.NET Type System

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.NET Type System Languages and Type Systems § CLR Type System Value Types § Reference Types § User-Defined Object Type Interfaces of Value Types Assignment Compatibility Nested Types Visibility Accessibility Summary

© 2003 Microsoft Corp.

This article—.NET Type System—is from Programming in the .NET Environment, by Brad Abrams, Mark Hammond, Damien Watkins. Copyright © 2003 Microsoft Corp. All rights reserved. Reproduced by permission. This article has been edited especially for C# Online.NET.

Programming in .NET: The Type System

As noted in Chapter 1, the facilities provided by the type, metadata, and execution systems are not new. However, the CLR does provide functionality in addition to the services provided by other architectures, such as COM/DCOM, CORBA, and Java. For example:

• The type system supports many programming styles and languages, allowing types defined in one language to be first-class citizens in other languages.

• The metadata system supports an extensibility mechanism, called custom attributes, that allows developers to extend the metadata annotations.

• The execution system ensures security and supports versioning on types in the CLR.

Using the .NET Framework, developers can both define and share types. Defining and sharing new types in a single language is not particularly challenging; allowing a newly defined type to be used in other languages is much more problematic. This chapter offers a sufficiently detailed understanding of the CLR type system so that developers can appreciate how it achieves type interoperability.