1、Information technology Common Language Infrastructure (CLI)CAN/CSA-ISO/IEC 23271:13(ISO/IEC 23271:2012, IDT)National Standard of CanadaNOT FOR RESALE. / PUBLICATION NON DESTINE LA REVENTE.Legal Notice for StandardsCanadian Standards Association (operating as “CSA Group”) develops standards through a
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18、hes the standard.The responsibility for approving standards as National Standards of Canada rests with theStandards Council of Canada270 Albert Street, Suite 200Ottawa, Ontario, K1P 6N7CanadaAlthough the intended primary application of this Standard is stated in its Scope, it is importantto note tha
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20、acteur.TMA trade-mark of the Canadian Standards Association, operating as “CSA Group”National Standard of CanadaPublished in January 2013 by CSA GroupA not-for-profit private sector organization5060 Spectrum Way, Suite 100, Mississauga, Ontario, Canada L4W 5N61-800-463-6727 416-747-4044Visit our Onl
21、ine Store at shop.csa.caApproved byStandards Council of CanadaCAN/CSA-ISO/IEC 23271:13Information technology Common Language Infrastructure (CLI)Prepared by InternationalOrganizationforStandardization/ International Electrotechnical CommissionReviewed byCAN/CSA-ISO/IEC 23271:13 Information technolog
22、y Common Language In frastructure (CLI)CSA/4 2013 CSA Group January 2013CAN/CSA-ISO/IEC 23271:13Information technology Common Language Infrastructure (CLI)CSA PrefaceStandards development within the Information Technology sector is harmonized with international standards development. Through the CSA
23、 Technical Committee on Information Technology (TCIT), Canadians serve as the Canadian Advisory Committee (CAC) on ISO/IEC Joint Technical Committee 1 on Information Technology (ISO/IEC JTC1) for the Standards Council of Canada (SCC), the ISO member body for Canada and sponsor of the Canadian Nation
24、al Committee of the IEC. Also, as a member of the International Telecommunication Union (ITU), Canada participates in the International Telegraph and Telephone Consultative Committee (ITU-T).This Standard supersedes CAN/CSA-ISO/IEC 23271-07 (adoption of ISO/IEC 23271:2006).At the time of publication
25、, ISO/IEC 23271:2012 is available from ISO and IEC in English only. CSA Group will publish the French version when it becomes available from ISO and IEC.This International Standard was reviewed by the TCIT under the jurisdiction of the Strategic Steering Committee on Information Technology and deeme
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27、ithout modification, by the Technical Committee and has been approved as a National Standard of Canada by the Standards Council of Canada. 2013 CSA GroupAll rights reserved. No part of this publication may be reproduced in any form whatsoever without the prior permission of thepublisher. ISO/IEC mat
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30、opriate committee. To submit a proposal for change, please send the following information to inquiriescsagroup.org and include “Proposal for change” in the subject line:(a) Standard designation (number);(b) relevant clause, table, and/or figure number;(c) wording of the proposed change; and(d) ratio
31、nale for the change.Reference numberISO/IEC 23271:2012(E)ISO/IEC 2012INTERNATIONAL STANDARD ISO/IEC23271Third edition2012-02-15Information technology Common Language Infrastructure (CLI) Technologies de linformation Infrastructure commune de langage (ICL) ISO/IEC 23271:2012(E) COPYRIGHT PROTECTED DO
32、CUMENT ISO/IEC 2012 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISOs membe
33、r body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org ii ISO/IEC 2012 All rights reservedCAN/CSA-ISO/IEC 23271:13ISO/IEC 23271:2012(E) ISO/IEC 2012 All rights reserved. iii T
34、able of Contents Foreword xxi I.1 Scope 1 I.2 Conformance 2 I.3 Normative references 3 I.4 Conventions 5 I.4.1 Organization 5 I.4.2 Informative text 5 I.5 Terms and definitions 6 I.6 Overview of the Common Language Infrastructure 9 I.6.1 Relationship to type safety 9 I.6.2 Relationship to managed me
