php - When would you need to use late static binding?

Question

After reading this description of late static binding (LSB) I see pretty clearly what is going on. Now, under which sorts of circumstances might that be most useful or needed?

Answer 1

I needed LSB this for the following scenario:

• Imagine you're building a "mail processor" daemon that downloads the message from an email server, classifies it, parses it, saves it, and then does something, depending on the type of the message.
• Class hierarchy: you have a base Message class, with children "BouncedMessage" and "AcceptedMessage".
• Each of the message types has its own way to persist itself on disk. For example, all messages of type BouncedMessage try to save itself as BouncedMessage-id.xml. AcceptedMessage, on the other hand, needs to save itself differently - as AcceptedMessage-timestamp.xml. The important thing here is that the logic for determining the filename pattern is different for different subclasses, but shared for all items within the subclass. That's why it makes sense for it to be in a static method.
• Base Message class has an abstract static method (yes, abstract AND static) "save". BouncedMessage implements this method with a concrete static method. Then, inside the class that actually retrieves the message, you can call "::save()"

If you want to learn more about the subject:

• http://www.qcodo.com/forums/topic.php/2356
• http://community.livejournal.com/php/585907.html
• http://bugs.php.net/bug.php?id=42681