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  • links for 2010-03-31

    - by Bob Rhubart
    Andy Mulholland: Rethinking the narrow and deep expertise model "We increasingly realise that we have to read requirements in a more open way to decide what techniques can be used, what business experience can be added, etc, so the whole idea of encouraging ‘cross’ discipline understanding seems to look increasingly necessary as we look at how technology touches every part of business, and/or any other aspect of life. It is time to rethink the narrow and deep expertise model and consider T-shaped approaches where the depth is complimented by the width to understand how it might be used and how it fits with other capabilities and disciplines too." -- Andy Mulholland (tags: enterprisearchitecture) @vambenepe: Smoothing a discrete world "For the short term (until we sell one) there are three cars in my household. A manual transmission, an automatic and a CVT (continuous variable transmission). This makes me uniquely qualified to write about Cloud Computing." -- William Vambenepe (tags: otn oracle cloud) @fteter: The Price of Progress "I wonder about the price of progress on the business world. Do some of us get attached to old business models or software applications? Do we resist change for the better for emotional reasons? Are we sometimes impediments to progress just because we don't want things to change?" -- Oracle ACE Director Floyd Teter (tags: otn oracle oracleace progress innovation) Pat Shepherd: Enterprise Architecture should not be Arbitrary "If done properly the Business, Application and Information architectures are nailed down BEFORE any technological direction (SOA or otherwise) is set. Those 3 layers and Governance (people and processes), IMHO, are layers that should not vary much as they have everything to do with understanding the business -- from which technological conclusions can later be drawn." - Pat Shepherd, responding to a post by Jordan Braunstein. (tags: oracle otn enterprisearchitecture soa)

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  • How to slow down a sprite that updates every frame?

    - by xiaohouzi79
    I am going through a Allegro 5 tutorial which has a game loop. There is also a variable "active" which determines if a key is being held down. Thus if the left key is being held down active is on and it begins looping through the row on the sprite sheet that corresponds to moving left. The problem is that this logic is checked everytime the loop is performed thus at approximately 60 fps the three images that are used to do the left walking animation cycle round super fast which means my character looks like it is in a rush. Total beginner question: so what is the correct way to slow down the transition between sprites so that the walking looks like it is done at a moderate pace. Here is the code used to transition across the sprite between the three different phases of the person walking: if (active) { sourceX += al_get_bitmap_width(player) / 3; } else { sourceX = 32; } if (sourceX >= al_get_bitmap_width(player)) { sourceX = 0; } I can kind of guess what it should be in plain English: update sourceX only every certain part of a second but I can't think of how to put this into code.

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  • Can't complete dropbox installation from behind proxy

    - by Mark Jones
    Problem: My PC on campus sits behind a proxy (requiring authentication) and I can't setup Dropbox. I am convinced that this is a proxy issue as I can't setup Ubuntu one either (but I don't use Ubuntu One so that is not a problem). I have looked at the Ubuntu One fix but it seems to be to modify settings explicitly related to Ubuntu One. I can install the nautilus-dropbox package (compiled from source and from .deb package from website and from software centre) but once I click OK from the "Dropbox Installation" dialog box (prompting me to download the proprietary daemon) the installation just freezes with the OK button pressed. When I look at its process in System Monitor its waiting channel is inet_wait_for_connect. I have set the following proxy directives thus far: Added mj22:**@proxy.waikato.ac.nz:80 information to network proxy settings under network in settings. Added http_host and http_port variables under gconf-editor-system-proxy Added 'host', 'authentication_password' 'authentication_user' and ticked 'user authentication' and 'use_http_proxy' under gconf-editor-system-http_proxy Added export http_proxy="http://mj22:**@proxy.waikato.ac.nz:80/" to /etc/bash.bashrc Added Acquire::http::proxy "http://mj22:**@proxy.waikato.ac.nz:80/"; to /etc/apt/apt.conf (which is what I imagine is letting Software Center retrieve packages). (where ** is my password) I have also added the equivalent ftp and https lines for the above entries. I get the internet fine and Software Centre can download packages but thats it. Related issues: The software centre can't fetch reviews (but can download packages). When trying to add an online account in Gnome 3 a dialog pop up appears with "Error getting a Request Token: Cannot connect to proxy (proxy.waikato.ac.nz)" Updates: After some time (10mins ish) Dropbox shows an error dialog box that reads: Trouble connecting to Dropbox servers. Maybe your internet connection is down, or you need to set you http_proxy environment variable. Is there a way I can see what environment variables are currently set?

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  • .wine-pipelight folder not present

    - by DaimyoKirby
    Following the instructions on the pipelight installation page, I installed pipelight on Ubuntu 14.04. However, upon opening firefox the .wine-pipelight folder isn't present in my home folder, and I get the following errors: [PIPELIGHT:LIN:unknown] attached to process. [PIPELIGHT:LIN:unknown] checking environment variable PIPELIGHT_SILVERLIGHT5_1_CONFIG. [PIPELIGHT:LIN:unknown] searching for config file pipelight-silverlight5.1. [PIPELIGHT:LIN:unknown] trying to load config file from '/home/alden/.config/pipelight-silverlight5.1'. [PIPELIGHT:LIN:silverlight5.1] basicplugin.c:427:checkSilverlightGraphicDriver(): error in execlp command - probably silverlightGraphicDriverCheck not found or missing execute permission. [PIPELIGHT:LIN:silverlight5.1] basicplugin.c:441:checkSilverlightGraphicDriver(): GPU driver check - Your driver is not in the whitelist, hardware acceleration disabled. [PIPELIGHT:LIN:silverlight5.1] using wine prefix directory /home/alden/.wine-pipelight. [PIPELIGHT:LIN:silverlight5.1] checking plugin installation - this might take some time. [PIPELIGHT:LIN:silverlight5.1] basicplugin.c:374:checkPluginInstallation(): error in execvp command - probably dependencyInstaller/sandbox not found or missing execute permission. [PIPELIGHT:LIN:silverlight5.1] basicplugin.c:384:checkPluginInstallation(): Plugin installer did not run correctly (exitcode = 1). [PIPELIGHT:LIN:silverlight5.1] basicplugin.c:108:attach(): plugin not correctly installed - aborting. I've reinstalled quite a few times and ran through many of the common fixes offered on the pipelight Launchpad pages and here on AskUbunta and still it fails to run. Is there a reason why this folder isn't present, or why I'm getting these errors? Edit: Oddly enough, the .wine-pipelight folder is created wtih I open Nitro, although this still doesn't fix the issue.

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  • Row Number Transformation

