From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: ** X-Spam-Status: No, score=2.6 required=5.0 tests=BAYES_00,HEADER_SPAM, REPLYTO_WITHOUT_TO_CC,TO_NO_BRKTS_PCNT autolearn=no autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII X-Google-Thread: f7ded,2bfc088af2464387,start X-Google-Attributes: gidf7ded,public X-Google-Thread: 103376,2bfc088af2464387,start X-Google-Attributes: gid103376,public X-Google-Thread: 100062,2bfc088af2464387,start X-Google-Attributes: gid100062,public X-Google-ArrivalTime: 1995-03-21 10:11:12 PST Path: nntp.gmd.de!stern.fokus.gmd.de!ceres.fokus.gmd.de!zib-berlin.de!news.mathworks.com!zombie.ncsc.mil!paladin.american.edu!gatech!howland.reston.ans.net!math.ohio-state.edu!jussieu.fr!univ-lyon1.fr!swidir.switch.ch!epflnews!dinews.epfl.ch!usenet From: Magnus.Kempe@di.epfl.ch (Magnus Kempe) Newsgroups: comp.lang.ada,comp.answers,news.answers Subject: Ada FAQ: Programming with Ada (part 3 of 3) Followup-To: poster Date: 21 Mar 1995 18:11:12 GMT Organization: None Distribution: world Message-ID: <3kn4s0$bd7@disunms.epfl.ch> Reply-To: Magnus.Kempe@di.epfl.ch (Magnus Kempe) NNTP-Posting-Host: lglsun4.epfl.ch Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Summary: Ada Programmer's Frequently Asked Questions (and answers), part 3 of 3. Please read before posting. Keywords: advanced language, artificial languages, computer software, data processing, programming languages, Ada Xref: nntp.gmd.de comp.lang.ada:19961 comp.answers:10871 news.answers:40021 Date: 1995-03-21T18:11:12+00:00 List-Id: Archive-name: computer-lang/Ada/programming/part3 Comp-lang-ada-archive-name: programming/part3 Posting-Frequency: monthly Last-modified: 20 March 1995 Last-posted: 20 February 1995 Ada Programmer's Frequently Asked Questions (FAQ) IMPORTANT NOTE: No FAQ can substitute for real teaching and documentation. There is an annotated list of Ada books in the companion comp.lang.ada FAQ. This is part 3 of a 3-part posting. Part 2 begins with question 5.6. Parts 1 and 2 should be the previous postings in this thread. 8.6: How to write an Ada program to compute when one has had too much alcohol to legally drive? Someone asked if there is an Ada archive of this sort of program. Each drink has a number of units of alcohol, max legal level, etc. (from Bob Kitzberger :-) Oh, this is much to vague. Don't touch that whizzy development environment until you fully analyze the problem domain (unless that whizzy development environment includes Rose, in which case, you get to avoid paper and pencil from the git-go). Let's see, we have several classes to describe before we get to the implementation: Person subclass Drinker attributes: weight, age, timeline for amount consumed Drink attributes: percentage of alcohol, quantity of drink Country attributes: legal age to drink; max legal level of alcohol in blood Turn on the stereo, perhaps the Brandenburg Concertos. Then, flesh out the domain classes. Then, have a Belgian beer and consider what to do next. You decide on implementing these classes in a simple way, leading to your first successful prototype. Then, have another beer and decide what to do next. "Identify risk areas" you mutter to yourself, and off you go... If the beer wasn't too strong, you'd probably realize that the only thing of any difficulty in this is the amount consumed / rate of decay. Decide on investigating this aspect further. Create implementation classes for this and include a reference from the Drinker class to this new timeline/decay Class. Have another beer. Implement your second prototype. Congratulate yourself for making progress so quickly. Have another beer. Wander over to the stereo and change the CD to something more in the mood, maybe some Hendrix or Stevie Ray Vaughn. Back in front of the computer; pop another beer. Decide that it would be very cool if each drink was its own subclass of drink, and start cataloguing every drink out of your "Pocket Bartender's Guide". Have a slightly muddled epiphany that you really should create a class for each kind of alcohol (vodka, tequila, etc.) and the individual drink classes should each multiply inherit from all relevant Alcohol classes. Ooh, this is going to be a bit rough, so you have another beer. Draw a few of the hundreds of new class relationships needed, put that on the back burner when you think "persistence! that's what's missing!" Change the CD to Kraftwerk. Start your PPP connection, ask the people on comp.object for recommendations on a good OODBMS to use to keep track of all of those persistent objects. Make many many typos in your posting; everyone ignores it. Fall asleep on the keyboard. _________________________________________________________________ 9: Ada and Other Programming Languages 9.1: Where can I find programs that will translate from [some language] to Ada? It is generally advisable to simply interface from Ada to the existing code segments that (should) already work. Note that Ada (95) now has an annex devoted to specifying how to interface with code written in other programming languages (C, Fotran, and Cobol), and there are already interfaces to C++ too. Another option is to redesign the code, taking of course