Instantiation of an Object only thru "new Operator"

[Mysooru]

How to restrict an object to be instantiated only using new operator?

I mean, one should not be allowed to create an object like AnObject obj; it
should be AnObject obj = new AnObject;

[John Harrison]

Re: Instantiation of an Object only thru "new Operator"


"Mysooru" <nags_bhel@yaho o.com> wrote in message
news:bg2f3h$djk $2@news.mch.sbs .de...[color=blue]
> How to restrict an object to be instantiated only using new operator?
>
> I mean, one should not be allowed to create an object like AnObject obj;[/color]
it[color=blue]
> should be AnObject obj = new AnObject;
>[/color]

Make the constructor private and write a static member function that uses
new

class AnObject
{
public:
static AnObject* createAnObject( ); { return new AnObject(); }
private:
AnObject(); // private ctor
};

AnObject* obj = createAnObject( );

john

[Jonathan Mcdougall]

Re: Instantiation of an Object only thru &quot;new Operator&quot;

>> >How to restrict an object to be instantiated only using new operator?[color=blue][color=green][color=darkred]
>> >
>> >I mean, one should not be allowed to create an object like AnObject obj;[/color][/color]
>it[color=green][color=darkred]
>> >should be AnObject obj = new AnObject;[/color]
>>
>> And why would you want that?[/color]
>
>Perhaps because the object wants to do a "delete this;"?[/color]

Isn't it allowed to do it even if it is an automatic object (assuming
a placement new will be made) ?

Jonathan

[John Harrison]

Re: Instantiation of an Object only thru &quot;new Operator&quot;


"Jonathan Mcdougall" <DELjonathanmcd ougall@yahoo.ca > wrote in message
news:qcj9ivcitp rp92r82bkb28osc 1tkuvnomv@4ax.c om...[color=blue][color=green][color=darkred]
> >> >How to restrict an object to be instantiated only using new operator?
> >> >
> >> >I mean, one should not be allowed to create an object like AnObject[/color][/color][/color]
obj;[color=blue][color=green]
> >it[color=darkred]
> >> >should be AnObject obj = new AnObject;
> >>
> >> And why would you want that?[/color]
> >
> >Perhaps because the object wants to do a "delete this;"?[/color]
>
> Isn't it allowed to do it even if it is an automatic object (assuming
> a placement new will be made) ?
>
> Jonathan[/color]

You can't delete this on an automatic object. What does placement new have
to do with anything?

john

[Jonathan Mcdougall]

Re: Instantiation of an Object only thru &quot;new Operator&quot;

On Mon, 28 Jul 2003 08:28:37 +0100, "John Harrison"
<john_andronicu s@hotmail.com> wrote:
[color=blue]
>
>"Jonathan Mcdougall" <DELjonathanmcd ougall@yahoo.ca > wrote in message
>news:qcj9ivcit prp92r82bkb28os c1tkuvnomv@4ax. com...[color=green][color=darkred]
>> >> >How to restrict an object to be instantiated only using new operator?
>> >> >
>> >> >I mean, one should not be allowed to create an object like AnObject[/color][/color]
>obj;[color=green][color=darkred]
>> >it
>> >> >should be AnObject obj = new AnObject;
>> >>
>> >> And why would you want that?
>> >
>> >Perhaps because the object wants to do a "delete this;"?[/color]
>>
>> Isn't it allowed to do it even if it is an automatic object (assuming
>> a placement new will be made) ?
>>
>> Jonathan[/color]
>
>You can't delete this on an automatic object. What does placement new have
>to do with anything?[/color]

Nothing. Who said that?


A sad Jonathan

[Jonathan Mcdougall]

Re: Instantiation of an Object only thru &quot;new Operator&quot;

>> >You can't delete this on an automatic object. What does placement new[color=blue]
>have[color=green][color=darkred]
>> >to do with anything?[/color]
>>
>> Nothing. Who said that?
>>
>>
>> A sad Jonathan
>>[/color]
>
>Quote '(assuming a placement new will be made)'.
>
>Just trying to understand your point, not pick an argument. Perhaps you
>could illustrate with some code.[/color]

I think irony does not travel very well through cable modems.

I don't know why I said that, I even started an answer like

class A
{
public:
void f()
{
delete this;
this =

and then

const_cast<A*>( this) =

and worst

const_cast<A*>( this) = new (this) A;

before understanding the profound stupidity of my point. I then made
a joke, hoping nobody would notice. Too bad :)

Sorry about that,


Jonathan