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• Process Improvement and the Data Professional

  - by BuckWoody

  Don’t be afraid of that title – I’m not talking about Six Sigma or anything super-formal here. In many organizations, there are more folks in other IT roles than in the Data Professional area. In other words, there are more developers, system administrators and so on than there are the “DBA” role. That means we often have more to do than the time we need to do it. And, oddly enough, the first thing that is sacrificed is process improvement – the little things we need to do to make the day go faster in the first place. Then we get even more behind, the work piles up and…well, you know all about that. Earlier I challenged you to find 10-30 minutes a day to study. Some folks wrote back and asked “where do I start”? Well, why not be super-efficient and combine that time with learning how to make yourself more efficient? Try out a new scripting language, learn a new tool that automates things or find out ways others have automated their systems. In general, find out what you’re doing and how, and then see if that can be improved. It’s kind of like doing a performance tuning gig on yourself! If you’re pressed for time, look for bite-sized articles (like the ones I’ve done here for PowerShell and SQL Server) that you can follow in a “serial” fashion. In a short time you’ll have a new set of knowledge you can use to make your day faster. Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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• How to visualize code?

  - by gablin

  I've mostly only had to read my own code. As such, I've had no need to visualize the code as I already know how each and every class and module communicate with one another. But the few times I've had to read someone else's code - let us now assume we are talking about at least one larger module which contains several internal classes - I've almost always found myself wishing "This would have been so much easier to understand if I could just visualize it!" So what are the common methods or tools for enabling this? Which do you use, and why do you prefer them over the others? I've heard stuff like UML, module and class diagrams, but I imagine there are more. Furthermore, any of these is most likely better than anything I can devise on my own. EDIT: For those who answer with "Use pen and paper and just draw it": This isn't very helpful unless you explain this further. What exactly am I supposed to draw? A box for each class? Should I include the public methods? What about its fields? How should I draw connections that explain how one class uses another? What about modules? What if the language isn't object-oriented but functional or logical, or even just imperative (C, for instance)? What about global variables and functions? Is there an already-standardized way of drawing this, or do I need to think up of a method of my own? You get the drift.

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• Which architecture should I choose for this project?

  - by Jichao

  I have a project. The server which based on a phone PCI-board is responsible for received phone calls from the customer and then redirect the phone calls to the operators. I have decided to code the server using c++ programming language and qt framework because the PCI-board SDK's interface is c/c++ originated and for the sake of portability. The server need to send the information of the the customer to the operator while ringing the operator and the ui interface of the operator client should be browser-based. Now the key problem is how could the server notify the operator that there is a phone call for he/she. One architecture I have considered is like this, The operator browser client use ajax pooling the web server to check whether there is call to the client; the web server pooling the database server to check whether there is call; the desktop server(c++) wait for the phone calls and set the information in the database. The other operations such as hang up the phone call from the client, retransfer the phone call to the other operator also use this architecture. Then, is there any way other than pooling the server(js code setInterval('getDail', 1000)) to decide whether there is a call to the operator? Is this architecture feasible or should I use some terrific techniques that I do know such as web services,xml-rpc, soap???

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• Maintaining Two Separate Software Versions From the Same Codebase in Version Control

  - by Joseph

  Let's say that I am writing two different versions of the same software/program/app/script and storing them under version control. The first version is a free "Basic" version, while the second is a paid "Premium" version that takes the codebase of the free version and expands upon it with a few extra value-added features. Any new patches, fixes, or features need to find their way into both versions. I am currently considering using master and develop branches for the main codebase (free version) along side master-premium and develop-premium branches for the paid version. When a change is made to the free version and merged to the master branch (after thorough testing on develop of course), it gets copied over to the develop-premium branch via the cherry-pick command for more testing and then merged into master-premium. Is this the best workflow to handle this situation? Are there any potential problems, caveats, or pitfalls to be aware of? Is there a better branching strategy than what I have already come up with? Your feedback is highly appreciated! P.S. This is for a PHP script stored in Git, but the answers should apply to any language or VCS.

