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• Which is preferable? To know jQuery well, or to know JavaScript well? [closed]

  - by Marwan

  I'm quite familiar with using jQuery, but I've come to feel like a bit of a dummy using it, as my knowledge of JavaScript itself is rather poor. So I'm considering abandoning jQuery and spending time working in straight JS... perhaps even creating my own framework as a learning experience. Does this make sense though? Is there any real point to obtaining more than a passing knowledge of JavaScript when jQuery allows me to accomplish so much, so quickly?

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• Push-Based Events in a Services Oriented Architecture

  - by Colin Morelli

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

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• Are there currently any modern, standardized, aptitude test for software engineering?

  - by Matthew Patrick Cashatt

  Background I am a working software engineer who is in the midst of seeking out a new contract for the next year or so. In my search, I am enduring several absurd technical interviews as indicated by this popular question I asked earlier today. Even if the questions I was being asked weren't almost always absurd, I would be tired nonetheless of answering them many times over for various contract opportunities. So this got me thinking that having a standardized exam that working software professionals could take would provide a common scorecard that could be referenced by interviewers in lieu of absurd technical interview questions (i.e. nerd hazing). Question Is there a standardized software engineering aptitude test (SEAT??) available for working professionals to take? If there isn't a such an exam out there, what questions or topics should be covered? An additional thought Please keep in mind, if suggesting a question or topic, to focus on questions or topics that would be relevant to contemporary development practices and realistic needs in the workforce as that would be the point of a standard aptitude test. In other words, no clown traversal questions.

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• Refactoring and Open / Closed principle

  - by Giorgio

  I have recently being reading a web site about clean code development (I do not put a link here because it is not in English). One of the principles advertised by this site is the Open Closed Principle: each software component should be open for extension and closed for modification. E.g., when we have implemented and tested a class, we should only modify it to fix bugs or to add new functionality (e.g. new methods that do not influence the existing ones). The existing functionality and implementation should not be changed. I normally apply this principle by defining an interface I and a corresponding implementation class A. When class A has become stable (implemented and tested), I normally do not modify it too much (possibly, not at all), i.e. If new requirements arrive (e.g. performance, or a totally new implementation of the interface) that require big changes to the code, I write a new implementation B, and keep using A as long as B is not mature. When B is mature, all that is needed is to change how I is instantiated. If the new requirements suggest a change to the interface as well, I define a new interface I' and a new implementation A'. So I, A are frozen and remain the implementation for the production system as long as I' and A' are not stable enough to replace them. So, in view of these observation, I was a bit surprised that the web page then suggested the use of complex refactorings, "... because it is not possible to write code directly in its final form." Isn't there a contradiction / conflict between enforcing the Open / Closed Principle and suggesting the use of complex refactorings as a best practice? Or the idea here is that one can use complex refactorings during the development of a class A, but when that class has been tested successfully it should be frozen?

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

  - by Channel72

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

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

  - by Ramkumar

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

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• undefined control sequence in a NOWEB document

  - by Jean Baldraque

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

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• Which web site gives the most accurate indication of a programmer's capabilities?

  - by Jerry Coffin

  If you were hiring programmers, and could choose between one of (say) the top 100 coders on topcoder.com, or one of the top 100 on stackoverflow.com, which would you choose? At least to me, it would appear that topcoder.com gives a more objective evaluation of pure ability to solve problems and write code. At the same time, despite obvious technical capabilities, this person may lack any hint of social skills -- he may be purely a "lone coder", with little or no ability to help/work with others, may lack mentoring ability to help transfer his technical skills to others, etc. On the other hand, stackoverflow.com would at least appear to give a much better indication of peers' opinion of the coder in question, and the degree to which his presence and useful and helpful to others on the "team". At the same time, the scoring system is such that somebody who just throws up a lot of mediocre (or even poor answers) will almost inevitably accumulate a positive total of "reputation" points -- a single up-vote (perhaps just out of courtesy) will counteract the effects of no fewer than 5 down-votes, and others are discouraged (to some degree) from down-voting because they have to sacrifice their own reputation points to do so. At the same time, somebody who makes little or no technical contribution seems unlikely to accumulate a reputation that lands them (even close to) the top of the heap, so to speak. So, which provides a more useful indication of the degree to which this particular coder is likely to be useful to your organization? If you could choose between them, which set of coders would you rather have working on your team?

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• Is the copy/paste approach professionally viable when working with the Google Maps API?

