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• Dynamic Query Generation : suggestion for better approaches

  - by Gaurav Parmar

  I am currently designing a functionality in my Web Application where the verified user of the application can execute queries which he wishes to from the predefined set of queries with where clause varying as per user's choice. For example,Table ABC contains the following Template query called SecretReport "Select def as FOO, ghi as BAR from MNO where " SecretReport can have parameters XYZ, ILP. Again XYZ can have values as 1,2 and ILP can have 3,4 so if the user chooses ILP=3, he will get the result of the following query on his screen "Select def as FOO, ghi as BAR from MNO where ILP=3" Again the user is allowed permutations of XYZ / ILP My initial thought is that User will be shown a list of Report names and each report will have parameters and corresponding values. But this approach although technically simple does not appear intuitive. I would like to extend this functionality to a more generic level. Such that the user can choose a table and query based on his requirements. Of course we do not want the end user to take complete control of DB. But only tables and fields that are relevant to him. At present we are defining what is relevant in the code. But I want the Admin to take over this functionality such that he can decide what is relevant and expose the same to the user. On user's side it should be intuitive what is available to him and what queries he can form. Please share your thoughts what is the most user friendly way to provide this feature to the end user.

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• Have you worked with a well designed application?

  - by Vilx-

  Inspired by this question, I started wondering - is there or has there ever been such a thing as a "well designed application"? One where the architecture would be perfect and no refactoring would ever be needed; code would be easy to read and understand even for someone new to the project; changes could be done with a 100% certainty that they won't break anything; etc? I must admit that whatever codebases I've worked with, they've all been more or less a mess. Even code that I start myself only stays organized at the start, and then slowly deteriorates as the time passes. I'm even starting to accept this as part of life and can't figure out whether I should be worried about that or not. So... is there such a thing as a "well designed application"? Or is all our code so shitty that there isn't even a point in trying to make it better, because it will never be good anyway?

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• Directx vs XNA - Which is better for me? [closed]

  - by tristo

  Recently I got Visual Studio 2012 from visual studio 2010, although did not expect Visual Studio to 2012 to designed the way it was. Anyway I am pleased with some of VS 2012 technology and have moved all of my projects to it. At this point of time since I got VS 2012 I have been into making windows applications and other non-game activities. ALTHOUGH have recently gotten into the spirit of game development and I am planning to make a 3d comical game, shader effects, not too complicated meshes, but it requires alot of lighting effects to emphasise certain parts of the game. When I was using VS 2010 I had a great time making 2d games with XNA, it uses a great language, and has a very awesome system. But I no longer have XNA with me, and the workarounds described in stackoverflow always gives me errors while using xna. Anyway it seems that microsoft have stuffed themselves up with xna anyway with the weirdness of Windows 8, and it being only avaliabe on pc and xbox. Due to these reasons I have decided to work with Directx and Direct3d to produce my new game, although the overflowing credits after each directx game gives me the shivers, and the low-level coding of directx also puts me on thin ice with my games, left in a confusional mess with what decision I should make. I don't know anything about directx or direct3d. I am an indie developer, but I am planning to take on alot of professional aspects of games. I don't have heaps of time(2-3 hours a day) I don't mind the complexity of how directx works, as long as I can learn how to make the fundementals of a game in a week. I am also unsure if directx is really for my situation, and keep with xna game development. Anyone can tell me the best technology for me would be great.

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• Finding the displacment of a robot [closed]

  - by Jordan Brown

  I'm building a quadruped (4 legs 3 DOF) for my major work in electronics at high school. I need to know the displacement of the robot and I can't use an encoding wheel. I've done my research and I found a system where I use an accelerometer, gyroscope and a magnetometer to determine the displacement but I'm not sure how to code it. I'm using Arduino and will use compatible sensors. I would like to be able to implement something similar to this video which demonstrates the principles evaluated in this paper. I don't need to map the data on a screen, just be able to read its displacement from its last recorded position. EG. (Read Position) --- (Do "stuff") --- (Read Position) --- (Calculate displacement caused by "stuff")

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• Can the Abstract Factory pattern be considered as a case of polymorphism?

  - by rogcg

  I was looking for a pattern/solution that allows me call a method as a runtime exception in a group of different methods without using Reflection. I've recently become aware of the Abstract Factory Pattern. To me, it looks so much like polymorphism, and I thought it could be a case of polymorphism but without the super class WidgetFactory, as you can see in the example of the link above. Am I correct in this assumption?