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• General List of Common Programming Errors

  - by javamonkey79

  As one journey's from apprentice to journeyman to master I've noticed that one accumulates a list of best practices for things they've been bitten by. Personally, I write most of my stuff in java & SQL so my list tends to be slated towards them. I've accumulated the following: When doing list removal, always reverse iterate Avoid adding items to a list you are currently iterating on Watch out for NullPointerExceptions Now, I know there are language specific "common errors" links out there like this one. And I'm also aware of the pragmatic programmer tips, Martin Fowler's "code smells". Does anyone know of any good lists out there of things like I've listed above (re: list removal, adding items, etc). My guess is that there are some good QA folks out there that can probably throw me a bone here. I'm not looking for things the compiler can catch - I'm looking for common things that cause bugs. In the event that there isn't a list out there already then I welcome posting your own findings here. Thanks in advance!

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• Server-side Architecture for Online Game

  - by Draiken

  basically I have a game client that has communicate with a server for almost every action it takes, the game is in Java (using LWJGL) and right now I will start making the server. The base of the game is normally one client communicating with the server alone, but I will require later on for several clients to work together for some functionalities. I've already read how authentication server should be sepparated and I intend on doing it. The problem is I am completely inexperienced in this kind of server-side programming, all I've ever programmed were JSF web applications. I imagine I'll do socket connections for pretty much every game communication since HTML is very slow, but I still don't really know where to start on my server. I would appreciate reading material or guidelines on where to start, what architecture should the game server have and maybe some suggestions on frameworks that could help me getting the client-server communication. I've looked into JNAG but I have no experience with this kind of thing, so I can't really tell if it is a solid and good messaging layer. Any help is appreciated... Thanks ! EDIT: Just a little more information about the game. It is intended to be a very complex game with several functionalities, making some functionalities a "program" inside the program. It is not an usual game, like FPS or RPG but I intend on having a lot of users using these many different "programs" inside the game. If I wasn't clear enough, I'd really appreciate people that have already developed games with java client/server architecture, how they communicated, any frameworks, apis, messaging systems, etc. It is not a question of lack of knowledge of language, more a question for advice, so I don't end up creating something that works, but in the later stages will have to be rewriten for any kind of limiting reason. PS: sorry if my english is not perfect...

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• Most suited technology for browser games?

  - by Tingle

  I was thinking about making a 2D MMO which I would in the long run support on various plattforms like desktop, mac, browser, android and ios. The server will be c++/linux based and the first client would go in the browser. So I have done some research and found that webgl and flash 11 support hardware accelerated rendering, I saw some other things like normal HTML5 painting. So my question is, which technology should I use for such a project? My main goal would be that the users have a hassle free experience using what there hardware can give them with hardware acceleration. And the client should work on the most basic out-of-the-box pc's that any casual pc or mac user has. And another criteria would be that it should be developer friendly. I've messed with webgl abit for example and that would require writing a engine from scratch - which is acceptable but not preferred. Also, in case of non-actionscript, which kind language is most prefered in terms of speed and flexability. I'm not to fond of javascript due to the garbage collector but have learned to work around it. Thank you for you time.

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• Review of TechEd 2012 - so far

  - by Stefan Barrett

  Disclaimer: probably going to next years TechEd.  (but not 100% sure) As with most TechEd's, this is not one of the best - but it's not bad.  Some impressions so far: The food is not bad, through perhaps not as much choice as in previous years.  The snacks, while a bit limited, are at least available.  The alumni lounge is ok, through perhaps not as good as last years.  Wifi is a bit worse than previous years - not really working in the big room, and a bit sporadic in the rest of the building. The device seems to make a big difference - the iPad seems to connect the easiest, while the iPhone & Lumia 800 are really struggling.  The real problem is the content - not as developer focused as in previous years.  This shows up in a number of different ways, for example while there is a visual studio booth, there is not much sign of anybody from the language teams.  This is one of few TechEd's where I don't feel very surprised about anything - seen most of the developer stuff in previews. One example where I was surprised was the pre-conf on c++ - its been years since I did any c++, but based on that session perhaps I should start again. While there are sessions, I'm not finding my schedule very challenged. For each time-slot there only seems to 1, or rarely 2, interesting sessions.  The focus seems to be on windows 8, Azure and the phone, which while interesting (might give win8 a go), are not enough.

