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• Earmarks of a Professional PHP Programmer

  - by Scotty C.

  I'm a 19 year old student who really REALLY enjoys programming, and I'm hoping to glean from your years of experience here. At present, I'm studying PHP every chance I get, and have been for about 3 years, although I've never taken any formal classes. I'd love to some day be a programmer full time, and make a good career of it. My question to you is this: What do you consider to be the earmarks or traits of a professional programmer? Mainly in the field of PHP, but other, more generalized qualifications are also more than welcome, as I think PHP is more of a hobbyist language and may not be the language of choice in the eyes of potential employers. Please correct me if I'm wrong. Above all, I don't want to wast time on something that isn't worth while. I'm currently feeling pretty confident in my knowledge of PHP as a language, and I know that I could build just about anything I need and have it "work", but I feel sorely lacking in design concepts and code structure. I can even write object oriented code, but in my personal opinion, that isn't worth a hill of beans if it isn't organized well. For this reason, I bought Matt Zandstra's book "PHP Objects, Patterns, and Practice" and have been reading that a little every day. Anyway, I'm starting to digress a little here, so back to the original question. What advice would you give to an aspiring programmer who wants to make an impact in this field? Also, on a side note, I've been working on a project with a friend of mine that would give a fairly good idea of where I'm at coding wise. I'm gonna give a link, I don't want anyone to feel as though I'm pushing or spamming here, so don't click it if you don't want to. But if you are interested on giving some feedback there as well, you can see the code on github. I'm known as The Craw there. https://github.com/PureChat/PureChat--Beta-/tree/

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• Implementing a ILogger interface to log data

  - by Jon

  I have a need to write data to file in one of my classes. Obviously I will pass an interface into my class to decouple it. I was thinking this interface will be used for testing and also in other projects. This is my interface: //This could be used by filesystem, webservice public interface ILogger { List<string> PreviousLogRecords {get;set;} void Log(string Data); } public interface IFileLogger : ILogger { string FilePath; bool ValidFileName; } public class MyClassUnderTest { public MyClassUnderTest(IFileLogger logger) {....} } [Test] public void TestLogger() { var mock = new Mock<IFileLogger>(); mock.Setup(x => x.Log(Is.Any<string>).AddsDataToList()); //Is this possible?? var myClass = new MyClassUnderTest(mock.Object); myClass.DoSomethingThatWillSplitThisAndLog3Times("1,2,3"); Assert.AreEqual(3,mock.PreviousLogRecords.Count); } This won't work I don't believe as nothing is storing the items so is this possible using Moq and also what do you think of the design of the interface?

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• What conventions or frameworks exist for MVVM in Perl?

  - by Will Sheppard

  We're using Catalyst to render lots of webforms in what will become a large application. I don't like the way all the form data is confusingly into a big hash in the Controller, before being passed to the template. It seems jumbled up and messy for the template. I'm sure there are real disadvantages that I haven't described properly... Are there? One solution is to just decide on a convention for the hash, e.g.: { defaults => { type => ['a', 'b', 'c'] }, input => { type => 'a' }, output => { message => "2 widgets found of type a", widgets => [ 'foo', 'bar' ] } } Another way is to store the page/form data as attributes in a class (a ViewModel?), and pass a whole object to the template, which it could use like this: <p class="message">[% model.message %]<p> [% FOREACH widget IN model.widgets %] Which way is more flexible for large applications? Are there any other solutions or existing Catalyst-compatible frameworks?