  - by Ian Campbell

  I find that I understand much of the Javascript concepts used in the Google Maps API code, but then again there is quite a bit that is way over my head in syntax. For example, the geocoder syntax seems to be of Ajax form, though I don't understand what is happening under the hood (especially with lines like results[0].geometry.location). I am able to modify the body of if (status == google.maps.GeocoderStatus.OK) for different purposes though. So, being that I am able to take various code from the Developer's Guide and rework it to an extent for my own purposes, all the while not fully understanding what Google Maps is actually doing, does this make me a copy-paste programmer? Is this a bad practice, or is this professionally viable? I am, of course, interested in learning as much as I can, but what if time-constraints outweigh the learning process?

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• Generalise variable usage inside code

  - by Shirish11

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

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

  - by Griffin

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

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• Should I modify an entity with many parameters or with the entity itself?

  - by Saeed Neamati

  We have a SOA-based system. The service methods are like: UpdateEntity(Entity entity) For small entities, it's all fine. However, when entities get bigger and bigger, to update one property we should follow this pattern in UI: Get parameters from UI (user) Create an instance of the Entity, using those parameters Get the entity from service Write code to fill the unchanged properties Give the result entity to the service Another option that I've experienced in previous experiences is to create semantic update methods for each update scenario. In other words instead of having one global all-encompasing update method, we had many ad-hoc parametric methods. For example, for the User entity, instead of having UpdateUser (User user) method, we had these methods: ChangeUserPassword(int userId, string newPassword) AddEmailToUserAccount(int userId, string email) ChangeProfilePicture(int userId, Image image) ... Now, I don't know which method is truly better, and for each approach, we encounter problems. I mean, I'm going to design the infrastructure for a new system, and I don't have enough reasons to pick any of these approaches. I couldn't find good resources on the Internet, because of the lack of keywords I could provide. What approach is better? What pitfalls each has? What benefits can we get from each one?

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

  - by Gopinath

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

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

  - by Ken

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

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• Why to say, my function is of IFly type rather than saying it's Airplane type

  - by Vishwas Gagrani

  Say, I have two classes: Airplane and Bird, both of them fly. Both implement the interface IFly. IFly declares a function StartFlying(). Thus both Airplane and Bird have to define the function, and use it as per their requirement. Now when I make a manual for class reference, what should I write for the function StartFlying? 1) StartFlying is a function of type IFly . 2) StartFlying is a function of type Airplane 3) StartFlying is a function of type Bird. My opinion is 2 and 3 are more informative. But what i see is that class references use the 1st one. They say what interface the function is declared in. Problem is, I really don't get any usable information from knowing StartFlying is IFly type. However, knowing that StartFlying is a function inside Airplane and Bird, is more informative, as I can decide which instance (Airplane or Bird ) to use. Any lights on this: how saying StartFlying is a function of type IFly, can help a programmer understanding how to use the function?

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• At $20/month Windows Azure host my website with 99.97% uptime

  - by Gopinath

  Couple of years ago a reliable and decent performing Windows hosting was not affordable to many enthusiastic developers who want to try a startup idea or build a hobby site. I tried to start an ASP.NET website few years ago to provide services like – Mobile Tracing, Vehicle Tracing. But due to high cost of Windows hosting I developed those services using PHP (not an easy task for .NET developer) and hosted on them Linux servers.  But with recent evolution of Windows Azure, hosting ASP.NET websites on highly reliable servers is affordable. Today anyone can host a high responsive and available ASP.NET website for just $20/month using Windows Azure. My website coziie.com is running on Windows Azure and serves close to quarter millions visitors a month with 99.97% of uptime and most of the page load times are less than 3 seconds. All I spend to run this website is just around $20, if you translate it to India rupees its roughly Rs.1000. The web sever of coziie.com is powered by a single Extra Small Web role instance and the backend is powered by a SQL Azure instance. Azure is quite impressive to provide 99.97% of uptime. Response times during peak are around 3 seconds and on nomarl loads it is around 1.5 seconds. Here is the report of uptime provided by Royal Pingdom over last one year For just $20/month Windows Azure takes care of the following apart from hosting Patches up Windows OS to the latest version Upgrades ASP.NET to the latest version – coziie.com is running on ASP.NET MVC 3 and soon I’ll upgrade it to ASP.NET MVC 4 Hosts data on latest and best version Sql Server database SQL Azure maintains 3 copies of database and automatically recovers in case of server failures and disasters. I never worry about database backups/restore. Provides staging environment for deploying applications for testing purpose and move them to production – I upgrade  twice a month on average With Windows Azure I no longer focus on server maintenance or data backups. They are taken up by Microsoft team and I just focus on building my website. Wish there is a low cost Linux version of Windows Azure so that I can stop worrying about server maintenance of this blog!! If you are looking for a Windows hosting, look no further than Windows Azure. If you find $20/month is a bit expensive to start with you may explore Azure Website (sort of shared hosted environment) which is free to start with and as your traffic grows you can move to paid hosting.

