Generalized Type Conversion
The .NET Framework provides the following two mechanisms for converting user-defined data types (custom types) to other data types:
- Defining a type converter for a custom type by extending the System.ComponentModel.TypeConverter class and associating the type converter with the type through a System.ComponentModel.TypeConverterAttribute attribute.
- Implementing the System.IConvertible interface on a custom type.
The following table highlights the differences between these two mechanisms.
Note Design-time support can be provided for a custom type only if it has a type converter defined for it.
|Conversion using TypeConverter||Conversion using IConvertible|
|Can be used both at design time and at run time.||Can be used only at run time.|
|Uses reflection; therefore, is slower than conversion enabled by IConvertible.||Does not use reflection.|
|Allows two-way type conversions from the custom type to other data types and from other data types to the custom type. For example, a TypeConverter defined for MyType allows conversions from MyType to String and from String to MyType.||Allows conversion from a custom type to other data types but not from other data types to the custom type.|
Note A TypeConverter for a type is implemented outside the type and associated with the type by applying a TypeConverterAttribute attribute.
Note IConvertible is implemented by a custom type. To convert a type, a user of the type invokes a conversion method (of the IConvertible contract) on the type.
For details about using type converters to perform conversions, see System.ComponentModel.TypeConverter. For information about implementing a type converter to provide design-time support for a custom type, see Implementing a Type Converter.