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  • How to store the path of a game pawn in a turn based game ?

    - by panzerschreck
    Hello, I have a square grid, for a turn based game ( grid is similar to the chess board ), but the moves in the games are different based on whether you have lapped your opponent pawn at least once or not. i.e if you have not lapped (beaten any of the opponents pawns) in the outer most grid as below if you have lapped your opponent pawn once at least, then you get to reach home,this way.Any player having all his pawns reaching "home" first wins. The ones in yellow are safe-houses, i.e both the opponent pawn and the player's pawn get to stay in the same grid, this is not considered to be lapping ( the opponent ).The lapped pawn will return to its start point. Now the question is, what is the effective way to store the paths for the all the pawns.we will have 4 pawns for the player and 4 opponent pawns. Is there any pattern to store such static information, in a elegant way ? Thanks for your time

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  • What makes static initialization functions good, bad, or otherwise?

    - by Richard Levasseur
    Suppose you had code like this: _READERS = None _WRITERS = None def Init(num_readers, reader_params, num_writers, writer_params, ...args...): ...logic... _READERS = new ReaderPool(num_readers, reader_params) _WRITERS = new WriterPool(num_writers, writer_params) ...more logic... class Doer: def __init__(...args...): ... def Read(self, ...args...): c = _READERS.get() try: ...work with conn finally: _READERS.put(c) def Writer(...): ...similar to Read()... To me, this is a bad pattern to follow, some cons: Doers can be created without its preconditions being satisfied The code isn't easily testable because ConnPool can't be directly mocked out. Init has to be called right the first time. If its changed so it can be called multiple times, extra logic has to be added to check if variables are already defined, and lots of NULL values have to be passed around to skip re-initializing. In the event of threads, the above becomes more complicated by adding locking Globals aren't being used to communicate state (which isn't strictly bad, but a code smell) On the other hand, some pros: its very convenient to call Init(5, "user/pass", 2, "user/pass") It simple and "clean" Personally, I think the cons outweigh the pros, that is, testability and assured preconditions outweigh simplicity and convenience.

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  • Creating colour schemes based on an existing scheme

    - by Neil Barnwell
    I have a colour scheme based around yellow, for warning messages on a website. It amounts to a slightly orange bordered box, with a pale yellow fill. The exact colours are: #FED626 (border) #FFF7C0 (fill) I want to know if it's possible to convert this scheme mathematically or algorithmically somehow, to come up with a blue version where the border is the "same amount" of blue as this one is yellow. Is this possible, or do I just "pin the tail on the donkey" on a colour pallet to get roughly the right one? I ask, because I'd quite like to be able to calculate this on the fly, to perhaps implement something in .less. To give you an idea, I tried swopping the red and blue values on those two, and came up with this: #26D6FE (border) #C0F7FF (fill) That wasn't too hard, but think about if I wanted a pink colour scheme... :)

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  • Question regarding factory pattern

    - by eriks
    I have a factory class to build objects of base class B. The object (D) that uses this factory received a list of strings representing the actual types. What is the correct implementation: the factory receives an Enum (and uses switch inside the Create function) and D is responsible to convert the string to Enum. the factory receives a string and checks for a match to a set of valid strings (using ifs') other implementation i didn't think of.

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  • Seperation of game- and rendering logic

    - by Qua
    What is the best way to seperate rendering code from the actually game engine/logic code? And is it even a good idea to seperate those? Let's assume we have a game object called Knight. The Knight has to be rendered on the screen for the user to see. We're now left with two choices. Either we give the Knight a Render/Draw method that we can call, or we create a renderer class that takes care of rendering all knights. In the scenario where the two is seperated the Knight should the knight still contain all the information needed to render him, or should this be seperated as well? In the last project we created we decided to let all the information required to render an object be stored inside the object itself, but we had a seperate component to actually read those informations and render the objects. The object would contain information such as size, rotation, scale, and which animation was currently playing and based on this the renderer object would compose the screen. Frameworks such as XNA seem to think joining the object and rendering is a good idea, but we're afraid to get tied up to a specific rendering framework, whereas building a seperate rendering component gives us more freedom to change framework at any given time.

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  • Empty data problem - data layer or DAL?

    - by luckyluke
    I designing the new App now and giving the following question a lot of thought. I consume a lot of data from the warehouse, and the entities have a lot of dictionary based values (currency, country, tax-whatever data) - dimensions. I cannot be assured though that there won't be nulls. So I am thinking: create an empty value in each of teh dictionaries with special keyID - ie. -1 do the ETL (ssis) do the correct stuff and insert -1 where it needs to let the DAL know that -1 is special (Static const whatever thing) don't care in the code to check for nullness of dictionary entries because THEY will always have a value But maybe I should be thinking: import data AS IS let the DAL do the thinking using empty record Pattern still don't care in the code because business layer will have what it needs from DAL. I think is more of a approach thing but maybe i am missing something important here... What do You think? Am i clear? Please don't confuse it with empty record problem. I do use emptyCustomer think all the time and other defaults too.