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• Implementing `fling` logic without pan gesture recognizers

  - by KDiTraglia

  So I am trying to port over a simple game that I originally wrote to iphone into cocos2d-x. I've hit a minor bump however in implementing simple 'fling' logic I had in the iphone version that is difficult to port over to the c++. In iOS I could get the velocity of a pan gesture very easily: CGPoint velocity = [recognizer velocityInView:recognizer.view]; However now I basically only know where the touch began, where the touch ended, and all the touches that are logged in between. For now I logged all the pts onto a stack then pulled the last point and the 6th to last point (seemed to work the best), find the difference between those pts multiply by a constant and use that as the velocity. It works relatively well, but I'm wondering if anyone else has any better algorithms, when given a bunch of touch pts, to figure out a new speed upon releasing an object that feels natural (Note speed in my game is just a constant x and y, there's no drag or spin or anything tricky like that). Bonus points if anyone has figured out how to get pan gestures into the newest version (3.0 alpha) of cocos2d-x without losing ability to build cross platform.

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• ArchBeat Link-o-Rama for December 4, 2012

  - by Bob Rhubart

  Exalogic 2.0.1 Tea Break Snippets - Creating and using Distribution Groups | The Old Toxophilist "Although in many cases we, as Cloud Users, may not be to worried how the Virtualisation Algorithm decides where to place our vServers," says The Old Toxopholist, "there are cases where it is extremely important that vServers run on distinct physical compute nodes." There's plenty more on the subject in his blog post. Oracle Endeca (2.3) Record Level Security | Adam Seed Adam Sneed's blog post covers "the basics of security within Endeca Information Discovery, as these basic security objects are required in order to explain the implementation of record level security." ODI Handling DQ | Gurcan Orhan Oracle ACE Director Gurcan Orhan suggests you have fun with these scripts for Oracle Data Integrator. Parleys Testimonial at GlassFish Community Event - JavaOne 2012 Video of Parley's webmaster Stephan Janssen's presentation at the GlassFish Community Event at JavaOne 2012, in which he explains why Parley's moved from Tomcat to GlassFish. Java Spotlight Episode 109: Pete Muir on CDI 1.1 This edition of Roger Brinkley's Java Spotlight Podcast features an interview with CDI 1.1 spec lead Pete Muir of JBoss/Red Hat. Muir talks about the features in CDI 1.1 and what to expect in the future. Webcast: Java Management Extensions with Oracle WebLogic Server 12c Dr. Frank Munz and Dave Cabelus do the talking in this on-demand webcast focused on Oracle WebLogic Server 12c with Java Management Extensions (JMX). Using the Coherence API to get Portable Object Format bytes | Bruno Borges Bruno Borges shares a code snippet that illustrates how easy it is to use the Coherence API. Thought for the Day "Experience is something you don't get until just after you need it." — Anonymous Source: SoftwareQuotes.com

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• Unity calendar lens not showing events in Ubuntu 12.04

  - by David_G

  I'm trying to get proper/useful calendar integration into Ubuntu 12.04. I have a Google Calendar (& account) and I want to be able to use this without opening the browser. I want to get the Unity Calendar lens working, so that it shows events coming up, and it allows me a quick way to add new events. However, after installing it, it does not find any events, nor allow me to add a new event. Note that I've installed Lightning 1.4, Evolution mirror 0.2.3, Evolution, and unity-calendar lens. I've also installed Calendar-indicator. I suspect that somehow the lens is not getting the calendar information from thunderbird via evolution. A bit of searching around led me to try this command: /usr/lib/calendar-lens/calendar-lens-daemon.py. With this result: /usr/lib/python2.7/dist-packages/gobject/constants.py:24: Warning: g_boxed_type_register_static: assertion `g_type_from_name (name) == 0' failed import gobject._gobject Traceback (most recent call last): File "/usr/lib/calendar-lens/calendar-lens-daemon.py", line 324, in daemon = Daemon() File "/usr/lib/calendar-lens/calendar-lens-daemon.py", line 80, in init for calendar in evolution.ecal.list_calendars(): AttributeError: 'NoneType' object has no attribute 'list_calendars' Any ideas?

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• How to improve Minecraft-esque voxel world performance?

