return a heap allocated pointer created using the new operator? If not auto_ptr cannot be used!

In your second example, assuming it does, you're trying to use a pointer to initialise the constructor of a IMAP_Folder object. Is this correct?

Did you try this?

std::auto_ptr imf ( (*auto_mbox)->get_select_folder() );

heres tehd eclaration of auto_mbox

auto_ptr<MailboxAutoOpener> auto_mbox(new MailboxAutoOpener(_session.mb
ox()));

That doesn't really help much :)

Please see my previous post where I show how to use auto_ptr based upon my understanding of the type returned but also the importance of making sure the pointer returned is suitable to be managed by an auto_ptr.

Folder* get_select_folder(bool update = false)
heres what you need, is it ok to use auto_ptr?

>> heres what you need, is it ok to use auto_ptr?
Again, I can't answer that since all that tells me is it returns a pointer but that doesn't tell me if the memory the pointer references was created using new.

What I can tell you is that syntactically the example I show you above will work. What I can't tell you is if this will be safe. You need to check to see how the memory the pointer references is allocated. If this is a 3rd partly library you'll need to refer to the documentation.

thanks gazillion, i will check it out

bool  Command::fne(
    const char* tag,
    const char* name,
     Folder *imf
if i wanted to sent the auto pointer to this function  (assuming its correct) what would be the equibvalent signature

sorry i am new to auto_ptrs...

The canonical form for using auto_ptr is always this...


auto_ptr< TYPE > varname

So, if you wish to define an auto_ptr of type Folder the form will be this

auto_ptr< Folder> varname

To get from a pointer to an auto_ptr just lose the * and move the type into the angled brackets.

Folder *

Lose the *

Folder

Put type in angled brackets

< Folder >

Prefix with auto_ptr

auto_ptr< Folder >

Does that make sense?

thanks that helps

i have changed the signatures for the function,

bool  Command::fne(
    const char* tag,
    const char* name,
     auto_ptr<Folder>


before changing the function, imf was passed as follows:


bool  Command::fne(
    tag,
    name,
     imf)

now that i have chanhed teh interfaces, the compiler complains that i am passing
 auto_ptr<Folder> in my call when the signature is

auto_ptr<Folder> &

Can you show me the code please?

actually let me try this out, i could be wrong

although i do understand how instances of *imf are to be replaced

i have places where  imf->uidnext()

how would use of imf like above (without the *) change after using auto_ptrs

It doesn't. The whole point is that from an interface point of view auto_ptr is the same as a normal pointer. It respects all the normal pointer dereference and indirection operators that you would normally use on a pointer.

Folder * pf1 = new Folder;
auto_ptr pf2(new Folder);

pf1->uidnext() ;
pf2->uidnext() ;

Folder const & r1 = *pf1;
Folder const & r2 = *pf2;

what is the imapct if teh auto_ptr above is created for a memory created using malloc and not new?...what re the safety issue?

thanks a million!!!!