I want to make a basic library management system in prolog. The program should answer queries like which book is issued by which student and which date book will be returned. I want guidance in terms what exact components i need to learn for it (as I am very much new to prolog), i wanna develop it rapidly as i dun have time to learn the whole thing. I will be using visual prolog 7.3
Thanks in Advance
MGD
You haven't given us much of an idea what your programming background is, so I've interpolated a couple of comments below to suggest what existing experience might help in doing parts of the Visual-Prolog application asked about.
With Visual-Prolog you have to begin with user-interface design, something that I frankly found discouraging for playing around with the Prolog coding. Think of the "window" elements you want: perhaps an input field to input a user name and another input field to enter a book title, with some buttons for "search" as your "program should answer queries" spec suggests. The output will contain information about whether a book is checked out, when it is due, etc.
Then the functional part of your design can begin. Visual-Prolog asks you to declare certain things: domains (equivalent to datatypes in other languages) and predicates (the names relations and the domains to which their various arguments apply, roughly the equivalent to routines in other languages).
Your library application sounds like it is similar to a database, a "knowledge-base" containing information about users, books, and the relationship between them (e.g. this user has this book checked out), possibly with some history (who checked out a book when, and when was it returned).
Since you want to "develop it rapidly", you will probably want to start with a very simple set of domains and predicates. Perhaps "user" and "book" are the basic domains to start with, and checkOut/2 the basic predicate (indicating the fact that a particular user currently has the particular book). Then you will probably need to add (at least) the feature of storing the book's return date. This kind of design will be easier if you've done some relational database development before.
Connecting the user-interface (UI) to the "knowledge-base" of library users & books is a matter of writing predicates that serve as event-handlers for the visual elements of the UI. This is somewhat easier if you are familiar with Visual Basic. In any case you can "stub out" the event handlers while you are building the "look and feel" part of the UI, replacing them with substantive implementations as your design moves into developing the "knowledge-base".
Related
I used to have a nice set of coding standards I could print for coldfusion that was almost a framework but much looser with some code examples. Like teh use of createObject, more cfscript, error and message integration, Application.cfc usage and examples. Also seperation of buisness (actions) and display using cfincludes to make an index.cfm page 'a generator' of many actions leveraginf cfswitch/cfcase...etc. I am looking for some doucmentation or anything that I can print our and sit on my desk and refer to so my coding stays clean. Any help from the community would be very much appreciated.
Although rather dated, You may find what you are looking for among the many posts listed under the "Coding Guidelines" section on the "Articles" page of the MDCFUG - Mayryland ColdFusion User's Group website.
Here are some other options:
Univ. of Maryland ColdFusion Programming Standards
Sample Applications Methodology Guidelines provided by Adobe.com
SBA ColdFusion Programming Standards contains 126 pages of coding standard written for the U.S. Small Business Administration to insure security, promote code re-use, easy readability, and easy maintenance.
Oregon Health & Science University - Coding Guidelines which contains a number of GOOD versus BAD coding examples.
I'm unaware of any "official" Coldfusion specific coding standards. Where I work we collectively came up with our own based on many years of experience working with the language. A simple one for example is to use camel case. From what I've seen camelCase is preferred over snake case in Coldfusion, so as a rule we have:
In general, for files use lowerCamelCase starting with a lower-case letter, except for CFCs which should start with an upper-case letter as they represent a class in ColdFusion.
We have other standards broken up under headings such as:
Variable Naming
Operators
Scopes
Functions
ColdFusion Native
Functions
Indentation
......
I am looking for some doucmentation or anything that I can print our
and sit on my desk and refer to so my coding stays clean.
In addition to this I recommend you create a set of generic code snippets, such as you can use in Eclipse, that conform to any standard you decide to go with. These can then be easily distributed among team members, helping to keep things consistent as well as saving typing time.
I realise this is quite an old post now, but thought it would be worth mentioning http://wiki.coldbox.org/wiki/DevelopmentBestPractices.cfm. I think this is a good set of standards for writing CFML.
I worked on different projects in different countries and remarked that sometimes the code became internationalized, like
SetLargeurEtHauteur() (for SetWidthAndHeight, fr)
Dim _ListaDeObiecte as List(Of Object) (for _ObjectList, ro)
internal void SohranenieUserov() (for SaveUsers, ru)
etc.
It happens that in countries with Latin alphabet this mix is more pronounced, because there is no need of transliteration.
More than that, often the programming "jargon" is inspired by the project specifications language. There are cases that terms in "project language" have a meaning that is not "translatable" in English.
There are also projects on which works only, say a French team, uses French words (say, Personne, Vehicule, Projet etc).
In that cases I personally add in specifications a "Dictionary" that explains all business object names and only these objects are used in other (French) language.
