標準號：ISO/IEC TR 25438-2006
中文標準名稱：信息技術.通用語言結構(CLI).技術報告:普通遺傳學
英文標準名稱：Information technology - Common Language Infrastructure (CLI) - Technical Report: Common Generics
標準類型：L74
發布日期：2006/8/1 12:00:00
實施日期：1999/12/31 12:00:00
中國標準分類號：L74
國際標準分類號：35.060
適用范圍：The CLI standard libraries (ISO/IEC 23271) provide a collection of common types that can be used by multiplelanguages. With the addition of generics to the CLI, the standard libraries have been extended to include anumber of common generic types, in particular, collections. However, at present, these libraries do not includemany simple generic types found in a number of different languages. Any language which uses thesecommon types must implement them rather than deferring to the CLI library, thereby reducing language interoperability.This Technical Report addresses this issue by providing a number of these common types.Generic tuples (product types) are standard in a number of languages: C++ (template Pair), Ada, Haskell,and Standard ML (SML). However, languages differ in the number of pre-defined tuple sizes supported bytheir standard libraries; e.g. C++ provides just one (Pair) while Haskell provides eight (sizes 2 to 9) and SMLallows any size of tuple. This Technical Report provides nine (sizes 2 to 10).Generic programming encourages “higher order” programming where generic functions (methods) takefunction (delegate) type arguments that have generic types. Examples include Ada’s with and genericconstraints, and function arguments in Haskell and SML. In the CLI, function values are provided in the formof delegates, so this proposal defines standard generic delegate types for functions (which return a value) andprocedures (which do not).Another two types that occur in a number of languages are an optional type, which either contains a value ofsome other type or an indication that such a value is not present; and an either type, which holds a value ofone of two possible types and an indication of which one is present. This proposal provides both of these.Note The optional type is similar to, but different from, the type System.Nullable.Finally, in existing generic languages, a need has been found for a filler type to be used when a particulargeneric parameter is not required for a particular use of the generic type. A standard one-value type is oftenprovided for this purpose, often called Unit or Void. This Technical Report includes such a type.