advantage of one's knowledge of the current system. For instance, Job�Honig reported that he did this twice, once for Coco, a parser generator for LALR left attributed grammars, and once for Flex, the well known scanner generator. Both attempts revealed errors in the original software; they were uncovered by designing the new system using the higher abstraction level allowed by Ada... So there is support for the requirements analysis (transition to Ada), but it is not obvious that the proposed implementation (using a source code translator) is a good solution. Still, you may have compelling reasons to translate your existing source to Ada. In that case, here is a list of available translators: * Pascal to Ada: R.R. Software's Pastran program (Pascal to Ada Translator). To see the differences in programming style, see "Ada for Experienced Programmers", by A. Nico Habermann and Dewayne E. Perry (Addison-Wesley Pub. Co., Reading, Mass., 1983). Covers Ada and Pascal. * Fortran to Ada: ??? * COBOL to Ada: ??? * C++ to Ada: ??? * C to Ada: ??? * Modula-2 to Ada: (from Wayne R. Lawton) The Idaho National Engineering Laboratory (INEL), a Dept of Energy Lab has a basic capability for Modula-2 to Ada-83. The tool is "research grade" quality, but may provide a starting point for what you need. This is the same group of people who brought you AdaSAGE. Give them a ring at (208) 526-0656. This is an answer desk hotline in the section that wrote the tool. If you are looking for commercial quality, I wish you the best of luck. If you just need something to perform 80% of the grunt code translation, I think this might meet your needs. I know of two systems comprising about 250,000 lines of code that were originally developed in Modula-2 then translated and cleaned up in Ada 83 after Alsys 1.0 for the PC came out back around 1987. * Visual Basic to Ada: NOT! :-) 9.2: How can I convert Ada 83 sources to Ada 9X? First you should read the following document, which will provide you with much useful information: "Changes to Ada -- 1987 to 1995", file ch83.{ps,doc}, in directory ftp://sw-eng.falls-church.va.us/public/AdaIC/docs/standard/95lrm_rat/ v6.0 If you're using GNAT, the tool you are probably looking for is "gnatchop". In csh you could use something like this to quickly process existing files: cd dest_dir # The destination directory foreach f ( ../src_dir/*.a ) # ../src_dir is the source directory gnatchop $f end gnatchop will show you what sources are causing problems. 9.3: I hear that Ada is slower than Fortran or C, is that true? First, note that you are comparing compilers, not languages. There is no such thing as "fast" Ada code any more than there is "fast" C++ or Fortran code. Now, when comparing execution speeds on similar platforms, you must keep in mind the optimization levels, OS tuning, etc. while making the comparisons. The bottom line is that benchmarking, especially between two different languages, requires _very_ careful measurement. In general, such results should be viewed with caution. (A message from Bevin Brett of DEC) I have been asked to comment on the relative performance of algorithms coded in Ada and in Fortran. This question has come up repeatedly over the years, and deserves a complete answer, rather than a simplistic one. There are many factors which influence the size and execution speed of the running program, and they all play together to get a full answer. I shall then discuss an exact Ada v. Fortran comparison that Digital was involved in. First, a position statement: The variation between Ada and Fortran is less than the variation within the language caused by the exact implementation details. A person versed in the Ada issues should do as well in Ada as a person versed in the Fortran issues will do in Fortran. The size and execution speed of the result should be within a few percent of each other. (a) Differences due to the compiler In the case of the DEC Ada and Fortran compilers, the optimizer and code generator are the same. Never-the-less, the exact inputs into the optimizer and code generator may differ slightly when the same algorithm is compiled by the Ada and Fortran compilers, and this can result in major differences in the generated code. In these cases the compiler front ends can usually be modified to correct the slower one. We have not observed any major differences in generated code quality between the DEC Ada and DEC Fortran compilers caused by such issues. (b) Differences due to the language It is very important that the same algorithm be written in the two languages. The biggest differences we have observed are 1. Having the wrong dimension varying fastest, since it is desireable to have the first dimension changing fastest in Fortran, and the last dimension in Ada. Thus when an algorithm is transliterated, the array indexes must be reversed. 