    The Row Number Transformation calculates a row number for each row, and adds this as a new output column to the data flow. The column number is a sequential number, based on a seed value. Each row receives the next number in the sequence, based on the defined increment value. The final row number can be stored in a variable for later analysis, and can be used as part of a process to validate the integrity of the data movement. The Row Number transform has a variety of uses, such as generating surrogate keys, or as the basis for a data partitioning scheme when combined with the Conditional Split transformation. Properties Property Data Type Description Seed Int32 The first row number or seed value. Increment Int32 The value added to the previous row number to make the next row number. OutputVariable String The name of the variable into which the final row number is written post execution. (Optional). The three properties have been configured to support expressions, or they can set directly in the normal manner. Expressions on components are only visible on the hosting Data Flow task, not at the individual component level. Sometimes the data type of the property is incorrectly set when the properties are created, see the Troubleshooting section below for details on how to fix this. Installation The component is provided as an MSI file which you can download and run to install it. This simply places the files on disk in the correct locations and also installs the assemblies in the Global Assembly Cache as per Microsoft’s recommendations. You may need to restart the SQL Server Integration Services service, as this caches information about what components are installed, as well as restarting any open instances of Business Intelligence Development Studio (BIDS) / Visual Studio that you may be using to build your SSIS packages. For 2005/2008 Only - Finally you will have to add the transformation to the Visual Studio toolbox manually. Right-click the toolbox, and select Choose Items.... Select the SSIS Data Flow Items tab, and then check the Row Number transformation in the Choose Toolbox Items window. This process has been described in detail in the related FAQ entry for How do I install a task or transform component? We recommend you follow best practice and apply the current Microsoft SQL Server Service pack to your SQL Server servers and workstations, and this component requires a minimum of SQL Server 2005 Service Pack 1. Downloads The Row Number Transformation  is available for SQL Server 2005, SQL Server 2008 (includes R2) and SQL Server 2012. Please choose the version to match your SQL Server version, or you can install multiple versions and use them side by side if you have more than one version of SQL Server installed. Row Number Transformation for SQL Server 2005 Row Number Transformation for SQL Server 2008 Row Number Transformation for SQL Server 2012 Version History SQL Server 2012 Version 3.0.0.6 - SQL Server 2012 release. Includes upgrade support for both 2005 and 2008 packages to 2012. (5 Jun 2012) SQL Server 2008 Version 2.0.0.5 - SQL Server 2008 release. (15 Oct 2008) SQL Server 2005 Version 1.2.0.34 – Updated installer. (25 Jun 2008) Version 1.2.0.7 - SQL Server 2005 RTM Refresh. SP1 Compatibility Testing. Added the ability to reuse an existing column to hold the generated row number, as an alternative to the default of adding a new column to the output. (18 Jun 2006) Version 1.2.0.7 - SQL Server 2005 RTM Refresh. SP1 Compatibility Testing. Added the ability to reuse an existing column to hold the generated row number, as an alternative to the default of adding a new column to the output. (18 Jun 2006) Version 1.0.0.0 - Public Release for SQL Server 2005 IDW 15 June CTP (29 Aug 2005) Screenshot Code Sample The following code sample demonstrates using the Data Generator Source and Row Number Transformation programmatically in a very simple package. Package package = new Package(); package.Name = "Data Generator & Row Number"; // Add the Data Flow Task Executable taskExecutable = package.Executables.Add("STOCK:PipelineTask"); // Get the task host wrapper, and the Data Flow task TaskHost taskHost = taskExecutable as TaskHost; MainPipe dataFlowTask = (MainPipe)taskHost.InnerObject; // Add Data Generator Source IDTSComponentMetaData100 componentSource = dataFlowTask.ComponentMetaDataCollection.New(); componentSource.Name = "Data Generator"; componentSource.ComponentClassID = "Konesans.Dts.Pipeline.DataGenerator.DataGenerator, Konesans.Dts.Pipeline.DataGenerator, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b2ab4a111192992b"; CManagedComponentWrapper instanceSource = componentSource.Instantiate(); instanceSource.ProvideComponentProperties(); instanceSource.SetComponentProperty("RowCount", 10000); // Add Row Number Tx IDTSComponentMetaData100 componentRowNumber = dataFlowTask.ComponentMetaDataCollection.New(); componentRowNumber.Name = "FlatFileDestination"; componentRowNumber.ComponentClassID = "Konesans.Dts.Pipeline.RowNumberTransform.RowNumberTransform, Konesans.Dts.Pipeline.RowNumberTransform, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b2ab4a111192992b"; CManagedComponentWrapper instanceRowNumber = componentRowNumber.Instantiate(); instanceRowNumber.ProvideComponentProperties(); instanceRowNumber.SetComponentProperty("Increment", 10); // Connect the two components together IDTSPath100 path = dataFlowTask.PathCollection.New(); path.AttachPathAndPropagateNotifications(componentSource.OutputCollection[0], componentRowNumber.InputCollection[0]); #if DEBUG // Save package to disk, DEBUG only new Application().SaveToXml(String.Format(@"C:\Temp\{0}.dtsx", package.Name), package, null); #endif package.Execute(); foreach (DtsError error in package.Errors) { Console.WriteLine("ErrorCode : {0}", error.ErrorCode); Console.WriteLine(" SubComponent : {0}", error.SubComponent); Console.WriteLine(" Description : {0}", error.Description); } package.Dispose(); Troubleshooting Make sure you have downloaded the version that matches your version of SQL Server. We offer separate downloads for SQL Server 2005, SQL Server 2008 and SQL Server 2012. If you get an error when you try and use the component along the lines of The component could not be added to the Data Flow task. Please verify that this component is properly installed.  ... The data flow object "Konesans ..." is not installed correctly on this computer, this usually indicates that the internal cache of SSIS components needs to be updated. This is held by the SSIS service, so you need restart the the SQL Server Integration Services service. You can do this from the Services applet in Control Panel or Administrative Tools in Windows. You can also restart the computer if you prefer. You may also need to restart any current instances of Business Intelligence Development Studio (BIDS) / Visual Studio that you may be using to build your SSIS packages. Once installation is complete you need to manually add the task to the toolbox before you will see it and to be able add it to packages - How do I install a task or transform component? Please also make sure you have installed a minimum of SP1 for SQL 2005. The IDtsPipelineEnvironmentService was added in SQL Server 2005 Service Pack 1 (SP1) (See  http://support.microsoft.com/kb/916940). If you get an error Could not load type 'Microsoft.SqlServer.Dts.Design.IDtsPipelineEnvironmentService' from assembly 'Microsoft.SqlServer.Dts.Design, Version=9.0.242.0, Culture=neutral, PublicKeyToken=89845dcd8080cc91'. when trying to open the user interface, it implies that your development machine has not had SP1 applied. Very occasionally we get a problem to do with the properties not being created with the correct data type. Since there is no way to programmatically to define the data type of a pipeline component property, it can only infer it. Whilst we set an integer value as we create the property, sometimes SSIS decides to define it is a decimal. This is often highlighted when you use a property expression against the property and get an error similar to Cannot convert System.Int32 to System.Decimal. Unfortunately this is beyond our control and there appears to be no pattern as to when this happens. If you do have more information we would be happy to hear it. To fix this issue you can manually edit the package file. In Visual Studio right click the package file from the Solution Explorer and select View Code, which will open the package as raw XML. You can now search for the properties by name or the component name. You can then change the incorrect property data types highlighted below from Decimal to Int32. <component id="37" name="Row Number Transformation" componentClassID="{BF01D463-7089-41EE-8F05-0A6DC17CE633}" … >     <properties>         <property id="38" name="UserComponentTypeName" …>         <property id="41" name="Seed" dataType="System.Int32" ...>10</property>         <property id="42" name="Increment" dataType="System.Decimal" ...>10</property>         ... If you are still having issues then contact us, but please provide as much detail as possible about error, as well as which version of the the task you are using and details of the SSIS tools installed.

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  • What are the packages/libraries I should install before compiling Python from source?

