Standardization, Internationalization Programming Language Design and Implementation (4th Edition) by T. Pratt and M. Zelkowitz Prentice Hall, 2001 Section

2 Who defines a language?  Is: I = 1 && | 4; legal in C? What is assigned to I if it is?  3 ways typically to answer this:  1. Read language manual (Problem: Can you find one?)  부정확  2. Read language standard (Problem: Have you ever seen it?)  BNF, Vienna definition language,  3. Write a program to see what happens. (Easy to do!)  C 의 표준은 CC (UNIX)  Most do 3, but current compilers may not give correct answer

3 Creation of standards  Language standards defined by national standards bodies:  ISO - International Standards organization  IEEE - Institute of Electrical and Electronics Engineers  ANSI - American National Standards Institute   code, 언어, 통신규약, XML, 전자책, …  WWW Consortium, EPC Global, …  SMTP(7bits)  MIME(8bits) : Plain text, 음성, 영상,..  All work in a similar way:  1. Working group of volunteers set up to define standard  2. Agree on features for new standard  3. Vote on standard  4. If approved by working group, submitted to parent organization for approval.

4 Creation of standards  Standards in the US are voluntary:  There is no federal standards-making organization.  NIST - National Institute for Standards and Technology develops standards that are only required on federal agencies, not for commercial organizations.  But: Consensus is the key to standards making:  Contentious features often omitted to gain consensus  Only vendors have a vested interest in the results  Users don't care until standard approved, and then it is too late!  한국 ::: 표준연구소, 지경부, 교과부

5 Standards conforming programs  Standards define behavior for a standards conforming program - one that meets the rules of the language standard  In general (except for Ada), behavior of non-conforming program is not specified, so any extensions to a standards conforming compiler may still be standards conforming, even though the program is not standards conforming. –Java 와 관련된 MS 전략  Standards supposed to be reviewed every 5 years  Examples: –FORTRAN 1966, 1977, 1990, 1995, 2003 –Ada 1983, 1995  Not quite 5 years, but at least periodically

6 표준과 특허  De facto 표준  ISO 에서는 주로 특허로 제한된 기술은 표준으로 정하지 않음  국제표준에 따라 정해진 내용이 특허로 되면 심각한 법적 문제를 낳을 수 있음  특허에 의해 “ ㅈㅈㅈ ” -> “www” 로 고치 지 못함 ::: 특허와 관련된 몇 사례 !!!

7 숙제  한글코드의 표준화 과정을 조사한다. 특히 Unicode 가 어떻게 표준화되었 는지 조사한다. 또 KS5601, ISo646, ISO2422, UTF8, UTF16 은 무엇인가 ? – 정희성 박사 특허  자판을 중심으로 표준화가 낳을 수 있는 문제점을 조사한다. 실제 우리가 쓰는 자판은 최대한 글쇠가 엉키지 않게 만듦으로써 오히려 입력속도가 느리다 (QWERT). 이에 따라 새로운 자판 ( 이름을 조사 ) 이 나왔지만 익숙 하지 않아서 아직 보급되지 않고 있다. 한글자판도 2 벌식과 3 벌식이 있는 데 비슷한 문제점이 있다.  현재 XML 을 이용하여 각 분야의 문서표준화가 진행되고 있다. 그 예와 현재 진행상황을 설명하라 !! ( 예, eBook, vXML, 전자상거래 … ), 한 분야 만 잡아서 조사한다.  핸드폰과 스마트폰에서 한글 문자를 입력하는 방법은 표준화되어 있는 가 ? 현재 표준화 상황을 조사하라.  C, C++, Pyton, PHP, HTML, XHTML 의 표준화 과정을 설명하라.

8 When to standardize a language?  Problem: When to standardize a language? –If too late - many incompatible versions - FORTRAN in 1960s was already a de facto standard, but no two were the same –If too early - no experience with language - Ada in 1983 had no running compilers –Just right - Probably Pascal in 1983, although it is rapidly becoming a dead language  Other languages: –C in 1988 : ANSI C –LISP in Way too late : common LISP –De facto standards: ML - One major implementation - SML –Smalltalk - none –Prolog - none

9 Internationalization  I18N issue - Internationalization - How to specify languages useful in a global economy?  Characters used internationally: –Single 8-bit byte; usual format today character values. A lot in 1963, but insufficient today –ASCII is a 7 bit 128 character code  What about other languages? –Additional letters: German umlaut-ä, French accent-é, Scandanavian symbols-ö, –Russian, other alphabets (Greek, Arabic, Hebrew), ideographs (Chinese), 한글 –Unicode - 16 bit code allows for 65K symbols. 8-bit byte is insufficient

10 Internationalization (continued)  I18N name avoids deciding between internationalization and localization  Some of the internationalization issues:  What character codes to use?  Collating sequences? - How do you alphabetize various languages?  Dates? - What date is 10/12/01? Is it a date in October or December?  Time? - How do you handle time zones, summer time in Europe, daylight savings time in US, Southern hemisphere is 6 months out of phase with northern hemisphere, Date to change from summer to standard time is not consistent.  Currency? - How to handle dollars, pounds, marks, francs, euros, 원, etc.  XML 에서는 dublin core 를 사용

11 Summary  Language design today must:  Allow program solution to match physical structure of problem  Allow for world-wide use  Be easy to prove solution correct  Rest of course will work on these goals

12 Programming Environment  The environments in which programs are created and tested  Separate compilation –Co-development of any large program –Function prototypes, external variables(COMMON, extern), naming convention(_…), Scope rule (Pascal, C, Ada), inheritance (Ada, C++), polymorphism, overloaded (Ada) –Stub : a subprogram call made to a subprogram that has not yet been compiled –To provide information for separate compilation FOTRAN : COMMON <- redeclaration Compile 순서 관리 <- Ada. A library containing specifications –Consistency of the external data or subprograms Linking?

13 Programming Environment (cont.)  Testing and debugging –Execution trace features (LISP, Prolog, … C debugger) Statements, variables –Breakpoints –Assertions Assert(X>0)  % Exception handling