  - by SomeXnaChump

  After playing Minecraft I marveled a bit at its large worlds but at the same time I found them extremely slow to navigate, even with a quad core and meaty graphics card. Now I assume Minecraft is fairly slow because: A) It's written in Java, and as most of the spatial partitioning and memory management activities happen in there, it would naturally be slower than a native C++ version. B) It doesn't partition its world very well. I could be wrong on both assumptions; however it got me thinking about the best way to manage large voxel worlds. As it is a true 3D world, where a block can exist in any part of the world, it is basically a big 3D array [x][y][z], where each block in the world has a type (i.e BlockType.Empty = 0, BlockType.Dirt = 1 etc.) Now, I am assuming to make this sort of world perform well you would need to: A) Use a tree of some variety (oct/kd/bsp) to split all the cubes out; it seems like an oct/kd would be the better option as you can just partition on a per cube level not a per triangle level. B) Use some algorithm to work out which blocks can currently be seen, as blocks closer to the user could obfuscate the blocks behind, making it pointless to render them. C) Keep the block object themselves lightweight, so it is quick to add and remove them from the trees. I guess there is no right answer to this, but I would be interested to see peoples' opinions on the subject. How would you improve performance in a large voxel-based world?

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• What is the proper response to lousy error message?

  - by William Pursell

  I've just come across (for the 47 millionth time) some code that looks like this: except IOError, e: print "Problems reading file: %s." % filename sys.exit( 1 ) My first reaction is very visceral: the person who coded this is a complete idiot. How hard is it to print error messages to stderr and to include the system error message in the string? I haven't used python in years, and it took me all of 4 minutes to track down the documentation to figure out how to get the error message from the exception object e and the syntax for printing to stderr. My "complete idiot" reaction was slightly lessened since at least a non-zero value is passed to sys.exit, but I still find this code offensive. My prime thought is that the developer who wrote this is a complete novice for whom I have zero respect. Am I over-reacting? Surely there are excuses for all sorts of bad coding practices, but is there anything that can possibly excuse this sort of $#|t? I guess there are two question here: one is a duplicate of What are developer's problems with helpful error messages?, and the other is "am I over-reacting, or is it valid to conclude that the author of the above code is a novice?"

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• Uses of persistent data structures in non-functional languages

  - by Ray Toal

  Languages that are purely functional or near-purely functional benefit from persistent data structures because they are immutable and fit well with the stateless style of functional programming. But from time to time we see libraries of persistent data structures for (state-based, OOP) languages like Java. A claim often heard in favor of persistent data structures is that because they are immutable, they are thread-safe. However, the reason that persistent data structures are thread-safe is that if one thread were to "add" an element to a persistent collection, the operation returns a new collection like the original but with the element added. Other threads therefore see the original collection. The two collections share a lot of internal state, of course -- that's why these persistent structures are efficient. But since different threads see different states of data, it would seem that persistent data structures are not in themselves sufficient to handle scenarios where one thread makes a change that is visible to other threads. For this, it seems we must use devices such as atoms, references, software transactional memory, or even classic locks and synchronization mechanisms. Why then, is the immutability of PDSs touted as something beneficial for "thread safety"? Are there any real examples where PDSs help in synchronization, or solving concurrency problems? Or are PDSs simply a way to provide a stateless interface to an object in support of a functional programming style?

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• Vector vs Scalar velocity?

  - by Serguei Fedorov

  I am revamping an engine I have been working on and off on for the last few weeks to use a directional vector to dictate direction; this way I can dictate the displacement based on a direction. However, the issue I am trying to overcome is the following problem; the speed towards X and speed towards Y are unrelated to one another. If gravity pulls the object down by an increasing velocity my velocity towards the X should not change. This is very easy to implement if my speed is broken into a Vector datatype, Vector.X dictates one direction Vector.Y dictates the other (assuming we are not concerned about the Z axis). However, this defeats the purpose of the directional vector because: SpeedX = 10 SpeedY = 15 [1, 1] normalized = ~[0.7, 0.7] [0.7, 0.7] * [10, 15] = [7, 10.5] As you can see my direction is now "scaled" to my speed which is no longer the direction that I want to be moving in. I am very new to vector math and this is a learning project for me. I looked around a little bit on the internet but I still want to figure out things on my own (not just look at an example and copy off it). Is there way around this? Using a directional vector is extremely useful but I am a little bit stumped at this problem. I am sorry if my mathematical understanding maybe completely wrong.

