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  • Why do memory-managed languages retain the `new` keyword?

    - by Channel72
    The new keyword in languages like Java, Javascript, and C# creates a new instance of a class. This syntax seems to have been inherited from C++, where new is used specifically to allocate a new instance of a class on the heap, and return a pointer to the new instance. In C++, this is not the only way to construct an object. You can also construct an object on the stack, without using new - and in fact, this way of constructing objects is much more common in C++. So, coming from a C++ background, the new keyword in languages like Java, Javascript, and C# seemed natural and obvious to me. Then I started to learn Python, which doesn't have the new keyword. In Python, an instance is constructed simply by calling the constructor, like: f = Foo() At first, this seemed a bit off to me, until it occurred to me that there's no reason for Python to have new, because everything is an object so there's no need to disambiguate between various constructor syntaxes. But then I thought - what's really the point of new in Java? Why should we say Object o = new Object();? Why not just Object o = Object();? In C++ there's definitely a need for new, since we need to distinguish between allocating on the heap and allocating on the stack, but in Java all objects are constructed on the heap, so why even have the new keyword? The same question could be asked for Javascript. In C#, which I'm much less familiar with, I think new may have some purpose in terms of distinguishing between object types and value types, but I'm not sure. Regardless, it seems to me that many languages which came after C++ simply "inherited" the new keyword - without really needing it. It's almost like a vestigial keyword. We don't seem to need it for any reason, and yet it's there. Question: Am I correct about this? Or is there some compelling reason that new needs to be in C++-inspired memory-managed languages like Java, Javascript and C#?

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  • Maximum Length Of IP Address: 15 (IPv4) & 39(IPv6)

    - by Gopinath
    Problem You are designing a database table for a web application that requires to store IP address of users who visits the site. The IP address is required to be stored a character data in the table. To define size of the character column you need to know maximum length of IP address. So, what is the maximum length of an IP address? Solution The IPv4 version of IP address is in the following format 255.255.255.255 To store IPv4 address we require 15 characters. The IPv6 version of IP address is grouped into sets of 4 hex digits separated by colons, like the below 2001:0db8:85a3:0000:0000:8a2e:0370:7334 To store IPv6 address you require a 39 characters long column. Conclusion As IPv4 and IPv6 are the commonly use protocols, you better define a column with 39 characters length so that both the format address are saved in to the table without any issues. This article titled,Maximum Length Of IP Address: 15 (IPv4) & 39(IPv6), was originally published at Tech Dreams. Grab our rss feed or fan us on Facebook to get updates from us.

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  • Push-Based Events in a Services Oriented Architecture

    - by Colin Morelli
    I have come to a point, in building a services oriented architecture (on top of Thrift), that I need to expose events and allow listeners. My initial thought was, "create an EventService" to handle publishing and subscribing to events. That EventService can use whatever implementation it desires to actually distribute the events. My client automatically round-robins service requests to available service hosts which are determined using Zookeeper-based service discovery. So, I'd probably use JMS inside of EventService mainly for the purpose of persisting messages (in the event that a service host for EventService goes down before it can distribute the message to all of the available listeners). When I started considering this, I began looking into the differences between Queues and Topics. Topics unfortunately won't work for me, because (at least for now), all listeners must receive the message (even if they were down at the time the event was pushed, or hadn't made a subscription yet because they haven't completed startup (during deployment, for example) - messages should be queued until the service is available). However, I don't want EventService to be responsible for handling all of the events. I don't think it should have the code to react to events inside of it. Each of the services should do what it needs with a given event. This would indicate that each service would need a JMS connection, which questions the value of having EventService at all (as the services could individually publish and subscribe to JMS directly). However, it also couples all of the services to JMS (when I'd rather that there be a single service that's responsible for determining how to distribute events). What I had thought was to publish an event to EventService, which pulls a configuration of listeners from some configuration source (database, flat file, irrelevant for now). It replicates the message and pushes each one back into a queue with information specific to that listener (so, if there are 3 listeners, 1 event would become 3 events in JMS). Then, another thread in EventService (which is replicated, running on multiple hots) would be pulling from the queue, attempting to make the service call to the "listener", and returning the message to the queue (if the service is down), or discarding the message (if the listener completed successfully). tl;dr If I have an EventService that is responsible for receiving events and delegating service calls to "event listeners," (which are really just endpoints on other services), how should it know how to craft the service call? Should I create a generic "Event" object that is shared among all services? Then, the EventService can just construct this object and pass it to the service call. Or is there a better answer to this problem entirely?

