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lity with Turbo Pascal, but they might be dropped entirely from future versions of Delphi.
Old-style object types are more like records than new-style objects. Fields in an old-style object are laid out in the same manner as in records. If the object type does not have any virtual methods, there is no hidden field for the VMT pointer, for example. Unlike records, object types can use inheritance. Derived fields appear after inherited fields. If a class declares a virtual method, its first field is the VMT pointer, which appears after all the inherited fields. (Unlike a new-style object, where the VMT pointer is always first because TObject declares virtual methods.)
An old-style object type can have private, protected, and public sections, but not published or automated sections. Because it cannot have a published section, an old object type cannot have any runtime type information. An old object type cannot implement interfaces.
Constructors and destructors work differently in old-style object types than in new-style class types. To create an instance of an old object type, call the New procedure. The newly allocated object is initialized to all zero. If you declare a constructor, you can call it as part of the call to New. Pass the constructor name and arguments as the second argument to New. Similarly, you can call a destructor when you call Dispose to free the object instance. The destructor name and arguments are the second argument to Dispose.
You don''''t have to allocate an old-style object instance dynamically. You can treat the object type as a record type and declare object-type variables as unit-level or local variables. Delphi automatically initializes string, dynamic array, and Variant fields, but does not initialize other fields in the object instance.
Unlike new-style class types, exceptions in old-style constructors do not automatically cause Delphi to free a dynamically created object or call the destructor.
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