    - by Lennart Regebro
    Once in a while I need to install a new Ubuntu (I used it both for desktop and servers) and I always forget a couple of libraries I should have installed before compiling, meaning I have to recompile, and it's getting annoying. So now I want to make a complete list of all library packages to install before compiling Python (and preferably how optional they are). This is the list I compiled with below help and by digging in setup.py. It is complete for Ubuntu 10.04 and 11.04 at least: build-essential (obviously) libz-dev (also pretty common and essential) libreadline-dev (or the Python prompt is crap) libncursesw5-dev libssl-dev libgdbm-dev libsqlite3-dev libbz2-dev More optional: tk-dev libdb-dev Ubuntu has no packages for v1.8.5 of the Berkeley database, nor (for obvious reasons) the Sun audio hardware, so the bsddb185 and sunaudiodev modules will still not be built on Ubuntu, but all other modules are built with the above packages installed. Python 2.5 and Python 2.6 also needs to have LDFLAGS set on Ubuntu 11.04 and later, to handle the new multi-arch layout: export LDFLAGS="-L/usr/lib/$(dpkg-architecture -qDEB_HOST_MULTIARCH)" For Python 2.6 and 2.7 you also need to explicitly enable SSL after running the ./configure script and before running make. In Modules/Setup there are lines like this: #SSL=/usr/local/ssl #_ssl _ssl.c \ # -DUSE_SSL -I$(SSL)/include -I$(SSL)/include/openssl \ # -L$(SSL)/lib -lssl -lcrypto Uncomment these lines and change the SSL variable to /usr: SSL=/usr _ssl _ssl.c \ -DUSE_SSL -I$(SSL)/include -I$(SSL)/include/openssl \ -L$(SSL)/lib -lssl -lcrypto Python 2.6 also needs Modules/_ssl.c modified to be used with OpenSSL 1.0, which is used in Ubuntu 11.10. At around line 300 you'll find this: else if (proto_version == PY_SSL_VERSION_SSL3) self->ctx = SSL_CTX_new(SSLv3_method()); /* Set up context */ else if (proto_version == PY_SSL_VERSION_SSL2) self->ctx = SSL_CTX_new(SSLv2_method()); /* Set up context */ else if (proto_version == PY_SSL_VERSION_SSL23) self->ctx = SSL_CTX_new(SSLv23_method()); /* Set up context */ Change that into: else if (proto_version == PY_SSL_VERSION_SSL3) self->ctx = SSL_CTX_new(SSLv3_method()); /* Set up context */ #ifndef OPENSSL_NO_SSL2 else if (proto_version == PY_SSL_VERSION_SSL2) self->ctx = SSL_CTX_new(SSLv2_method()); /* Set up context */ #endif else if (proto_version == PY_SSL_VERSION_SSL23) self->ctx = SSL_CTX_new(SSLv23_method()); /* Set up context */ This disables SSL_v2 support, which apparently is gone in OpenSSL1.0.

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  • Screwed up terminal after modifying bashrc

    - by omgzor
    I ended up screwing up my terminal, while setting up Sbt for the Coursera Scala course. I can't summon gedit (or anything else) anymore. I get the following error: Command 'gedit' is available in '/usr/bin/gedit' The command could not be located because '/usr/bin' is not included in the PATH environment variable. Also, each new instance of Terminal writes these messages before any command is written: -bash: :/home/antonio/jdk7/jdk1.7.0_07/bin: No such file or directory -bash: export: `/home/antonio/Desktop/Scala/install/sbt/bin:/home/antonio/jdk7/jdk1.7.0_07/bin': not a valid identifier I recently did a manual installation of the jdk 7, which apparently works: java -version java version "1.7.0_07" Java(TM) SE Runtime Environment (build 1.7.0_07-b10) Java HotSpot(TM) 64-Bit Server VM (build 23.3-b01, mixed mode) While setting up Sbt, I made the mistake of editing bashrc by writing gedit ~/.bashrc on my terminal instead of writing gedit .bashrc, I wrote the following lines at the end of the bashrc file that opened: export PATH=/PATH/TO/YOUR/jdk1.7.0-VERSION/bin:$PATH export PATH=/home/antonio/jdk7/jdk1.7.0_07/bin:$PATH What is wrong here? How can I access my bashrc file and modify it again?

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  • Why do programmers seem to be such bad spellers?

    - by Joel Etherton
    Programming languages are very precise tools based on explicit grammars. They're very picky, and when being used they require an exacting amount of detail. C#, for instance, is case sensitive so even getting the case of an argument wrong will cause an error. Questions asked all over the StackExchange are replete with misspellings, grammatical errors, and other problems that seem to indicate a lack of attention to detail when it comes to the language itself. Now, I understand there are a lot of programmers out there whose native language is not English, and I am not directing this question (rant one might say) at them. I'm referring to the individuals who are clearly from an English speaking background who refuse to pay attention to these simple details. I am not perfect by any means, but I try to use the language correctly so that my meaning will be understood correctly. I find programmers misspelling variable names, classes, and all manner of words in any kind of technical documentation they might write. I have had to withstand code where I am repeatedly referring to the subit[sic] button or HttpWebResponse reponse. The general complaint about bad spelling is one thing, and it will always be there. I accept that. But my question/comment is about the proclivity of bad spelling within the programming community. I would think that people who deal with such exacting tools to be more naturally predisposed towards proper spelling. Yet this doesn't seem to be the case.

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  • Slick2D + LWJGL collision system

    - by Connor W
    So I've been learning java for a while and have explored slick and lwjgl before but went away from using Slick for a while. But I've recently gone back to using it (as I'm making a platformer and Tiled will be really helpful). But here's where my problems begin: collision. I have a player polygon and I check to see if it's colliding with my tiled map with this method: public static boolean playerCollisionWith() { for(int i = 0; i < Blockmap.entities.size(); i++) { Block entity1 = (Block) Blockmap.entities.get(i); if(playerPoly.intersects(entity1.poly)) { return true; } } return false; } This would work normally but I'm using a different method for movement. Instead of just adding a speed variable to the player's x axis. I move like this: if(Keyboard.isKeyDown(Keyboard.KEY_RIGHT)) { speedX = Math.min(5, speedX + 1); moving = true; playerPoly.setX(x); if(playerCollisionWith()) { speedX = -5; playerPoly.setX(x); } } That Math.min call is what is messing me up =. I can't just call speedX = -5, because when I do the player "bounces" when the right mouse button is down and it's colliding. Bounces as in flashes back and forth REALLY quickly. But I don't really know how I would make it so that collisions on the y axis would work either, whether the player is jumping or not. So if I could get some help with how to fix this problem that would be great. Thank you for the help!

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  • How can I retrieve the details of the file from an outbound operation in BPEL 11g

    - by [email protected]
    Several times, we come across requirements where we need to capture the details of the file that got written out as a part of a BPEL process invoking a File/Ftp Adapter. Consider a case where we're using FileNamingConvention as "PurchaseOrder_%SEQ%.txt" and we need to do some post processing based on the filename (please remember that we wouldn't know the filename until the adapter invocation completes) In order to achieve this, we need to manually tweak the WSDL so that the File/Ftp Adapter can return the metadata of the file that was written out. In general, the File/Ftp Write/Put WSDL operations are one way as shown below:         The File/Ftp Adapters are designed to return the metadata back if this WSDL is tweaked into a two-way WSDL. In addition, the <wsdl:output/> must import the fileread.xsd schema (see below). You will need to copy fileread.xsd from  here into the xsd folder of your composite.       Finally, we will need to tweak the  WSDL. (highlighted below)           Finally, the BPEL <invoke> would look as shown below. Please note that the file metadata would be returned as a part of the BPEL output variable:

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  • How should Code Review be Carried Out?

    - by Graviton
    My previous question has to do with how to advance code review among the developers. Here I am interested in how the code review session should be carried out, so that both the reviewer and reviewed are feeling comfortable about it. I have done some code review before, but the experience sucks big time. My previous manager would come to us-- on an ad hoc basis-- and tell us to explain our code to him. Since he wasn't very familiar with the code base, I spent a huge amount of times explaining just the most basic structure of my code to him. This took a long time and by the time we were done, we were both exhausted. Then he would raise issues with my code. Most issues he raised were cosmetic in nature ( e.g, don't use region for this code block, change the variable name from xxx to yyy even though the later makes even less sense, and so on). We did this a few rounds, and the review session didn't derive much benefits for us, and we stopped. What do you have to do, in order to make code review a natural, enjoyable, thought stimulating, bug-fixing and mutual-learning experience?

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  • How to refactor while keeping accuracy and redundancy?