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• Frame Independent Movement

  - by ShrimpCrackers

  I've read two other threads here on movement: Time based movement Vs Frame rate based movement?, and Fixed time step vs Variable time step but I think I'm lacking a basic understanding of frame independent movement because I don't understand what either of those threads are talking about. I'm following along with lazyfoo's SDL tutorials and came upon the frame independent lesson. http://lazyfoo.net/SDL_tutorials/lesson32/index.php I'm not sure what the movement part of the code is trying to say but I think it's this (please correct me if I'm wrong): In order to have frame independent movement, we need to find out how far an object (ex. sprite) moves within a certain time frame, for example 1 second. If the dot moves at 200 pixels per second, then I need to calculate how much it moves within that second by multiplying 200 pps by 1/1000 of a second. Is that right? The lesson says: "velocity in pixels per second * time since last frame in seconds. So if the program runs at 200 frames per second: 200 pps * 1/200 seconds = 1 pixel" But...I thought we were multiplying 200 pps by 1/1000th of a second. What is this business with frames per second? I'd appreciate if someone could give me a little bit more detailed explanation as to how frame independent movement works. Thank you.

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• Another Exchange 2003 to Exchange 2010 mail flow issue

  - by Ryan Roussel

  During a migration recently, we came across another internal mail routing issue.  The symptoms were identical to my previous post about Exchange internal mail routing.  Mail was flowing from 2010 to 2003, from 2010 to the internet, but not from 2003 to 2010.   I went through the normal check list looking at permissions, DNS, and the routing group connectors.  I verified that both servers listed in the routing group connectors were the routing master in their respective routing groups through the 2003 ESM.  I also verified that inheritable permissions were enabled for the Exchange 2003 server object in the schema.  No luck with either.   For my previous post about this issue in which inheritable permissions were the culprit: Exchange 2010, Exchange 2003 Mail Flow issue   And for Routing Group issues: Exchange 2007 Routing Group Connector Mayhem   I finally enabled logging on the SMTP virtual server on Exchange 2003 and the Default Receive Connector on 2010 and sent a few test e-mails where I found 2003 was having issues authenticating to 2010.  By default 2003 uses Exchange Server Authentication to communicate to 2010. The exact error was: 4.7.0 Temporary Authentication Failure which was found in the SMTP logs on the Exchange 2003 side   After scouring based on this error, I found the solution:   The Access this computer from the network user rights in the local computer policy on the Exchange 2010 server were changed from the default.  The network administrator had modified the Default Domain policy and changed this user right assignment to only list Domain Users.   The fix was to clear this setting in the Default Domain policy,  force gpupdate to refresh the group policy settings, then ensure the appropriate users and groups were listed.   This immediately fixed the problem and the Exchange 2003 server was able to route mail to the Exchange 2010 mailboxes.   The default user rights assignments for Access this computer from the network On Workstations and Servers: Administrators Backup Operators Power Users Users Everyone On Domain Controllers: Administrators Authenticated Users Everyone More can be found here: http://technet.microsoft.com/en-us/library/cc740196(WS.10).aspx

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• Accessing ADF Faces components that are read-only from JavaScript

  - by Frank Nimphius

  Almost as a note to myself and to justify the time I spent on analyzing aproblem, a quick note on what to watch out for when working trying to access read-only ADF Faces components from JavaScript.  Those who tried JavaScript in ADF Faces probably know that you need to ensure the ADF Faces component  is represented by a JavaScript object on the client. You do this either implicitly by adding an af:clientListener component (in case you want to listen for a component event) or explicitly by setting the ADF Faces component clientComponent property to true. For the use case I looked at in JDeveloper 11g R1 (11.1.1.7) I needed to make an output text component clickable to call a JavaScript function in response. Though I added the af:clientComponent tag to the component I recognized that it also needed the clientComponent property set to true. Though I remember this as not being required in 11.1.1.6, I like the new behavior as it helps preventing read-only components from firing client side events unless you tell it to do so by setting the clientComponent property to true. Note: As the time of writing, JDeveloper 11.1.1.7 is not publicly available and I put the note in this blog as a reminder in case you ever hit a similar challenge so you know what to do.

