[openbeos] Re: Pointer or reference?

On 2004-03-31 at 16:12:36 [-0500], Scott MacMaster wrote:
> > >Unfortunately, the BeAPI adds more places where pointers must be used
> mainly
> > >because some BeAPI objects delete themselves (why anyone would make
> objects that
> > >behave like that is beyond me).
> >
> > Actually, this is a good thing. Other environments work too like this. In
> delphi, for example, objects delete themselves if they are part of a visual 
> hierarchy. Otherwise you would have to keep track of all the objects 
(mostly 
> views) you add (or keep a pointer to them in the parent class, which isn't 
> needed, since you can use FindView() instead).
> 
> First, I would not want my objects to automatically be destroyed when they 
> are removed from the hierarchy, because I may want to use the object 
> somewhere else.

There are ways around it. Specifically removing your object from the 
hierarchy before the object is destructed will do it. It is provided as a 
service. It is bad enough that we have to write code to explicitly allocate 
every single GUI widget. Deleting them explicitly, too, just piles code on 
top of code.
 
> I'm not familiar with these other API's, however I still say it's a bad 
> thing.  For one thing it forces you C++ differently then it was intended. 
> Objects you explicitly allocate memory for should be explicitly 
deallocated. 
> The biggest issue this introduces, is that you can't trust any pointer to 
the 
> object.

Not at all. People write code all of the time that hands control of an object 
over to some other class. 
 
> You would have to manually destroy objects you created dynamically.  Which, 
> of course could be done by using FindView() or a stored pointer.  For, the 
> few cases where it would be more convenient to create a object dynamically 
it 
> would also be more convenient to store the pointer rather then repeated use 
> if FindView().  For the majority of the time your could just create objects 
> on the stack and they will be implicitly destroyed when the parent is 
> destroyed.

IIRC, there is a huge issue with R5 and static object creation of GUI 
components. I don't think you can do it (but I am going on a vague memory and 
not enough sleep). That would be a good thing to fix - it would make a lot of 
stuff easier.
 
> The only time where automatic deletion of any kind is ok is in garbage 
> collection.

Eh. I disagree.

Other related posts: