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• How do I connect to my running VM via virsh?

  - by Avery Chan

  My VM has already been started via virsh start chameleon.ootbdev. When I do a virsh console chameleon.ootbdev I get the following output: Connected to domain chameleon.ootbdev Escape character is ^] error: internal error cannot find character device (null) Doing a google search on this led me to this "solution". Unfortunately, editing the domain via virsh edit chameleon.ootbdev doesn't seem to stick. I suspect the issue is that I'm inserting the XML incorrectly: the instructions from the link ask me to insert the following XML into the domain XML file. <serial type='pty'> <target port='0'/> </serial> <console type='pty'> <target type='serial' port='0'/> </console> I've posted my domain XML file to pastebin here. This is AFTER I've tried to insert the above XML. I inserted this XML after the </devices> block. My primary question is: How do I connect to the running VM? A secondary question would be: How do I edit the domain file with the above XML and get the changes to stick?

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• How to See Your Current Wi-Fi Connection Speed in Mac OS X

  - by The Geek

  Ever since I’ve been using my new MacBook Air, I’ve been befuddled by how to do some of the simplest tasks in Mac OS X that I would normally do from my Windows laptop—like show the connection speed for the current Wi-Fi network. So am I using Wireless-N or not? Normally, on my Windows 7 laptop, all I’d have to do is hover over the icon, or pop up the list—you can even go into the network details and see just about every piece of data about the network, all from the system tray. Here’s how to see your current connection information on your Mac Latest Features How-To Geek ETC The Complete List of iPad Tips, Tricks, and Tutorials The 50 Best Registry Hacks that Make Windows Better The How-To Geek Holiday Gift Guide (Geeky Stuff We Like) LCD? LED? Plasma? The How-To Geek Guide to HDTV Technology The How-To Geek Guide to Learning Photoshop, Part 8: Filters Improve Digital Photography by Calibrating Your Monitor Free Shipping Day is Friday, December 17, 2010 – National Free Shipping Day Find an Applicable Quote for Any Programming Situation Winter Theme for Windows 7 from Microsoft Score Free In-Flight Wi-Fi Courtesy of Google Chrome Peaceful Winter Road at Sunset Wallpaper Everything You Ever Wanted to Know About Why Pac-Man’s Ghosts Move the Way They Do

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• Let's introduce the Oracle Enterprise Data Quality family!

  - by Sarah Zanchetti

  The Oracle Enterprise Data Quality family of products helps you to achieve maximum value from their business applications by delivering fit-­for-­purpose data. OEDQ is a state-of-the-art collaborative data quality profiling, analysis, parsing, standardization, matching and merging product, designed to help you understand, improve, protect and govern the quality of the information your business uses, all from a single integrated environment. Oracle Enterprise Data Quality products are: Oracle Enterprise Data Quality Profile and Audit Oracle Enterprise Data Quality Parsing and Standardization Oracle Enterprise Data Quality Match and Merge Oracle Enterprise Data Quality Address Verification Server Oracle Enterprise Data Quality Product Data Parsing and Standardization Oracle Enterprise Data Quality Product Data Match and Merge Also, the following are some of the key features of OEDQ: Integrated data profiling, auditing, cleansing and matching Browser-based client access Ability to handle all types of data – for example customer, product, asset, financial, operational Connection to any JDBC-compliant data sources and targets Multi-user project support (role-based access, issue tracking, process annotation, and version control) Services Oriented Architecture (SOA) - support for designing processes that may be exposed to external applications as a service Designed to process large data volumes A single repository to hold data along with gathered statistics and project tracking information, with shared access Intuitive graphical user interface designed to help you solve real-world information quality issues quickly Easy, data-led creation and extension of validation and transformation rules Fully extensible architecture allowing the insertion of any required custom processing  If you need to learn more about EDQ, or get assistance for any kind of issue, the Oracle Technology Network offers a huge range of resources on Oracle software. Discuss technical problems and solutions on the Discussion Forums. Get hands-on step-by-step tutorials with Oracle By Example. Download Sample Code. Get the latest news and information on any Oracle product. You can also get further help and information with Oracle software from: My Oracle Support Oracle Support Services An Information Center is available, where you can find technical information and fast solutions to the most common already solved issues: Information Center: Oracle Enterprise Data Quality [ID 1555073.2]

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• Items Affecting Performance of the MySQL Database

  - by Antoinette O'Sullivan

  To learn about the many factors that can affect the performance of the MySQL Database, take the MySQL Performance Tuning course. You will learn: How your hardware and operating system can affect performance How to set up and logging to improve performance Best practices for backup and recovery And much more You can take this 4-day instructor-led course through the following formats: Training-on-Demand: Start training within 24 hours of registering for training, following lectures at your own pace through streaming video and booking time on a lab environment to suit your schedule. Live-Virtual Event: Attend a live event from your own desk, no travel required. Choose from a selection of events on the schedule to suit different time-zones. In-Class Event: Travel to an education center to attend this course. Below is a selection of events already on the schedule.  Location  Date  Delivery Language  Brussels, Beligum  10 November 2014  English  Sao Paolo, Brazil  25 August 2014  Brazilian Portuguese  London, England  20 October 2014  English  Milan, Italy  20 October 2014  Italian  Rome, Italy  1 December 2014  Italian  Riga, Latvia  29 September 2014  Latvian  Petaling Jaya, Malaysia  22 September 2014  English  Utrecht, Netherlands  10 November 2014  English  Warsaw, Poland  1 September 2014  Polish  Barcelona, Spain  14 October 2014  Spanish To register for an event, request an additional event, or learn more about the authentic MySQL Curriculum, go to http://education.oracle.com/mysql.

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• Get Trained on Oracle VM Server for x86 in your timezone or location

  - by Antoinette O'Sullivan

  Register now to get trained on Oracle VM Server for x86 in your location or timezone - and frequently in your local language. You have a choice between the 3 day course, Oracle VM Administration: Oracle VM Server for x86, providing you with a wide range of hands-on exercises or a 1 day seminar, Oracle VM with Oracle VM Server for x86 Seminar. And you have a choice of attending these instructor-led courses Live from your desk through Oracle Universities Live Virtual Classes. For these virtual events there are hundreds of scheduled events across many timezones and there is no need to travel! Schedule details available on the Oracle University portal and visit the Virtualization space. In a classroom with a subset of scheduled events shown below:  Where  When  Delivery Language  3 day Hands-On Course      Dusseldorf, Germany  6 August 2012  German  Munich, Germany  9 July 2012  German  Paris, France  17 October 2012  French  Sydney, Australia  3 September 2012  English  Denver, United States  30 July 2012  English  Roseville, United States  25 June 2012  English  1 day Seminar      Paris, France  4 September 2012  French  Roseville, United States  15 June 2012  English  Mexico City, Mexico  20 June 2012  Spanish To find additional classes, go to the Oracle University portal and visit the Virtualization space. Should you not find an event on the schedule that suits you, register your interest for a specific event/date.

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• Distributed transactions and queues, ruby, erlang

  - by chrispanda

  I have a problem that involves several machines, message queues, and transactions. So for example a user clicks on a web page, the click sends a message to another machine which adds a payment to the user's account. There may be many thousands of clicks per second. All aspects of the transaction should be fault tolerant. I've never had to deal with anything like this before, but a bit of reading suggests this is a well known problem. So to my questions. Am I correct in assuming that secure way of doing this is with a two phase commit, but the protocol is blocking and so I won't get the required performance? It appears that DBs like redis and message queuing system like Rescue, RabbitMQ etc don't really help me a lot - even if I implement some sort of two phase commit, the data will be lost if redis crashes because it is essentially memory-only. All of this has led me to look at erlang - but before I wade in and start learning a new language, I would really like to understand better if this is worth the effort. Specifically, am I right in thinking that because of its parallel processing capabilities, erlang is a better choice for implementing a blocking protocol like two phase commit, or am I confused?

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• Would Using a PHP Framework Be Beneficial in My Context?

