Derived From:
Mix-in Classes:
Declared In:support/Archivable.h
Class Overview

Constructor and Destructor


BArchivable(); BArchivable(BMessagearchive);

Does nothing.


virtual ~BArchivable();

Does nothing.

Member Functions


virtual status_t Archive(BMessagearchive,
                         bool deep = true) const;

The default implementation adds the name of the object's class to archive's class field. Derived classes must override Archive() to augment this implementation by adding, to the BMessage, data that describes the current state of the object. Each implementation of this function should begin by incorporating the inherited version:

/* We'll assume that MyView inherits from BView. */
status_t MyView::Archive(BMessage* archive, bool deep)
   BView::Archive(archive, deep);
   . . .

If the class can be instantiated directly from a derived class, it should also add its name to the "class" array:

archive->AddString("class", "MyView");

The deep flag declares whether Archive() should include objects that "belong" to the archiving object. For example, a deep BView archive would include archived forms of the view's children.

Archive() should return B_OK if it's successful; otherwise, it should return B_ERROR or a more descriptive error code.

Static Functions


static BArchivable* Instantiate(BMessagearchive);

Derived classes should implement Instantiate() to return a new BArchivable object that was constructed from the BMessage archive. For example:

BArchivable* TheClass::Instantiate(BMessage* archive)
   if ( !validate_instantiation(archive, "TheClass") )
      return NULL;
   return new TheClass(archive);}

Instantiate() must return a BArchivable*, regardless of the actual class in which it's implemented.

This function depends on a constructor that can initialize the new object from the archive BMessage. See "Instantiability" TODO for more information.

The default implementation returns NULL.

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