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• Is this an acceptable approach to undo/redo in Python?

  - by Codemonkey

  I'm making an application (wxPython) to process some data from Excel documents. I want the user to be able to undo and redo actions, even gigantic actions like processing the contents of 10 000 cells simultaneously. I Googled the topic, and all the solutions I could find involves a lot of black magic or is overly complicated. Here is how I imagine my simple undo/redo scheme. I write two classes - one called ActionStack and an abstract one called Action. Every "undoable" operation must be a subclass of Action and define the methods do and undo. The Action subclass is passed the instance of the "document", or data model, and is responsible for committing the operation and remembering how to undo the change. Now, every document is associated with an instance of the ActionStack. The ActionStack maintains a stack of actions (surprise!). Every time actions are undone and new actions are performed, all undone actions are removed for ever. The ActionStack will also automatically remove the oldest Action when the stack reaches the configurable maximum amount. I imagine the workflow would produce code looking something like this: class TableDocument(object): def __init__(self, table): self.table = table self.action_stack = ActionStack(history_limit=50) # ... def delete_cells(self, cells): self.action_stack.push( DeleteAction(self, cells) ) def add_column(self, index, name=''): self.action_stack.push( AddColumnAction(self, index, name) ) # ... def undo(self, count=1): self.action_stack.undo(count) def redo(self, count=1): self.action_stack.redo(count) Given that none of the methods I've found are this simple, I thought I'd get the experts' opinion before I go ahead with this plan. More specifically, what I'm wondering about is - are there any glaring holes in this plan that I'm not seeing?

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• Need advice for approach for a web-based app that loads excel worksheet but exposes only the charts

  - by John

  I'm looking for suggestions on the Visual Studio approach to take for a web application that is in the conceptual stage. My environment has a lot of tools: Windows Server 2008 R2 Standard 64bit Visual Studio 2010 Professional Edition Sharepoint 2010 Server Enterprise Edition SQL Server 2008 R2 Office 2010 Professional I know I will need this app to retrieve data from a database (or a web service - not sure exactly at this point). The data needs to be placed in an Excel workbook dynamically. The app will need to have a nice user interface (standard web controls - perhaps with some Javascript effects). The Excel ribbon and worksheet grid will need to be hidden. Some web control(s) will cause the Excel chart(s) to be rendered. I am thinking this sounds like Visual Studio Tools for Office (VSTO) so as to leverage .Net and hide Excel. Can you offer suggestions regarding: One ASP.Net Web App Project One Class Library Project for Excel or perhaps which one of the several different Excel 2010 project types (addin, template, document) Would Excel Services for Sharepoint be useful (or required) ? I am feeling a little overwhelmed with so many choices at this early stage of conceptualizing the app. Can you suggest some ideas for this sort of thing? Also, I am a bit more experienced with C# but I've read VB.Net is better for work with the Excel object model. What are general advises with regard to tool choice and overall approach tradeoffs?