  - by Fractal

  I've just started work at a small start-up company who mainly uses PHP to develop their front-end apps. I had no prior PHP experience before joining, and this has led to my apps becoming large pieces of spaghetti code. I essentially started by adding code to implement an initial feature, and then continued to hack in more code to implement further features – without much thought for the overall design. The apps themselves output XML to render on small mobile devices. I recently started looking into frameworks that I could use. I reckon an advantage would be that they seem to force developers to modularise their programs using good-practice design patterns. This seems great for someone in my position. The extra functions they provide, for example: interfacing with databases in such a way as to make SQL injection impossible, would be very useful too. The downside I can see is that there will be a lot of overhead for me in terms of the time taken to learn the framework itself (while still getting to grips with PHP itself). I'm also worried that it will be overkill for the scale of the apps we develop. They tend to be programs that interface with a fairly simple back-end DB, and will generate about 5 different XML screens. Probably around 1 or 2 thousand lines of code. The time it takes just to configure the frameworks may not be worth it. The final problem I can see is that developers in the company – who have to go over my code, and who do not know the PHP framework I may use – will have a much harder time understanding it. Given those pros and cons, I'm still not sure on what the best course of action will be; so any advice will be greatly appreciated.

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• Examples of limitations in IT due to different bit length by design

  - by Alaudo

  I am teaching the course "Introduction in Programming" for the first-year students and would like to find interesting examples where the datatype size in bits, chosen by design, led to certain known restrictions or important values. Here are some examples: Due to the fact that the Bell teleprinter used 7-bit-code (later accepted as ASCII) until now have we often to encode attachments in electronic messages to contain only 7 bit data. Classical limitation of 32-bit address space leads to the 4Gb maximal RAM size available for 32-bit systems and 4Gb maximal file size in FAT32. Do you know some other interesting examples how the choice of the data type (and especially its binary length) influenced the modern IT world. Added after some discussion in comments: I am not going to teach how to overcome limitations. I just want them to know that 1 byte can hold the values from -127..0..+127 o 0..255, 2 bytes cover the range 0..65535 etc by proving examples they know from other sources, like the above-mentioned base64 encoding etc. We are just learning the basic datatypes and I am trying to find a good reference for "how large" these types are.

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• The Twelve Days of Geekmas

  - by YatriTrivedi

  Looking for some last minute shopping for your favorite geek? We put a few holiday shopping items into the form of a song to show off just how geeky your Christmas can be. Make sure that you read through the list to the tune of the Twelve Days of Christmas. Yes, we’re really being silly today. Have fun! Image by dawolf On the twelfth day of Geekmas, a dear friend gave to me… Latest Features How-To Geek ETC The Complete List of iPad Tips, Tricks, and Tutorials The 50 Best Registry Hacks that Make Windows Better The How-To Geek Holiday Gift Guide (Geeky Stuff We Like) LCD? LED? Plasma? The How-To Geek Guide to HDTV Technology The How-To Geek Guide to Learning Photoshop, Part 8: Filters Improve Digital Photography by Calibrating Your Monitor The Brothers Mario – Epic Gangland Style Mario Brothers Movie Trailer [Video] Score Awesome Games on the Cheap with the Humble Indie Bundle Add a Colorful Christmas Theme to Your Windows 7 Desktop This Windows Hack Changes the Blue Screen of Death to Red Edit Images Quickly in Firefox with Pixlr Grabber Zoho Writer, Sheet, and Show Now Available in Chrome Web Store

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• Edd strikes again &ndash; IronRuby for Rubyists on InfoQ

  - by Eric Nelson

  Colleague, friend and generally top guy on IronRuby Edd Morgan has just been published over on InfoQ. To wet the appetite… a snippet or three. IronRuby for Rubyists IronRuby is Microsoft's implementation of the Ruby language we all know and love with the added bonus of interoperability with the .NET framework — the Iron in the name is actually an acronym for 'Implementation running on .NET'. It's supported by the .NET Common Language Runtime as well as, albeit unofficially, the Mono project. You'd be forgiven for harbouring some question in your mind about running a dynamic language such as Ruby atop the CLR - that's where the DLR (Dynamic Language Runtime) comes in. The DLR is Microsoft's way of providing dynamic language capability on top of the CLR. Both IronRuby and the DLR are, as part of Microsoft's commitment to open source software, available as part of the Microsoft Public License on GitHub and CodePlex respectively… And Metaprogramming with IronRuby The art and science of metaprogramming — especially in Ruby, where it's an absolute joy — is something that could very easily span an entire article. As you would hope, IronRuby code is fully able to manipulate itself allowing you to bend your classes to your whim just as you would expect with a good dynamic language… And Riding the irails? So let's get to the point. I think it's a solid bet to make that a large proportion of Ruby programmers are familiar with the Rails framework - perhaps it's even safe to assume that most were first led to the Ruby language by the siren song of the Rails framework itself. Long story short, IronRuby is compatible enough to run your Rails app… Now… get yourself over to the full article and also check out some of Edds other work below. Related Links: 5 Steps to getting started with IronRuby Mini Book Review of IronRuby Unleashed by Shay Friedman Guest Post: Using IronRuby and .NET to produce the ‘Hello World of WPF’ – also by Edd Getting PhP and Ruby working on Windows Azure and SQL Azure Guest Post: What's IronRuby, and how do I put it on Rails? – also by Edd

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• Can't enable wireless lan on Fujitsu Siemens A1665G with Ubuntu 11.10 installed

  - by Theo

  I saw my old Notebook yesterday and wanted to make that work again. On Windows XP the wireless worked still fine. Then I installed new Ubuntu 11.10 32bit and I'm sadly not able to make the wireless enabled. [I replaced Win XP entirely] lspci lists following network: 08:0a.0 Network controller: Broadcom Corporation BCM4318 [AirForce One 54g] 802.11g Wireless LAN Controller (rev 02) So after recommendation from this link I installed the b43 firmware module. iwconfig prints the following: wlan0 IEEE 802.11bg ESSID:off/any Mode:Managed Access Point: Not-Associatd Tx-Power=off Retry long limit:7 RTS thr:off Fragment thr:off Power Management: off As you can see, my wireless lan adapter is not turned on. sudo iwconfig wlan0 txpower auto Doesn't change anything. Then I tried to make it work with rfkill. rfkill list 0: phy0: Wirless LAN Soft blocked: no Hard blocked: yes sudo rfkill unblock all rfkill list 0: phy0: Wireless LAN Soft blocked: no Hard blocked: yes remains the same. The question is now, how I could enable the hard blocked wireless LAN. There is no hardware switch for wlan integrated. However there is a button to change the state. I always thought this would be software sided, but it seems to make some hardware changes as well... The wireless LED is also not blinking (as it did on windows xp) I reset bios and searched for some settings in there, but it has only a few options and nothing to do with wireless settings, nothing works here.. At last I tried to install the acer hotkeys but I was not able to manage that. I installed the acerhkgui package, but in initializing progress, it was not able to compile acer hotkeys for my machine. There was a message that asm/linkage.h was not found while compiling. Do you have any ideas what I could do to make this hard blocked stuff disabled and my wireless card work? PS: I also tried sudo rm /dev/rfkill and a reboot to reinit that stuff... No success :(

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• Should a programmer "think" for the client?

  - by P.Brian.Mackey

  I have gotten to the point where I hate requirements gathering. Customer's are too vague for their own good. In an agile environment, where we can show the client a piece of work to completion it's not too bad as we can make small regular corrections/updates to functionality. In a "waterfall" type in environment (requirements first, nearly complete product next) things can get ugly. This kind of environment has led me to constantly question requirements. E.G. Customer wants "automatically convert input to the number 1" (referring to a Qty in an order). But what they don't think about is that "input" could be a simple type-o. An "x" in a textbox could be a "woops" not I want 1 of those "toothpaste" products. But, there's so much in the air with requirements that I could stand and correct for hours on end smashing out what they want. This just isn't healthy. Working for a corporation, I could try to adjust the culture to fit the agile model that would help us (no small job, above my pay grade). Or, sweep ugly details under the rug and hope for the best. Maybe my customer is trying to get too close to the code? How does one handle the problem of "thinking for the client" without pissing them off with too many questions?

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• Turning laptop into WAP using netgear WNA1100? (stuck at hostapd)