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• Styling specific columns and rows

  - by hattenn

  I'm trying to style some specific parts of a 5x4 table that I create. It should be like this: Every even numbered row and every odd numbered row should get a different color. Text in the second, third, and fourth columns should be centered. I have this table: <table> <caption>Some caption</caption> <colgroup> <col> <col class="value"> <col class="value"> <col class="value"> </colgroup> <thead> <tr> <th id="year">Year</th> <th>1999</th> <th>2000</th> <th>2001</th> </tr> </thead> <tbody> <tr class="oddLine"> <td>Berlin</td> <td>3,3</td> <td>1,9</td> <td>2,3</td> </tr> <tr class="evenLine"> <td>Hamburg</td> <td>1,5</td> <td>1,3</td> <td>2,0</td> </tr> <tr class="oddLine"> <td>München</td> <td>0,6</td> <td>1,1</td> <td>1,0</td> </tr> <tr class="evenLine"> <td>Frankfurt</td> <td>1,3</td> <td>1,6</td> <td>1,9</td> </tr> </tbody> <tfoot> <tr class="oddLine"> <td>Total</td> <td>6,7</td> <td>5,9</td> <td>7,2</td> </tr> </tfoot> </table> And I have this CSS file: table, th, td { border: 1px solid black; border-collapse: collapse; padding: 0px 5px; } #year { text-align: left; } .oddLine { background-color: #DDDDDD; } .evenLine { background-color: #BBBBBB; } .value { text-align: center; } And this doesn't work. The text in the columns are not centered. What is the problem here? And is there a way to solve it (other than changing the class of all the cells that I want centered)? P.S.: I think there's some interference with .evenLine and .oddLine classes. Because when I put "background: black" in the class "value", it changes the background color of the columns in the first row. The thing is, if I delete those two classes, text-align still doesn't work, but background attribute works perfectly. Argh...

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• Extension objects pattern

  - by voroninp

  In this MSDN Magazine article Peter Vogel describes Extension Objects partten. What is not clear is whether extensions can be later implemented by client code residing in a separate assembly. And if so how in this case can extension get acces to private members of the objet being extended? I quite often need to set different access levels for different classes. Sometimes I really need that descendants does not have access to the mebmer but separate class does. (good old friend classes) Now I solve this in C# by exposing callback properties in interface of the external class and setting them with private methods. This also alows to adjust access: read only or read|write depending on the desired interface. class Parent { private int foo; public void AcceptExternal(IFoo external) { external.GetFooCallback = () => this.foo; } } interface IFoo { Func<int> GetFooCallback {get;set;} } Other way is to explicitly implement particular interface. But I suspect more aspproaches exist.

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• How to control messages to the same port from different emitters?

  - by Alex In Paris

  Scene: A company has many factories X, each emits a message to the same receive port in a Biztalk server Y; if all messages are processed without much delay, each will trigger an outgoing message to another system Z. Problem: Sometimes a factory loses its connection for a half-day or more and, when the connection is reestablished, thousands of messages get emitted. Now, the messages still get processed well by Y (Biztalk can easily handle the load) but system Z can't handle the flood and may lock up and severely delay the processing of all other messages from the other X. What is the solution? Creating multiple receive locations that permits us to pause one X or another would lose us information if the factory isn't smart enough to know whether the message was received or not. What is the basic pattern to apply in Biztalk for this problem? Would some throttling parameters help to limit the flow from any one X? Or are their techniques on the end part of Y which I should use instead ? I would prefer this last one since I can be confident that the message box will remember any failures, which could then be resumed.

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• Structuring Access Control In Hierarchical Object Graph

  - by SB2055

  I have a Folder entity that can be Moderated by users. Folders can contain other folders. So I may have a structure like this: Folder 1 Folder 2 Folder 3 Folder 4 I have to decide how to implement Moderation for this entity. I've come up with two options: Option 1 When the user is given moderation privileges to Folder 1, define a moderator relationship between Folder 1 and User 1. No other relationships are added to the db. To determine if the user can moderate Folder 3, I check and see if User 1 is the moderator of any parent folders. This seems to alleviate some of the complexity of handling updates / moved entities / additions under Folder 1 after the relationship has been defined, and reverting the relationship means I only have to deal with one entity. Option 2 When the user is given moderation privileges to Folder 1, define a new relationship between User 1 and Folder 1, and all child entities down to the grandest of grandchildren when the relationship is created, and if it's ever removed, iterate back down the graph to remove the relationship. If I add something under Folder 2 after this relationship has been made, I just copy all Moderators into the new Entity. But when I need to show only the top-level Folders that a user is Moderating, I need to query all folders that have a parent folder that the user does not moderate, as opposed to option 1, where I just query any items that the user is moderating. Thoughts I think it comes down to determining if users will be querying for all parent items more than they'll be querying child items... if so, then option 1 seems better. But I'm not sure. Is either approach better than the other? Why? Or is there another approach that's better than both? I'm using Entity Framework in case it matters.