    - by jluzwick
    Before I ask this question I will preface it with our environment. My team consists of 3 programmers working on multiple different projects. Due to this, our use of testing is mostly limited to very general black box testing. Take the following assumptions also: Unit Tests will eventually be written but I'm under strict orders to refactor first Ignore common Test-Driven Development techniques when given this environment, my time is limited. I understand that if this were done correctly, our team would actually save money in the long-term by building Unit-Tests before hand. I'm about to refactor a fairly large portion of the code that is critical. While I believe my code will accurately work when done and after our black box testing, I realize that there will be new data that the new code might not be able to handle. What I wanted to know is how to keep old code that functions 98% of the time so that we can call those subroutines in case the new code doesn't work properly. Right now I'm thinking of separating the old code in a separate class file and adding a variable to our config that will tell the program which code to use. Is there a better way to handle this? NOTE: We do use revision control and we have archived builds so the client could always revert to a previous build, but I would like to see if there is a decent way of doing this besides reverting. I want this so they can use the other new functionality delivered in the new build. Edit: While I agree I will need to write Unit Tests for this, I don't believe I will capture everything with them. I'm looking for ways to easily be able to revert to the old, functional code should anything happen. While I know this is a poor practice, I'm planning on removing this code after our team can guarantee that the new code works to the same standards as the old.

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  • How to explain pointers to a Java/VB programmer

    - by Skeith
    I am writing a game and my friend has offered to help me as it is a RPG and will take a long time to do the "scripting" bit of the game. The problem is IMO he's not that good a programmer :( (add flame war here). He has only programmed in Java and VB and keeps saying really stupid things to me like "Why don't you drag and drop an onClick event" to design my UI when I'm using DirectX. I tried explaining pointers to him but his response was, if it's just a variable that holds a memory address, why don't you just use an int? I create an instance of an attack class and give the creature a pointer to it so if several creatures use the same attack there is only one instance of it. He keeps saying why not put if statements in the creature class for every attack class and set true for the ones that are there. He has programmed mainly in VB and a little in Java just to learn OOP. How can I explain advanced C++ concepts like pointers and memory management to him? He just doesn't understand there are no super functions like form.show in C++.

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  • apt-get does not work with proxy

    - by tommyk
    For a command sudo apt-get update I get following error W: Failed to fetch http://ch.archive.ubuntu.com/ubuntu/dists/maverick-updates/multiverse/binary-i386/Packages.gz 407 Proxy Authentication Required ( The ISA Server requires authorization to fulfill the request. Access to the Web Proxy filter is denied. ) I am running Ubuntu 10.10 installed on Windows XP using VirtualBox. For internet connections I am using proxy server with an authentication. I tried to use gnome-network-proxy tool to set proxy settings system-wide. After that /etc/environment has been updated by http_proxy variable with the format http://my_proxy:port/, there were no authentication data. I checked this with firefox. Browser asked my for login and password and everything was working fine. It was unfortunately not the case for apt-get. I have also tried to do as described here. Unfortunately it does not work. May it be somehow related to the fact that a proxy is in a Windows domain, any ideas ? EDIT: My proxy name is http-proxy. Is '-' a special character here ?

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  • Using Native Drag and Drop in HTML 5 pages

    - by nikolaosk
    This is going to be the eighth post in a series of posts regarding HTML 5. You can find the other posts here, here , here , here, here , here and here. In this post I will show you how to implement Drag and Drop functionality in an HTML 5 page using JQuery.This is a great functionality and we do not need to resort anymore to plugins like Silverlight and Flash to achieve this great feature. This is also called a native approach on Drag and Drop.I will use some events and I will write code to respond when these events are fired.As I said earlier we need to write Javascript to implement the drag and drop functionality. I will use the very popular JQuery Library. Please download the library (minified version) from http://jquery.com/downloadI will create a simple HTML page.There will be two thumbnails pics on it. There will also be the drag and drop area where the user will drag the thumb pics into it and they will resize to their actual size. The HTML markup for the page follows<!doctype html><html lang="en"><head><title>Liverpool Legends Gallery</title><meta charset="utf-8"><link rel="stylesheet" type="text/css" href="style.css"><script type="text/javascript" charset="utf-8" src="jquery-1.8.1.min.js"></script>  <script language="JavaScript" src="drag.js"></script>   </head><body><header><h1>A page dedicated to Liverpool Legends</h1><h2>Drag and Drop the thumb image in the designated area to see the full image</h2></header><div id="main"><img src="thumbs/steven-gerrard.jpg"  big="large-images/steven-gerrard-large.jpg" alt="John Barnes"><img src="thumbs/robbie-fowler.jpg" big="large-images/robbie-fowler-large.jpg" alt="Ian Rush"><div id="drag"><p>Drop your image here</p> </div></body></html> There is nothing difficult or fancy in the HTML markup above. I have a link to the external JQuery library and another javascript file that I will implement the whole drag and drop functionality.The code for the css file (style.css) follows#main{  float: left;  width: 340px;  margin-right: 30px;}#drag{  float: left;  width: 400px;  height:300px;  background-color: #c0c0c0;}These are simple CSS rules. This post cannot be a tutorial on CSS.For all these posts I assume that you have the basic HTML,CSS,Javascript skills.Now I am going to create a javascript file (drag.js) to implement the drag and drop functionality.I will provide the whole code for the drag.js file and then I will explain what I am doing in each step.$(function() {          var players = $('#main img');          players.attr('draggable', 'true');                    players.bind('dragstart', function(event) {              var data = event.originalEvent.dataTransfer;               var src = $(this).attr("big");              data.setData("Text", src);               return true;          });          var target = $('#drag');          target.bind('drop', function(event) {            var data = event.originalEvent.dataTransfer;            var src = ( data.getData('Text') );                         var img = $("<img></img>").attr("src", src);            $(this).html(img);            if (event.preventDefault) event.preventDefault();            return(false);          });                   target.bind('dragover', function(event) {                if (event.preventDefault) event.preventDefault();            return false;          });           players.bind('dragend', function(event) {             if (event.preventDefault) event.preventDefault();             return false;           });        });   In these lines var players = $('#main img'); players.attr('draggable', 'true');We grab all the images in the #main div and store them in a variable and then make them draggable.Then in following lines I am using the dragstart event.  players.bind('dragstart', function(event) {              var data = event.originalEvent.dataTransfer;               var src = $(this).attr("big");              data.setData("Text", src);               return true;          }); In this event I am associating the custom data attribute value with the item I am dragging.Then I create a variable to get hold of the dropping area var target = $('#drag'); Then in the following lines I implement the drop event and what happens when the user drops the image in the designated area on the page. target.bind('drop', function(event) {            var data = event.originalEvent.dataTransfer;            var src = ( data.getData('Text') );                         var img = $("<img></img>").attr("src", src);            $(this).html(img);            if (event.preventDefault) event.preventDefault();            return(false);          }); The dragend  event is fired when the user has finished the drag operation        players.bind('dragend', function(event) {             if (event.preventDefault) event.preventDefault();             return false;           }); When this method event.preventDefault() is called , the default action of the event will not be triggered.Please have a look a the picture below to see how the page looks before the drag and drop takes place. Then simply I drag and drop a picture in the dropping area.Have a look at the picture below It works!!! Hope it helps!!  

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  • C# Role Provider for multiple applications

    - by Juventus18
    I'm making a custom RoleProvider that I would like to use across multiple applications in the same application pool. For the administration of roles (create new role, add users to role, etc..) I would like to create a master application that I could login to and set the roles for each additional application. So for example, I might have AppA and AppB in my organization, and I need to make an application called AppRoleManager that can set roles for AppA and AppB. I am having troubles implementing my custom RoleProvider because it uses an initialize method that gets the application name from the config file, but I need the application name to be a variable (i.e. "AppA" or "AppB") and passed as a parameter. I thought about just implementing the required methods, and then also having additional methods that pass application name as a parameter, but that seems clunky. i.e. public override CreateRole(string roleName) { //uses the ApplicationName property of this, which is set in web.config //creates role in db } public CreateRole(string ApplicationName, string roleName) { //creates role in db with specified params. } Also, I would prefer if people were prevented from calling CreateRole(string roleName) because the current instance of the class might have a different applicationName value than intended (what should i do here? throw NotImplementedException?). I tried just writing the class without inheriting RoleProvider. But it is required by the framework. Any general ideas on how to structure this project? I was thinking make a wrapper class that uses the role provider, and explicitly sets the application name before (and after) and calls to the provider something like this: static class RoleProviderWrapper { public static CreateRole(string pApplicationName, string pRoleName) { Roles.Provider.ApplicationName = pApplicationName; Roles.Provider.CreateRole(pRoleName); Roles.Provider.ApplicationName = "Generic"; } } is this my best-bet?