  - by Vivek Sharma

  I have a Netgear WNA1100 usb wifi adapter. I have installed Atheros driver from Forum Details (btw name of the file is ath9k_htc-installer.1.0.1-maverick-fixed.deb). I wish to make a setup like connectify(windows) on ubuntu, so that I can connect my phone wirelessly to my laptop via Netgear WNA1100 (behaving as AP) and eventually use internet via my wired lan. I have installed the above mentioned driver, hostapd and hostap-utils. Following is my hostapd.conf file. ssid=vks interface=wlan1 # The interface name of the card driver=ath9k_htc # The card driver macaddr_acl=0 accept_mac_file=/etc/hostapd.accept deny_mac_file=/etc/hostapd.deny ieee80211x=1 # Use 802.1X authentication auth_algs=1 ignore_broadcast_ssid=0 wpa=2 wpa_passphrase=88888888 wpa_key_mgmt=WPA-PSK wpa_pairwise=TKIP rsn_pairwise=CCMP When i run sudo hostapd /etc/hostapd/hostapd.conf I get an error invalid/unknown driver 'ath9k_htc # The card driver I think the driver is installed fine, as i can see the blue led blinking on the netgear adapter, which was not blinking earlier. Can someone please guide me how to achieve this setup? I will appreciate an example hostapd.conf file with a simple wpa_psk security setup. Please be detailed and descriptive with commands. How to run and end it. Following is output from lsmod, i have only pasted the entries which had ath and ath related info. Which driver shall i use. Module Size Used by ath9k_htc 42903 0 ath9k_common 2563 1 ath9k_htc ath9k_hw 285176 2 ath9k_htc,ath9k_common ath 13001 2 ath9k_htc,ath9k_hw cfg80211 139811 3 ath9k_htc,mac80211,ath compat 4020 1 cfg80211 led_class 2633 3 ath9k_htc,thinkpad_acpi,sdhci Thanks.

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• Spotlight: How Scandinavia's Largest Nuclear Power Plant Increased Productivity and Reduced Costs wi

  - by [email protected]

  Ringhals nuclear power plant, which is part of the Vattenfall Group, is located about 60 km south-west of the beautiful coastal city of Gothenburg in Sweden. A deep concern to reduce environmental impact coupled with an effort to increase plant safety and operational efficiency have led to a recent surge in investments and initiatives around plant modification and plant optimization at Ringhals. A multitude of challenges were faced by the users in various groups that were involved in these projects. First, it was very difficult for users to easily access complex and layered asset and engineering information, which was critical to increased productivity and completing projects on time. Moreover, the 20 or so different solutions that were being used to view various document formats, not only resulted in collaboration complexity but also escalated IT administration costs and woes. Finally, there was a considerable non-engineering community comprising non-CAD specialists that needed easy access to plant data in an effort to minimize engineering disruption. Oracle's AutoVue significantly simplified the ability to efficiently view and use digital asset information by providing a standardized visualization solution for the enterprise. The key benefits achieved by Ringhals include: Increased productivity of plant optimization and plant modification by 3% Saved around $ 500 K annually Cut IT maintenance costs by 50% by using a single solution Reduced engineering disruption by allowing non-CAD users easy access to digital plant data The complete case-study can be found here

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• No WIFI or LAN on Ubuntu 12.04 or 12.10 Live CD/USB using Toshiba qosmio x870

  - by Mighty

  I recently had issues with secure boot and couldn't boot the Live CD/USB but after disabling secure boot, I was able to 'TRY UBUNTU'. My currently problem is that I can't access WIFI or LAN from either Ubuntu 12.04 or 12.10 Live CD/USB which I do from Windows 8. Also, the wireless button is able to turn on and off the wireless LED but doesn't find available WIFI. Please, what should I do to get both WIFI and LAN working on Ubuntu using Toshiba qosmio x870? UPDATED: Here's the output of lspci: ubuntu@ubuntu:~$ lspci 00:00.0 Host bridge: Intel Corporation 3rd Gen Core processor DRAM Controller (rev 09) 00:01.0 PCI bridge: Intel Corporation Xeon E3-1200 v2/3rd Gen Core processor PCI Express Root Port (rev 09) 00:02.0 VGA compatible controller: Intel Corporation 3rd Gen Core processor Graphics Controller (rev 09) 00:14.0 USB controller: Intel Corporation 7 Series/C210 Series Chipset Family USB xHCI Host Controller (rev 04) 00:16.0 Communication controller: Intel Corporation 7 Series/C210 Series Chipset Family MEI Controller #1 (rev 04) 00:1a.0 USB controller: Intel Corporation 7 Series/C210 Series Chipset Family USB Enhanced Host Controller #2 (rev 04) 00:1b.0 Audio device: Intel Corporation 7 Series/C210 Series Chipset Family High Definition Audio Controller (rev 04) 00:1c.0 PCI bridge: Intel Corporation 7 Series/C210 Series Chipset Family PCI Express Root Port 1 (rev c4) 00:1c.1 PCI bridge: Intel Corporation 7 Series/C210 Series Chipset Family PCI Express Root Port 2 (rev c4) 00:1c.4 PCI bridge: Intel Corporation 7 Series/C210 Series Chipset Family PCI Express Root Port 5 (rev c4) 00:1d.0 USB controller: Intel Corporation 7 Series/C210 Series Chipset Family USB Enhanced Host Controller #1 (rev 04) 00:1f.0 ISA bridge: Intel Corporation HM76 Express Chipset LPC Controller (rev 04) 00:1f.2 SATA controller: Intel Corporation 7 Series Chipset Family 6-port SATA Controller [AHCI mode] (rev 04) 00:1f.3 SMBus: Intel Corporation 7 Series/C210 Series Chipset Family SMBus Controller (rev 04) 01:00.0 VGA compatible controller: NVIDIA Corporation Device 1213 (rev a1) 07:00.0 Ethernet controller: Atheros Communications Inc. AR8161 Gigabit Ethernet (rev 10) 08:00.0 Network controller: Realtek Semiconductor Co., Ltd. Device 8723 09:00.0 Unassigned class [ff00]: Realtek Semiconductor Co., Ltd. RTS5229 PCI Express Card Reader (rev 01)