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• Would it be possible to build a client portal on Squarespace6?

  - by aBathologist

  I'm helping a family member set up a site which will need to include a secure client portal, providing access to documents and a simple database. I have been encouraging them to go with a more established, open source CSM like drupal or joomla, whose capability in this area is evident. However, they have a strong preference for Squarespace. Does any one know if it would be possible to accomplish this with the new developer platform for squarespace 6? I've spent well over an hour searching google, the squarespace site and stackexchange, but can't seem to find any clear answer to this question. I'm grateful for any insight you all can provide.

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• Anemic Domain Model, Business Logic and DataMapper (PHP)

  - by sunwukung

  I've implemented a rudimentary ORM layer based on DataMapper (I don't want to use a full blown ORM like Propel/Doctrine - for anything beyond simple fetch/save ops I prefer to access the data directly layer using a SQL abstraction layer). Following the DataMapper pattern, I've endeavoured to keep all persistence operations in the Mapper - including the location of related entities. My Entities have access to their Mapper, although I try not to call Mapper logic from the Entity interface (although this would be simple enough). The result is: // get a mapper and produce an entity $ProductMapper = $di->get('product_mapper'); $Product = $ProductMapper->find('[email protected]','email'); //.. mutaute some values.. save $ProductMapper->save($Product) // uses __get to trigger relation acquisition $Manufacturer = $Product->manufacturer; I've read some articles regarding the concept of an Anemic Domain model, i.e. a Model that does not contain any "business logic". When demonstrating the sort of business logic ideally suited to a Domain Model, however, acquiring related data items is a common example. Therefore I wanted to ask this question: Is persistence logic appropriate in Domain Model objects?

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• How to run around another football player

  - by Lumis

  I have finished a simple 2D one-on-one indoor football Android game. The thing that it seemed so simple to me, a human being, turned out to be difficult for a computer: how to go around the opponent … At the moment the game logic of the computer player is that if it hits into the human player will step back few points on the pixel greed and then try again to go towards the ball. The problem is if the human player is in-between then the computer player will oscillate in one place, which does not look very nice and the human opponent can use this weakness to control the game. You can see this in the photo – at the moment the computer will go along the red line indefinitely. I tried few ideas but it proved not easy to do it when both the human player and the ball are constantly moving so at each step computer would change directions and “oscillate” again. Once when the computer player reaches the ball it will kick it with certain amount of random strength and direction towards the human’s goal. The question here is how to formulate the logic of going around the ever moving human opponent and how to translate it into the co-ordinate system and frame by frame animation… any suggestions welcome.

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• Good university for computer science with plans for Game Dev.

  - by DukeYore

  I am starting my Computer science degree at a local community college in Programming using C++. However, i will be transferring to a 4-year university. Does anyone have any insight on university programs? I know Cal State Fullerton has a degree with a minor in Game Dev. however, is that as important as getting a degree from a really great school? if i could shoot for something like Cal Poly would that be better? Or even Stanford or SF state being so close to so many gaming companies up there in the bay area? thank you in advance for any guidance.

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• share distribution question

  - by facebook-100000781341887

  Hi, I just developed a facebook game(mifia like), but the graphic I make is not good, because it is reference with some existing photo, trace with AI, and coloring it. Therefore, I invite my friend to join me, he is a graphic designer, own a company with his friend (I know both of them), for the share, I expect at least 70% for me, and at most 30% for them (both of them want to join). Therefore, they give me a counter offer, 60% for me and 40% for them, of course, I feel their counter offer is unacceptable because they only build the image in part time, and all the other work just like coding, webhosting...etc, is what I do in full time. Why they said they worth 40% is that they will make a good graphic, they can provide a advertise channel(on local magazine), etc... Actually, I don't think the game need advertisement on local magazine because the game is not target for local... Please give me some comments on this issue(is the share fair? what is the importance of the image of the game, is it worth more than 30%), or can anyone share the experience on this. Thanks in advance.

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• Combinatorial explosion of interfaces: How many is too many?