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  • Designing configuration for subobjects

    - by Stefano Borini
    I have the following situation: I have a class (let's call it Main) encapsulating a complex process. This class in turn orchestrates a sequence of subalgorithms (AlgoA, AlgoB), each one represented by an individual class. To configure Main, I have a configuration stored into a configuration object MainConfig. This object contains all the config information for AlgoA and AlgoB with their specific parameters. AlgoA has no interest to the information relative to the configuration of AlgoB, so technically I could have (and in practice I have) a contained MainConfig.AlgoAConfig and MainConfig.AlgoBConfig instances, and initialize as AlgoA(MainConfig.AlgoAConfig) and AlgoB(MainConfig.AlgoBConfig). The problem is that there is some common configuration data. One example is the printLevel. I currently have MainConfig.printLevel. I need to propagate this information to both AlgoA and AlgoB, because they have to know how much to print. MainConfig also needs to know how much to print. So the solutions available are I pass the MainConfig to AlgoA and AlgoB. This way, AlgoA has technically access to the whole configuration (even that of AlgoB) and is less self-contained I copy the MainConfig.printLevel into AlgoAConfig and AlgoBConfig, so I basically have three printLevel information repeated. I create a third configuration class PrintingConfig. I have an instance variable MainConfig.printingConfig, and then pass to AlgoA both MainConfig.AlgoAConfig and MainConfig.printingConfig. Have you ever found this situation? How did you solve it ? Which one is stylistically clearer to a new reader of the code ?

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  • How should I share variables between instances/classes?

    - by tesselode
    I'm making a game using LOVE, so everything is programmed in Lua. I've been experimenting with using classes and object orientation recently. I've found out that a nice system to use is having most of the game's code in different classes, and having a table of instances with all of the instances of any class in it. This way, I can go through every instance of every class and update and draw it by calling the same function. There is a problem, though. Let's say I have an instance of a player with variables for health and recharge time of a weapon. I also have a master instance which is responsible for drawing the HUD. How can I tell the master instance what the player's health is? Bad solutions: Assuming that the player instance will always have the same position in the table - that can be easily changed. Using global variables. Global variables are evil. Have the master instance outside of the instances table, and have the player set variables inside the master instance, which it then uses for HUD drawing. This is really bad because now I have to make a duplicate of every variable the master instance needs. What is the proper, standard way of sharing variables between instances? Do I need to change the way I keep track of instances?

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  • Powershell: Install-dotNET4 function

    - by marc dekeyser
    This function will download and install ,NET 4.0. It uses the Get-Framework-Versions function to determine if the installation is necessary or not. Internet Connectivity will be required as the script auto downloads the setup file (and sleeps for 360 seconds... I had a function in there to monitor for install completion at first, turns out the setup file spawns so many childprocesses the function just got confused and locked up -_-)Alternatively you could drop the installation file in the folder specified on the $folderPath variable too. That will skip the download and use the file. This function easily adapts in to other versions f.e. I use it for Powershell 3 installs as well!Function install-dotNet4 () {    if(($InstalledDotNET -eq "4.0") -or ($InstalledDotNET -eq "4.0c")){        write-host ".NET 4.0 Framework is already installed" -foregroundcolor Green    } else{            #set a var for the folder you are looking for        $folderPath = 'C:\Temp'        #Check if folder exists, if not, create it        if (Test-Path $folderpath){            Write-Host "The folder $folderPath exists." -ForeGroundColor Green        } else{            Write-Host "The folder $folderPath does not exist, creating..." -NoNewline -ForegroundColor Red            New-Item $folderpath -type directory | Out-Null            Write-Host " - done!" -ForegroundColor Green        }        # Check if file exists, if not, download it        $file = $folderPath+"\dotNetFx40_Full_x86_x64.exe"        if (Test-Path $file){            write-host "The file $file exists." -ForeGroundColor Green        } else {            #Download Microsoft .Net 4.0 Framework            Write-Host "Downloading Microsoft .Net 4.0 Framework..." -nonewline -ForeGroundColor DarkYellow            $clnt = New-Object System.Net.WebClient            $url = "http://download.microsoft.com/download/9/5/A/95A9616B-7A37-4AF6-BC36-D6EA96C8DAAE/dotNetFx40_Full_x86_x64.exe"            $clnt.DownloadFile($url,$file)            Write-Host " - done!" -ForegroundColor Green        }        #Install Microsoft .Net Framework        Write-Host "Installing Microsoft .Net Framework..." -nonewline -ForegroundColor DarkYellow        $dotNET4 = $folderPath+"\dotNetFx40_Full_x86_x64.exe /quiet /norestart"        Invoke-Expression $dotNET4        write-host " - done!" -ForegroundColor Green        start-sleep -seconds 360    }}

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  • Implementing a post-notification function to perform custom validation

    - by Alejandro Sosa
    Introduction Oracle Workflow Notification System can be extended to perform extra validation or processing via PLSQL procedures when the notification is being responded to. These PLSQL procedures are called post-notification functions since they are executed after a notification action such as Approve, Reject, Reassign or Request Information is performed. The standard signature for the post-notification function is     procedure <procedure_name> (itemtype  in varchar2,                                itemkey   in varchar2,                                actid     in varchar2,                                funcmode  in varchar2,                                resultout in out nocopy varchar2); Modes The post-notification function provides the parameter 'funcmode' which will have the following values: 'RESPOND', 'VALIDATE, and 'RUN' for a notification is responded to (Approve, Reject, etc) 'FORWARD' for a notification being forwarded to another user 'TRANSFER' for a notification being transferred to another user 'QUESTION' for a request of more information from one user to another 'QUESTION' for a response to a request of more information 'TIMEOUT' for a timed-out notification 'CANCEL' when the notification is being re-executed in a loop. Context Variables Oracle Workflow provides different context information that corresponds to the current notification being acted upon to the post-notification function. WF_ENGINE.context_nid - The notification ID  WF_ENGINE.context_new_role - The new role to which the action on the notification is directed WF_ENGINE.context_user_comment - Comments appended to the notification   WF_ENGINE.context_user - The user who is responsible for taking the action that updated the notification's state WF_ENGINE.context_recipient_role - The role currently designated as the recipient of the notification. This value may be the same as the value of WF_ENGINE.context_user variable, or it may be a group role of which the context user is a member. WF_ENGINE.context_original_recipient - The role that has ownership of and responsibility for the notification. This value may differ from the value of the WF_ENGINE.context_recipient_role variable if the notification has previously been reassigned.  Example Let us assume there is an EBS transaction that can only be approved by a certain people thus any attempt to transfer or delegate such notification should be allowed only to users SPIERSON or CBAKER. The way to implement this functionality would be as follows: Edit the corresponding workflow definition in Workflow Builder and open the notification. In the Function Name enter the name of the procedure where the custom code is handled, for instance, TEST_PACKAGE.Post_Notification In PLSQL create the corresponding package TEST_PACKAGE with a procedure named Post_Notification, as follows:     procedure Post_Notification (itemtype  in varchar2,                                  itemkey   in varchar2,                                  actid     in varchar2,                                  funcmode  in varchar2,                                  resultout in out nocopy varchar2) is     l_count number;     begin       if funcmode in ('TRANSFER','FORWARD') then         select count(1) into l_count         from WF_ROLES         where WF_ENGINE.context_new_role in ('SPIERSON','CBAKER');               --and/or any other conditions         if l_count<1 then           WF_CORE.TOKEN('ROLE', WF_ENGINE.context_new_role);           WF_CORE.RAISE('WFNTF_TRANSFER_FAIL');         end if;       end if;     end Post_Notification; Launch the workflow process with the changed notification and attempt to reassign or transfer it. When trying to reassign the notification to user CBROWN the screen would like like below: Check the Workflow API Reference Guide, section Post-Notification Functions, to see all the standard, seeded WF_ENGINE variables available for extending notifications processing. 