2. Using compile-time-known bounds for arrays in Fortran, and using unconstrained arrays in the Ada code. Knowing the exact values of the dimensions at compile-time results in much better code. 3. Not suppressing all the runtime checks in Ada. The Fortran compiler assumes all array bounds are in range, and all arithmetic operations do not overflow. You must use a pragma Suppress to tell this to the Ada compiler as well. 4. Don't use arrays of Ada Booleans to match arrays of Fortran Integers, because accessing bytes on a RISC system might be much worse than accessing fullwords. (c) Differences due to the bindings The biggest bindings differences are related to Fortran's built-in support for complex types, and for various math routines such as SQRT and SIN, compared with Ada code that often uses hand-coded or ISO standardised versions of these functions with different requirements than are imposed on the Fortran versions. DEC Ada has built-in support for complex types, and also has bindings directly to the same primitives that Fortran uses for its math routines and so gets the same performance as Fortran does. (d) Differences due to the author The use of good Ada and Fortran style can also effect the generated code. Provided the author writes in good Ada style, and follows the above guidelines, the generated code should do as well as Fortran. The Ada Performance Benchmark A DEC Ada customer had a Fortran benchmark that had been translated into Ada without awareness of the above issues, and was running substantially slower with DEC Ada than the original was with DEC Fortran. Bevin Brett, a DEC Ada team member, developed the above guidelines in the process of retranslating the code into Ada. Portions of this translation are shown here (a) as an illustration of the application of the above rules, and (b) as an illustration of the kind of operations that were present in the benchmark. The whole benchmark has not been provided to avoid possible issues of ownership. The resulting Ada benchmark components each ran within a few percent of their Fortran counterparts. The Ada code is available by FTP, in file ftp://lglftp.epfl.ch/pub/Ada/FAQ/ada-vs-fortran.ada 9.4: Isn't Ada less "elegant" than Eiffel? While it is true that programming-language support for "assertions" is an important contribution of Eiffel to software construction, this is not an issue of "elegance", and there are many other important factors to consider. Note also that preconditions and postconditions can be fairly easily and efficiently included in Ada code. Invariants seem difficult to emulate directly in Ada. If you're really interested in the formal use of assertions with Ada, maybe Anna is a solution for you. (Tucker Taft comments) I guess one thing that bothers me a little is that people are quick to say that Eiffel is "elegant" without really looking at it. I fear that such statements will become self-fulfilling prophecies, with those programmers interested in elegance migrating over to Eiffel rather than sticking with Ada. In particular, although I like the assertion stuff in Eiffel, I think the language has a number of "inelegant" aspects. For example: 1. exception handlers only at the top level of a routine, with the only way to "handle" an exception being by retrying the whole routine. 2. No way to return from a routine in the middle. This makes it a pain in the neck to search through a list for something in a loop, and then return immediately when you find what you want. (I have never found the addition of extra boolean control variable a help to the understanding of an algorithm.) 3. Namespace control handled by a separate sublanguage, and no real higher level concept of "module" or "subsystem." 4. An obscure notation like "!!" being used for an important and frequent operation (construction). 5. No way to conveniently "use" another abstraction without inheriting from it. 6. No strong distinctions between integer types used for array indexing. 7. Using the same operator ":=" for both (aliasing) pointer assignment, and for value assignment, depending on whether the type is "expanded." (Simula's solution was far preferable, IMHO). And most critically: 8. No separate interface for an abstraction. You can view a interface by running a tool, but this misses completely the importance of having a physical module that represents the interface, and acts as a contract between the specifier or user of an abstraction and its implementor. In Eiffel, one might not even be truly aware when one is changing the interface to an abstraction, because there is no particular physical separation between interface and implementation. I consider many of the above problems quite serious, with some of them being real throwbacks to the old style of programming languages where there were no well defined interfaces or modules. Hence, I cringe a bit when people say that Eiffel is the "most elegant" OOP and that they would use it if only it were practical to do so. In many ways, I think Ada is much better human-engineered than Eiffel, with important things like range constraints built into the language in a way that makes them convenient to use. Although general assertions are nice, they don't give you the kind of line-by-line consistency checks that Ada can give you. To summarize -- Although Eiffel certainly has a number of nice features, I don't consider it ready for prime time as far as building and maintaining large systems with large numbers of programmers. And from a human engineering point of view, I think Ada is significantly better. 