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  • Implementing a FSM with ActionScript 2 without using classes?

    - by Up2u
    I have seen several references of A.I. and FSM, but sadly I still can't understand the point of an FSM in AS2.0. Is it a must to create a class for each state? I have a game-project which also it has an A.I., the A.I. has 3 states: distanceCheck, ChaseTarget, and Hit the target. It's an FPS game and played via mouse. I have created the A.I. successfully, but I want to convert it to FSM method... My first state is CheckDistanceState() and in that function I look for the nearest target and trigger the function ChaseState(), there I insert the Hit() function to destroy the enemy, The 3 functions that I created are being called in AI_cursor.onEnterframe. Is there any chance to implement an FSM without the need to create a class? From what I've read before, you have to create a class. I prefer to write the code on frames in flash and I still don't understand how to have external classes.

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  • BDD: Getting started

    - by thom
    I'm starting with BDD and this is my story: Feature: Months and days to days In order to see months and days as days As a date conversion fan I need a webpage where users can enter days and months and convert them to days. I have some doubts ... Should I write my scenarios before coding anything or should I first write a scenario and then write code, write a scenario again and then write code, and so on ... ? If I should write my scenarios before, can my steps be approved and production code still does not get done? When should I do refactoring on my code? After the feature is done or after each scenario implementation?

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  • How do I print values of an array in Three Rows?

    - by Ramkumar
    I need this output.. 1 3 5 2 4 6 I want to use array function like array(1,2,3,4,5,6). If I edit this array like array(1,2,3), it means the output need to show like 1 2 3 The concept is maximum 3 column only. If we give array(1,2,3,4,5), it means the output should be 1 3 5 2 4 Suppose we will give array(1,2,3,4,5,6,7,8,9), then it means output is 1 4 7 2 5 8 3 6 9 that is, maximum 3 column only. Depends upon the the given input, the rows will be created with 3 columns. Is this possible with PHP? I am doing small Research & Development in array functions. I think this is possible. Will you help me? For more info: * input: array(1,2,3,4,5,6,7,8,9,10,11,12,13,14,15) * output: 1 6 11 2 7 12 3 8 13 4 9 14 5 10 15

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  • design a model for a system of dependent variables

    - by dbaseman
    I'm dealing with a modeling system (financial) that has dozens of variables. Some of the variables are independent, and function as inputs to the system; most of them are calculated from other variables (independent and calculated) in the system. What I'm looking for is a clean, elegant way to: define the function of each dependent variable in the system trigger a re-calculation, whenever a variable changes, of the variables that depend on it A naive way to do this would be to write a single class that implements INotifyPropertyChanged, and uses a massive case statement that lists out all the variable names x1, x2, ... xn on which others depend, and, whenever a variable xi changes, triggers a recalculation of each of that variable's dependencies. I feel that this naive approach is flawed, and that there must be a cleaner way. I started down the path of defining a CalculationManager<TModel> class, which would be used (in a simple example) something like as follows: public class Model : INotifyPropertyChanged { private CalculationManager<Model> _calculationManager = new CalculationManager<Model>(); // each setter triggers a "PropertyChanged" event public double? Height { get; set; } public double? Weight { get; set; } public double? BMI { get; set; } public Model() { _calculationManager.DefineDependency<double?>( forProperty: model => model.BMI, usingCalculation: (height, weight) => weight / Math.Pow(height, 2), withInputs: model => model.Height, model.Weight); } // INotifyPropertyChanged implementation here } I won't reproduce CalculationManager<TModel> here, but the basic idea is that it sets up a dependency map, listens for PropertyChanged events, and updates dependent properties as needed. I still feel that I'm missing something major here, and that this isn't the right approach: the (mis)use of INotifyPropertyChanged seems to me like a code smell the withInputs parameter is defined as params Expression<Func<TModel, T>>[] args, which means that the argument list of usingCalculation is not checked at compile time the argument list (weight, height) is redundantly defined in both usingCalculation and withInputs I am sure that this kind of system of dependent variables must be common in computational mathematics, physics, finance, and other fields. Does someone know of an established set of ideas that deal with what I'm grasping at here? Would this be a suitable application for a functional language like F#? Edit More context: The model currently exists in an Excel spreadsheet, and is being migrated to a C# application. It is run on-demand, and the variables can be modified by the user from the application's UI. Its purpose is to retrieve variables that the business is interested in, given current inputs from the markets, and model parameters set by the business.