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  • What is the best way to handle validity dates in applications ?

    - by user214626
    Hello, How do we model these objects ? Scenario 1: Price changes in a time period EffectiveDate ExpiryDate Price 2009-01-01 2009-01-31 800$ 2009-02-01 Null 900$ So, if the price changes to 910$ on 2009-02-15, then the system should automatically update the expiry date on the previous effective price to 2009-02-14, to keep it consistent. Scenario 2: No price specified between 2009-02-01 to 2009-02-28 EffectiveDate ExpiryDate Price 2009-01-01 2009-01-31 800$ 2009-03-01 Null 900$ So, if new price is specified for 2009-02-15 onwards , then the system should automatically set the expiry date on the record to be inserted to 2009-02-28, because already a record effective from 2009-03-01 exists. Please suggest an effective way to handle these scenarios to model my framework, or are there any frameworks around that can do this . Thanks

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  • Overlay 2d weapon sprite over character sprite ?

    - by Mr.Gando
    Hello, I'm working on a game where my character needs to be able to have different weapons. For that I think that somehow overlaying the weapon over the moving sprite would be the correct choice, but I'm not sure about how could I do this. Assuming my Character spritesheet looks like this: And my preliminar weapon spritesheet ( haven't decided on a fixed square size for the weapon yet ), looks like this: How would you make the overlay to set the weapon correctly over the character hand for each of his frames? I know that one way would be just to have a weapon frame the same size as my character sprites, and overlay those too, but I think that if the game has way too much weapons (say 15 different kinds of one hand weaps) this could get pretty insane ( having one weapon sprite sheet the same size as the character sprite sheet for each type of weapon ) Do you guys have any advice on how to implement this? (supporting overlaying the weapon sprites over the character sprites) Thanks!

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  • Factory Method Pattern clarification

    - by nettguy
    My understanding of Factory Method Pattern is (Correct me if i am wrong) Factory Method Pattern "Factory Method allow the client to delegates the product creation (Instance Creation) to the subclass". There are two situation in which we can go for creating Factory Method pattern. (i) When the client is restricted to the product (Instance) creation. (ii) There are multiple products available.But a decision to be made which product instance need to be returned. If you want to create Abstract Method pattern You need to have abstract product Concrete Product Factory Method to return the appropriate product. Example : public enum ORMChoice { L2SQL, EFM, LS, Sonic } //Abstract Product public interface IProduct { void ProductTaken(); } //Concrete Product public class LinqtoSql : IProduct { public void ProductTaken() { Console.WriteLine("OR Mapping Taken:LinqtoSql"); } } //concrete product public class Subsonic : IProduct { public void ProductTaken() { Console.WriteLine("OR Mapping Taken:Subsonic"); } } //concrete product public class EntityFramework : IProduct { public void ProductTaken() { Console.WriteLine("OR Mapping Taken:EntityFramework"); } } //concrete product public class LightSpeed : IProduct { public void ProductTaken() { Console.WriteLine("OR Mapping Taken :LightSpeed"); } } public class Creator { //Factory Method public IProduct ReturnORTool(ORMChoice choice) { switch (choice) { case ORMChoice.EFM:return new EntityFramework(); break; case ORMChoice.L2SQL:return new LinqtoSql(); break; case ORMChoice.LS:return new LightSpeed(); break; case ORMChoice.Sonic:return new Subsonic(); break; default: return null; } } } **Client** Button_Click() { Creator c = new Creator(); IProduct p = c.ReturnORTool(ORMChoice.L2SQL); p.ProductTaken(); } Is my understanding of Factory Method is correct?

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  • UML Class Relationships

    - by 01010011
    Hi, I would like to confirm whether I am on the right track when identifying common UML class relationships. For example, is the relationship between: 1 a stackoverflow member and his/her stackoverflow user account categorized as a composition relationship or an aggregation relationship? At first I thought it was an association because this member "has a" account. However on second thought, I am thinking its composition because each "part" (user account) belongs to only one whole (user) at a time, meaning for as long as I am logged into stackoverflow, I have to use this one and only account until I log off. If I log back onto stackoverflow with a different account then its composition again. Do you agree? 2 a database and a person's user account an aggregation relationship? I think so because 1 database (the whole) can store 0...* number of user accounts (the parts) but another database can store the same user accounts. Finally, can anyone recommend a website that specializes in designing code using UML? Thanks in advance

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  • Concurency problem with Isolation - read-committed

    - by Ratn Deo--Dev
    I have to write a simple demo for amount withdrawl from a joint Bank amount .Andy and Jen holds a joint bank account with number 123 . Suppose they have 100$ in their account .Jen and Andy are operating their account at the same time and both are trying to withdraw 90$ at the time being .My transaction Isolation is set to read-committed and both are able to withdraw money leaving the balance to -(minus)80$ although I have constraint that balance should never be less than 0. I am using hibernate .Is versioning only way to solve this problem or I should go for another Isolation level ?

