Delphi Language Guide Delphi for Microsoft Win32 Delphi for the Microsoft. Net framework

Dispatch interface properties
Properties of a dispatch interface do not include access specifiers. They can be declared as read only or write only.
To specify a dispatch ID for a property, include the dispid directive in its declaration, followed by an integer constant;
specifying an already used ID causes an error. Array properties can be declared as default. No other directives are
allowed in dispatch-interface property declarations.
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Accessing Automation Objects
Automation object method calls are bound at runtime and require no previous method declarations. The validity of
these calls is not checked at compile time.
The following example illustrates Automation method calls. The 
CreateOleObject
 function (defined in 
ComObj
)
returns an 
IDispatch
 reference to an Automation object and is assignment-compatible with the variant Word.
var
 Word: Variant;
  begin
   Word := CreateOleObject('Word.Basic');
   Word.FileNew('Normal');
   Word.Insert('This is the first line'#13);
   Word.Insert('This is the second line'#13);
   Word.FileSaveAs('c:\temp\test.txt', 3);
  end;
You can pass interface-type parameters to Automation methods.
Variant arrays with an element type of 
varByte
 are the preferred method of passing binary data between Automation
controllers and servers. Such arrays are subject to no translation of their data, and can be efficiently accessed using
the 
VarArrayLock
 and 
VarArrayUnlock
 routines.