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  • How should bots be recognised in a game?

    - by Bane
    I'm interested in how bots are usually written. Here's my situation: I plan to make an online 2D mecha game in HTML5, and the server-side will be done with node. It is intended to be multiplayer, but I also want to make bots in case there aren't enough players. How does my game logic see them, as players or as bots? Is there a standard by which I should make them? Also, any general tips and hints will be OK.

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  • What is So Unique About Node.js?

    - by Adrian Shum
    Recently there has been a lot of praise for Node.js. I am not a developer that has had much exposure to network application. From my bare understanding of Nodes.js, its strength is: we have only one thread handling multiple connections, providing an event-based architecture. However, for example in Java, I can create only one thread using NIO/AIO (which is non-blocking APIs from my bare understanding), and handle multiple connections using that thread, and I provide an event-based architecture to implement the data handling logic (shouldn't be that difficult by providing some callback etc) ? Given JVM being a even more mature VM than V8 (I expect it to run faster too), and event-based handling architecture seems to be something not difficult to create, I am not sure why Node.js is attracting so much attention. Did I miss some important points?

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  • Attributes of an Ethical Programmer?

    - by ahmed
    Software that we write has ramifications in the real world. If not, it wouldn't be very useful. Thus, it has the potential to sweep across the world faster than a deadly manmade virus or to affect society every bit as much as genetic manipulation. Maybe we can't see how right now, but in the future our code will have ever-greater potential for harm or good. Of course, there's the issue of hacking. That's clearly a crime. Or is it that clear? Isn't hacking acceptable for our government in the event of national security? What about for other governments? Cases of life-and-death emergency? Tracking down deadbeat parents? Screening the genetic profile of job candidates? Where is the line drawn? Who decides? Do programmers have responsibility for how their code is used? What if a programmer writes code to pry into confidential information or copy-protected material? Does he bear responsibility along with the person who used the program? What about a programmer who knowingly or unknowingly writes code to "fix the books?" Should he be liable?

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  • What to use C++ for?

    - by futlib
    I really love C++. However, I'm struggling to find good uses for it lately. It is still the language to use if you're building huge systems with huge performance requirements. Like backend/infrastructure code at Google and Facebook, or high-end games. But I don't get to do stuff like that. It's also a good choice for code that runs close to the hardware. I'd like to do more low-level stuff, but it isn't part of my job, and I can't think of useful private projects that would involve that. Traditionally, C++ was also a good choice for rich client applications, but those are mostly written in C# and Obj-C lately - and aren't really that important anymore, with everything being a web app. Or a mobile app, which are mostly written in Obj-C and Java. And of course, web-based desktop and mobile apps are quite prominent, too. At my job, I work mostly on web applications, using Java, JavaScript and Groovy. Java is a good/popular choice for non-Google-scale backends, Groovy (or Python, or Ruby or Node.js) is pretty good for the server-side of web apps and JavaScript is the only real choice for the client-side. Even the little games I'm writing in my spare time are lately mostly written in JavaScript, so they can run in the browser. So what would you suggest I could use C++ for? I'm aware that this question is very similar. However, I don't want to learn C++, I was a professional C++ programmer for years. I want to keep doing it and find good new use cases for it. I know that I can use C++ for web apps/games. I could even compile C++ to JavaScript with Emscripten. However, it doesn't seem like a good idea. I'm looking for something C++ is really good at to stay competent in the language. If your answer is: Just give up and forget C++, you'll probably never need it again, so be it.