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  • How to avoid injecting dependencies into an object so that it can pass them on?

    - by Pheter
    I am interested in applying dependency injection to my current project, which makes use of the MVC pattern. My controllers will call the models and therefore will need to inject the dependencies into the models. To do this, the controller must have the dependencies (such as a database object) in the first place. The controller doesn't need to make use of some of these dependencies (such as the database object), so I feel that it shouldn't be given this dependency. However, it has to have these dependencies if it is to inject them into the model objects. How can I avoid having dependencies injected into an object just so that it can pass them on? Doing so feels wrong and can result in many dependencies being injected into an object. Edit: I am using PHP.

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  • Hierarchy / Flyweight / Instancing Problem in Python

    - by Dan
    Here is the problem I am trying to solve, (I have simplified the actual problem, but this should give you all the relevant information). I have a hierarchy like so: 1.A 1.B 1.C 2.A 3.D 4.B 5.F (This is hard to illustrate - each number is the parent, each letter is the child). Creating an instance of the 'letter' objects is expensive (IO, database costs, etc), so should only be done once. The hierarchy needs to be easy to navigate. Children in the hierarchy need to have just one parent. Modifying the contents of the letter objects should be possible directly from the objects in the hierarchy. There needs to be a central store containing all of the 'letter' objects (and only those in the hierarchy). 'letter' and 'number' objects need to be possible to create from a constructor (such as Letter(**kwargs) ). It is perfectably acceptable to expect that when a letter changes from the hierarchy, all other letters will respect the same change. Hope this isn't too abstract to illustrate the problem. What would be the best way of solving this? (Then I'll post my solution) Here's an example script: one = Number('one') a = Letter('a') one.addChild(a) two = Number('two') a = Letter('a') two.addChild(a) for child in one: child.method1() for child in two: print '%s' % child.method2()

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  • Is It Incorrect to Make Domain Objects Aware of The Data Access Layer?

    - by Noah Goodrich
    I am currently working on rewriting an application to use Data Mappers that completely abstract the database from the Domain layer. However, I am now wondering which is the better approach to handling relationships between Domain objects: Call the necessary find() method from the related data mapper directly within the domain object Write the relationship logic into the native data mapper (which is what the examples tend to do in PoEAA) and then call the native data mapper function within the domain object. Either it seems to me that in order to preserve the 'Fat Model, Skinny Controller' mantra, the domain objects have to be aware of the data mappers (whether it be their own or that they have access to the other mappers in the system). Additionally it seems that Option 2 unnecessarily complicates the data access layer as it creates table access logic across multiple data mappers instead of confining it to a single data mapper. So, is it incorrect to make the domain objects aware of the related data mappers and to call data mapper functions directly from the domain objects? Update: These are the only two solutions that I can envision to handle the issue of relations between domain objects. Any example showing a better method would be welcome.

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  • Conventions for the behavior of double or triple "click to select text" features?

    - by John Sullivan
    Almost any mature program that involves text implements "double click to select the word" and, in some cases, "triple click to select additional stuff like an entire line" as a feature. I find these features useful but they are often inconsistent between programs. Example - some programs' double clicks do not select the ending space after a word, but most do. Some recognize the - character as the end of a word, others do not. SO likes to select the entire paragraph as I write this post when I triple click it, VS web developer 2005 has no triple click support, and ultra-edit 32 will select one line upon triple clicking. We could come up with innumerable inconsistencies about how double and triple click pattern matching is implemented across programs. I am concerned about how to implement this behavior in my program if nobody else has achieved a convention about how the pattern matching should work. My question is, does a convention (conventions? maybe an MS or Linux convention?) exist that dictates how these features are supposed to behave to the end user? What, if any, are they?

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  • Can a binary tree or tree be always represented in a Database as 1 table and self-referencing?

    - by Jian Lin
    I didn't feel this rule before, but it seems that a binary tree or any tree (each node can have many children but children cannot point back to any parent), then this data structure can be represented as 1 table in a database, with each row having an ID for itself and a parentID that points back to the parent node. That is in fact the classical Employee - Manager diagram: one boss can have many people under him... and each person can have n people under him, etc. This is a tree structure and is represented in database books as a common example as a single table Employee.