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• DataContractSerializer truncated string when used with MemoryStream,but works with StringWriter

  - by Michael Freidgeim

  We've used the following DataContractSerializeToXml method for a long time, but recently noticed, that it doesn't return full XML for a long object, but  truncated it and returns XML string with the length of  multiple-of-1024 , but the reminder is not included. internal static string DataContractSerializeToXml<T>(T obj) { string strXml = ""; Type type= obj.GetType();//typeof(T) DataContractSerializer serializer = new DataContractSerializer(type); System.IO.MemoryStream aMemStr = new System.IO.MemoryStream(); System.Xml.XmlTextWriter writer = new System.Xml.XmlTextWriter(aMemStr, null); serializer.WriteObject(writer, obj); strXml = System.Text.Encoding.UTF8.GetString(aMemStr.ToArray()); return strXml; }   I tried to debug and searched Google for similar problems, but didn't find explanation of the error. The most closed http://forums.codeguru.com/showthread.php?309479-MemoryStream-allocates-size-multiple-of-1024-( talking about incorrect length, but not about truncated string.fortunately replacing MemoryStream to StringWriter according to http://billrob.com/archive/2010/02/09/datacontractserializer-converting-objects-to-xml-string.aspxfixed the issue.   1: var serializer = new DataContractSerializer(tempData.GetType());   2: using (var backing = new System.IO.StringWriter())   3: using (var writer = new System.Xml.XmlTextWriter(backing))   4: {   5:     serializer.WriteObject(writer, tempData);   6:     data.XmlData = backing.ToString();   7: }v

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• Entity system in Lua, communication with C++ and level editor. Need advice.

  - by Notbad

  Hi!, I know this is a really difficult subject. I have been reading a lot this days about Entity systems, etc... And now I'm ready to ask some questions (if you don't mind answering them) because I'm really messed. First of all, I have a 2D basic editor written in Qt, and I'm in the process of adding entitiy edition. I want the editor to be able to receive RTTI information from entities to change properties, create some logic being able to link published events to published actions (Ex:A level activate event throws a door open action), etc... Because all of this I guess my entity system should be written in scripting, in my case Lua. In the other hand I want to use a component based design for my entities, and here starts my questions: 1) Should I define my componentes en C++? If I do this en C++ won't I loose all the RTTI information I want for my editor?. In the other hand, I use box2d for physics, if I define all my components in script won't it be a lot of work to expose third party libs to lua? 2) Where should I place the messa system for my game engine? Lua? C++?. I'm tempted to just have C++ object to behave as servers, offering services to lua business logic. Things like physics system, rendering system, input system, World class, etc... And for all the other things, lua. Creation/Composition of entities based on components, game logic, etc... Could anyone give any insight on how to accomplish this? And what aproach is better?. Thanks in advance, HexDump.

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• How do references work in R?

  - by djechlin

  I'm finding R confusing because it has such a different notion of reference than I am used to in languages like C, Java, Javascript... Ruby, Python, C++, well, pretty much any language I have ever programmed in ever. So one thing I've noticed is variable names are not irrelevant when passing them to something else. The reference can be part of the data. e.g. per this tutorial a <- factor(c("A","A","B","A","B","B","C","A","C")) results <- table(a) Leads to $a showing up as an attribute as $dimnames$a. We've also witnessed that calling a function like a <- foo(alpha=1, beta=2) can create attributes in a of names alpha and beta, or it can assign or otherwise compute on 1 and 2 to properties already existing. (Not that there's a computer science distinction here - it just doesn't really happen in something like Javascript, unless you want to emulate it by passing in the object and use key=value there.) Functions like names(...) return lvalues that will affect the input of them. And the one that most got me is this. x <- c(3, 5, 1, 10, 12, 6) y = x[x <= 5] x[y] <- 0 is different from x <- c(3, 5, 1, 10, 12, 6) x[x <= 5] <- 0 Color me confused. Is there a consistent theory for what's going on here?

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• How to use mount points in MilkShape models?

