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• When should one use "out" parameters?

  - by qegal

  In Objective-C, there are several methods like initWithContentsOfFile:encoding:error: where one passes in a reference to an NSError object for the error: parameter. In this example, the value of the NSError object passed in can change based on what goes on at runtime when the method is being called and whether the body of the method was executed in a certain way successfully. In a way I think of this NSError object as sort of like a second return value from the method, and only differs from an object anObject in the statement return anObject; in that when this statement is called, execution leaves the method. So my question is, not only in the context of error handling in Objective-C, but in general, when should one use an "out" parameter in place of returning said value in a return statement?

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• Non-trivial functions that operate on any monad

  - by Strilanc

  I'm looking for examples of interesting methods that take an arbitrary monad and do something useful with it. Monads are extremely general, so methods that operate on monads are widely applicable. On the other hand, methods I know of that can apply to any monad tend to be... really, really trivial. Barely worth extracting into a function. Here's a really boring example: joinTwice. It just flattens an m m m t into an m t: join n = n >>= id joinTwice n = (join . join) n main = print (joinTwice [[[1],[2, 3]], [[4]]]) -- prints [1,2,3,4] The only non-trivial method for monads that I know of is bindFold (see my answer below). Are there more?

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• How to perform game object smoothing in multiplayer games

  - by spaceOwl

  We're developing an infrastructure to support multiplayer games for our game engine. In simple terms, each client (player) engine sends some pieces of data regarding the relevant game objects at a given time interval. On the receiving end, we step the incoming data to current time (to compensate for latency), followed by a smoothing step (which is the subject of this question). I was wondering how smoothing should be performed ? Currently the algorithm is similar to this: Receive incoming state for an object (position, velocity, acceleration, rotation, custom data like visual properties, etc). Calculate a diff between local object position and the position we have after previous prediction steps. If diff doesn't exceed some threshold value, start a smoothing step: Mark the object's CURRENT POSITION and the TARGET POSITION. Linear interpolate between these values for 0.3 seconds. I wonder if this scheme is any good, or if there is any other common implementation or algorithm that should be used? (For example - should i only smooth out the position? or other values, such as speed, etc) any help will be appreciated.

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• Entry level engineer question regarding memory mangement

  - by Ealianis

  It has been a few months since I started my position as an entry level software developer. Now that I am past some learning curves (e.g. the language, jargon, syntax of VB and C#) I'm starting to focus on more esoteric topics, as to write better software. A simple question I presented to a fellow coworker was responded with "I'm focusing on the wrong things." While I respect this coworker I do disagree that this is a "wrong thing" to focus upon. Here was the code (in VB) and followed by the question. Note: The Function GenerateAlert() returns an integer. Dim alertID as Integer = GenerateAlert() _errorDictionary.Add(argErrorID, NewErrorInfo(Now(), alertID)) vs... _errorDictionary.Add(argErrorID, New ErrorInfo(Now(), GenerateAlert())) I originally wrote the ladder and rewrote it with the "Dim alertID" so that someone else might find it easier to read. But here was my concern and question. "Should one write this with the Dim AlertID, it would in fact take up more memory; finite but more, and should this method be called many times could it lead to an issue? How will .NET handle this object AlertID. Outside of .NET should one manually dispose of the object after use (near the end of the sub)." I want to ensure I become a knowledgeable programmer that does not just rely upon garbage collection. Am I over thinking this? Am I focusing on the wrong things?

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• Is deserializing complex objects instead of creating them a good idea, in test setup?

  - by Chris Bye

  I'm writing tests for a component that takes very complex objects as input. These tests are mixes of tests against already existing components, and test-first tests for new features. Instead of re-creating my input objects (this would be a large chunk of code) or reading one from our data store, I had the thought to serialize a live instance of one of these objects, and just deserialize it into test setup. I can't decide if this is a reasonable idea that will save effort in long run, or whether it's the worst idea that I've ever had, causing those that will maintain this code will hunt me down as soon as they read it. Is deserialization of inputs a valid means of test setup in some cases? To give a sense of scale of what I'm dealing with, the size of serialization output for one of these input objects is 93KB. Obtained by, in C#: new BinaryFormatter().Serialize((Stream)fileStream, myObject);

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• What are the benefits vs costs of comment annotation in PHP?