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• I have an MIS degree. How do I sell myself as a programmer?

  - by hydroparadise

  So, I graduated with a BSBA in Management Information Systems with honors almost 2 years ago which is more of a business degree. As of right now, I do have a job title of "Programmer", but it's more of a report writing position in an arbitrary, proprietary language called PowerOn with the occasional interesting project using more mainstream technologies like .Net and Java. I am also somewhat isoloated being the only programmer in the workplace, which I beleive is a detriment to my career path. The only people I have to bounce ideas against are those on the various SE sites. I don't regret going MIS, but over the past couple of years I have discovered my passion for coding, even though I have been doing some form of coding profesionally and as an enthusiast for years. I do want to persue my Masters in CS (at a later time), but I am not sure if I necessarily need a CS degree to get in with a team of programmers. In addition, I do have a number classes I have taken for different laguanges on the way (C++, Java, SQL, and VB.Net) I beleive my strength is in problem solving where code is just a tool to tackling to problem if needed. My question: How do I best sell myself as a programmer? Should I continue pounding out reports and wait till I have my masters in CS? Or am I viable to be a programmer as I stand?

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• Generic rule parser for RPG board game rules - how to do it?

  - by burzum

  I want to build a generic rule parser for pen and paper style RPG systems. A rule can involve usually 1 to N entities 1 to N roles of a dice and calculating values based on multiple attributes of an entity. For example: Player has STR 18, his currently equipped weapon gives him a bonus of +1 STR but a malus of DEX -1. He attacks a monster entity and the game logic now is required to run a set of rules or actions: Player rolls the dice, if he gets for example 8 or more (base attack value he needs to pass is one of his base attributes!) his attack is successfully. The monster then rolls the dice to calculate if the attack goes through it's armor. If yes the damage is taken if not the attack was blocked. Besides simple math rules can also have constraints like applying only to a certain class of user (warrior vs wizzard for example) or any other attribute. So this is not just limited to mathematical operations. If you're familiar with RPG systems like Dungeon and Dragons you'll know what I'm up to. My issue is now that I have no clue how to exactly build this the best possible way. I want people to be able to set up any kind of rule and later simply do an action like selecting a player and a monster and run an action (set of rules like an attack). I'm asking less for help with the database side of things but more about how to come up with a structure and a parser for it to keep my rules flexible. The language of choice for this is php by the way.

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• Java Magazine: Developer Tools and More

  - by Tori Wieldt

  The May/June issue of Java Magazine explores the tools and techniques that can help you bring your ideas to fruition and make you more productive. In “Seven Open Source Tools for Java Deployment,” Bruno Souza and Edson Yanaga present a set of tools that you can use now to drastically improve the deployment process on projects big or small—enabling you and your team to focus on building better and more-innovative software in a less stressful environment. We explore the future of application development tools at Oracle in our interview with Oracle’s Chris Tonas, who discusses plans for NetBeans IDE 9, Oracle’s support for Eclipse, and key trends in the software development space. For more on NetBeans IDE, don’t miss “Quick and Easy Conversion to Java SE 8 with NetBeans IDE 8” and “Build with NetBeans IDE, Deploy to Oracle Java Cloud Service.” We also give you insight into Scrum, an iterative and incremental agile process, with a tour of a development team’s Scrum sprint. Find out if Scrum will work for your team. Other article topics include mastering binaries in Maven-based projects, creating sophisticated applications with HTML5 and JSF, and learning to program with BlueJ. At the end of the day, tools don’t make great code—you do. What tools are vital to your development process? How are you innovating today? Let us know. Send a tweet to @oraclejavamag. The next big thing is always just around the corner—maybe it’s even an idea that’s percolating in *your* brain. Get started today with this issue of Java Magazine. Java Magazine is a FREE, bi-monthly, online publication. It includes technical articles on the Java language and platform; Java innovations and innovators; JUG and JCP news; Java events; links to online Java communities; and videos and multimedia demos. Subscriptions are free, registration required.