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• Remap keyboard Ubuntu 12.04; Asus Q500A

  - by hydroxide

  I have an Asus Q500A with win8 and Ubuntu 12.04 64 bit; linux kernel 3.8.0-32-generic. I am using gnome-panel, and xserver-xorg-lts-raring. I have been experiencing problems with the keyboard short-cuts since I had a fresh install. fn+f10 is supposed to mute my system, but instead it will repeatedly press d. fn+f11 is volume down, but it presses c. fn+f12 is volume up, presses b repeatedly. Most of the other on-board short-cuts such as adjusting screen and led brightness work most of the time, but sometimes press other letters repeatedly. Also, sometimes my cntr gets held down for no reason. Everything works fine in windows. I have tried installing all recommends and sudo dpkg-reconfigure -a to reconfigure all packages, which did not solve my problem. I have tried using KeyTouch editor to edit keymaps, navigating to /usr/shar/x11/xkb/keymap when I try opening any of these files it says file contains no keyboard element. I think If I were just able to remap my keyboard it might solve my issues, otherwise if anyone knows where I can get asus drivers for 12.04 please let me know Apparently I didn't have all repositories enabled. I executed the following commands and am trying the updates they give me. Getting linux_kernel 3.8.0-33 generic as well as a bunch of other packages. sudo add-apt-repository "deb http://archive.ubuntu.com/ubuntu $(lsb_release -sc) universe" sudo add-apt-repository "deb http://archive.ubuntu.com/ubuntu $(lsb_release -sc) main universe restricted multiverse" sudo add-apt-repository "deb http://archive.canonical.com/ubuntu $(lsb_release -sc) partner"

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• Where is the line drawn with domain names which include a trademark?

  - by Thomas Clayson

  A search on google for "iphone developer" turns up loads of websites which have "iphone" in them, a trademarked name by Apple. So I'm led to believe that having a domain such as iphonedeveloper.com is ok? Well, you're still using Apple's trademark, but it would be hard to brand yourself otherwise. You're an IPHONE DEVELOPER... right? Well, what if I want to provide a website where users pay to get a list of the best offers from Ebay? I might have a domain like ebaydeals.com (I don't... i'm just speculating!). Now I've heard that places like Ebay are really hot on the trigger and fire out emails to people who register domains like that straight away. But whats the difference? In both cases I'm making money from the trademark, effectively, so is it just down to how lenient the company who owns the trademark is? Or are there rules? Is there a specific "line" you don't cross? Thanks

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• How do I install kivy?

  - by aspasia

  I was trying to install Kivy (by following the instructions here). I downloaded and installed all packages where the installation process went through without giving me any errors. However, when later I enter below command; sudo easy_install kivy It looked like it was going to work but it ends with an error by displaying following lines, which I don't comprehend: Detected compiler is unix /tmp/easy_install-BtOA_u/Kivy-1.8.0/kivy/graphics/texture.c:8:22: fatal error: pyconfig.h: No such file or directory #include "pyconfig.h" ^ compilation terminated. error: Setup script exited with error: command 'x86_64-linux-gnu-gcc' failed with exit status 1 I saw a similar question asked as; Problem with kivy installation. However, this didn't work for me though the question suggests installing libgles-mesa-dev-lts-raring which I did as below; sudo apt-get install libgles-mesa-dev-lts-raring which then gave below; E: Unable to locate package libgles-mesa-dev-lts-raring (sorry for being so specific and perhaps obvious, but I'm in the early stage of learning my way around linux). This user was running Ubuntu 12.04, and most other questions related to this I've seen came from people with a different release from mine, which has led me to believe that that is the reason why the suggestions to those didn't solve my problem. I'm using Ubuntu 13.10

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• Be liberal in what you accept... or not?