9.5: Are there any papers detailing the differences between Ada and C++? Below are two references. Bear in mind that it is difficult to make such a comparison without exposing biases. However, the two papers below are well worth reading. "A Comparison of the OO features of Ada9x and C++" in Springer Lecture Notes in CS: "Ada Europe 93" pp.125-141 (short paper, good reading, enlightens idioms) ftp ajpo.sei.cmu.edu in directory: /public/ada9x, document: 9x_cplus.hlp 9.6: I keep hearing that Ada is a "strongly typed language", but it seems different from what's meant in C++. Are they different? (Tucker Taft responds) I certainly agree that ANSI C and C++ are statically typed languages, but I would debate the "strength" of their typing. Essentially any support for implicit conversion (implicit "casting," "promotion", "usual" arithmetic conversions, etc.) "weakens" a type system (but also makes it "friendlier" in some ways). C allows implicit conversion between all integer types and all enumeration types. C++ at least cuts off implicit conversion to enumeration types, but retains implicit conversion among all integer (and floating-point) types. Also, in both C and C++, typedefs for pointer/array types are essentially "macros"; all pointer types with the same target type are implicitly interconvertible. Finally C++ allows the user to define a number of their own implicit conversion operators, which basically allows the user to "weaken" the type system as they see fit. Of course, all of this implicit conversion serves a purpose, but it does tend to move C/C++ toward the "weaker" end of the weak vs. strong typing spectrum. Note that the "strong" distinctions between integer types helps dramatically in catching (at compile-time) array indexing errors in Ada programs, by making sure that if you have an array indexed by a count of apples, you don't index into it with a count of oranges (without an *explicit* conversion). The advantages of "strongly" distinguishing enumeration types is even more obvious (and the designers of C++ recognized this). The strong distinctions between access types (pointer types) in Ada also has advantages, allowing access types to be represented as offsets within their storage pool rather than as addresses, and giving more high-level control over storage management. Strong typing can be carried too far, and some amount of implicit conversion is essential to make OOP palatable. But note that in Ada 9X, even with OOP, we don't allow implicit conversions that truncate the extension part of a record (this is a relatively common mistake in C++ when passing parameters by value). Instead, in Ada 9X, the language distinguishes between a specific type T and the class-wide type T'Class, and allows implicit conversions to T'Class from T or any of its derivatives, but not to the specific type T. Conversions to the class-wide type never implicitly truncate the extension part. Conversions to a specific type can truncate, and hence must be explicit. Note also that in Ada there are three distinct kinds of conversions, implicit ones, explicit ones, and unchecked ones. Only the unchecked ones are potentially unsafe. The explicit ones are safe, with either compile-time or run-time checks to ensure that. In C there are only implicit and explicit/unchecked conversions. C++ has recently added a checked, explicit "dynamic" cast, but still it will be common to use "normal" explicit casts for both checked and unchecked conversions, thereby making it more difficult to identify places where the type system might be compromised. Hence, the bottom line is that the type checking is (objectively) "stronger" in Ada than C/C++, though that doesn't necessarily mean "better" -- whether one is "better" for a particular style of programming than the other is a "religious" issue IMHO. I know my religion currently favors the stronger checking of Ada in most cases [except perhaps for multiply/divide, where I personally believe the checking should either be weaker, or directly support the concept of "units"/"dimensions"]. 9.7: I'm told Ada does all sorts of static type checking, but can't you get the same effect using a tool like "lint" with C? No, here are a few reasons why (this list is by no means complete): (Submitted by Norm Cohen) * Running both Lint and a C compiler requires the program text to be parsed and semantically analyzed twice. The results of an Ada compiler's parse and semantic analysis are used directly in performing consistency checks. * The rules of Ada provide the opportunity for stronger consistency checks than are possible with C. For example, an Ada programmer can declare distinct integer types to represent distinct abstractions. An Ada compiler will catch an inadvertent intermixing of these two types, but there is no way a corresponding distinction can be made in C, so there is no way for Lint to perform a corresponding check. Similarly, in C, a pointer to an object of type T is indistinguishable from an array of objects of type T. * The rules of the Ada language ensure that the program text provides information allowing PRECISE consistency checks. For example, the expression