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  • Grid-Based 2D Lighting Problems

    - by Lemoncreme
    I am aware this question has been asked before, but unfortunately I am new to the language, so the complicated explanations I've found do not help me in the least. I need a lighting engine for my game, and I've tried some procedural lighting systems. This method works the best: if (light[xx - 1, yy] > light[xx, yy]) light[xx, yy] = light[xx - 1, yy] - lightPass; if (light[xx, yy - 1] > light[xx, yy]) light[xx, yy] = light[xx, yy - 1] - lightPass; if (light[xx + 1, yy] > light[xx, yy]) light[xx, yy] = light[xx + 1, yy] - lightPass; if (light[xx, yy + 1] > light[xx, yy]) light[xx, yy] = light[xx, yy + 1] - lightPass; (Subtracts adjacent values by 'lightPass' variable if they are more bright) (It's in a for() loop) This is all fine and dandy except for a an obvious reason: The system favors whatever comes first in the for() loop This is what the above code looks like applied to my game: If I could get some help on creating a new procedural or otherwise lighting system I would really appreciate it!

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  • Programming and Ubiquitous Language (DDD) in a non-English domain

    - by Sandor Drieënhuizen
    I know there are some questions already here that are closely related to this subject but none of them take Ubquitous Language as the starting point so I think that justifies this question. For those who don't know: Ubiquitous Language is the concept of defining a (both spoken and written) language that is equally used across developers and domain experts to avoid inconsistencies and miscommunication due to translation problems and misunderstanding. You will see the same terminology show up in code, conversations between any team member, functional specs and whatnot. So, what I was wondering about is how to deal with Ubiquitous Language in non-English domains. Personally, I strongly favor writing programming code in English completely, including comments but ofcourse excluding constants and resources. However, in a non-English domain, I'm forced to make a decision either to: Write code reflecting the Ubiquitous Language in the natural language of the domain. Translate the Ubiquitous Language to English and stop communicating in the natural language of the domain. Define a table that defines how the Ubiquitous Language translates to English. Here are some of my thoughts based on these options: 1) I have a strong aversion against mixed-language code, that is coding using type/member/variable names etc. that are non-English. Most programming languages 'breathe' English to a large extent and most of the technical literature, design pattern names etc. are in English as well. Therefore, in most cases there's just no way of writing code entirely in a non-English language so you end up with a mixed languages. 2) This will force the domain experts to start thinking and talking in the English equivalent of the UL, something that will probably not come naturally to them and therefore hinders communication significantly. 3) In this case, the developers communicate with the domain experts in their native language while the developers communicate with each other in English and most importantly, they write code using the English translation of the UL. I'm sure I don't want to go for the first option and I think option 3 is much better than option 2. What do you think? Am I missing other options?

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  • A Look Inside JSR 360 - CLDC 8

    - by Roger Brinkley
    If you didn't notice during JavaOne the Java Micro Edition took a major step forward in its consolidation with Java Standard Edition when JSR 360 was proposed to the JCP community. Over the last couple of years there has been a focus to move Java ME back in line with it's big brother Java SE. We see evidence of this in JCP itself which just recently merged the ME and SE/EE Executive Committees into a single Java Executive Committee. But just before that occurred JSR 360 was proposed and approved for development on October 29. So let's take a look at what changes are now being proposed. In a way JSR 360 is returning back to the original roots of Java ME when it was first introduced. It was indeed a subset of the JDK 4 language, but as Java progressed many of the language changes were not implemented in the Java ME. Back then the tradeoff was still a functionality, footprint trade off but the major market was feature phones. Today the market has changed and CLDC, while it will still target feature phones, will have it primary emphasis on embedded devices like wireless modules, smart meters, health care monitoring and other M2M devices. The major changes will come in three areas: language feature changes, library changes, and consolidating the Generic Connection Framework.  There have been three Java SE versions that have been implemented since JavaME was first developed so the language feature changes can be divided into changes that came in JDK 5 and those in JDK 7, which mostly consist of the project Coin changes. There were no language changes in JDK 6 but the changes from JDK 5 are: Assertions - Assertions enable you to test your assumptions about your program. For example, if you write a method that calculates the speed of a particle, you might assert that the calculated speed is less than the speed of light. In the example code below if the interval isn't between 0 and and 1,00 the an error of "Invalid value?" would be thrown. private void setInterval(int interval) { assert interval > 0 && interval <= 1000 : "Invalid value?" } Generics - Generics add stability to your code by making more of your bugs detectable at compile time. Code that uses generics has many benefits over non-generic code with: Stronger type checks at compile time. Elimination of casts. Enabling programming to implement generic algorithms. Enhanced for Loop - the enhanced for loop allows you to iterate through a collection without having to create an Iterator or without having to calculate beginning and end conditions for a counter variable. The enhanced for loop is the easiest of the new features to immediately incorporate in your code. In this tip you will see how the enhanced for loop replaces more traditional ways of sequentially accessing elements in a collection. void processList(Vector<string> list) { for (String item : list) { ... Autoboxing/Unboxing - This facility eliminates the drudgery of manual conversion between primitive types, such as int and wrapper types, such as Integer.  Hashtable<Integer, string=""> data = new Hashtable<>(); void add(int id, String value) { data.put(id, value); } Enumeration - Prior to JDK 5 enumerations were not typesafe, had no namespace, were brittle because they were compile time constants, and provided no informative print values. JDK 5 added support for enumerated types as a full-fledged class (dubbed an enum type). In addition to solving all the problems mentioned above, it allows you to add arbitrary methods and fields to an enum type, to implement arbitrary interfaces, and more. Enum types provide high-quality implementations of all the Object methods. They are Comparable and Serializable, and the serial form is designed to withstand arbitrary changes in the enum type. enum Season {WINTER, SPRING, SUMMER, FALL}; } private Season season; void setSeason(Season newSeason) { season = newSeason; } Varargs - Varargs eliminates the need for manually boxing up argument lists into an array when invoking methods that accept variable-length argument lists. The three periods after the final parameter's type indicate that the final argument may be passed as an array or as a sequence of arguments. Varargs can be used only in the final argument position. void warning(String format, String... parameters) { .. for(String p : parameters) { ...process(p);... } ... } Static Imports -The static import construct allows unqualified access to static members without inheriting from the type containing the static members. Instead, the program imports the members either individually or en masse. Once the static members have been imported, they may be used without qualification. The static import declaration is analogous to the normal import declaration. Where the normal import declaration imports classes from packages, allowing them to be used without package qualification, the static import declaration imports static members from classes, allowing them to be used without class qualification. import static data.Constants.RATIO; ... double r = Math.cos(RATIO * theta); Annotations - Annotations provide data about a program that is not part of the program itself. They have no direct effect on the operation of the code they annotate. There are a number of uses for annotations including information for the compiler, compiler-time and deployment-time processing, and run-time processing. They can be applied to a program's declarations of classes, fields, methods, and other program elements. @Deprecated public void clear(); The language changes from JDK 7 are little more familiar as they are mostly the changes from Project Coin: String in switch - Hey it only took us 18 years but the String class can be used in the expression of a switch statement. Fortunately for us it won't take that long for JavaME to adopt it. switch (arg) { case "-data": ... case "-out": ... Binary integral literals and underscores in numeric literals - Largely for readability, the integral types (byte, short, int, and long) can also be expressed using the binary number system. and any number of underscore characters (_) can appear anywhere between digits in a numerical literal. byte flags = 0b01001111; long mask = 0xfff0_ff08_4fff_0fffl; Multi-catch and more precise rethrow - A single catch block can handle more than one type of exception. In addition, the compiler performs more precise analysis of rethrown exceptions than earlier releases of Java SE. This enables you to specify more specific exception types in the throws clause of a method declaration. catch (IOException | InterruptedException ex) { logger.log(ex); throw ex; } Type Inference for Generic Instance Creation - Otherwise known as the diamond operator, the type arguments required to invoke the constructor of a generic class can be replaced with an empty set of type parameters (<>) as long as the compiler can infer the type arguments from the context.  map = new Hashtable<>(); Try-with-resource statement - The try-with-resources statement is a try statement that declares one or more resources. A resource is an object that must be closed after the program is finished with it. The try-with-resources statement ensures that each resource is closed at the end of the statement.  try (DataInputStream is = new DataInputStream(...)) { return is.readDouble(); } Simplified varargs method invocation - The Java compiler generates a warning at the declaration site of a varargs method or constructor with a non-reifiable varargs formal parameter. Java SE 7 introduced a compiler option -Xlint:varargs and the annotations @SafeVarargs and @SuppressWarnings({"unchecked", "varargs"}) to supress these warnings. On the library side there are new features that will be added to satisfy the language requirements above and some to improve the currently available set of APIs.  The library changes include: Collections update - New Collection, List, Set and Map, Iterable and Iteratator as well as implementations including Hashtable and Vector. Most of the work is too support generics String - New StringBuilder and CharSequence as well as a Stirng formatter. The javac compiler  now uses the the StringBuilder instead of String Buffer. Since StringBuilder is synchronized there is a performance increase which has necessitated the wahat String constructor works. Comparable interface - The comparable interface works with Collections, making it easier to reuse. Try with resources - Closeable and AutoCloseable Annotations - While support for Annotations is provided it will only be a compile time support. SuppressWarnings, Deprecated, Override NIO - There is a subset of NIO Buffer that have been in use on the of the graphics packages and needs to be pulled in and also support for NIO File IO subset. Platform extensibility via Service Providers (ServiceLoader) - ServiceLoader interface dos late bindings of interface to existing implementations. It helpe to package an interface and behavior of the implementation at a later point in time.Provider classes must have a zero-argument constructor so that they can be instantiated during loading. They are located and instantiated on demand and are identified via a provider-configuration file in the METAINF/services resource directory. This is a mechansim from Java SE. import com.XYZ.ServiceA; ServiceLoader<ServiceA> sl1= new ServiceLoader(ServiceA.class); Resources: META-INF/services/com.XYZ.ServiceA: ServiceAProvider1 ServiceAProvider2 ServiceAProvider3 META-INF/services/ServiceB: ServiceBProvider1 ServiceBProvider2 From JSR - I would rather use this list I think The Generic Connection Framework (GCF) was previously specified in a number of different JSRs including CLDC, MIDP, CDC 1.2, and JSR 197. JSR 360 represents a rare opportunity to consolidated and reintegrate parts that were duplicated in other specifications into a single specification, upgrade the APIs as well provide new functionality. The proposal is to specify a combined GCF specification that can be used with Java ME or Java SE and be backwards compatible with previous implementations. Because of size limitations as well as the complexity of the some features like InvokeDynamic and Unicode 6 will not be included. Additionally, any language or library changes in JDK 8 will be not be included. On the upside, with all the changes being made, backwards compatibility will still be maintained. JSR 360 is a major step forward for Java ME in terms of platform modernization, language alignment, and embedded support. If you're interested in following the progress of this JSR see the JSR's java.net project for details of the email lists, discussions groups.