  - by mga

  I'm a relative newcomer to OOP, and I'm having a bit of trouble creating good designs when it comes to interfaces. Consider a class A with N public methods. There are a number of other classes, B, C, ..., each of which interacts with A in a different way, that is, accesses some subset (<= N) of A's methods. The maximum degree of encapsulation is achieved by implementing an interface of A for each other class, i.e. AInterfaceForB, AInterfaceForC, etc. However, if B, C, ... etc. also interact with A and with each other, then there will be a combinatorial explosion of interfaces (a maximum of n(n-1), to be precise), and the benefit of encapsulation becomes outweighed by a code-bloat. What is the best practice in this scenario? Is the whole idea of restricting access to a class's public functions in different ways for other different classes just silly altogether? One could imagine a language that explicitly allows for this sort of encapsulation (e.g. instead of declaring a function public, one could specify exactly which classes it is visible to); Since this is not a feature of C++, maybe it's misguided to try to do it through the back door with interaces?

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• Why is x=x++ undefined?

  - by ugoren

  It's undefined because the it modifies x twice between sequence points. The standard says it's undefined, therefore it's undefined. That much I know. But why? My understanding is that forbidding this allows compilers to optimize better. This could have made sense when C was invented, but now seems like a weak argument. If we were to reinvent C today, would we do it this way, or can it be done better? Or maybe there's a deeper problem, that makes it hard to define consistent rules for such expressions, so it's best to forbid them? So suppose we were to reinvent C today. I'd like to suggest simple rules for expressions such as x=x++, which seem to me to work better than the existing rules. I'd like to get your opinion on the suggested rules compared to the existing ones, or other suggestions. Suggested Rules: Between sequence points, order of evaluation is unspecified. Side effects take place immediately. There's no undefined behavior involved. Expressions evaluate to this value or that, but surely won't format your hard disk (strangely, I've never seen an implementation where x=x++ formats the hard disk). Example Expressions x=x++ - Well defined, doesn't change x. First, x is incremented (immediately when x++ is evaluated), then it's old value is stored in x. x++ + ++x - Increments x twice, evaluates to 2*x+2. Though either side may be evaluated first, the result is either x + (x+2) (left side first) or (x+1) + (x+1) (right side first). x = x + (x=3) - Unspecified, x set to either x+3 or 6. If the right side is evaluated first, it's x+3. It's also possible that x=3 is evaluated first, so it's 3+3. In either case, the x=3 assignment happens immediately when x=3 is evaluated, so the value stored is overwritten by the other assignment. x+=(x=3) - Well defined, sets x to 6. You could argue that this is just shorthand for the expression above. But I'd say that += must be executed after x=3, and not in two parts (read x, evaluate x=3, add and store new value). What's the Advantage? Some comments raised this good point. It's not that I'm after the pleasure of using x=x++ in my code. It's a strange and misleading expression. What I want is to be able to understand complicated expressions. Normally, a complicated expression is no more than the sum of its parts. If you understand the parts and the operators combining them, you can understand the whole. C's current behavior seems to deviate from this principle. One assignment plus another assignment suddenly doesn't make two assignments. Today, when I look at x=x++, I can't say what it does. With my suggested rules, I can, by simply examining its components and their relations.

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• Why is facebook cache buggy?

  - by IAdapter

  I just started using facebook and I see that many times when I add something to my profile and visit it later its not there. I bet the reason is that the page is cached and not updated very often. Is this on purpose or is it a bug? P.S. For example I added the music I like and later I see that I did not add it, but next day when I visit again its there. I saw it in two web-browsers, so its a facebook bug. Does it has something to do with scalability?

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• How do you prevent inflation in a virtual economy?

  - by Tetrad

  With your typical MMORPG, players can usually farm the world for raw materials essentially forever. Monsters/mineral veins/etc are usually on some sort of respawn timer, so other than time there really isn't a good way to limit the amount of new currency entering the system. That really only leaves money sinks to try to take money out of the system. What are some strategies to prevent inflation of the in-game currency?

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• Tester/Doer pattern: Assume the caller conforms to the pattern or be defensive and repeat the check?

  - by Daniel Hilgarth

  Assume a simple class that implements the Tester/Doer pattern: public class FooCommandHandler : ICommandHandler { public bool CanHandle(object command) { return command is FooCommand; } public void Handle(object command) { var fooCommand = (FooCommand)command; // Do something with fooCommand } } Now, if someone doesn't conform to the pattern and calls Handle without verifying the command via CanHandle, the code in Handle throws an exception. However, depending on the actual implementation of Handle this can be a whole range of different exceptions. The following implementation would check CanHandle again in Handle and throw a descriptive exception: public void Handle(object command) { if(!CanHandle(command)) throw new TesterDoerPatternUsageViolationException("Please call CanHandle first"); // actual implementation of handling the command. } This has the advantage that the exception is very descriptive. It has the disadvantage that CanHandle is called twice for "good" clients. Is there a consensus on which variation should be used?