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• Motivation and use of move constructors in C++

  - by Giorgio

  I recently have been reading about move constructors in C++ (see e.g. here) and I am trying to understand how they work and when I should use them. As far as I understand, a move constructor is used to alleviate the performance problems caused by copying large objects. The wikipedia page says: "A chronic performance problem with C++03 is the costly and unnecessary deep copies that can happen implicitly when objects are passed by value." I normally address such situations by passing the objects by reference, or by using smart pointers (e.g. boost::shared_ptr) to pass around the object (the smart pointers get copied instead of the object). What are the situations in which the above two techniques are not sufficient and using a move constructor is more convenient?

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• "Opportunity" to take over maintenance of a small internal website. What should I do?

  - by Dan

  I have been offered an "opportunity" to take over maintenance of a small internal website run by my group that provides information about schedules and photos of events the groups done. My manager sent me the link to the site and checked it out. The site looked clean and neat but loaded in ~5 seconds. I thought this was a little long considering the site really didn't contain a lot of content. This prompted me to take a look under the hood at the pages source code. To my horror it'd been totally hacked together using nested tables! I'm new so I really can't say no to this "opportunity" so what should I do with it? Every fiber of my being feels that the only correct thing to do is over hall the site using CSS, Div's, Span's and any other appropriate tags that a sane/good web developer would used to begin with instead of depending on the render incentive magic of tables. But I'd like to ask programmers with more experienced then me, who have been in this situation. What should I do? Is my only realistic option to leave the horror as is and only adjusting the content as requested? I'm really torn between good development and the corporate reality I'm part of. Is there some kind of middle ground where things can be made better even if they're not perfect? Thanks ahead of time.

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• What is the meaning of 'high cohesion'?

  - by Max

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

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• What is the difference between industrial development and open source development?

  - by Ida

  Intuitively, I think open source development should be much more "casual" than industrial development process (like in Microsoft). Because for OSS development: Duty separation is not that strict than in big companies (maybe developers == testers in open source development?) People come in and out of the open source community, much more frequently than in big companies However, above are just my guesses. I really want to know more about the major difference between the open source and industrial development. Is their division of duty totally different (e.g., is there a leader/manager-like role in open source development?)? Maybe it is their communication style that differs a lot? Or their workflow? Please share your opinions. Thanks a lot!

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

  - by Nocturne

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

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• Is it bad practice to output from within a function?

  - by Nick

  For example, should I be doing something like: <?php function output_message($message,$type='success') { ?> <p class="<?php echo $type; ?>"><?php echo $message; ?></p> <?php } output_message('There were some errors processing your request','error'); ?> or <?php function output_message($message,$type='success') { ob_start(); ?> <p class="<?php echo $type; ?>"><?php echo $message; ?></p> <?php return ob_get_clean(); } echo output_message('There were some errors processing your request','error'); ?> I understand they both achieve the same end result, but are there benefits doing one way over the other? Or does it not even matter?

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• BDD: Getting started

  - by thom

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

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

  - by Ilian Pinzon

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

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• Objects won't render when Texture Compression + Mipmapping is Enabled