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  • Organising levels / rooms in a MUD-style text based world

    - by Polynomial
    I'm thinking of writing a small text-based adventure game, but I'm not particularly sure how I should design the world from a technical standpoint. My first thought is to do it in XML, designed something like the following. Apologies for the huge pile of XML, but I felt it important to fully explain what I'm doing. <level> <start> <!-- start in kitchen with empty inventory --> <room>Kitchen</room> <inventory></inventory> </start> <rooms> <room> <name>Kitchen</name> <description>A small kitchen that looks like it hasn't been used in a while. It has a table in the middle, and there are some cupboards. There is a door to the north, which leads to the garden.</description> <!-- IDs of the objects the room contains --> <objects> <object>Cupboards</object> <object>Knife</object> <object>Batteries</object> </objects> </room> <room> <name>Garden</name> <description>The garden is wild and full of prickly bushes. To the north there is a path, which leads into the trees. To the south there is a house.</description> <objects> </objects> </room> <room> <name>Woods</name> <description>The woods are quite dark, with little light bleeding in from the garden. It is eerily quiet.</description> <objects> <object>Trees01</object> </objects> </room> </rooms> <doors> <!-- a door isn't necessarily a door. each door has a type, i.e. "There is a <type> leading to..." from and to are references the rooms that this door joins. direction specifies the direction (N,S,E,W,Up,Down) from <from> to <to> --> <door> <type>door</type> <direction>N</direction> <from>Kitchen</from> <to>Garden</to> </door> <door> <type>path</type> <direction>N</direction> <from>Garden</type> <to>Woods</type> </door> </doors> <variables> <!-- variables set by actions --> <variable name="cupboard_open">0</variable> </variables> <objects> <!-- definitions for objects --> <object> <name>Trees01</name> <displayName>Trees</displayName> <actions> <!-- any actions not defined will show the default failure message --> <action> <command>EXAMINE</command> <message>The trees are tall and thick. There aren't any low branches, so it'd be difficult to climb them.</message> </action> </actions> </object> <object> <name>Cupboards</name> <displayName>Cupboards</displayName> <actions> <action> <!-- requirements make the command only work when they are met --> <requirements> <!-- equivilent of "if(cupboard_open == 1)" --> <require operation="equal" value="1">cupboard_open</require> </requirements> <command>EXAMINE</command> <!-- fail message is the message displayed when the requirements aren't met --> <failMessage>The cupboard is closed.</failMessage> <message>The cupboard contains some batteires.</message> </action> <action> <requirements> <require operation="equal" value="0">cupboard_open</require> </requirements> <command>OPEN</command> <failMessage>The cupboard is already open.</failMessage> <message>You open the cupboard. It contains some batteries.</message> <!-- assigns is a list of operations performed on variables when the action succeeds --> <assigns> <assign operation="set" value="1">cupboard_open</assign> </assigns> </action> <action> <requirements> <require operation="equal" value="1">cupboard_open</require> </requirements> <command>CLOSE</command> <failMessage>The cupboard is already closed.</failMessage> <message>You closed the cupboard./message> <assigns> <assign operation="set" value="0">cupboard_open</assign> </assigns> </action> </actions> </object> <object> <name>Batteries</name> <displayName>Batteries</displayName> <!-- by setting inventory to non-zero, we can put it in our bag --> <inventory>1</inventory> <actions> <action> <requirements> <require operation="equal" value="1">cupboard_open</require> </requirements> <command>GET</command> <!-- failMessage isn't required here, it'll just show the usual "You can't see any <blank>." message --> <message>You picked up the batteries.</message> </action> </actions> </object> </objects> </level> Obviously there'd need to be more to it than this. Interaction with people and enemies as well as death and completion are necessary additions. Since the XML is quite difficult to work with, I'd probably create some sort of world editor. I'd like to know if this method has any downfalls, and if there's a "better" or more standard way of doing it.