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  • What is the meaning of 'high cohesion'?

    - by Max
    I am a student who recently joined a software development company as an intern. Back at the university, one of my professors used to say that we have to strive to achieve "Low coupling and high cohesion". I understand the meaning of low coupling. It means to keep the code of separate components separately, so that a change in one place does not break the code in another. But what is meant by high cohesion. If it means integrating the various pieces of the same component well with each other, I dont understand how that becomes advantageous. What is meant by high cohesion? Can an example be explained to understand its benefits?

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  • Which is a better practice - helper methods as instance or static?

    - by Ilian Pinzon
    This question is subjective but I was just curious how most programmers approach this. The sample below is in pseudo-C# but this should apply to Java, C++, and other OOP languages as well. Anyway, when writing helper methods in my classes, I tend to declare them as static and just pass the fields if the helper method needs them. For example, given the code below, I prefer to use Method Call #2. class Foo { Bar _bar; public void DoSomethingWithBar() { // Method Call #1. DoSomethingWithBarImpl(); // Method Call #2. DoSomethingWithBarImpl(_bar); } private void DoSomethingWithBarImpl() { _bar.DoSomething(); } private static void DoSomethingWithBarImpl(Bar bar) { bar.DoSomething(); } } My reason for doing this is that it makes it clear (to my eyes at least) that the helper method has a possible side-effect on other objects - even without reading its implementation. I find that I can quickly grok methods that use this practice and thus help me in debugging things. Which do you prefer to do in your own code and what are your reasons for doing so?

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  • Where can I find game postmortems with a programmer perspective [on hold]

    - by Ken
    There are a number of interesting game post-mortems in places like GDC vault or gamastura.com. The post-mortems are generally give with a CEO/manager perspective or a designer perspective, or, more often a combination of both e.g DOOM postmortem But I have not been able to find many post-mortems which are primarily from the programmers perspective. I'm looking for discussions and rational for technical choices and tradeoffs and how technical problems were overcome. The motivation here is to learn what kind of problems real game programmers encounter and how they go about solving them. A perfect example of what I'm looking for is Renaud Bédard's excellent GDC talk on the development of Fez, "Cubes all the way down". Where can I find more like that?

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  • How can I optimize my development machines files/dirs?

    - by LuxuryMode
    Like any programmer, I've got a lot of stuff on my machine. Some of that stuff is projects of my own, some are projects I'm working on for my employer, others are open-source tools and projects, etc. Currently, I have my files organized as follows: /Code --/development (things I'm sort of hacking on plus maybe libraries used in other projects) --/scala (organized by language...why? I don't know!) --/android --/ruby --/employer_name -- /mobile --/android --/ios --/open-source (basically my forks that I'm pushing commits back upstream from) --/some-awesome-oss-project --/another-awesome-one --/tools random IDE settings sprinkled in here plus some other apps As you can see, things are kind of a mess here. How can I keep things organized in some sort of coherent fashion?

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  • What is the philosophy/reasoning behind C#'s Pascal-casing method names?

    - by Nocturne
    I'm just starting to learn C#. Coming from a background in Java, C++ and Objective-C, I find C#'s Pascal-casing its method-names rather unique, and a tad difficult to get used to at first. What is the reasoning and philosophy behind this? I'm guessing it is because of C# properties. Unlike in Objective-C, where method names can be exactly the same as an instance variables, this is not the case with C#. I would guess one of the goals with properties (as it is with most of the languages that support it) is to make properties truly indistinguishable from variables and methods. So, one can have an "int x" in C#, and the corresponding property becomes X. To ensure that properties and methods are indistinguishable, all method names I'm guessing are also therefore expected to start with an uppercase letter. (This is just my hypothesis based on what I know of C# so far—I'm still learning). I'm very curious to know how this curious guideline came into being (given that it's not something one sees in most other languages where method names are expected to start with a lowercase letter) (EDIT: By Pascal-casing, I mean PascalCase (which is basically camelCase but starting with a capital letter). Method names typically start with a lowercase letter in most languages)