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• Engine for 2D Top-Down Physics-Based Skeletal Animation

  - by RylandAlmanza

  I just watched at the Sui Generis video, and was completely amazed. Specifically, the part where the big troll thing is beating up the player with his flail. This got me really excited, and I would like to try implementing something like this in a 2D Top-Down format. Something like this. That atloria example seems simple enough, but it's not exactly what I'm looking to make. I think atloria is using predefined animations, where as I would like to make something more physics-based like the Sui Generis engine does. So, I'm wondering what physics engines might work for something like this, and if I'd need to implement my own skeletal system, or if I could just use "joints" and such from the engine. The only experience I have in terms of physics engines is Box2D, which I've heard shouldn't be used for top-down settings, and I can think of a few reasons it wouldn't work out well. One of those reasons being gravity. In box 2D, gravity pulls towards a side of the screen (usually the bottom.) I wouldn't want my player's forearms constantly being pulled to one side. :) Also should mention that the programming language doesn't matter all that much to me. I'm currently playing with HTML5 stuff, though. :) Thanks in advance!

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• Is learning how to use C (or C++) a requirement in order to be a good (excellent) programmer?

  - by blueberryfields

  When I first started to learn how to program, real programmers could write assembly in their sleep. Any serious schooling in computer science would include a hefty bit of training and practice in programming using assembly. That has since changed, to the point where I see Computer Science degrees with assembly, if included at all, is relegated to one assignment, and one chapter, for a total of two weeks' work out of 4 years' schooling. C/C++ programming seems to have followed a similar path. I'm no longer surprised to interview university graduates who have not spent more than two weeks programming in C++, and have only read of C in a book somewhere. While the most serious CS degrees still seem to include significant time learning and using one or both of the languages, the trend is clearly towards less enforced C/C++ in school. It's clearly possible to make a career producing good work without ever reading or writing a single line of C or C++ code. Given all of that, is learning the two languages worth the effort? Are they at all required to excel? (beyond the obvious, non-language specific advice, such as "a good selection of languages is probably important for a comprehensive education", and "it's probably a good idea to keep trying out and learning new languages throughout a programmers' career, just to stretch the gray cells")

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• Understanding Application binary interface (ABI)

  - by Tim

  I am trying to understand the concept of Application binary interface (ABI). From The Linux Kernel Primer: An ABI is a set of conventions that allows a linker to combine separately compiled modules into one unit without recompilation, such as calling conventions, machine interface, and operating-system interface. Among other things, an ABI defines the binary interface between these units. ... The benefits of conforming to an ABI are that it allows linking object files compiled by different compilers. From Wikipedia: an application binary interface (ABI) describes the low-level interface between an application (or any type of) program and the operating system or another application. ABIs cover details such as data type, size, and alignment; the calling convention, which controls how functions' arguments are passed and return values retrieved; the system call numbers and how an application should make system calls to the operating system; and in the case of a complete operating system ABI, the binary format of object files, program libraries and so on. I was wondering whether ABI depends on both the instruction set and the OS. Are the two all that ABI depends on? What kinds of role does ABI play in different stages of compilation: preprocessing, conversion of code from C to Assembly, conversion of code from Assembly to Machine code, and linking? From the first quote above, it seems to me that ABI is needed for only linking stage, not the other stages. Is it correct? When is ABI needed to be considered? Is ABI needed to be considered during programming in C, Assembly or other languages? If yes, how are ABI and API different? Or is it only for linker or compiler? Is ABI specified for/in machine code, Assembly language, and/or of C?

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• Sucking Less Every Year ?