35、tadata-driven execution 10 I.6.2.1 Managed code 10 I.6.2.2 Managed data 11 I.6.2.3 Summary 11 I.7 Common Language Specification 12 I.7.1 Introduction 12 I.7.2 Views of CLS compliance 12 I.7.2.1 CLS framework 12 I.7.2.2 CLS consumer 13 I.7.2.3 CLS extender 13 I.7.3 CLS compliance 14 I.7.3.1 Marking i
36、tems as CLS-compliant 14 I.8 Common Type System 16 I.8.1 Relationship to object-oriented programming 19 I.8.2 Values and types 19 I.8.2.1 Value types and reference types 19 I.8.2.2 Built-in value and reference types 20 I.8.2.3 Classes, interfaces, and objects 21 I.8.2.4 Boxing and unboxing of values
37、 21 I.8.2.5 Identity and equality of values 22 I.8.3 Locations 23 I.8.3.1 Assignment-compatible locations 23 I.8.3.2 Coercion 23 I.8.3.3 Casting 24 CAN/CSA-ISO/IEC 23271:13ISO/IEC 23271:2012(E) iv ISO/IEC 2012 All rights reserved. I.8.4 Type members 24 I.8.4.1 Fields, array elements, and values 24 I
38、.8.4.2 Methods 24 I.8.4.3 Static fields and static methods 25 I.8.4.4 Virtual methods 25 I.8.5 Naming 25 I.8.5.1 Valid names 25 I.8.5.2 Assemblies and scoping 26 I.8.5.3 Visibility, accessibility, and security 27 I.8.6 Contracts 30 I.8.6.1 Signatures 30 I.8.7 Assignment compatibility 34 I.8.7.1 Assi
39、gnment compatibility for signature types 37 I.8.7.2 Assignment compatibility for location types 38 I.8.7.3 General assignment compatibility 39 I.8.8 Type safety and verification 39 I.8.9 Type definers 39 I.8.9.1 Array types 40 I.8.9.2 Unmanaged pointer types 41 I.8.9.3 Delegates 41 I.8.9.4 Interface
40、 type definition 42 I.8.9.5 Class type definition 43 I.8.9.6 Object type definitions 44 I.8.9.7 Value type definition 47 I.8.9.8 Type inheritance 47 I.8.9.9 Object type inheritance 47 I.8.9.10 Value type inheritance 48 I.8.9.11 Interface type derivation 48 I.8.10 Member inheritance 48 I.8.10.1 Field
41、 inheritance 48 I.8.10.2 Method inheritance 48 I.8.10.3 Property and event inheritance 49 I.8.10.4 Hiding, overriding, and layout 49 I.8.11 Member definitions 50 I.8.11.1 Method definitions 50 I.8.11.2 Field definitions 51 I.8.11.3 Property definitions 51 I.8.11.4 Event definitions 52 I.8.11.5 Neste
42、d type definitions 52 CAN/CSA-ISO/IEC 23271:13ISO/IEC 23271:2012(E) ISO/IEC 2012 All rights reserved. v I.9 Metadata 53 I.9.1 Components and assemblies 53 I.9.2 Accessing metadata 53 I.9.2.1 Metadata tokens 54 I.9.2.2 Member signatures in metadata 54 I.9.3 Unmanaged code 54 I.9.4 Method implementati
43、on metadata 54 I.9.5 Class layout 55 I.9.6 Assemblies: name scopes for types 55 I.9.7 Metadata extensibility 56 I.9.8 Globals, imports, and exports 57 I.9.9 Scoped statics 58 I.10 Name and type rules for the Common Language Specification 59 I.10.1 Identifiers 59 I.10.2 Overloading 59 I.10.3 Operator
44、 overloading 60 I.10.3.1 Unary operators 60 I.10.3.2 Binary operators 61 I.10.3.3 Conversion operators 62 I.10.4 Naming patterns 62 I.10.5 Exceptions 63 I.10.6 Custom attributes 63 I.10.7 Generic types and methods 64 I.10.7.1 Nested type parameter re-declaration 64 I.10.7.2 Type names and arity enco
45、ding 65 I.10.7.3 Type constraint re-declaration 66 I.10.7.4 Constraint type restrictions 67 I.10.7.5 Frameworks and accessibility of nested types 67 I.10.7.6 Frameworks and abstract or virtual methods 68 I.11 Collected Common Language Specification rules 69 I.12 Virtual Execution System 72 I.12.1 Su
46、pported data types 72 I.12.1.1 Native size: native int, native unsigned int, O and as exact type matches always took precedence over matches-by-variance. In this edition the dispatch rules for interfaces (II.12.2) allow a match-by-variance to take precedence over an exact match, so all language CAN/
47、CSA-ISO/IEC 23271:13ISO/IEC 23271:2012(E) xxii ISO/IEC 2012 All rights reserved. implementation targeting the CLI must be aware of the behavior even if it is not supported in the language (I.1.8). Additional requirements on ilasm to metadata conversion. The left-to-right order of interfaces listed i
48、n a type header (II.10.2) must now be preserved as a top-to-bottom order in the InterfaceImpl table (II.22.23); and the top-to-bottom of method definitions (II.10.2, II.25) must now be preserved as a top-to-bottom order in the MethodDef table (II.22.26). Both these additional requirements are required to support the revised variance semantics. System.Math and Sys
