Destructors, pointers and scope

[Lilith]

I'm working on a class that contains a pointer to a different class
object that behaves as a linked list. What I'm not sure of is, if I
do a delete on the pointer to the object of the second class, will the
destructor of the second class be implemented? Or do I need to delete
any downstream pointers manually?

TIA
--
Lilith

[Alf P. Steinbach]

Re: Destructors, pointers and scope

* Lilith:[color=blue]
> I'm working on a class that contains a pointer to a different class
> object that behaves as a linked list. What I'm not sure of is, if I
> do a delete on the pointer to the object of the second class, will the
> destructor of the second class be [executed]? Or do I need to delete
> any downstream pointers manually?[/color]

When you delete a pointer, the pointed to object is destroyed, and when
an object of class type is destroyed, its destructor is executed.

However, instead of doing list management using raw pointers, consider
using std::list.

And if you must use pointers, for some reason, consider packing them in
smart pointer objects such as std::auto_ptr or (probably best for your
needs, because std::auto_ptr is tricky) boost::shared_p tr -- the
latter is part of the Boost library, at <url: http://www.boost.org/>.

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[Lilith]

Re: Destructors, pointers and scope

On Sun, 19 Feb 2006 20:42:07 +0100, "Alf P. Steinbach"
<alfps@start.no > wrote:
[color=blue]
>* Lilith:[color=green]
>> I'm working on a class that contains a pointer to a different class
>> object that behaves as a linked list. What I'm not sure of is, if I
>> do a delete on the pointer to the object of the second class, will the
>> destructor of the second class be [executed]? Or do I need to delete
>> any downstream pointers manually?[/color][/color]
[color=blue]
>When you delete a pointer, the pointed to object is destroyed, and when
>an object of class type is destroyed, its destructor is executed.[/color]
[color=blue]
>However, instead of doing list management using raw pointers, consider
>using std::list.[/color]

You're probably right. I just got used to using linked structures in
years past. I was out of programming for a while was never really in
mainstream programming to begin with. So I didn't keep up with
developing tools.
[color=blue]
>And if you must use pointers, for some reason, consider packing them in
>smart pointer objects such as std::auto_ptr or (probably best for your
>needs, because std::auto_ptr is tricky) boost::shared_p tr -- the
>latter is part of the Boost library, at <url: http://www.boost.org/>.[/color]

I'll be taking a look.

Thanks,
Lilith

[Eyeless]

Re: Destructors, pointers and scope

Hi![color=blue]
>std::auto_pt r or (probably best for your
>needs, because std::auto_ptr is tricky) boost::shared_p tr[/color]
It will really be better to use boost::shared_p tr 'cause std::auto_ptr
has very special copy semantics and may confuse you if you'd like to
copy one list to another...

[Ferdi Smit]

Re: Destructors, pointers and scope

Eyeless wrote:[color=blue]
> Hi!
>[color=green]
>>std::auto_p tr or (probably best for your
>>needs, because std::auto_ptr is tricky) boost::shared_p tr[/color]
>
> It will really be better to use boost::shared_p tr 'cause std::auto_ptr
> has very special copy semantics and may confuse you if you'd like to
> copy one list to another...
>[/color]

Also don't forget that an STL container cannot contain std::auto_ptr,
the C++ standard explicitly disallows this! So even if you could work
around all the tricky issues, it's not even allowed.

--
Regards,

Ferdi Smit (M.Sc.)
Email: Ferdi.Smit@cwi. nl
Room: C0.07 Phone: 4229
INS3 Visualization and 3D Interfaces
CWI Amsterdam, The Netherlands