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Posted by Oli Filth on 10/26/59 11:33
Chung Leong wrote:
> Oli Filth wrote:
> > I think the OP has phrased this badly. He actually has an object
> > passing this ($this) to a method in another object, which is hardly
> > uncommon practice in most OO languages (e.g. registering a callback
> > interface with a child object).
>
> That's very different from object A calling a method of object B which
> in turns invokes methods on object A now isn't it? What the OP
> described
As I said, it's really not a great example (of something that's a good
idea in principle).
His example, which basically boils down to:
$book = new Book();
$plainVisitor = new PlainDescriptionVisitor();
$book->accept($plainVisitor);
$plainVisitor->getDescription();
has a pointless line $book->accept(), i.e. the Book is "doing" the
work.
$book = new Book();
PlainDescriptionVisitor::describe($book);
would have made much more sense, or if polymorphism of the visitors is
a concern:
$book = new Book();
$plainVisitor = new PlainDescriptionVisitor();
$plainVisitor->visit($book);
....
$plainVisitor->getDescription();
Either way, it avoids the $book->accept() call, which offers no
semantic value.
> can be more aptly called the prostitution design pattern.
> Object J has a need that it cannot satisfy, so it visits object H to
> get its private part operated upon. It's sick. It's immoral. Objects
> should only play around with their own thingies.
:)
--
Oli
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