  - by vividos

  I have bought the Warriors & Commoners model pack from Frogames and the pack contains (among other formats) two animated models and several non-animated objects (axe, shield, pilosities, etc.) in MilkShape3D format. I looked at the official "MilkShape 3D Viewer v2.0" (msViewer2.zip at http://www.chumba.ch/chumbalum-soft/ms3d/download.html) source code and implemented loading the model, calculating the joint matrices and everything looks fine. In the model there are several joints that are designated as the "mount points" for the static objects like axe and shield. I now want to "put" the axe into the hand of the animated model, and I couldn't quite figure out how. I put the animated vertices in a VBO that gets updated every frame (I know I should do this with a shader, but I didn't have time to do this yet). I put the static vertices in another VBO that I want to keep static and not updated every frame. I now tried to render the animated vertices first, then use the joint matrix for the "mount joint" to calculate the location of the static object. I tried many things, and what about seems to be right is to transpose the joint matrix, then use glMatrixMult() to transform the modelview matrix. For some objects like the axe this is working, but not for others, e.g. the pilosities. Now my question: How is this generally implemented when using bone/joint models, and especially with MilkShape3D models? Am I on the right track?

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• What's the proper term for a function inverse to a constructor - to unwrap a value from a data type?

  - by Petr Pudlák

  Edit: I'm rephrasing the question a bit. Apparently I caused some confusion because I didn't realize that the term destructor is used in OOP for something quite different - it's a function invoked when an object is being destroyed. In functional programming we (try to) avoid mutable state so there is no such equivalent to it. (I added the proper tag to the question.) Instead, I've seen that the record field for unwrapping a value (especially for single-valued data types such as newtypes) is sometimes called destructor or perhaps deconstructor. For example, let's have (in Haskell): newtype Wrap = Wrap { unwrap :: Int } Here Wrap is the constructor and unwrap is what? The questions are: How do we call unwrap in functional programming? Deconstructor? Destructor? Or by some other term? And to clarify, is this/other terminology applicable to other functional languages, or is it used just in the Haskell? Perhaps also, is there any terminology for this in general, in non-functional languages? I've seen both terms, for example: ... Most often, one supplies smart constructors and destructors for these to ease working with them. ... at Haskell wiki, or ... The general theme here is to fuse constructor - deconstructor pairs like ... at Haskell wikibook (here it's probably meant in a bit more general sense), or newtype DList a = DL { unDL :: [a] -> [a] } The unDL function is our deconstructor, which removes the DL constructor. ... in The Real World Haskell.

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• Boolean checks with a single quadtree, or multiple quadtrees?

  - by Djentleman

  I'm currently developing a 2D sidescrolling shooter game for PC (think metroidvania but with a lot more happening at once). Using XNA. I'm utilising quadtrees for my spatial partitioning system. All objects will be encompassed by standard bounding geometry (box or sphere) with possible pixel-perfect collision detection implemented after geometry collision (depends on how optimised I can get it). These are my collision scenarios, with < representing object overlap (multiplayer co-op is the reason for the player<player scenario): Collision scenarios (true = collision occurs): Player <> Player = false Enemy <> Enemy = false Player <> Enemy = true PlayerBullet <> Enemy = true PlayerBullet <> Player = false PlayerBullet <> EnemyBullet = true PlayerBullet <> PlayerBullet = false EnemyBullet <> Player = true EnemyBullet <> Enemy = false EnemyBullet <> EnemyBullet = false Player <> Environment = true Enemy <> Environment = true PlayerBullet <> Environment = true EnemyBullet <> Environment = true Going off this information and the fact that were will likely be several hundred objects rendering on-screen at any given time, my question is as follows: Which method is likely to be the most efficient/optimised and why: Using a single quadtree with boolean checks for collision between the different types of objects. Using three quadtrees at once (player, enemy, environment), only testing the player and enemy trees against each other while testing both the player and enemy trees against the environment tree.