  - by Patrick

  I have just started working with symfony2 and have run across comment annotations. Although comment annotation is not an inherent part of PHP, symfony2 adds support for this feature. My understanding of commenting is that it should make the code more intelligible to the human. The computer shouldn't care what is in comments. What benefits come from doing this type of annotation versus just putting a command in the normal PHP code? ie- /** * @Route("/{id}") * @Method("GET") * @ParamConverter("post", class="SensioBlogBundle:Post") * @Template("SensioBlogBundle:Annot:post.html.twig", vars={"post"}) * @Cache(smaxage="15") */ public function showAction(Post $post) { }

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• Would you want a language to support something like "Retry/Fix"?

  - by Aaron Anodide

  I was just wondering if a language could support something like a Retry/Fix block? The answer to this question is probably the reason it's a bad idea or equivalent to something else, but the idea keeps popping into my head. void F() { try { G(); } fix(WrongNumber wn, out int x) { x = 1; } } void G() { int x = 0; retry<int> { if(x != 1) throw new WrongNumber(x); } } After the fix block ran, the retry block would run again...

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• Which parallel pattern to use?

  - by Wim Van Houts

  I need to write a server application that fetches mails from different mail servers/mailboxes and then needs to process/analyze these mails. Traditionally, I would do this multi-threaded, launching a thread for fetching mails (or maybe one per mailbox) and then process the mails. We are moving more and more to servers where we have 8+ cores, so I would like to make use of these cores as much as possible (and not use 1 at 100% and leave the seven others untouched). So conceptually, as an example, it would be nice that I could write the application in such a way that two cores are "continuously" fetching emails and four cores are "continuously" processing/analyzing the emails (since processing and analyzing mails is more CPU intensive than fetching mails). This seems like a good concept, but after studying some parallel patterns, I'm not really sure how this is best implemented. None of the patterns really fit. I'm working in VS2012, native C++, but I guess from a design point of view this does not really matter and just some pointers on how to organize this would be great!

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• Immutable design with an ORM: How are sessions managed?

  - by Programmin Tool

  If I were to make a site with a mutable language like C# and use NHibernate, I would normally approach sessions with the idea of making them as create only when needed and dispose at request end. This has helped with keeping a session for multiple transactions by a user but keep it from staying open too long where the state might be corrupted. In an immutable system, like F#, I would think I shouldn't do this because it supposes that a single session could be updated constantly by any number of inserts/updates/deletes/ect... I'm not against the "using" solution since I would think that connecting pooling will help cut down on the cost of connecting every time, but I don't know if all database systems do connection pooling. It just seems like there should be a better way that doesn't compromise the immutability goal. Should I just do a simple "using" block per transaction or is there a better pattern for this?

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• I'm having trouble understanding these exercises wording.

  - by KasHKoW

  Exercise 1-20. Write a program detab that replaces tabs in the input with the proper number of blanks to space to the next tab stop. Assume a fixed set of tab stops, say every n columns. Should n be a variable or a symbolic parameter? Exercise 1-21. Write a program entab that replaces strings of blanks by the minimum number of tabs and blanks to achieve the same spacing. Use the same tab stops as for detab. When either a tab or a single blank would suffice to reach a tab stop, which should be given preference? could you paraphrase these for me. thanks

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• Is it a bad practice to include all the enums in one file and use it in multiple classes?

  - by Bugster

  I'm an aspiring game developer, I work on occasional indie games, and for a while I've been doing something which seemed like a bad practice at first, but I really want to get an answer from some experienced programmers here. Let's say I have a file called enumList.h where I declare all the enums I want to use in my game: // enumList.h enum materials_t { WOOD, STONE, ETC }; enum entity_t { PLAYER, MONSTER }; enum map_t { 2D, 3D }; // and so on. // Tile.h #include "enumList.h" #include <vector> class tile { // stuff }; The main idea is that I declare all enums in the game in 1 file, and then import that file when I need to use a certain enum from it, rather than declaring it in the file where I need to use it. I do this because it makes things clean, I can access every enum in 1 place rather than having pages openned solely for accessing one enum. Is this a bad practice and can it affect performance in any way?

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• How to export user input data from python to excel?