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  • Passing data structures to different threads

    - by Robb
    I have an application that will be spawning multiple threads. However, I feel there might be an issue with threads accessing data that they shouldn't be. I'm relatively new to threading so bare with me. Here is the structure of the threaded application (sorry for the crudeness): MainThread / \ / \ / \ Thread A Thread B / \ / \ / \ / \ / \ / \ Thread A_1 Thread A_2 Thread B_1 Thread B_2 Under each lettered thread (which could be many), there will only be two threads and they are fired of sequentially. The issue i'm having is I'm not entirely sure how to pass in a datastructure into these threads. So, the datastructure is created in MainThread, will be modified in the lettered thread (Thread A, etc) specific to that thread and then a member variable from that datastructure is sent to Letter_Numbered threads. Currently, the lettered thread class has a member variable and when the class is constructed, the datastructure from mainthread is passed in by reference, invoking the copy constructor so the lettered thread has it's own copy to play with. The lettered_numbered thread simply takes in a string variable from the data structure within the lettered thread. My question is, is this accceptable? Is there a much better way to ensure each lettered thread gets its own data structure to play with? Sorry for the somewhat poor explanation, please leave comments and i'll try to clarify.

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  • date representation in user interface

    - by Samuel
    Most of the sites capture the date (e.g. birth date) information as either a single entity (i.e via a calendar control) or instead as separate fields (date, month, year). Are there any benefits in showing them as separate fields? Are they represented in the database as DATE data type or as separate fields. I am just trying to understand the pros & cons of representing the date field.

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  • How do i structure my SQL Database (tables, Schemas, users, stored procedures etc.) to prepare it fo

    - by AlexRednic
    I think the title is self explanatory. What I'm looking for is material so I can further my knowledge. I've never developed a full application before so building one from scratch is a bit overwhelming for me. And the first bump in the road is the database. Websites, articles, books, elaborate answers, anything will do as long as they keep me on the right track. Thanks

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  • Is Abstract Factory Pattern implemented correctly for given scenario.... ???

    - by Amit
    First thing... I am novice to pattern world, so correct me if wrong anywhere Scenario: There are multiple companies providing multiple products of diff size so there are 3 entities i.e. Companies, Their Product and size of product I have implement Abstract Pattern on this i.e. so that I will create instance of IProductFactory interface to get desired product... Is below implementation of Abstract Factory Pattern correct ??? If not then please correct the approach + Also tell me if any other pattern can be used for such scenario Thanks in advance... public enum Companies { Samsung = 0, LG = 1, Philips = 2, Sony = 3 } public enum Product { PlasmaTv = 0, DVD = 1 } public enum ProductSize { FortyTwoInch, FiftyFiveInch } interface IProductFactory { IPhilips GetPhilipsProduct(); ISony GetSonyProduct(); } interface ISony { string CreateProducts(Product product, ProductSize size); } interface IPhilips { string CreateProducts(Product product, ProductSize size); } class ProductFactory : IProductFactory { public IPhilips GetPhilipsProduct() { return new Philips(); } public ISony GetSonyProduct() { return new Sony(); } } class Philips : IPhilips { #region IPhilips Members public string CreateProducts(Product product, ProductSize size) {// I have ingnore size for now.... string output = string.Empty; if (product == Product.PlasmaTv) { output = "Plasma TV Created !!!"; } else if (product == Product.DVD) { output = "DVD Created !!!"; } return output; } #endregion } class Sony : ISony {// I have ingnore size for now.... #region ISony Members public string CreateProducts(Product product, ProductSize size) { string output = string.Empty; if (product == Product.PlasmaTv) { output = "Plasma TV Created !!!"; } else if (product == Product.DVD) { output = "DVD Created !!!"; } return output; } #endregion } IProductFactory prodFactory = new ProductFactory(); IPhilips philipsObj = prodFactory.GetPhilipsProduct(); MessageBox.Show(philipsObj.CreateProducts(Product.DVD, ProductSize.FortyTwoInch)); or //ISony sonyObj = prodFactory.GetSonyProduct(); //MessageBox.Show(sonyObj.CreateProducts(Product.DVD, ProductSize.FortyTwoInch));

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  • Java init method

    - by Johan Sjöberg
    What's a good way to make sure an init method is invoked in java? The alternatives I see are Don't test it, let the method fail by itself, likely by a NullPointerException Test if method was initialized or throw public void foo() { if (!inited) { throw new IllegalArgumentException("not initalized"); } ... } Delagate public void foo() { if (!inited) { throw new IllegalArgumentException("not initalized"); } fooInternal(); } private void fooInternal(){ ... }; Always init, and make init a noop otherwise public void foo() { init(); ... } public void init() { if(!inited) { ... } } Silently init public void foo() { if (!inited) { init(); } ... } Most of these approaches are very verbose and decreases overall readability.

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