in an Ada case statement can be written to have a static subtype, allowing the compiler to ascertain that all possible values have been covered without resorting to a default (when others) arm. * With lack of precise information, Lint has no choice but to be overly pessimistic or, with different settings for a complicated set of options, overly optimistic. When it is overly pessimistic, the user sees too many "false alarms" and may end up ignoring valid warnings. When it is overly optimistic, Lint overlooks certain errors. * It is impossible to forget to run consistency checks when using an Ada compiler. (Of course a C programming environment could be set up so that the C compiler could only be invoked from a script that also invokes Lint.) * A compilation that fails Ada consistency checks is rejected. A compilation that fails Lint consistency checks may still be compiled, and its object file used (intentionally or accidently) in building the system. (One cannot automate the rejection of programs that fail Lint unless one is certain that there will never be any false warnings.) * Ada enforces consistency among separately compiled units. Of course even stronger arguments can be made about Ada's RUN-TIME checks (which can be used with little additional overhead because the information contained in an Ada program and the knowledge that the program has passed compile-time consistency checks make it possible to optimize away the majority of the checks). These checks, which are absent in C, tend to smoke out errors early by detecting internal inconsistencies that might not otherwise be detected during testing. This reduces the likelihood of fielding a system that appears to work well during testing but fails in operational use. 9.8: Does Ada have something like the Standard Template Library (STL) in C++, or components like you find in Smalltalk environments? Yes, in various ways. Few components are part of the ISO standard. Ada 95 has an expanded set of predefined library units, covering e.g. strings of varying- or dynamic-length, elementary numerical functions, random number generators, complex numbers, and more; in addition, the Special Needs Annexes standardize many advanced services which have commonly been provided by separate components in the past. A lot of free Ada software components are available from anonymous FTP sites. There is also an upcoming release of the Booch Components for Ada 95 under the GNU Library General Public License (LGPL); this will give you the ability to freely include the library components in your application without any cost or obligation. (Contact dweller@neosoft.com for more details.) What about STL and the Smalltalk library? The C++ STL doesn't contain much. Really. Breaking its source code down, it contains less than 3000 semicolons (~7000 total lines). The entire library exists in C++ header files as inlineable code (supposedly within a few percent of the efficiency of hand-optimized code). STL class hierarchy bool, heap -- of course Ada does not need a bool class! \ function, pair, stack \ iterator, tempbuf, projection \ algobase \ algorithms, bitvector, deque, list, tree, vector \ map, multimap, set, multiset The main author of the library, Alexander Stepanov, created the Ada Generic Library in the 1980's -- and later borrowed from this to create STL. (There is an interview with Stepanov in the March 1995 issue of Dr. Dobb's Journal -- in the C Programming column beginning on page 115. Stepanov explains that these components were first done in Ada.) The Smalltalk library is quite eclectic. It covers everything from Boolean to bitmaps, dictionaries and other collections. Parts of it have direct equivalents in Ada 95, parts are already available in components from anonymous FTP sites and/or will be in the Booch Ada 95 components, and other parts are available from commercial Ada component suppliers. 9.9: Where can I find the equivalent of "printf" in Ada? While the standard package Text_IO provides many features, the request for a printf-like function is not unusual. (solution based on a suggestion by Tucker Taft) It is possible to produce a printf-like capability by overloading the "&" operator to take an object of type Format and an object of some type and return the Format, properly advanced, after having performed the appropriate output. The remaining format can be converted back to a string--e.g. to examine what is left at the end of the format string-- or simply printed to display whatever remains at the end. For example: with Text_IO; package Formatted_Output is type Format is limited private; function Fmt (Str : String) return Format; function "&" (Left : Format; Right : Integer) return Format; function "&" (Left : Format; Right : Float) return Format; function "&" (Left : Format; Right : String) return Format; ... -- other overloadings of "&" procedure Print (Fmt : Format); function To_String (Fmt : Format) return String; private ... end Formatted_Output; with Formatted_Output; use Formatted_Output; procedure Test is X, Y : Float; begin Print (Fmt("%d * %d = %d\n") & X & Y & X*Y); end Test; The private part and body of Formatted_Output are left as an exercise for the reader ;-). A "File : File_Type" parameter could be added to an overloading of Fmt if desired (to create something analogous to fprintf). This capability is analogous to that provided by the "<<" stream operator of C++. _________________________________________________________________ 10: Interfacing with Ada 10.1: I am writing software that used the Distributed Interactive Simulation (DIS) interface, does an interface exist in Ada? Yes. DIS is a standard for communications between simulators using an Internet Protocol network (IP). DIS provides a unified virtual environment for multiple simulator users on a network. It is used mostly in the DoD simulations business, but it is applicable to ANY simulation. It is an industry initiative involving military training and procurement organisations, simulator vendors and universities mostly in the US, but the technology is unclassified. The US Army is funding quite a bit of DIS research and development. The Institute of Simulation and Training, URL http://www.tiig.ist.ucf.edu/ is a center at the University of Central Florida (UCF) which serves as the support contractor for the UCF IST, as are BBS's for the DIS working groups who are attempting to push those standards forward. The BBS contains an Ada binding for DIS. Note that the above provides a thin binding to C code. It may be worthwhile to take the time to make high level DIS bindings. Someone reports having done it in over 2 man-months using an experienced Ada engineer, and that it was well worth it. Many bugs were found in the C DIS code of the machine they were networked with. "A strongly-typed interface is the network programmer's best friend." At TRI-Ada'94 there was a demonstration by Coleman Research Corporation (CRC); here's their short pitch: "CRC presents Ada VR-Link, the first commercially available DIS NIV. It provides all of the facilities necessary to jump start your DIS compliant simulation development efforts. For more information call (205) 922-6000." Also, the AJPO sponsored an Ada Technology Insertion Program (ATIP) relating to this: FY93 ATIP project 17, titled "Ada Distributed Interactive Simulation (ADIS)". The Ada Distributed Interactive Simulation (ADIS) provides an Ada interface to the IEEE 1278 Distributed Interactive Simulation (DIS) protocols. The project was developed in Ada 83 (MIL-STD-1815), on Silicon Graphics Indigo R4000 machines using Verdix Ada 6.2.1 under the IRIX operating system, version 5.2. The Graphical User Interfaces (GUIs) were developed for X Window version X11R5 using Motif 1.2. There are several sources of information available on DIS itself. The IEEE version of the DIS standard is available through (and only through) the IEEE (std IEEE 1278). Draft versions of the standard are available from the Institute for Simulation and Training at the University of Central Florida. They take orders at (407) 855-0881, and questions (about ordering) at (407) 658-5054. 10.2: Is there any support for Common Object Request Broker Architecture (CORBA) for Ada 9X? (from Bill Beckwith, Bill.Beckwith@ois.com) Objective Interface Systems, Inc. (OIS), MITRE, and DISA have been working on a mapping from CORBA IDL to Ada 95 for about six months. I will send a recent copy of the mapping document to any interested parties. OC Systems, Rational, and OIS are planning on selling CORBA products for Ada. Note that CORBA IDL to Ada 95 mapping specifies a mapping, not a binding. This will put Ada 95 on equal footing with the C++ and Smalltalk products. (except, of course, the Ada mapping is cleaner ;-) _________________________________________________________________ 11: Finding Additional Information 11.1: Where can I find Ada books? Try the comp.lang.ada FAQ, or the Ada WWW homepage (http://lglwww.epfl.ch/Ada/). Michael Feldman maintains the "Annotated Sampling of Ada-Oriented Textbooks", if you don't have access to WWW, drop him a note at mfeldman@seas.gwu.edu 11.2: Are there other Ada-related FAQs? Yes. They all appear in comp.lang.ada at regular intervals: comp.lang.ada FAQ, public Ada library FAQ, and Ada WWW server FAQ. All these are permanently available in hypertext format from the Ada WWW Server (see below) and in ASCII format from ftp://lglftp.epfl.ch/Ada/FAQ 11.3: What is the "Ada WWW Server"? The Ada WWW Server is alive and heavily used. It is a hypertext, multimedia information server for the Ada programming language. The URL of the Ada WWW Server is http://lglwww.epfl.ch/Ada/ [don't forget the trailing '/'.] The Ada WWW Server provides Ada-related information and hypertext access in areas including: * Historical notes on Ada * References * Ada FAQs * State of Ada 9X revision process * Standards * Bindings * Tools and Components * Intellectual Ammunition * Introductory Material * Resources * CS Technical Reports * FTP and WWW Sites--including mirror sites * Calendar of Ada-related events * Ada Today * Frequently Asked Questions--with Answers (from comp.lang.ada) For instance, you will find a list of schools using Ada in CS1 or CS2, an article on commercial success stories, information about software components, as well as hypertext versions of the Ada reference manual (both 83 and draft 