  - by felipedrl

  I'm optimizing my game and I've just implemented compressed (DXTn) texture loading in OpenGL. I've worked my way removing bugs but I can't figure out this one: objects w/ DXTn + mipmapped textures are not being rendered. It's not like they are appearing with a flat color, they just don't appear at all. DXTn textured objs render and mipmapped non-compressed textures render just fine. The texture in question is 256x256 I generate the mips all the way down 4x4, i.e 1 block. I've checked on gDebugger and it display all the levels (7) just fine. I'm using GL_LINEAR_MIPMAP_NEAREST for min filter and GL_LINEAR for mag one. The texture is being compressed and mipmaps being created offline with Paint.NET tool using super sampling method. (I also tried bilinear just in case) Source follow: [SNIPPET 1: Loading DDS into sys memory + Initializing Object] // Read header DDSHeader header; file.read(reinterpret_cast<char*>(&header), sizeof(DDSHeader)); uint pos = static_cast<uint>(file.tellg()); file.seekg(0, std::ios_base::end); uint dataSizeInBytes = static_cast<uint>(file.tellg()) - pos; file.seekg(pos, std::ios_base::beg); // Read file data mData = new unsigned char[dataSizeInBytes]; file.read(reinterpret_cast<char*>(mData), dataSizeInBytes); file.close(); mMipmapCount = header.mipmapcount; mHeight = header.height; mWidth = header.width; mCompressionType = header.pf.fourCC; // Only support files divisible by 4 (for compression blocks algorithms) massert(mWidth % 4 == 0 && mHeight % 4 == 0); massert(mCompressionType == NO_COMPRESSION || mCompressionType == COMPRESSION_DXT1 || mCompressionType == COMPRESSION_DXT3 || mCompressionType == COMPRESSION_DXT5); // Allow textures up to 65536x65536 massert(header.mipmapcount <= MAX_MIPMAP_LEVELS); mTextureFilter = TextureFilter::LINEAR; if (mMipmapCount > 0) { mMipmapFilter = MipmapFilter::NEAREST; } else { mMipmapFilter = MipmapFilter::NO_MIPMAP; } mBitsPerPixel = header.pf.bitcount; if (mCompressionType == NO_COMPRESSION) { if (header.pf.flags & DDPF_ALPHAPIXELS) { // The only format supported w/ alpha is A8R8G8B8 massert(header.pf.amask == 0xFF000000 && header.pf.rmask == 0xFF0000 && header.pf.gmask == 0xFF00 && header.pf.bmask == 0xFF); mInternalFormat = GL_RGBA8; mFormat = GL_BGRA; mDataType = GL_UNSIGNED_BYTE; } else { massert(header.pf.rmask == 0xFF0000 && header.pf.gmask == 0xFF00 && header.pf.bmask == 0xFF); mInternalFormat = GL_RGB8; mFormat = GL_BGR; mDataType = GL_UNSIGNED_BYTE; } } else { uint blockSizeInBytes = 16; switch (mCompressionType) { case COMPRESSION_DXT1: blockSizeInBytes = 8; if (header.pf.flags & DDPF_ALPHAPIXELS) { mInternalFormat = GL_COMPRESSED_RGBA_S3TC_DXT1_EXT; } else { mInternalFormat = GL_COMPRESSED_RGB_S3TC_DXT1_EXT; } break; case COMPRESSION_DXT3: mInternalFormat = GL_COMPRESSED_RGBA_S3TC_DXT3_EXT; break; case COMPRESSION_DXT5: mInternalFormat = GL_COMPRESSED_RGBA_S3TC_DXT5_EXT; break; default: // Not Supported (DXT2, DXT4 or any compression format) massert(false); } } [SNIPPET 2: Uploading into video memory] massert(mData != NULL); glGenTextures(1, &mHandle); massert(mHandle!=0); glBindTexture(GL_TEXTURE_2D, mHandle); commitFiltering(); uint offset = 0; Renderer* renderer = Renderer::getInstance(); switch (mInternalFormat) { case GL_RGB: case GL_RGBA: case GL_RGB8: case GL_RGBA8: for (uint i = 0; i < mMipmapCount + 1; ++i) { uint width = std::max(1U, mWidth >> i); uint height = std::max(1U, mHeight >> i); glTexImage2D(GL_TEXTURE_2D, i, mInternalFormat, width, height, mHasBorder, mFormat, mDataType, &mData[offset]); offset += width * height * (mBitsPerPixel / 8); } break; case GL_COMPRESSED_RGB_S3TC_DXT1_EXT: case GL_COMPRESSED_RGBA_S3TC_DXT1_EXT: case GL_COMPRESSED_RGBA_S3TC_DXT3_EXT: case GL_COMPRESSED_RGBA_S3TC_DXT5_EXT: { uint blockSize = 16; if (mInternalFormat == GL_COMPRESSED_RGB_S3TC_DXT1_EXT || mInternalFormat == GL_COMPRESSED_RGBA_S3TC_DXT1_EXT) { blockSize = 8; } uint width = mWidth; uint height = mHeight; for (uint i = 0; i < mMipmapCount + 1; ++i) { uint nBlocks = ((width + 3) / 4) * ((height + 3) / 4); // Only POT textures allowed for mipmapping massert(width % 4 == 0 && height % 4 == 0); glCompressedTexImage2D(GL_TEXTURE_2D, i, mInternalFormat, width, height, mHasBorder, nBlocks * blockSize, &mData[offset]); offset += nBlocks * blockSize; if (width <= 4 && height <= 4) { break; } width = std::max(4U, width / 2); height = std::max(4U, height / 2); } break; } default: // Not Supported massert(false); } Also I don't understand the "+3" in the block size computation but looking for a solution for my problema I've encountered people defining it as that. I guess it won't make a differente for POT textures but I put just in case. Thanks.

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