Re: delete pointers in destructor

From:
"Victor Bazarov" <v.Abazarov@comAcast.net>
Newsgroups:
comp.lang.c++
Date:
Wed, 19 Dec 2007 10:48:51 -0500
Message-ID:
<fkbeh4$2v6$1@news.datemas.de>
TBass wrote:

Sorry. I didn't mean to be vague.

[snip]
The exceptions to that rule is if your list is of pointers to
dynamically created objects.
[/snip]

I am using std::list, but it is a list of pointers to an instance of
the class, which I created with the new statement.


Do you really need to? What if you keep a list of tags or list of
devices instead? 'std::list' creates its elements dynamically
anyway. Let your lists manage memory.

If you _have to_ keep a list of pointers, you're doing it correctly,
with a bit of excess, see below.

Here's a quick outline of what I'm doing:

class tag
{
 ...
}

class device
{
  ...
  std::list<tag *> m_listTags


Why not change it to

    std::list<tag> m_listTags;

?

}

device::AddTag
{
  tag *mytag = new tag;
  m_listTags.push_back( mytag );


In case you decide to change, you would just do

    m_listTags.push_back(tag());

Isn't it better?

}

class project
{
  ...
  std::list<device *> m_listDevices


Same here, why not just

    std::list<device> m_listDevices;

? I know one possible answer, but I don't want to speculate.

}

project::AddDevice
{
  device *mydevice = new device;
  m_listDevices.push_back( device );
}

So I'm thinking I should just add to the destructors:


Below my comments assume you still go with the lists of pointers.

device::~device(void)
{
   std::list<tag *>::iterator item;
   device *mytag;

     ^^^^^^^^^^^^^
You don't need this.

   for ( item = m_listTags.begin(); item != m_listTags.end(); +
+item )
   {
      mytag = *item;

        ^^^^^^^^^^^^^^
You don't need this either.

      delete mytag


Change it to

        delete *item;

   }

   m_listTags.empty()


No need to empty, it's about to be destructed.

}

project::~project(void)
{
   std::list<device *>::iterator item;
   device *mydevice;


Same thing. No need for this local var.

   for ( item = m_listDevices.begin(); item != m_listDevices.end(); +
+item )
   {
      mydevice = *item;
      delete mydevice


Just do

        delete *item;

instead.

   }

   m_listDevices.empty()


No need to empty, it's about to be destructed.

}

Thanks!
T


V
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