Say:
Collectif - ensemble des Personnes;
All the actions(Get, Set, Update, Modify, Load, etc) are in English.
Now that "strong" names could be used in code:
AddPersonneToCollectif.
What is your approach to "internationalization"?
PS.
I was amused that VisualStudio compiles and runs projects in .NET with buttons named à la "btnAddÉlève" or "кпкСтоп"...
My personal approach, which is shared by many but not all in the programming community, is that source code should be in English and, if possible, all the development tools should be in English too.
The most important reason for this is being able to share your problems and solutions with the world (like we are doing now in StackOverflow, no less) without having to translate class names, error messages, paths and other artifacts every time.
It also helps consistency, because most libraries are written in English and having element names that mix two languages doesn't really help anyone, besides being a constant focus of internal conflicts when a verb like Add isn't always traslated.
English code also makes it easier to add foreign people to a project without worrying about comprehension and misunderstandings (especially between closely related languages, like Spanish and Portuguese, which have lots of false cognates)
A good link on this subject: http://www.codinghorror.com/blog/2009/03/the-ugly-american-programmer.html
(In case anyone wonders, I'm south-american and English is not my primary language)
Even if everyone on the team is a good English speaker (which is not a given), they may not necessarily know the English equivalent of all the business terminology.
I think it's a project-specific decision what to allow, but I would generally tolerate and in some cases encourage business terms (e.g. entity names) in the local language, but not technical terms (i.e. not Largeur/Hauteur instead of Width/Height).
For example in the financial world in France, everyone knows what is meant by OPCVM and FCP - if you attempt English translations you might end up with more misunderstandings than you do by allowing mixed languages.
I have the same issue with Norwegian currently. I guess it depends on your position in the project, the available time and the role of the software.
In my case, I have decided to keep all terms in an existing protocol and library I am working with in Norwegian, as I can reasonably expect that generations of administrative workers have gotten used to these, and since the library depends on the protocol. In a library wrapper for an international project, I have translated each method name literally, and added an English language documentation of the method.
Comments and documentation on the code are in English.
If designing a software from scratch, I would try to find English terms for all method names and even business terms (if reasonable. I can hardly think of an example where no term can be found though.), to keep it "portable".
If you're writing code that you may be used internationally one day, write it in English. In doubt, write it in English, even comments if you can (although I suppose you can add a few comments in the language of your workplace).
It's not specific to coding unfortunately. English isn't my native language, but I've been able to read a number of technical papers and participate to international conferences with people from all over the world. These collaborations simply wouldn't work if everyone published in their respective native languages.
It may be sad if you feel like defending your language at all cost, but you have to be realistic about it. I suppose English has the advantage to be relatively simple for achieving a basic level: no genders for names, no conjugations, no cases.
Generally code referring to language concepts should be in the same mother language as the programming language (i.e. English - for, while, string are all English words).
It's OK (but not great) to have variables and domain concepts in a local language, but you definitely don't want to be translating List, Object, Decimal, etc. into terms which cause programmers more work in reconciling two languages. Even still, I would strongly lobby to restrict very common domain concepts like Collection, Membership, Person, User and possibly less common domain concepts like Invoice, Receipt to English where this is possible.
It would be like coding half your classes in VB and half in C# - your brain has to make a cognitive shift. While this is good for hybrid apps (JavaScript on the web and C# on the backend) because it helps you keep what's running where clear, it isn't good for a general programming.
In addition, using English for everything makes the domain and language words work together better.
There are always exceptions. There are certain cases where you would use a native word anyway - where the word describes the domain best. For instance, in our (English) code base, we had references to Mexican Spanish terms for certain concepts which were only relevant for people running our software in Mexico. Typically, Japanese terms were spelled out phonetically/Romaji, though - it was difficult for non-Japanese to be able to pronounce the pictograms ;-).
I think I'd call a code base like that "abysmal" rather than "internationalized", but the general rule I've always heard is that if you ever think that someone other than one who speaks your language might ever touch the code, do it in english.
I think that good design guideline is to write code with use of English names and with english comments only (of course if your team is capable to do this, but in case of international team English seems to be natural choose, since it's a most popular language, expecially in IT world).
Good explanation of such guidline is that keywords in most of programming languages are taken from English so writing your code using English names gives more consistent look and thanks to this you end with code that is easier to read.
Another reason is that most of compilers can handle only ascii characters as names of classes, methods, etc. so probably you will end with some strange names when you decide to use some language with alphabet containing non ascii chars.
Third reason that came to my mind is sharing your code on site like SO. Today I opened a post with a piece of code where classes had Spanish names. It was hard for me to guess what was the purpose of this class (even if sometimes is not necessary it is good when you read code and understand all used words:)).
