ISO/IEC TR 25438-2006 信息技术.通用语言结构(CLI).技术报告:普通遗传学

标准号：ISO/IEC TR 25438-2006
中文标准名称：信息技术.通用语言结构(CLI).技术报告:普通遗传学
英文标准名称：Information technology - Common Language Infrastructure (CLI) - Technical Report: Common Generics
标准类型：L74
发布日期：2006/8/1 12:00:00
实施日期：1999/12/31 12:00:00
中国标准分类号：L74
国际标准分类号：35.060
适用范围：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.