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• Trouble using Ray.Intersect method on bounding boxes in a 2D XNA game

  - by getsauce

  I am trying to use a ray and bounding box to determine if a box is between the player and the mouse pointer in 2D space. When I try testing the code, the collision will return true when pointed at the box but it also returns true under other circumstances where it shouldn't. For instance. If I have a player on the left and a box directly to the right, I can put the mouse pointer a few hundred pixels above the box or a few hundred below and it will still return true. Also, I can put my mouse pointer to the left of the player and in a certain area it will still return true. Does anyone have any idea what might cause this? I have left out definitions for some of my members and properties just to make this code sample easier to read. The position property is just a Vector2 for where each object is located. ray = new Ray(new Vector3(player.Position, 0), new Vector3(mouse.Position, 0); box = new BoundingBox(new Vector3(box.Position, 0), new Vector3( new Vector2(box.Position + box.Width, box.Position + box.Height), 0); if (ray.Intersects(box) != null) collision = true; else collision = false;

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• Application Scope v's Static - Not Quite the same

  - by Duncan Mills

  An interesting question came up today which, innocent as it sounded, needed a second or two to consider. What's the difference between storing say a Map of reference information as a Static as opposed to storing the same map as an application scoped variable in JSF?  From the perspective of the web application itself there seems to be no functional difference, in both cases, the information is confined to the current JVM and potentially visible to your app code (note that Application Scope is not magically propagated across a cluster, you would need a separate instance on each VM). To my mind the primary consideration here is a matter of leakage. A static will be (potentially) visible to everything running within the same VM (OK this depends on which class-loader was used but let's keep this simple), and this includes your model code and indeed other web applications running in the same container. An Application Scoped object, in JSF terms, is much more ring-fenced and is only visible to the Web app itself, not other web apps running on the same server and not directly to the business model layer if that is running in the same VM. So given that I'm a big fan of coding applications to say what I mean, then using Application Scope appeals because it explicitly states how I expect the data to be used and a provides a more explicit statement about visibility and indeed dependency as I'd generally explicitly inject it where it is needed.  Alternative viewpoints / thoughts are, as ever, welcomed...

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• Name for Osherove's modified singleton pattern?

  - by Kazark

  I'm pretty well sold on the "singletons are evil" line of thought. Nevertheless, there are limited occurrences when you want to limit the creation of an object. Roy Osherove advises, If you're planning to use a singleton in your design, separate the logic of the singleton class and the logic that makes it a singleton (the part that initializes a static variables, for example) into two separate classes. That way, you can keep the single responsibility principle (SRP) and also have a way to override singleton logic. (The Art of Unit Testing 261-262) This pattern still perpetuates the global state. However, it does result in a testable design, so it seems to me to be a good pattern for mitigating the damage of a singleton. However, Osherove does not give a name to this pattern; but naming a pattern, according to the Gang of Four, is important: Naming a pattern immediately increases our design vocabulary. It lets us design at a higher level of abstraction. (3) Is there a standard name for this pattern? It seems different enough from a standard singleton to deserve a separate name. Decoupled Singleton, perhaps?

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• Develop and Use Applications with MySQL and PHP

  - by Antoinette O'Sullivan

  Want to develop and use applications with PHP and the MySQL database? Consider taking the MySQL and PHP: Developing Dynamic Web Applications training course. Before taking this course you should: Understand how HTML files are assembled Understand fundamental PHP syntax Have some programming experience (preferably PHP) Have some experience with relational databases Have some knowledge of Object-Oriented Programming This 4-day live, instructor-led course is perfect for developers who use PHP and MySQL to build and maintain their websites and who want to learn how PHP and MySQL can be used to rapidly prototype and deploy dynamic websites. You can take this course as a: Live-virtual event: Take this event from your own desk, no travel required, choosing from a selection of virtual events already on the schedule. In-class event: Travel to an education center to take this course. Below is a selection of events already on the schedule.  Location  Date  Delivery Language  Jakarta, Indonesia  3 December 2013 English   Rome, Italy  5 May 2014 Italian   Turin, Italy 17 March 2014  Italian   Warsaw, Poland 12 November 2013  Polish   Madrid, Spain  16 December 2013  Spanish  Tunis, Tunisia 17 March 2014  French For more information on the authentic MySQL curriculum, go to http://oracle.com/education/mysql.

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