To sum up I think that internationalization of code is not a good idea. You can imagine that keywords in programming languages (e.g. class, try, while) could also be localized and probably you can imagine also how hard life could be then...
To keep things consistent, I would make the code the same (human) language as the (programming) language. That is, if the programming language uses English keywords (like for, switch, public, etc) then keep the rest of the code in English. If you are using a compiler that recognizes (say) the Swahili translations of keywords, then keep the rest of the code in Swahili.
Many APIs have standardized naming schemes that are followed regardless of (human) language, and the accompanying documentation is translated as needed (instead of the source code).
No matter what (human) language you choose, pick one and stick with it. I'd much rather try to wade through source code in German than code that was a mix of German and English.
So - highly hypothetical question and more like discussion about your coding style and practice you use daily.
I will take as example: CodeGear RAD Studio 2009 (sorry to all D7 fans, but Unicode rules).
I have capability to expand/collapse functions/procedures/records and few other complex data structures, but what if code is lengthy?
What makes the task and its accomplishment efficient - the time required to add comments (its req actually) and expand/collapse necessary area or use OMT offered possibilities?
To give example input from myself - I have small app, about 1,5k lines and I do not use Modeling. Is it smart enough or do I lose a lot of time if I need to find some simple references or (event) calls?
If I understand your question correctly, it is a bout finding your way into code (yours or someone elses').
I use Model Maker Code Explorer for browsing through source code (and for refactoring existing code, and creating new code). At EUR 99, it is dead cheap for what it does.
It usually gives me a perfect overview of what I need, and has a nice 'search' interface as well.
If I need more complex searches, I usually use the GExperts (grep) search function: it is blazingly fast, and with good naming of your identifiers, it is usually a breeze to find stuff.
If I understand your question correctly, you want to know what is more efficient:
Use comments and expandable sections.
Use moddeling techniques.
I think it depends on personal style. Modeling can be great, but has dangers of spending too much time creating nice pictures.
We have a large app 500k+ lines. We do not use collapsable sections because we keep our file size acceptable and we have a good file organisation structure. We sometimes use modeling if complex parts are added (class diagrams and state diagrams). And we use lots of comment to explain difficult parts.
If you have Delphi 2009 you can use also the Delphi Class Explorer (in the View menu) in order to see your classes. It seems a little bit cryptic but only for the first 5 minutes. After this you will get used with it.
Also you can use CnPack a very impressive package in order to help you manage your project. Basically, in the IDE appears a new menu called 'CnPack' which has a bunch of wizards to help you find the way out in the source. Some examples:
Uses Cleaner
Procedure List (it gives you the incremental search capability for your procedures - very neat)
Bookmark Browser
etc.
I'm writing a small program in Ruby to parse a hand history log from a poker site.
The log is split over several lines and looks a bit like this:
Table 123456 NL Hold'em $1/$2
5 Players
Seat 3 is the button
Seat 1: randomGuy112 $152.56
Seat 2: randomGirl99 $200
Seat 3: PokerPro $357.12
Seat 4: FishCake556 $57.19
Seat 6: MooMoo $188.98
Dealt to MooMoo [Ah, Ks]
randomGuy112 folds
randomGirl99 raises to $7
etc.. etc..
I want to summarise this information in an object which then might, for example,
render it differently or save it to database.
When I originally thought of this problem I thought I'd just have one realativly straight forward class with a number of regexes and several if/else statements. I then realised this could turn into quite a large method and potentially be a nightmare to debug/maintain. Keep in mind it needs to loop at each stage of the game (preflop,flop etc) to collect player's actions.
I also want to tackle this with a TDD approach, but the 'one long method' way means that the tests for with checking later input will kind of rely on earlier tests.
I'm quite new to Ruby and havn't yet clicked on the 'Ruby way' to do things. I'm catching myself writing C# code
in a different language.
Can you give me some pointers on how to design the parser so it isn't one huge mess of if/else statements and more testable?
Use Treetop
It does look like you are on the borderline between what ad hoc string matching and RE's are good for, and what requires an actual parser.
There is nothing wrong with handwritten parsers, and as long as you keep your methods short, without a lot of complexity in any given one, it's OK to have as many if statements in total as the parser requires.
I'm not sure 10 lines with incomprehensible regular expressions is any better than 30 lines of nice looking code.
Now, Ruby does have an advanced PEG parser generator. I think in this case I wouldn't worry about whether it was overkill, I would just go ahead and use Treetop.
State Machine, anyone?