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  • I want to be a programmer! [closed]

    - by Mohamed Abd El Maged
    I am a doctor. I have a bachelor of medicine and general surgery. I want to change my career and work as a programmer in big companies such as Microsoft, Oracle, ... this is my dream ! I haven't got any degree in IT or Computer science. The question here is: Is it possible to achieve my dream and work as professional programmer in the future? Another question: if applicable, which certifications should I strive to get?

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  • Is 2 lines of push/pop code for each pre-draw-state too many?

    - by Griffin
    I'm trying to simplify vector graphics management in XNA; currently by incorporating state preservation. 2X lines of push/pop code for X states feels like too many, and it just feels wrong to have 2 lines of code that look identical except for one being push() and the other being pop(). The goal is to eradicate this repetitiveness,and I hoped to do so by creating an interface in which a client can give class/struct refs in which he wants restored after the rendering calls. Also note that many beginner-programmers will be using this, so forcing lambda expressions or other advanced C# features to be used in client code is not a good idea. I attempted to accomplish my goal by using Daniel Earwicker's Ptr class: public class Ptr<T> { Func<T> getter; Action<T> setter; public Ptr(Func<T> g, Action<T> s) { getter = g; setter = s; } public T Deref { get { return getter(); } set { setter(value); } } } an extension method: //doesn't work for structs since this is just syntatic sugar public static Ptr<T> GetPtr <T> (this T obj) { return new Ptr<T>( ()=> obj, v=> obj=v ); } and a Push Function: //returns a Pop Action for later calling public static Action Push <T> (ref T structure) where T: struct { T pushedValue = structure; //copies the struct data Ptr<T> p = structure.GetPtr(); return new Action( ()=> {p.Deref = pushedValue;} ); } However this doesn't work as stated in the code. How might I accomplish my goal? Example of code to be refactored: protected override void RenderLocally (GraphicsDevice device) { if (!(bool)isCompiled) {Compile();} //TODO: make sure state settings don't implicitly delete any buffers/resources RasterizerState oldRasterState = device.RasterizerState; DepthFormat oldFormat = device.PresentationParameters.DepthStencilFormat; DepthStencilState oldBufferState = device.DepthStencilState; { //Rendering code } device.RasterizerState = oldRasterState; device.DepthStencilState = oldBufferState; device.PresentationParameters.DepthStencilFormat = oldFormat; }

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  • Is there a Source Insight alternative?

    - by hansioux
    I am not a developer, but for my work I trace a lot of codes. It is actually rather difficult reading other people's code, especially for bigger projects. Source Insight is a great application that stores all the symbols in a data base, so you can see a new function being called, click on it and see how the function is written. You can see all the referrer of a object or jump to a caller. You don't need to break the train of thought and think up shell commands just to find these things every time you ran into a new variable/structure/function from some other files. I have it running on WINE, but there are little glitches that sometimes gets in the way. I know people will mention C-scope, I've tried it, but it really isn't the same. So, with so many huge open source projects out there for Ubuntu, are there native tools to help read them efficiently? EDIT: Thanks for the suggestions, but does CODE::BLOCKS or CodeLite provide abilities to see the function that the mouse clicked on without jumping to it, so I can see the caller and callee at the same time?