  - by mrn

  I am trying to develop a user form in python 2.7.3. Please note that I am a python beginner. I am trying to use xlwt to export data to excel. I want to write values of following variables i.e. a (value to write:'x1') & d (value to write: be user defined information in text box), to an excel sheet, a=StringVar() checkBox1=Checkbutton(root, text="text1", variable=a, onvalue="x1", offvalue="N/A") checkBox1.place(relx=0., rely=0., relwidth=0., relheight=0.) checkBox1.pack() d=StringVar() atextBox1=Entry(root, textvariable=d, font = '{MS Sans Serif} 10') atextBox1.pack() Need help badly. Thank you so much in advance

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• Draw contour around object in Opengl

  - by Maciekp

  I need to draw contour around 2d objects in 3d space. I tried drawing lines around object(+points to fill the gap), but due to line width, some part of it(~50%) was covering object. I tried to use stencil buffer, to eliminate this problem, but I got sth like this(contour is green): http://goo.gl/OI5uc (sorry I can't post images, due to my reputation) You can see(where arrow points), that some parts of line are behind object, and some are above. This changes when I move camera, but always there is some part, that is covering it. Here is code, that I use for drawing object: glColorMask(1,1,1,1); std::list<CObjectOnScene*>::iterator objIter=ptr->objects.begin(),objEnd=ptr->objects.end(); int countStencilBit=1; while(objIter!=objEnd) { glColorMask(1,1,1,1); glStencilFunc(GL_ALWAYS,countStencilBit,countStencilBit); glStencilOp(GL_REPLACE,GL_KEEP,GL_REPLACE ); (*objIter)->DrawYourVertices(); glStencilFunc(GL_NOTEQUAL,countStencilBit,countStencilBit); glStencilOp(GL_KEEP,GL_KEEP,GL_REPLACE); (*objIter)->DrawYourBorder(); ++objIter; ++countStencilBit; } I've tried different settings of stencil buffer, but always I was getting sth like that. Here is question: 1.Am I setting stencil buffer wrong? 2. Are there any other simple ways to create contour on such objects? Thanks in advance. EDIT: 1. I don't have normals of objects. 2. Object can be concave. 3. I can't use shaders(see below why).

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• Should I concentrate on writing code for money or my studies while in college?

  - by A-Cube

  I am college student of Software Engineering. My worries are that while I am concentrating on my studies, my peers are getting down with the code (e.g. HTML, ASP, PHP, etc) to earn money. Should I be worried that I am not doing coding like them? I was asked to be Microsoft Student Partner but I refused because the person what was doing before me told it was just arranging events. Nothing as such like getting with Microsoft and coding. Should I be writing code and earning money as I still am in 4th semester? I only have C++ as learning language in college. Will my job count on these projects that I do, or should I concentrate on studies for now to get maximum benefit?

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• is jargon related to a frameWork (concept)

  - by MaKo

  If this is not the right place to ask this question please inform where it would belong, to change it... I have a doubt for the correct word or concept in english language [not my native], about the relationship of language to framework for example i work with objective C, with the cocoa touch frame work || python with the django frame work My comparison is between natural languages and formal languages, So would be in a natural language english and the frame work a [computer, it]jargon? Does this make sense? Or what other concept would be the relationship between natural language - framework?

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• Why is this beat detection code failing to register some beats properly?

  - by Quincy

  I made this SoundAnalyzer class to detect beats in songs: class SoundAnalyzer { public SoundBuffer soundData; public Sound sound; public List<double> beatMarkers = new List<double>(); public SoundAnalyzer(string path) { soundData = new SoundBuffer(path); sound = new Sound(soundData); } // C = threshold, N = size of history buffer / 1024 B = bands public void PlaceBeatMarkers(float C, int N, int B) { List<double>[] instantEnergyList = new List<double>[B]; GetEnergyList(B, ref instantEnergyList); for (int i = 0; i < B; i++) { PlaceMarkers(instantEnergyList[i], N, C); } beatMarkers.Sort(); } private short[] getRange(int begin, int end, short[] array) { short[] result = new short[end - begin]; for (int i = 0; i < end - begin; i++) { result[i] = array[begin + i]; } return result; } // get a array of with a list of energy for each band private void GetEnergyList(int B, ref List<double>[] instantEnergyList) { for (int i = 0; i < B; i++) { instantEnergyList[i] = new List<double>(); } short[] samples = soundData.Samples; float timePerSample = 1 / (float)soundData.SampleRate; int sampleIndex = 0; int nextSamples = 1024; int samplesPerBand = nextSamples / B; // for the whole song while (sampleIndex + nextSamples < samples.Length) { complex[] FFT = FastFourier.Calculate(getRange(sampleIndex, nextSamples + sampleIndex, samples)); // foreach band for (int i = 0; i < B; i++) { double energy = 0; for (int j = 0; j < samplesPerBand; j++) energy += FFT[i * samplesPerBand + j].GetMagnitude(); energy /= samplesPerBand; instantEnergyList[i].Add(energy); } if (sampleIndex + nextSamples >= samples.Length) nextSamples = samples.Length - sampleIndex - 1; sampleIndex += nextSamples; samplesPerBand = nextSamples / B; } } // place the actual markers private void PlaceMarkers(List<double> instantEnergyList, int N, float C) { double timePerSample = 1 / (double)soundData.SampleRate; int index = N; int numInBuffer = index; double historyBuffer = 0; //Fill the history buffer with n * instant energy for (int i = 0; i < index; i++) { historyBuffer += instantEnergyList[i]; } // If instantEnergy / samples in buffer < instantEnergy for the next sample then add beatmarker. while (index + 1 < instantEnergyList.Count) { if(instantEnergyList[index + 1] > (historyBuffer / numInBuffer) * C) beatMarkers.Add((index + 1) * 1024 * timePerSample); historyBuffer -= instantEnergyList[index - numInBuffer]; historyBuffer += instantEnergyList[index + 1]; index++; } } } For some reason it's only detecting beats from 637 sec to around 641 sec, and I have no idea why. I know the beats are being inserted from multiple bands since I am finding duplicates, and it seems that it's assigning a beat to each instant energy value in between those values. It's modeled after this: http://www.flipcode.com/misc/BeatDetectionAlgorithms.pdf So why won't the beats register properly?

