1、BRITISH STANDARD BS ISO/IEC TR 10034:1990 Implementation of ISO/IEC TR 10034:1990 Guidelines for the preparation of conformity clauses in programming language standardsBSISO/IECTR 10034:1990 This British Standard, having been prepared under the directionof the Information Systems Technology Standard
2、sPolicy Committee, waspublished under the authorityof the Standards Boardand comes into effect on 29March1991 BSI 04-2000 The following BSI references relate to the work on this standard: Committee reference IST/5 Draft for comment 90/68135 DC ISBN 0 580 19350 0 Committees responsible for this Briti
3、sh Standard The preparation of this British Standard was entrusted by the Information Systems Technology Standards Policy Committee (IST/-) to Technical Committee IST/5, upon which the following bodies were represented: British APL Association British Computer Society British Gas plc Computing Servi
4、ces Association Department of Trade and Industry (National Physical Laboratory) EEA (The Electronics and Business Equipment Association) Electricity Supply Industry in England and Wales Engineering Equipment and Materials Users Association GAMBICA (BEAMA Ltd.) HM Treasury (Central Computer and Telec
5、ommunications Agency) Information Technology Users Standards Association Institution of Electrical Engineers Loughborough University of Technology National Computing Centre Ltd. National Council for Educational Technology (NCET) Polytechnics and Colleges Computer Committee (PCCC) Science and Enginee
6、ring Research Council (Rutherford Appleton Laboratory) University of Edinburgh University of Liverpool University of London User Standards Forum for Information Technology (Institute of Data Processing Management) Amendments issued since publication Amd. No. Date CommentsBSISO/IECTR 10034:1990 BSI 0
7、4-2000 i Contents Page Committees responsible Inside front cover National foreword ii 1 Introduction 1 2 Scope 1 3 Definitions 1 4 The guidelines 2 Annex A (informative) Checklist of potential language features that may depend on processor facilities 4BSISO/IECTR 10034:1990 ii BSI 04-2000 National f
8、oreword This British Standard reproduces verbatim ISO/IEC TR10034:1990 and implements it as the UK national standard. This British Standard is published under the direction of the Information Systems Technology Standards Policy Committee whose Technical Committee IST/5 has the responsibility to: aid
9、 enquirers to understand the text; present to the responsible international committee any enquiries on interpretation, or proposals for change, and keep UK interests informed; monitor related international and European developments and promulgate them in the UK. NOTEInternational and European Standa
10、rds, as well as overseas standards, are available from BSI Sales Department, BSI, Linford Wood, Milton Keynes, MK14 6LE. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance wit
11、h a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 to4 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This
12、 will be indicated in the amendment table on the inside front cover.BSISO/IECTR 10034:1990 BSI 04-2000 1 1 Introduction Conformity clauses are included within the language standard to aid the user of the standard in assessing conformity of processors and programs for adherence to the language standa
13、rd. If conformity requirements are imprecise, testing for compliance can be difficult and potentially impossible for large portions of the language standard. Therefore, these guidelines seek to encourage the inclusion of conformity clauses in programming language standards, and recommend that the la
14、nguage standard precisely identify the criteria that must be met in order that a valid claim may be made that a processor or program conforms to the language standard. 2 Scope Recognizing the dissimilarity of various language standards, the objective of this Technical Report is to provide guidelines
15、 for the preparation of conformity clauses for processors and conformity clauses for programs in language standards, together with an annex containing a checklist to aid in this preparation. It was not considered practical to provide model statements that would be suitable for inclusion in all langu
16、age standards. Therefore, examples have been given to illustrate the type of issues that should be addressed and it is anticipated that these will be adapted, where appropriate, for inclusion in a particular language standard. It should be borne in mind when reading this document that not all concep
17、ts will be applicable to all languages. As examples, language standards do not all specify subsets or permit extensions, and elements that are fully specified by one language standard may be dependent on the processor in another. 3 Definitions For the purpose of this Technical Report the following d
18、efinitions apply: 3.1 configuration host and target computers, any operating system(s) and software used to operate a language processor 3.2 processor compiler, translator or interpreter working in combination with a configuration 3.3 subset subset S of programming language, L is a programming langu
19、age such that every program inS is also a program in L and has the same meaning in S as it has in L. 3.4 extension facility in the processor that is not specified in the language standard but that does not cause any ambiguity or contradiction when added to the language standard (although, in some la
20、nguages, it may serve to lift a restriction) 3.5 implementation defined dependent on the processor, but required by the language standard to be defined and documented by the implementer 3.6 error incorrect program construct or incorrect functioning of a program, as defined by the language standard N
21、OTEFor the purposes of this guideline, “error” includes what may elsewhere be defined as “error” or “exception”. 3.7 deprecated language element element in the language standard which is intended to be deleted from the next revision of the language standard 3.8 conformity clause statement that is no
22、t part of the language definition but that specifies requirements for compliance with the language standard 3.9 conforming program program which is written in the language defined by the language standard and which obeys all the conformity clauses for programs in the language standard 3.10 conformin
23、g processor processor which processes conforming programs and program units and which obeys all the conformity clauses for processors in the language standardBSISO/IECTR 10034:1990 2 BSI 04-2000 4 The guidelines The technical terms and meanings used in describing conformity clauses should be the sam
24、e as those defined for describing the technical specifications in the language standard. When terms are used that are not defined in the language standard the terms and definitions used in ISO2382 Data Processing Vocabulary, should be used. If the language standard does not fully define a feature of
25、 the language, the effect of attempting to use such a language feature may be unpredictable. Therefore, these guidelines recommend that, wherever possible, the standard should identify these areas and require an implementer to document the action to be taken by a processor. (Annex A contains a list
26、of such possible features.) 4.1 Requirements of a conforming processor The language standard should specify the rules for a conforming processor, possibly including one or more of the following examples: “A conforming processor shall correctly translate and execute all programs conforming to both th