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  • graphical interface when using assembly language

    - by Hellbent
    Im looking to use assembly language to make a great game, not just an average game but a really great game. I want to learn a framework to use in assembly. I know thats not possible without learning the framework in c first. So im thinking of learning sdl in c and then learn, teach myself, how to interpret the program and run it as assembly language code which shouldnt be that hard. Then i will have a window and some graphics routines to display the game while using assembly to code everything in. I need to spend some time learning sdl and then some more time learning how to code all those statements using assembly while calling c functions and knowing what registers returned calls use and what they leave etc. My question is , Is this a good way to go or is there something better to get a graphical window display using assembly language? Regards HellBent

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  • undefined control sequence in a NOWEB document

    - by Jean Baldraque
    I'm writing a TeX-noweb document. I compile it with noweave -tex -filter "elide comment:*" texcode.nw > documentation.tex but when I try to compile the resulting file with xetex -halt-on-error documentation.tex I obtain the following error message ! Undefined control sequence. <argument> ...on}\endmoddef \nwstartdeflinemarkup \nwenddeflinemarkup It seems that \nwenddeflinemarkup is not recognized. If i delete from the document all the sequences \nwstartdeflinemarkup\nwenddeflinemarkup the document compile without exceptions. What can be the problem?

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  • Generalise variable usage inside code

    - by Shirish11
    I would like to know if it is a good practice to generalize variables (use single variable to store all the values). Consider simple example Strings querycre,queryins,queryup,querydel; querycre = 'Create table XYZ ...'; execute querycre ; queryins = 'Insert into XYZ ...'; execute queryins ; queryup = 'Update XYZ set ...'; execute queryup; querydel = 'Delete from XYZ ...'; execute querydel ; and Strings query; query= 'Create table XYZ ... '; execute query ; query= 'Insert into XYZ ...'; execute query ; query= 'Update XYZ set ...'; execute query ; query= 'Delete from XYZ ...'; execute query ; In first case I use 4 strings each storing data to perform the actions mentioned in their suffixes. In second case just 1 variable to store all kinds the data. Having different variables makes it easier for someone else to read and understand it better. But having too many of them makes it difficult to manage. Also does having too many variables hamper my performance?

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  • Is there a point to writing in C or C++ instead of C# without knowing specifically what would make a program faster?

    - by user828584
    I wrote a small library in Python for handling the xbox 360's STFS files to be used on my web applications. I would like to rewrite it for use in the many desktop programs people are writing for 360 game modding, but I'm not quite if I should continue using C# or delve into C++ or even C. STFS is an in-file file system used by the xbox 360 and the job of the library would be extracting/injecting files, which could take noticeable amounts of time to do. What I know in C# comes from internet tutorials and resources, as would anything I learn about C++, so what I'm asking is if it's better to bring myself to a slightly lower-level language without knowing beforehand the features of the language that increase performance, or continue assuming that compiler optimizations and that my lack of experience will mean that the language I choose won't matter.

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  • How can i manage my personal notes , code snippets files in one place online [closed]

    - by user1758043
    Whenever i work on any project , then i have so much notes , diagrams files , image s, brainstorming ideas which i want to keep. i want to put them in one place so that i can see the history of my work. Is there any toll whichere i can store this online. my company is using confluence but thats costly for me. I want something for single user but online in clou where i can store Notes Code snippets Diagrams , flowchart Attah files , images Books marks , sites

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  • Defining formula through user interface in user form

    - by BriskLabs Pakistan
    I am a student and developing a simple assignment - windows form application in visual studio 2010. The application is suppose to construct formulas as per user requirement. The process: It has to pick data from columns of Microsoft Access database and the user should be able to pick the data by column name like we do in a drop down menu. and create reusable formulas in it ( configure it once and can change it again). followings are column titles from database that can be picked for example. e.g Col -1 : Marks in Maths Col -2 : Total Marks in Maths Col -3 : Marks in science Col -4 : Total marks in science Finally we should be able to construct any formula in the UI like (Col 1 + Col 3 ) / ( col 2 + col 4) = Formula 1 once this is formula is set saved and a name is assigned to it by user. he/she can use the formula and results shall appear in a window below. i.e He would be able to calculate his desired figures (formula) by only manipulating underlying data on the UI layer....choose the data for a period and apply the formula and get the answer Problem: It looks like I have to create an app where rules are set through UI....... this means no stored procedures are required in SQL.... please suggest the right approach.

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