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• What is the term for a really BIG source code commit?

  - by Ida

  Sometimes when we check the commit history of a software, we may see that there are a few commits that are really BIG - they may change 10 or 20 files with hundreds of changed source code lines (delta). I remember that there is a commonly used term for such BIG commit but I can't recall exactly what that term is. Can anyone help me? What is the term that programmers usually use to refer to such BIG and giant commit? BTW, is committing a lot of changes all together a good practice? UPDATE: thank you guys for the inspiring discussion! But I think "code bomb" is the term that I'm looking for.

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• The advantages & disadvantages to be had from using a Web Framework?

  - by JHarley1

  Hello, This question is focused on extracting the advantages and disadvantages of using Web based Frameworks: such as Cake PHP, Zend, jQuery, ASP.NET). This question is completely language agnostic. Let me start with the notion of "Standing on the shoulders of Giants". Advantages: Empowers Developers - by taking features that would have previously have taken 100's of lines of code and compressing them into one simple function call empowers developers to integrate more complex features into their Web Sites. Allow for Quicker development of applications - this is very relevant for people that need websites created in a very small window (has anyone any examples of this?) Lower Costs - allows programmers to pass cost savings onto the customer, a whole new range of customers generated that wanted a website but previously could not afford the higher development costs. Disadvantages: Lost Understanding - by relying on the features of a framework a developer is in danger of loosing understanding on how things work (underneath the hood). The configuration cliff - once you go further than the configuration of your framework your productivity drops right off, it can be difficult to implement features outside of a frameworks configuration. Developer tramlines - you (the developer) has to do things the way that the developer want you to do things. Security issues - giving people these tools to develop professional looking websites fast is a potential risk, people can quickly create professional looking websites for fraudulent companies. I wonder what people make of my points, and whether any body disagrees with them? Also if people have additional points I would be grateful. Many Thanks, J

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• How Is there anyway to Compile Notepad++?

  - by user44179

  I really like using Notepad++ to write HTML and such. After I started using Ubuntu I looked around for an alternative to Notpad++. I found a thread which lead me to try Geany and a few others, but I really miss Notepad++. Is there anyway I could compile it from the source code to use on Ubuntu? I know its written in C++. Could I just open it in Code::Blocks and compile it? You can get the source here. I wouldn't mind hearing about other alternatives, but really want to know if compiling it is possible. Thanks

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• What is the annoying/lacking feature in C#, in your opinion?

  - by Vimvq1987

  To be honest, I'm working with C# everyday, and I can say that I love its elegant syntax. But no language is perfect, so does C#. In my opinion, these two features are missing: Full-featured enum. I was pretty happy with enum in C#, until I know about enum in Java. Of course, we can "simulate" a full-featured enum in C# by class, but it's much better if Microsoft simplify this. Immutable keyword. We are told to let a class/struct immutable whenever possible. But to do that, we have to add readonly keyword to every field, and then if we add setter by a mistake, our class will be mutable, and nobody knows. By immutable keyword, every field will be automatically readonly, and any setter will be prohibited (error when compile). It's like static keyword added to class in C# 2.0 well. what's is your annoying/lacking feature in C#?