At any point in the play of a poker hand there is a clearly-defined set of possible next actions. I'd think you could encapsulate them into a state machine. There are a few around, amongst which (no recommendations, I'm afraid - not enough experience with any) are
Alter Ego (updated July this year)
ruby-state-machine (seems also to be alive)
statemachine (looks a bit stale)
You can checkout this open source poker game hand parser
It looks like they created a hash of regular expressions and then they probably iterate over the regex data structures. It is a more simple machine than a parser and probably a more light weight approach.
I wrote hand history parser for PokerStars log files https://github.com/malikbakt/pokerstars
You may want to look at: StringScanner.
I have two different pointers for you, which will point you to the solution, on how to write code in the ruby way.
Get a ruby book. The ruby book will have a lot of examples on how to write code in the ruby way. From my personal expirience I can recommend you the pixake(is this spelled right?) book: http://www.ruby-doc.org/docs/ProgrammingRuby/html/index.html
Read existing ruby code. You seem to know enough ruby to write code? Then you should certainly be able to read existing code. I assume you already have installed ruby on your system. If so, you will find plenty of sourcecode on your harddrive. If not just use the internet.
I'd recommend the book Refactoring by Martin Fowler (available in both dead-tree and electronic formats, IIRC). He covers object-oriented remedies for exactly the design problems you're asking about, all in a test-driven context. This is one of those books that everyone in the profession should read.
I am writing a coding standards document for a team of about 15 developers with a project load of between 10 and 15 projects a year. Amongst other sections (which I may post here as I get to them) I am writing a section on code formatting. So to start with, I think it is wise that, for whatever reason, we establish some basic, consistent code formatting/naming standards.
I've looked at roughly 10 projects written over the last 3 years from this team and I'm, obviously, finding a pretty wide range of styles. Contractors come in and out and at times, and sometimes even double the team size.
I am looking for a few suggestions for code formatting and naming standards that have really paid off ... but that can also really be justified. I think consistency and shared-patterns go a long way to making the code more maintainable ... but, are there other things I ought to consider when defining said standards?
How do you lineup parenthesis? Do you follow the same parenthesis guidelines when dealing with classes, methods, try catch blocks, switch statements, if else blocks, etc.
Do you line up fields on a column? Do you notate/prefix private variables with an underscore? Do you follow any naming conventions to make it easier to find particulars in a file? How do you order the members of your class?
What about suggestions for namespaces, packaging or source code folder/organization standards? I tend to start with something like:
<com|org|...>.<company>.<app>.<layer>.<function>.ClassName
I'm curious to see if there are other, more accepted, practices than what I am accustomed to -- before I venture off dictating these standards. Links to standards already published online would be great too -- even though I've done a bit of that already.
First find a automated code-formatter that works with your language. Reason: Whatever the document says, people will inevitably break the rules. It's much easier to run code through a formatter than to nit-pick in a code review.
If you're using a language with an existing standard (e.g. Java, C#), it's easiest to use it, or at least start with it as a first draft. Sun put a lot of thought into their formatting rules; you might as well take advantage of it.
In any case, remember that much research has shown that varying things like brace position and whitespace use has no measurable effect on productivity or understandability or prevalence of bugs. Just having any standard is the key.
Coming from the automotive industry, here's a few style standards used for concrete reasons:
Always used braces in control structures, and place them on separate lines. This eliminates problems with people adding code and including it or not including it mistakenly inside a control structure.
if(...)
{
}
All switches/selects have a default case. The default case logs an error if it's not a valid path.
For the same reason as above, any if...elseif... control structures MUST end with a default else that also logs an error if it's not a valid path. A single if statement does not require this.
In the occasional case where a loop or control structure is intentionally empty, a semicolon is always placed within to indicate that this is intentional.
while(stillwaiting())
{
;
}
Naming standards have very different styles for typedefs, defined constants, module global variables, etc. Variable names include type. You can look at the name and have a good idea of what module it pertains to, its scope, and type. This makes it easy to detect errors related to types, etc.
There are others, but these are the top off my head.
-Adam
I'm going to second Jason's suggestion.
I just completed a standards document for a team of 10-12 that work mostly in perl. The document says to use "perltidy-like indentation for complex data structures." We also provided everyone with example perltidy settings that would clean up their code to meet this standard. It was very clear and very much industry-standard for the language so we had great buyoff on it by the team.
When setting out to write this document, I asked around for some examples of great code in our repository and googled a bit to find other standards documents that smarter architects than I to construct a template. It was tough being concise and pragmatic without crossing into micro-manager territory but very much worth it; having any standard is indeed key.
Hope it works out!
It obviously varies depending on languages and technologies. By the look of your example name space I am going to guess java, in which case http://java.sun.com/docs/codeconv/ is a really good place to start. You might also want to look at something like maven's standard directory structure which will make all your projects look similar.