  - by AdityaGameProgrammer

  Sucking Less Every Year A trail of thought that had been on my mind for a while Quoting directly from the post I've often thought that sucking less every year is how humble programmers improve. You should be unhappy with code you wrote a year ago. If you aren't, that means either A) you haven't learned anything in a year, B) your code can't be improved, or C) you never revisit old code. All of these are the kiss of death for software developers. How often does this happen or not happen to you? How long before you see an actual improvement in your coding ? month, year? Do you ever revisit Your old code? How often does your old code plague you? or how often do you have to deal with your technical debt. It is definitely very painful to fix old bugs n dirty code that we may have done to quickly meet a deadline and those quick fixes ,some cases we may have to rewrite most of the application/code. No arguments about that. Some of the developers i had come across argued that they were already at the evolved stage where their coding doesn't need improvement or cant get improved anymore. Does this happen? If so how many years into coding on a particular language does one expect this to happen?

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• Storing data offline with javascript

  - by Walker

  My question is about storing data offline and potentially whether I will need to bring in an outside programmer or could this be learned within a few weeks? The website I am working on will have an interface where users will login and go through a series of quizzes in the form of checkbox, drop down menus, and others. Each page/quiz area could have 20-100 total checkboxes in a series of 3-5 rows because of the comprehensive nature of course. This I can do - I know how to code the quiz and return a correct or incorrect answer based on each individual checkbox and present a cumulative score (ie: you got 57% correct). The issue lies in the fact that I would like to save the users results and keep them informed of their progress. When they complete all of the quizzes, I would like to have a visual output of their performance in each area. Storing the output from their results offline is where I think I may run into a problem with my lack of coding experience. I would also like to have a sidebar with their progress of each section (10-15) with a green percentage completion bar or a % correct which would draw from this. I have never had to code something that stores information like this offline - so back to my question - would it be better to learn the language needed or bring in a coder/developer for the back end stuff.

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• Structure of a .NET Assembly

  - by Om Talsania

  Assembly is the smallest unit of deployment in .NET Framework.When you compile your C# code, it will get converted into a managed module. A managed module is a standard EXE or DLL. This managed module will have the IL (Microsoft Intermediate Language) code and the metadata. Apart from this it will also have header information.The following table describes parts of a managed module.PartDescriptionPE HeaderPE32 Header for 32-bit PE32+ Header for 64-bit This is a standard Windows PE header which indicates the type of the file, i.e. whether it is an EXE or a DLL. It also contains the timestamp of the file creation date and time. It also contains some other fields which might be needed for an unmanaged PE (Portable Executable), but not important for a managed one. For managed PE, the next header i.e. CLR header is more importantCLR HeaderContains the version of the CLR required, some flags, token of the entry point method (Main), size and location of the metadata, resources, strong name, etc.MetadataThere can be many metadata tables. They can be categorized into 2 major categories.1. Tables that describe the types and members defined in your code2. Tables that describe the types and members referenced by your codeIL CodeMSIL representation of the C# code. At runtime, the CLR converts it into native instructions

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• Question regarding Readability vs Processing Time

  - by Jordy

  I am creating a flowchart for a program with multiple sequential steps. Every step should be performed if the previous step is succesful. I use a c-based programming language so the lay-out would be something like this: METHOD 1: if(step_one_succeeded()) { if(step_two_succeeded()) { if(step_three_succeeded()) { //etc. etc. } } } If my program would have 15+ steps, the resulting code would be terribly unfriendly to read. So I changed my design and implemented a global errorcode that I keep passing by reference, make everything more readable. The resulting code would be something like this: METHOD 2: int _no_error = 0; step_one(_no_error); if(_no_error == 0) step_two(_no_error); if(_no_error == 0) step_three(_no_error); if(_no_error == 0) step_two(_no_error); The cyclomatic complexibility stays the same. Now let's say there are N number of steps. And let's assume that checking a condition is 1 clock long and performing a step doesn't take up time. The processing speed of Method1 can be anywhere between 1 and N. The processing speed of Method2 however is always equal to N-1. So Method1 will be faster most of the time. Which brings me to my question, is it bad practice to sacrifice time in order to make the code more readable? And why (not)?