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  • The Return Of __FILE__ And __LINE__ In .NET 4.5

    - by Alois Kraus
    Good things are hard to kill. One of the most useful predefined compiler macros in C/C++ were __FILE__ and __LINE__ which do expand to the compilation units file name and line number where this value is encountered by the compiler. After 4.5 versions of .NET we are on par with C/C++ again. It is of course not a simple compiler expandable macro it is an attribute but it does serve exactly the same purpose. Now we do get CallerLineNumberAttribute  == __LINE__ CallerFilePathAttribute        == __FILE__ CallerMemberNameAttribute  == __FUNCTION__ (MSVC Extension)   The most important one is CallerMemberNameAttribute which is very useful to implement the INotifyPropertyChanged interface without the need to hard code the name of the property anymore. Now you can simply decorate your change method with the new CallerMemberName attribute and you get the property name as string directly inserted by the C# compiler at compile time.   public string UserName { get { return _userName; } set { _userName=value; RaisePropertyChanged(); // no more RaisePropertyChanged(“UserName”)! } } protected void RaisePropertyChanged([CallerMemberName] string member = "") { var copy = PropertyChanged; if(copy != null) { copy(new PropertyChangedEventArgs(this, member)); } } Nice and handy. This was obviously the prime reason to implement this feature in the C# 5.0 compiler. You can repurpose this feature for tracing to get your hands on the method name of your caller along other stuff very fast now. All infos are added during compile time which is much faster than other approaches like walking the stack. The example on MSDN shows the usage of this attribute with an example public static void TraceMessage(string message, [CallerMemberName] string memberName = "", [CallerFilePath] string sourceFilePath = "", [CallerLineNumber] int sourceLineNumber = 0) { Console.WriteLine("Hi {0} {1} {2}({3})", message, memberName, sourceFilePath, sourceLineNumber); }   When I do think of tracing I do usually want to have a API which allows me to Trace method enter and leave Trace messages with a severity like Info, Warning, Error When I do print a trace message it is very useful to print out method and type name as well. So your API must either be able to pass the method and type name as strings or extract it automatically via walking back one Stackframe and fetch the infos from there. The first glaring deficiency is that there is no CallerTypeAttribute yet because the C# compiler team was not satisfied with its performance.   A usable Trace Api might therefore look like   enum TraceTypes { None = 0, EnterLeave = 1 << 0, Info = 1 << 1, Warn = 1 << 2, Error = 1 << 3 } class Tracer : IDisposable { string Type; string Method; public Tracer(string type, string method) { Type = type; Method = method; if (IsEnabled(TraceTypes.EnterLeave,Type, Method)) { } } private bool IsEnabled(TraceTypes traceTypes, string Type, string Method) { // Do checking here if tracing is enabled return false; } public void Info(string fmt, params object[] args) { } public void Warn(string fmt, params object[] args) { } public void Error(string fmt, params object[] args) { } public static void Info(string type, string method, string fmt, params object[] args) { } public static void Warn(string type, string method, string fmt, params object[] args) { } public static void Error(string type, string method, string fmt, params object[] args) { } public void Dispose() { // trace method leave } } This minimal trace API is very fast but hard to maintain since you need to pass in the type and method name as hard coded strings which can change from time to time. But now we have at least CallerMemberName to rid of the explicit method parameter right? Not really. Since any acceptable usable trace Api should have a method signature like Tracexxx(… string fmt, params [] object args) we not able to add additional optional parameters after the args array. If we would put it before the format string we would need to make it optional as well which would mean the compiler would need to figure out what our trace message and arguments are (not likely) or we would need to specify everything explicitly just like before . There are ways around this by providing a myriad of overloads which in the end are routed to the very same method but that is ugly. I am not sure if nobody inside MS agrees that the above API is reasonable to have or (more likely) that the whole talk about you can use this feature for diagnostic purposes was not a core feature at all but a simple byproduct of making the life of INotifyPropertyChanged implementers easier. A way around this would be to allow for variable argument arrays after the params keyword another set of optional arguments which are always filled by the compiler but I do not know if this is an easy one. The thing I am missing much more is the not provided CallerType attribute. But not in the way you would think of. In the API above I did add some filtering based on method and type to stay as fast as possible for types where tracing is not enabled at all. It should be no more expensive than an additional method call and a bool variable check if tracing for this type is enabled at all. The data is tightly bound to the calling type and method and should therefore become part of the static type instance. Since extending the CLR type system for tracing is not something I do expect to happen I have come up with an alternative approach which allows me basically to attach run time data to any existing type object in super fast way. The key to success is the usage of generics.   class Tracer<T> : IDisposable { string Method; public Tracer(string method) { if (TraceData<T>.Instance.Enabled.HasFlag(TraceTypes.EnterLeave)) { } } public void Dispose() { if (TraceData<T>.Instance.Enabled.HasFlag(TraceTypes.EnterLeave)) { } } public static void Info(string fmt, params object[] args) { } /// <summary> /// Every type gets its own instance with a fresh set of variables to describe the /// current filter status. /// </summary> /// <typeparam name="T"></typeparam> internal class TraceData<UsingType> { internal static TraceData<UsingType> Instance = new TraceData<UsingType>(); public bool IsInitialized = false; // flag if we need to reinit the trace data in case of reconfigured trace settings at runtime public TraceTypes Enabled = TraceTypes.None; // Enabled trace levels for this type } } We do not need to pass the type as string or Type object to the trace Api. Instead we define a generic Api that accepts the using type as generic parameter. Then we can create a TraceData static instance which is due to the nature of generics a fresh instance for every new type parameter. My tests on my home machine have shown that this approach is as fast as a simple bool flag check. If you have an application with many types using tracing you do not want to bring the app down by simply enabling tracing for one special rarely used type. The trace filter performance for the types which are not enabled must be therefore the fasted code path. This approach has the nice side effect that if you store the TraceData instances in one global list you can reconfigure tracing at runtime safely by simply setting the IsInitialized flag to false. A similar effect can be achieved with a global static Dictionary<Type,TraceData> object but big hash tables have random memory access semantics which is bad for cache locality and you always need to pay for the lookup which involves hash code generation, equality check and an indexed array access. The generic version is wicked fast and allows you to add more features to your tracing Api with minimal perf overhead. But it is cumbersome to write the generic type argument always explicitly and worse if you do refactor code and move parts of it to other classes it might be that you cannot configure tracing correctly. I would like therefore to decorate my type with an attribute [CallerType] class Tracer<T> : IDisposable to tell the compiler to fill in the generic type argument automatically. class Program { static void Main(string[] args) { using (var t = new Tracer()) // equivalent to new Tracer<Program>() { That would be really useful and super fast since you do not need to pass any type object around but you do have full type infos at hand. This change would be breaking if another non generic type exists in the same namespace where now the generic counterpart would be preferred. But this is an acceptable risk in my opinion since you can today already get conflicts if two generic types of the same name are defined in different namespaces. This would be only a variation of this issue. When you do think about this further you can add more features like to trace the exception in your Dispose method if the method is left with an exception with that little trick I did write some time ago. You can think of tracing as a super fast and configurable switch to write data to an output destination or to execute alternative actions. With such an infrastructure you can e.g. Reconfigure tracing at run time. Take a memory dump when a specific method is left with a specific exception. Throw an exception when a specific trace statement is hit (useful for testing error conditions). Execute a passed delegate which e.g. dumps additional state when enabled. Write data to an in memory ring buffer and dump it when specific events do occur (e.g. method is left with an exception, triggered from outside). Write data to an output device. …. This stuff is really useful to have when your code is in production on a mission critical server and you need to find the root cause of sporadic crashes of your application. It could be a buggy graphics card driver which throws access violations into your application (ok with .NET 4 not anymore except if you enable a compatibility flag) where you would like to have a minidump or you have reached after two weeks of operation a state where you need a full memory dump at a specific point in time in the middle of an transaction. At my older machine I do get with this super fast approach 50 million traces/s when tracing is disabled. When I do know that tracing is enabled for this type I can walk the stack by using StackFrameHelper.GetStackFramesInternal to check further if a specific action or output device is configured for this method which is about 2-3 times faster than the regular StackTrace class. Even with one String.Format I am down to 3 million traces/s so performance is not so important anymore since I do want to do something now. The CallerMemberName feature of the C# 5 compiler is nice but I would have preferred to get direct access to the MethodHandle and not to the stringified version of it. But I really would like to see a CallerType attribute implemented to fill in the generic type argument of the call site to augment the static CLR type data with run time data.

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