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• User input and Automated input seperation

  - by tpaksu

  I have a mysql db and I have an automation script which modifies the data inside once a day. And, these columns may have changed by an user manually. What is the best approach to make the system only update the automated data, not the manually edited ones? I mean yes, flagging the cell which is manually edited is one way to do it, but I want to know if there's another way to accomplish this? Just curiosity.

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• Is my project a web site or a mobile app?

  - by Evik James

  I am a web developer. I have been developing web sites professionally for 15+ years using ColdFusion, SQL Server, and jQuery. I am doing a project for a client that uses the above technologies. The site has a mobile facet too. For that, I am using jQuery Mobile. The site enables retail store personnel to gather a store customer's preferences using any smart phone or tablet. The store personnel just needs to access a special link via a QR code and a login. Anyone can easily access the site from a PC's browser, too. Some sources suggest that mobile apps must be downloaded and installed using a third party, such as from Google, Amazon, or Apple. Others sources suggest that any information designed for use on mobile device is a mobile app. Regarding the site that is specifically designed for use by mobile devices that extensively uses jQuery Mobile, is this a "web site" or a "mobile app"? What is the "proper" description for this type of site? My customer insists that it is one and not the other. I insist that it is the other and not the one. Can you help me clarify this?

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• Collision Systems Implementation

  - by hrr4

  Just curious what might be a good way to implement a decent collision system. As a class inherited by a base Entity class? Currently I'm stuck and could just use a couple better ideas than my own. Any help is appreciated! Edit: Sorry, it's 2D Collisioning but honestly, I'm not looking for specific collision methods. I'm looking more about the lines of implementation. Just curious of some of the common methods of how to implement collision systems such as: Should the entire collision system be it's own class? What, if anything, should be inheritable? These are some of my questions. Sorry for the confusion.

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• MVC pattern synchronisation

  - by Hariprasad

  I am facing a problem in synchronizing my model and view threads I have a view which is table. In it, user can select a few rows. I update the view as soon as the user clicks on any row since I don't want the UI to be slow. This updating is done by a logic which runs in the controller thread below. At the same time, the controller will update the model data too, which takes place in a different thread. i.e., controller puts the query in a queue, which is then executed by the model thread - which is a single-threaded interface. As soon as the query executes, controller will get a signal. Now, In order to keep the view and model synchronized, I will update the view again based on the return value of the query (the data returned by model) - even though I updated the view already for that user action. But, I am facing issues because, its taking a lot of time for the model to return the result, by that time user would have performed multiple clicks. So, as a result of updating the view again based on the information from model, the view sometimes goes back to the state in which the previous clicks were made (Suppose user clicks thrice on different rows. I update the view as soon as the click happens. Also, I update the view when I get data back from the model - which is supposed to be same as the already updated state of the view. Now, when the user clicks third time, I get data for the first click from model. As a result, view goes back to a state which is generated by the first click) Is there any way to handle such a synchronization issue?

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• Avoiding null in a controller

  - by Kevin Burke

  I'm trying to work through how to write this code. def get(params): """ Fetch a user's details, or 404 """ user = User.fetch_by_id(params['id']) if not user: abort(404) # Render some template for the user... What's the best way to handle the case where the lookup fails? One principle says you should avoid returning null values from functions. These lead to mistakes and AttributeErrors etc. later on in the file. Another idea is to have fetch_by_id raise a ValueError or similar if no user exists with that id. However there's a general principle that you shouldn't use exceptions for control flow, either, which doesn't help much. What could be done better in this case?

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• How do I break down and plan a personal programming project?

  - by Pureferret

  I've just started a programming job where I'm applying my 'How to code' knowledge to what I'm being taught of 'How to Program' (They are different!). As part of this, I've been taught how to capture requirements from clients before starting a new project. But... How do I do this for a nebulous personal project? I say nebulous, as I often find halfway through programming something, I want to expand what my program will do, or alter the result. Eventually, I'm tangled in code and have to restart. This can be frustrating and off-putting. Conversely, when given a fixed task and fixed requirements, it's much easier to dig in and get it done. At work I might be told "Today/This week you need to add XYZ to program 1" That is easy to do. At home (for fun) I want to make, say, a program that creates arbitrary lists. It's a very generic task. How do I start with that? I don't need it to do anything, but I want it to do something. So how do I plan a personal programming project? Related: What to plan before starting development on a project?

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