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• Creating new games on Android and/or iPhone

  - by James Clifton

  I have a succesfull facebook poker game that is running very nicely, now some people have asked if I can port this to other platforms - mainly mobile devices (and I have been asked to make a tablet version, do I really need a seperate version?) I am currently a PHP programmer (and game designer) and I simply dont' have the time to learn Android and other languages - so I have decided to pay third parties to program them (if viable). The information I need to know is what programming language is needed for the following four devices - Android mobile phone, iPhone, iPad and tablets? Can they all run off a central sql database? If they can't then i'm not interested :( Do any of these run FLASH? Have I covered all my main bases here? For example if a person programs for a ANDROID mobile phone is that to much differant to an ANDROID tablet? They will have slightly differant graphics (because the tablet has a greater screen area might as well use it) but do they need to be started from scratch? Same goes for iPhone/iPad, do they really need to be programmed differantly if the only differance is the graphics?

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• Extracting Frustum Planes (Hartmann & Gribbs method)

  - by DAVco

  I have been grappling with the Hartmann/Gribbs method of extracting the Frustum planes for some time now, with little success. There doesn't appear to be a "definitive" topic or tutorial which combines all the necessary information, so perhaps this can be it First of all, I am attempting to do this in C# (For Playstation Mobile), using OpenGL style Column-Major matrices in a Right-Handed coordinate system but obviously the math will work in any language. My projection matrix has a Near plane at 1.0, Far plane at 1000, FOV of 45.0 and Aspect of 1.7647. I want to get my planes in World-Space, so I build my frustum from the View-Projection Matrix (that's projectionMatrix * viewMatrix). The view Matrix is the inverse of the camera's World-Transform. The problem is; regardless of what I tweak, I can't seem to get a correct frustum. I think that I may be missing something obvious. Focusing on the Near and Far planes for the moment (since they have the most obvious normals when correct), when my camera is positioned looking down the negative z-axis, I get two planes facing in the same direction, rather than opposite directions. If i strafe my camera left and right (while still looking along the z axis) the x value of the normal vector changes. Obviously, something is fundamentally wrong here; I just can't figure out what - maybe someone here can?

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• How to start and maintain an after-work project

  - by Sam

  I work as a full time developer. My workplace, however, is very limiting in the technologies and programming languages I can use. All of the work is done in C++. It is clear that C++ is rapidly losing (or maybe already lost) its leading position. (please don't flame me, I have years and years of C++ experience, and I love this language, I am merely stating a fact). I have a few ideas for java/android projects as well as a project I would like to implement in C#. I see this as a way for me to stay current with the job market's trends and I hope that it will help me find my next job in a more up to date area. So here's the problem, my normal workday is 10-11 hours, after finishing with the kids and house chores I get about 1-2.5 hours before I am too tired to think much less code. at that point I am going to bed frustrated, disappointed with myself for not being able to stick with my plans, and then I wake up the next morning to do it all again. I have a few hours more during the weekends but clearly I would need to do something different if I want to reach any of my goals. Is there any way for me to make better use of the time I have? Did any of you guys have a similar problem, and had succefully resolved it?

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• Is error suppression acceptable in role of logic mechanism?

  - by Rarst

  This came up in code review at work in context of PHP and @ operator. However I want to try keep this in more generic form, since few question about it I found on SO got bogged down in technical specifics. Accessing array field, which is not set, results in error message and is commonly handled by following logic (pseudo code): if field value is set output field value Code in question was doing it like: start ignoring errors output field value stop ignoring errors The reasoning for latter was that it's more compact and readable code in this specific case. I feel that those benefits do not justify misuse (IMO) of language mechanics. Is such code is being "clever" in a bad way? Is discarding possible error (for any reason) acceptable practice over explicitly handling it (even if that leads to more extensive and/or intensive code)? Is it acceptable for programming operators to cross boundaries of intended use (like in this case using error handling for controlling output)? Edit I wanted to keep it more generic, but specific code being discussed was like this: if ( isset($array['field']) ) { echo '<li>' . $array['field'] . '</li>'; } vs the following example: echo '<li>' . @$array['field'] . '</li>';