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• Is Akka a good solution for a concurrent pipeline/workflow problem?

  - by herpylderp

  Disclaimer: I am brand new to Akka and the concept of Actors/Event-Driven Architectures in general. I have to implement a fairly complex problem where users can configure a "concurrent pipeline": Pipeline: consists of 1+ Stages; all Stages execute sequentially Stage: consists of 1+ Tasks; all Tasks execute in parallel Task: essentially a Java Runnable As you can see above, a Task is a Runnable that does some unit of work. Tasks are organized into Stages, which execute their Tasks in parallel. Stages are organized into the Pipeline, which executes its Stages sequentially. Hence if a user specifies the following Pipeline: CrossTheRoadSafelyPipeline Stage 1: Look Left Task 1: Turn your head to the left and look for cars Task 2: Listen for cars Stage 2: Look right Task 1: Turn your head to the right and look for cars Task 2: Listen for cars Then, Stage 1 will execute, and then Stage 2 will execute. However, while each Stage is executing, it's individual Tasks are executing in parallel/at the same time. In reality Pipelines will become very complicated, and with hundreds of Stages, dozens of Tasks per Stage (again, executing at the same time). To implement this Pipeline I can only think of several solutions: ESB/Apache Camel Guava Event Bus Java 5 Concurrency Actors/Akka Camel doesn't seem right because its core competency is integration not synchrony and orchestration across worker threads. Guava is great, but this doesn't really feel like a subscriber/publisher-type of problem. And Java 5 Concurrency (ExecutorService, etc.) just feels too low-level and painful. So I ask: is Akka a strong candidate for this type of problem? If so, how? If not, then why, and what is a good candidate?

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• libgtk2.0-common fails to build with Gdk-2.0.gir error, Type reference 'GdkPixbuf' not found

  - by Stefano Palazzo

  I'm trying to build gtk, but it fails. Here's what I'm doing: sudo apt-get build-dep libgtk2.0-common sudo apt-get source libgtk2.0-common cd gtk+2.0-2.22.0/ sudo gedit gtk/gtktreeview.c & #...editing a few files (or not, it's the same error) sudo ./configure --prefix=/usr sudo make The compilation runs for a while and then quits: Gdk-2.0.gir: error: Type reference 'GdkPixbuf' not found ... make: *** [all] Error 2 What am I doing wrong?

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• What are the benefits of Android way of "saving memory" - explicitly passing Context objects everywhere?

  - by Sarge Borsch

  Turned out, this question is not easy to formulate for me, but let's try. In Android, pretty much any UI object depends on a Context, and has defined lifetime. It also can destroy and recreate UI objects and even whole application process at any time, and so on. This makes coding asynchronous operations correctly not straightforward. (and sometimes very cumbersome) But I never have seen a real explanation, why it's done that way? There are other OSes, including mobile OSes (iOS, for example), that don't do such things. So, what are the wins of Android way (Activities & Contexts)? Does that allow Android applications to use much less RAM, or maybe there are other benefits?

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• Develop a small size software using C only for copying same data to multiple external drives simultaneously [on hold]

  - by VSP

  I want to develop a software that can copy the same data to multiple external drives, simultaneously. For example, consider a file Movie and I have 3 external drives to copy it to, and I want to copy Movie to all these 3 drives(these drives can be flash storage or external hard-disk or pen-drive etc. but have one thing in common, i.e. they are all external drives) at the same time, means when I right-click on Movie there has to be 1 option saying Copy to All Drives. It's a sort of mini-project and I want to use C language only. For starting I would like it to work only on Windows OS. What are the requirements of developing this software (not the system requirements but what will I need to develop such a software, like editor,compiler etc.)? I know this type of software must have already been developed but I want to use C language and C Language only. So, is it possible to develop such a software?

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• Callbacks: when to return value, and when to modify parameter?

  - by MarkN

  When writing a callback, when is best to have the callback return a value, and when is it best to have the callback modify a parameter? Is there a difference? For example, if we wanted to grab a list of dependencies, when would you do this: function GetDependencies(){ return [{"Dep1" : 1.1}, {"Dept2": 1.2}, {"Dep3" : 1.3}]; } And when would you do this? function RegisterDependencies(register){ register.add("Dep1", 1.1); register.add("Dep2", 1.2); register.add("Dep3", 1.3); }

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