Mapping of Singletons

OpenOffice.org Developer's Guide

Professional UNO

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• Type Mappings

• Mapping of Sequence Types
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• Mapping of Exception Types
• Mapping of Interface Types
• Mapping of UNOIDL
• Mapping of Services
• Mapping of Singletons
• Inexact approximation of UNO Value Semantics

• C++ Language Binding

• Establishing Interprocess Connections
• Transparent Use of Office UNO Components
• Type Mappings

• Mapping of Struct Types
• Mapping of Interface Types
• Mapping of Sequence Types
• Mapping of Services
• Mapping of Singletons

• Using Weak References
• Exception Handling in C++

• OpenOffice.org Basic

• Handling UNO Objects

• Instantiating UNO Services
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• Mapping of UNO and Basic Types

• Mapping of Simple Types
• Mapping of Sequences and Arrays
• Mapping of Structs
• Mapping of Enums and Constant Groups

• Case Sensitivity
• Exception Handling
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• Automation Bridge

• The Service Manager Component
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• Calling Functions and Accessing Properties
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• Using Automation Objects from UNO
• Type Mappings

• Default Mappings

• Mapping of Simple Types
• Mapping of Hyper and Decimal
• Mapping of String
• Mapping of Interfaces and Structures
• Mapping of Sequence
• Mapping of Type

• Conversion Mappings
• Client-Side Conversions
• Value Objects
• Exceptions and Errorcodes

• Automation Objects with UNO Interfaces
• DCOM
• The Bridge Services
• Unsupported COM Features

• CLI Language Binding

• The Language Binding DLLs
• Type Mapping

• Type Name Decoration
• Type Mappings
• Additional Structures

• Lifetime Management and Obtaining Interfaces
• Writing Client Programs

• The Override Problem
• Important Interfaces and Implementations

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A new-style singleton of the form

 singleton Name: XIfc;

is mapped to a C++ class with the same name. The class has a single member function

 public:
 static com::sun::star::uno::Reference< XIfc > get(
     com::sun::star::uno::Reference< com::sun::star::uno::XComponentContext > const & context) 
     throw (com::sun::star::uno::RuntimeException) { ... }

The semantics of such a singleton getter function in C++ are as follows (they are the same as for Java):

• The com.sun.star.uno.XComponentContext argument must be non-null.
• The singleton getter uses com.sun.star.uno.XComponentContext:getValueByName to obtain the singleton instance (within the "/singletons/" name space).
• If no singleton instance could be obtained, the singleton getter fails by throwing a com.sun.star.uno.DeploymentException. The net effect is that a singleton getter either returns the requested non-null singleton instance, or throws an exception; a singleton getter will never return a null instance.

Old-style services are not mapped into the C++ language binding.

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