9X). The Ada WWW Server keeps growing. All comments, ideas, and requests for additions or corrections, are welcome (e-mail to Magnus.Kempe@di.epfl.ch). _________________________________________________________________ 12: Pretty-printing Ada Source Code 12.1: Is there software that generates a pretty PostScript file from Ada source code? Pretty Ada code in PostScript means that e.g. reserved words are in bold and comments are in italics. This is a separate issue from re-formatting and automatic indenting. If you use the new Ada Mode for GNU Emacs (available from ftp://cs.nyu.edu/pub/gnat), go and get the package ps-print.el from any emacs archive (e.g. in directory ftp://archive.cis.ohio-state.edu/pub/gnu/emacs/elisp-archive). With this package you can print your code as you see it on the screen, say with bold keywords and italic comments. Another possibility is to feed the source to "vgrind" (see below), then pipe the result through "pscat" (to get PostScript) or "lpr -t" (to print), e.g.: vgrind -d -lada -o1- -t -w $* | lpr -t 12.2: I use vgrind to do "pretty printing" of my source. Is there a vgrind definition for Ada? # Ada! ada|Ada:\ :pb=(^\d?(procedure|function|package|package body))\d\p:\ :bb=if|case|begin|loop:be=end:\ :cb=--:ce=$:\ :sb=":se=":\ :lb=':le=':\ :id=_.:\ :oc:\ :kw=abort abs abstract accept access aliased all and array at\ begin body case constant declare delay delta digits do else\ elsif end entry exception exit for function generic goto if in is\ limited loop mod new not null of or others out package pragma\ private procedure protected raise range record rem renames requeue\ return reverse select separate subtype tagged task terminate then\ type until use when while with xor: Note that the above has a problem with attributes, because the "lb" and "le" terms make two-attributes-20-lines-apart look like one "string literal." Ada 95 keywords are recognized. Here is another definition, which "fixes" this problem (not perfect, but probably better). Only Ada 83 keywords are recognized. # In order to get the ticks to work, we are assuming that there will be # whitespace before a literal (like '"') and *not* when used for an # attribute (like 'Length). # For sb/se, we are ALSO assuming that literals have whitespace before/after. Ada|ada:\ :pb=^\d?(procedure|function|package|package\dbody)\d\p:\ :bb=begin:be=end:\ :cb=--:ce=$:\ :sb=( |\t|\()":se="( |\t|;|,|\)):\ :lb=(>| |\t)':le='(\)| |\t|;):\ :tl:\ :oc:\ :kw=abort abs accept access all and array at begin body case constant\ declare delay delta digits do else elsif end entry exception exit for\ function generic goto if in is limited loop mod new not null of or\ others out package pragma private procedure raise range record rem\ renames return reverse select separate subtype task terminate then\ type use when while with xor: 12.3: How about a source code reformatter? If you can run a Perl script (Perl is freely available for almost every OS in the world), you can use the program aimap, written by Tom Quiggle of SGI. It can be found (where ???). 12.4: How can I count source lines of code (SLOC)? Under Unix and many operating systems (apparently even MS-DOS), the following works well: wc -l file_name If you only want to count "statement lines" (lines with semicolons), use sed 's/--.*$//' file_name | grep ';' | wc -l Some versions of grep have a '-c' option to print a count of the matching lines, but this may not be universal. You can fold the grepping into the sed command but that's not as readable: sed -n -e 's/--.*$//' -e '/;/p' file_name | wc -l Please note that measuring SLOC should be used to indicate an approximate relationship to the size of other projects, and as such, provided that there is some uniformity in the form and number of comments, it does not matter whether comments are counted or not. It has often been observed that there is a very high correlation between measurements of SLOC, semicolons, and Halstead bits (there is probably also a high enough correlation with the number of characters). With VMS, try the following, which will print out the number of lines ("records") and characters (use ";" instead of "~~~~~" to count lines with semicolons; note that "records" will match even in comments): $ search/stat file_name.ada "~~~~~" 12.5: Can I measure other things? There is ASAP, the Ada Static Analyzer Program, written in Ada and set up to compile under Dec Ada on a Vax running VMS. Gives SLOC, McCabe's, and more. It is available via anonymous ftp in file ftp://ftp.sei.cmu.edu/pub/dd/asap072490.tar.Z _________________________________________________________________ 13: Common Confusions 13.1: Wasn't Ada designed by some committee? What kind of a language could you possibly get from that kind of approach? (Tucker Taft, the principal designer of Ada 95, responds) I believe most reviewers of Ada 9X (and Ada 83 for that matter) will assure you that it was most certainly not designed by committee ;-). In fact, with respect to MI, the situation was just the opposite. There were several reviewers who pushed hard for building in a particular approach to MI. The principle designer (;-) was unconvinced that the benefits of building in a particular MI approach outweighed the costs as far as complexity. There was no clear winner to use as a model in the outside world; even Sather and Eiffel couldn't agree exactly on how to resolve the intricacies of MI, despite their strong similarities in other areas. 