Deleting class instance from static member function?

[lallous]

Is this acceptable?

class CTest

{

public:

static void selfDelete(CTes t *);

int method() { }

private:

};

void CTest::selfDele te(CTest *p)

{

delete p;

}

int main()

{


CTest *x = new CTest;

x->selfDelete(x );

return 0;

}
--
Elias

http://lgwm.org/

[jeffc]

Re: Deleting class instance from static member function?


"lallous" <lallous@lgwm.o rg> wrote in message
news:bleknh$bf0 f0$1@ID-161723.news.uni-berlin.de...[color=blue]
> Is this acceptable?
>
> class CTest
> {
> public:
> static void selfDelete(CTes t *);
> int method() { }
> private:
> };
>
> void CTest::selfDele te(CTest *p)
> {
> delete p;
> }
>
> int main()
> {
> CTest *x = new CTest;
> x->selfDelete(x );
> return 0;
> }[/color]

Sure, but it's a little misleading. It's not really a "self" delete. It's
merely a delete function that does a delete on the pointer you send it. You
could just as well write
CTest* x = new CTest;
int* p = new int;
x->selfDelete(p );

And you could just as easily take that selfDelete function out of the class
and just call it Delete. See why it's misleading? This is much more
interesting
void selfDelete()
{
delete this;
}

[lallous]

Re: Deleting class instance from static member function?

"jeffc" <nobody@nowhere .com> wrote in message news:<3f7adf52_ 2@news1.prserv. net>...[color=blue]
> "lallous" <lallous@lgwm.o rg> wrote in message
> news:bleknh$bf0 f0$1@ID-161723.news.uni-berlin.de...[color=green]
> > Is this acceptable?
> >
> > class CTest
> > {
> > public:
> > static void selfDelete(CTes t *);
> > int method() { }
> > private:
> > };
> >
> > void CTest::selfDele te(CTest *p)
> > {
> > delete p;
> > }
> >
> > int main()
> > {
> > CTest *x = new CTest;
> > x->selfDelete(x );
> > return 0;
> > }[/color][/color]
[color=blue]
>
> Sure, but it's a little misleading. It's not really a "self" delete. It's
> merely a delete function that does a delete on the pointer you send it. You
> could just as well write
> CTest* x = new CTest;
> int* p = new int;[/color]
[color=blue]
> x->selfDelete(p );[/color]
will that work? I mean even w/o casting the 'int *' to 'CTest *' ?

[color=blue]
> And you could just as easily take that selfDelete function out of the class
> and just call it Delete. See why it's misleading? This is much more
> interesting
> void selfDelete()
> {
> delete this;
> }[/color]
how would 'this' exist if I have the selfDelete() outside of the class?


Regards,
Elias

[jeffc]

Re: Deleting class instance from static member function?


"lallous" <lallous@lgwm.o rg> wrote in message
news:3bf2b2cf.0 310011046.79585 207@posting.goo gle.com...[color=blue][color=green]
> >
> > Sure, but it's a little misleading. It's not really a "self" delete.[/color][/color]
It's[color=blue][color=green]
> > merely a delete function that does a delete on the pointer you send it.[/color][/color]
You[color=blue][color=green]
> > could just as well write
> > CTest* x = new CTest;
> > int* p = new int;[/color]
>[color=green]
> > x->selfDelete(p );[/color]
> will that work? I mean even w/o casting the 'int *' to 'CTest *' ?[/color]

It's true I forgot about the cast to int*, but yes, it would work. Since
you're in a static function of CTest, you're not using anything specific to
any object (instance) of CTest. It's basically just working like a regular
function at that point (other than the fact that it's "inside" the class -
in this sense it works like a namespace.) You don't really even need the x
object or the x-> pointer notation to. You could just do this.

int* p = new int;
CTest::selfDele te( (CTest*)p );

The point I was trying to make was that "self" is really misleading. When a
function is static, there is no such thing as "self" or "this". (BTW, in
the Smalltalk language, "self" is actually a term analogous to "this" in
C++).
[color=blue][color=green]
> > And you could just as easily take that selfDelete function out of the[/color][/color]
class[color=blue][color=green]
> > and just call it Delete. See why it's misleading? This is much more
> > interesting
> > void selfDelete()
> > {
> > delete this;
> > }[/color]
> how would 'this' exist if I have the selfDelete() outside of the class?[/color]

You're right, it would not. I wrote that as a quick snippet out of context.
The context I should have written was

class CTest
{
public:
void selfDelete() { delete this; }
};
or alternatively
void CTest::selfDele te { delete this; }

[lallous]

Re: Deleting class instance from static member function?

"jeffc" <nobody@nowhere .com> wrote in message news:<3f7b30b2_ 3@news1.prserv. net>...[color=blue]
> "lallous" <lallous@lgwm.o rg> wrote in message
> news:3bf2b2cf.0 310011046.79585 207@posting.goo gle.com...[color=green][color=darkred]
> > >
> > > Sure, but it's a little misleading. It's not really a "self" delete.[/color][/color]
> It's[color=green][color=darkred]
> > > merely a delete function that does a delete on the pointer you send it.[/color][/color]
> You[color=green][color=darkred]
> > > could just as well write
> > > CTest* x = new CTest;
> > > int* p = new int;[/color][/color]
>[color=green][color=darkred]
> > > x->selfDelete(p );[/color]
> > will that work? I mean even w/o casting the 'int *' to 'CTest *' ?[/color]
>
> It's true I forgot about the cast to int*, but yes, it would work. Since
> you're in a static function of CTest, you're not using anything specific to
> any object (instance) of CTest. It's basically just working like a regular
> function at that point (other than the fact that it's "inside" the class -
> in this sense it works like a namespace.) You don't really even need the x
> object or the x-> pointer notation to. You could just do this.
>
> int* p = new int;
> CTest::selfDele te( (CTest*)p );
>
> The point I was trying to make was that "self" is really misleading. When a
> function is static, there is no such thing as "self" or "this". (BTW, in
> the Smalltalk language, "self" is actually a term analogous to "this" in
> C++).
>[color=green][color=darkred]
> > > And you could just as easily take that selfDelete function out of the[/color][/color]
> class[color=green][color=darkred]
> > > and just call it Delete. See why it's misleading? This is much more
> > > interesting
> > > void selfDelete()
> > > {
> > > delete this;
> > > }[/color]
> > how would 'this' exist if I have the selfDelete() outside of the class?[/color]
>
> You're right, it would not. I wrote that as a quick snippet out of context.
> The context I should have written was
>
> class CTest
> {
> public:
> void selfDelete() { delete this; }
> };
> or alternatively
> void CTest::selfDele te { delete this; }[/color]

Hello jeffc,

The name of this function is meaningful from the real case I got and
where I built this example from.

I had a static method and inside it I manage to do something like:
CTest *_this = GetThisForThisC lassInstanceFro mThisStaticFunc tion;
delete _this;

Also in Pascal language "Self" means "this"

Regards,
Elias

[jeffc]

Re: Deleting class instance from static member function?


"lallous" <lallous@lgwm.o rg> wrote in message
news:3bf2b2cf.0 310011938.16ab2 60d@posting.goo gle.com...[color=blue]
>
> The name of this function is meaningful from the real case I got and
> where I built this example from.
>
> I had a static method and inside it I manage to do something like:
> CTest *_this = GetThisForThisC lassInstanceFro mThisStaticFunc tion;
> delete _this;
>
> Also in Pascal language "Self" means "this"[/color]

In that case, I'm not sure why you (apparently) disagree that selfDelete is
a misleading name for a static function that has no access to anything like
"self", but whatever works for ya.....