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• Installation causing broken packages

  - by AWE

  Here I come I am so determined to use Ubuntu that I paid a professional to install it for me (dualboot). When I got it I got a lot of things from the software center. Skype did not have a download button so I googled it and Ubuntu help told me to do this: sudo add-apt-repository "deb http://archive.canonical.com/ $(lsb_release -sc) partner" and then this: sudo apt-get update && sudo apt-get install skype The terminal told me "that this is potentially harmful..." but I thought it was Ubuntu language meaning "are you sure?" Now items cannot be installed or removed until the package catalog is repaired, so I want to repair it but the package operation fails. "sudo aptitude -f install" - command not found Synaptic package manager tells me that I have two broken packages, libc6 and libc6-dev but doesn't help, only makes life complicated. What the *#$%&!!! I don't want to be forced to become a computer scientist just to be able to use a free source os. P.s. the sound stopped working

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• Languages with a clear distinction between subroutines that are purely functional, mutating, state-changing, etc?

  - by CPX

  Lately I've become more and more frustrated that in most modern programming languages I've worked with (C/C++, C#, F#, Ruby, Python, JS and more) there is very little, if any, language support for determining what a subroutine will actually do. Consider the following simple pseudo-code: var x = DoSomethingWith(y); How do I determine what the call to DoSomethingWith(y) will actually do? Will it mutate y, or will it return a copy of y? Does it depend on global or local state, or is it only dependent on y? Will it change the global or local state? How does closure affect the outcome of the call? In all languages I've encountered, almost none of these questions can be answered by merely looking at the signature of the subroutine, and there is almost never any compile-time or run-time support either. Usually, the only way is to put your trust in the author of the API, and hope that the documentation and/or naming conventions reveal what the subroutine will actually do. My question is this: Does there exist any languages today that make symbolic distinctions between these types of scenarios, and places compile-time constraints on what code you can actually write? (There is of course some support for this in most modern languages, such as different levels of scope and closure, the separation between static and instance code, lambda functions, et cetera. But too often these seem to come into conflict with each other. For instance, a lambda function will usually either be purely functional, and simply return a value based on input parameters, or mutate the input parameters in some way. But it is usually possible to access static variables from a lambda function, which in turn can give you access to instance variables, and then it all breaks apart.)

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• Are there legitimate reasons for returning exception objects instead of throwing them?

  - by stakx

  This question is intended to apply to any OO programming language that supports exception handling; I am using C# for illustrative purposes only. Exceptions are usually intended to be raised when an problem arises that the code cannot immediately handle, and then to be caught in a catch clause in a different location (usually an outer stack frame). Q: Are there any legitimate situations where exceptions are not thrown and caught, but simply returned from a method and then passed around as error objects? This question came up for me because .NET 4's System.IObserver<T>.OnError method suggests just that: exceptions being passed around as error objects. Let's look at another scenario, validation. Let's say I am following conventional wisdom, and that I am therefore distinguishing between an error object type IValidationError and a separate exception type ValidationException that is used to report unexpected errors: partial interface IValidationError { } abstract partial class ValidationException : System.Exception { public abstract IValidationError[] ValidationErrors { get; } } (The System.Component.DataAnnotations namespace does something quite similar.) These types could be employed as follows: partial interface IFoo { } // an immutable type partial interface IFooBuilder // mutable counterpart to prepare instances of above type { bool IsValid(out IValidationError[] validationErrors); // true if no validation error occurs IFoo Build(); // throws ValidationException if !IsValid(…) } Now I am wondering, could I not simplify the above to this: partial class ValidationError : System.Exception { } // = IValidationError + ValidationException partial interface IFoo { } // (unchanged) partial interface IFooBuilder { bool IsValid(out ValidationError[] validationErrors); IFoo Build(); // may throw ValidationError or sth. like AggregateException<ValidationError> } Q: What are the advantages and disadvantages of these two differing approaches?

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