13.2: I've heard the DoD is dropping all Military standards to reduce costs, doesn't that mean the mandate to use Ada goes away too? The following memo explains how that decision affects the Ada mandate: OFFICE OF THE SECRETARY OF DEFENSE Washington, DC 20301-1000 August 26, 1994 MEMORANDUM FOR SECRETARIES OF THE MILITARY DEPARTMENTS CHAIRMAN OF THE JOINT CHIEFS OF STAFF UNDER SECRETARY OF DEFENSE (PERSONNEL AND READINESS) UNDER SECRETARY OF DEFENSE (POLICY) COMPTROLLER OF THE DEPARTMENT OF DEFENSE GENERAL COUNSEL OF THE DEPARTMENT OF DEFENSE INSPECTOR GENERAL OF THE DEPARTMENT OF DEFENSE DIRECTOR OF OPERATIONAL TEST AND EVALUATION DIRECTORS OF THE DEFENSE AGENCIES SUBJECT: Use of Ada The purpose of this memorandum is to reiterate the Department of Defense (DoD) commitment to the use of Ada. It is DoD policy to use commercial off-the-shelf (COTS) software whenever it meets our requirements. However, when COTS software is not available to satisfy requirements and the DoD must develop unique software to meet its needs, that software must be written in the Ada programming language in accordance with DoD Directive 3405.1 and DoD Instruction 5000.2. Secretary Perry's June 29, 1994 memorandum, "Specification & Standards -- A New Way of Doing Business," states that military standards will only be used "as a last resort, with an appropriate waiver." This direction has caused some confusion regarding the Ada requirement since most references to Ada cite its MIL-STD nomenclature, MIL-STD-1815A. Ada is also a Federal Information Processing Standard (FIPS 119), an American National Standards Institute (ANSI) standard (ANSI-1815A-1983), and an International Standards Organization (ISO) standard (ISO 8652-1987). Any of these alternative references may be utilized in place of the MIL- STD reference in request for proposals, contracts, and other similar documents. Thus, the Ada requirement does not conflict with the Secretary's direction, and compliance with both policies can be achieved simultaneously. Use of other programming languages can be considered if proposed by a contractor as part of his best practices since waivers to the use of Ada can be granted, where cost-effective, in accordance with procedures established in the policy referenced above. However, such proposals require strong justification to prove that the overall life-cycle cost will be less than the use of Ada will provide. Secretary Perry's memorandum encourages practices that satisfy the Department's need to build high quality systems that meet requirements at affordable costs an in a timely manner. This includes practices which support the development of Defense Software. Ada is not only a facilitator of software engineering best practice, but also has inherent features which uniquely support both real-time systems and safety-critical systems. Use of Ada also facilitates software reuse and has demonstrated reduced support costs. Accordingly, Ada is a foundation for sound software engineering practice. /signed/ /signed/ Noel Longuemare Emmett Paige, Jr. Under Secretary of Defense Assistant Secretary of Defense (Acquisition and Technology) (Command, Control, (Acting) Communications, and Intelligence) cc: DDR&E _________________________________________________________________ 14: Credits The following persons have contributed (directly or indirectly, intentionally or unintentionally, through e.g. comp.lang.ada) to the information gathered in this FAQ: Tucker�Taft, Dave�Weller, Chris�Ausnit, Bill�Beckwith, Chip�Bennett, Bevin�Brett, Norm�Cohen, Marin�David�Condic, John�Cosby, Richard�Crutchfield, Theodore�E.�Dennison, Robert�Dewar, Bob�Duff, Robert�Eachus, Rolf�Ebert, Jeffrey�L.�Grover, Laurent�Guerby, Richard�G.�Hash, Job�Honig, Jean�D.�Ichbiah, Nasser�Kettani, Wayne�R.�Lawton, Robert�Martin, Robb�Nebbe, Jonathan�Parker, Isaac�Pentinmaki, Bruce�Petrick, Paul�Pukite, Richard�Riehle, David�Shochat, Keith�Thompson, Joyce�Tokar, Kevin�Weise, Fraser�Wilson, and the maintainer has simply :-) organized, polished, or added some information for your satisfaction. The general HTML structure of this FAQ was inspired by the WWW FAQ. _________________________________________________________________ 15: Copying this FAQ This FAQ is Copyright 1994, 1995 by Magnus Kempe. It may be freely redistributed as long as it is completely unmodified and that no attempt is made to restrict any recipient from redistributing it on the same terms. It may not be sold or incorporated into commercial documents without the explicit written permission of the copyright holder. Permission is granted for this document to be made available under the same conditions for file transfer from sites offering unrestricted file transfer on the Internet and from Forums on e.g. Compuserve and Bix. This document is provided as is, without any warranty. _________________________________________________________________ Magnus Kempe -- Magnus.Kempe@di.epfl.ch