27、e standard and the implementation defined features of the processor.” “A conforming processor shall reject all program units that contain errors whose detection is required by the standard.” “A conforming processor shall not implement any variation from the language standard except where the standar
28、d permits. Such permitted variations shall be implemented in the manner prescribed by the language standard and noted in the documentation accompanying the processor.” NOTEA variation is an alternative to the handling of a given feature of the language standard. 4.1.1 Documentation The technical spe
29、cifications of the language standard may require a conforming processor to document its handling of certain features of the language. The language standard should also require a conforming processor to include the following in its accompanying documentation: a list of all definitions or values for t
30、he implementation defined features in the language standard; a list of all the features of the language standard which are dependent on the processor and not implemented by this processor due to non-support of a particular facility, where such non-support is permitted by the standard; a list of all
31、the features of the language implemented by this processor which are extensions to the standard language; a statement of conformity, giving the complete reference of the language standard with which conformity is claimed, and, if appropriate, the subset of the language supported by this processor. T
32、here should also be a requirement of a conforming processor about the claims made in its documentation, e.g.: “A conforming processor shall conform to its accompanying documentation where that documentation relates to the requirements of this language standard.” 4.1.2 Processor dependencies The lang
33、uage standard should specify the criteria for determining conformity with regard to facilities which depend on the processor. Those cases in the language standard which pertain to specific facilities which depend on the processor should be identified, where known, in the language standard. Separate
34、conformity criteria should be specified where processor facilities which depend on the processor are available, as well as where the processor does not have a facility for supporting particular features of the language which depend on the processor, e.g.: “A conforming processor shall identify in it
35、s accompanying documentation the features of the language standard, supported by this processor, which depend on the processor.” “Language elements that pertain to specific facilities that are dependent on the processor and for which support is not claimed need not be implemented. The absence of suc
36、h facilities and pertaining language elements from an implementation must be documented.” Where the language standard imposes no limits at all upon an implementation defined value, the writer of portable programs must make certain assumptions about the values that are likely to be supported by all l
37、anguage processors, e.g., a minimum high value or a maximum low value. Similarly, the ability to test for conformity with the language standard may depend upon the tester making such assumptions when defining a test. For the purpose of determining processor conformity, consideration should be given
38、to the specification of reasonable limits for implementation defined elements. These may take the form of recommendations with a requirement that where they are not met this should be recorded in the documentation accompanying the processor.BSISO/IECTR 10034:1990 BSI 04-2000 3 4.1.3 Errors The langu
39、age standard should specify how each error, or type of error, is to be treated by a conforming processor. Possible treatments are: there shall be a statement in an accompanying document that the error is not reported; the processor shall report the error during preparation of the program for executi
40、on; the processor shall report the error during execution of the program and continue execution; the processor shall report the error during the execution of the program and terminate execution. The language standard should, where appropriate and practical, describe the recovery action to be taken b
41、y the processor on detection of an error. 4.1.4 Extensions to the language The language standard should address the question of extensions. If they are permitted, the language standard should require that such extensions be clearly described within the documentation accompanying the processor. In or
42、der that extensions do not restrict program portability the language standard may make some requirement about their implementation, e.g.: “A conforming processor shall offer a facility to report (or “flag”) the use of an extension which is statically determinable solely from inspection of a program
43、statement, without execution.” “A conforming processor shall offer a facility to reject the use of an extension in a program.” Extensions to the language could imply extra reserved words, The language standard may impose a restriction on the form of these words, e.g.: “Any words that are defined as
44、reserved for a particular processor and are in addition to those defined as reserved in this standard shall be outside the range of identifiers permitted in a program, thus ensuring that a conforming program will still be translated by a conforming processor in the manner prescribed by the language
45、standard.” If conformity may be claimed for a subset of the language, the language standard should address the question of extensions to the subset, e.g.: “Extensions to the subset shall not conflict with the requirements of the full language standard.” 4.1.5 Subsets of the language Where subsets of
46、 the language are permitted within the language standard, the language standard should specify the rules for conformity to a subset, e.g.: “A conforming processor shall fully support all the language elements of the subset with which conformity is claimed.” The language standard should specify wheth
47、er or not a conforming processor is permitted to support language elements of a higher subset, and may require that every processor conforming to a subset of the language provide a facility to report the use of language elements outside that subset, i.e.treat them as extensions. 4.1.6 Deprecated lan
48、guage elements Where appropriate, the language standard should address the use of deprecated language elements, e.g.: “A conforming processor shall provide a warning mechanism that may be invoked to indicate the use of deprecated elements in a program.” 4.2 Requirements of a conforming program The l
49、anguage standard should specify the rules for a conforming program, e.g.: “A conforming program shall use only the constructs specified in the language standard.” “A conforming program shall not depend on extensions implemented by a language processor.” “A conforming program shall not use any extensions implemented by a language processor.” “A program claiming conformity to a subset of a language shall not use any facility which is outside that subset.” The language standard should warn that use of deprecated language elements in a program could caus
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