  - by Matthieu M.

  [Disclaimer: this question is subjective, but I would prefer getting answers backed by facts and/or reflexions] I think everyone knows about the Robustness Principle, usually summed up by Postel's Law: Be conservative in what you send; be liberal in what you accept. I would agree that for the design of a widespread communication protocol this may make sense (with the goal of allowing easy extension), however I have always thought that its application to HTML / CSS was a total failure, each browser implementing its own silent tweak detection / behavior, making it near impossible to obtain a consistent rendering across multiple browsers. I do notice though that there the RFC of the TCP protocol deems "Silent Failure" acceptable unless otherwise specified... which is an interesting behavior, to say the least. There are other examples of the application of this principle throughout the software trade that regularly pop up because they have bitten developpers, from the top off my head: Javascript semi-colon insertion C (silent) builtin conversions (which would not be so bad if it did not truncated...) and there are tools to help implement "smart" behavior: name matching phonetic algorithms (Double Metaphone) string distances algorithms (Levenshtein distance) However I find that this approach, while it may be helpful when dealing with non-technical users or to help users in the process of error recovery, has some drawbacks when applied to the design of library/classes interface: it is somewhat subjective whether the algorithm guesses "right", and thus it may go against the Principle of Least Astonishment it makes the implementation more difficult, thus more chances to introduce bugs (violation of YAGNI ?) it makes the behavior more susceptible to change, as any modification of the "guess" routine may break old programs, nearly excluding refactoring possibilities... from the start! And this is what led me to the following question: When designing an interface (library, class, message), do you lean toward the robustness principle or not ? I myself tend to be quite strict, using extensive input validation on my interfaces, and I was wondering if I was perhaps too strict.

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• What's the relationship between meta-circular interpreters, virtual machines and increased performance?

  - by Gomi

  I've read about meta-circular interpreters on the web (including SICP) and I've looked into the code of some implementations (such as PyPy and Narcissus). I've read quite a bit about two languages which made great use of metacircular evaluation, Lisp and Smalltalk. As far as I understood Lisp was the first self-hosting compiler and Smalltalk had the first "true" JIT implementation. One thing I've not fully understood is how can those interpreters/compilers achieve so good performance or, in other words, why is PyPy faster than CPython? Is it because of reflection? And also, my Smalltalk research led me to believe that there's a relationship between JIT, virtual machines and reflection. Virtual Machines such as the JVM and CLR allow a great deal of type introspection and I believe they make great use it in Just-in-Time (and AOT, I suppose?) compilation. But as far as I know, Virtual Machines are kind of like CPUs, in that they have a basic instruction set. Are Virtual Machines efficient because they include type and reference information, which would allow language-agnostic reflection? I ask this because many both interpreted and compiled languages are now using bytecode as a target (LLVM, Parrot, YARV, CPython) and traditional VMs like JVM and CLR have gained incredible boosts in performance. I've been told that it's about JIT, but as far as I know JIT is nothing new since Smalltalk and Sun's own Self have been doing it before Java. I don't remember VMs performing particularly well in the past, there weren't many non-academic ones outside of JVM and .NET and their performance was definitely not as good as it is now (I wish I could source this claim but I speak from personal experience). Then all of a sudden, in the late 2000s something changed and a lot of VMs started to pop up even for established languages, and with very good performance. Was something discovered about the JIT implementation that allowed pretty much every modern VM to skyrocket in performance? A paper or a book maybe?

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• Why does Ubuntu gets stuck on the loading screen?

  - by mohit

  I've been experiencing many problem lately since I fresh installed Ubuntu 12.04 LTS on my SONY VAIO VPCEH with Windows 7 previously installed. Sometimes when I try to boot Ubuntu, it gets stuck at loading screen. There seems to be some problem with driver (as far I can judge). Following is the log generated, when I press Esc during the boot (before the problem occurs): ... * Stopping System V initialization compatibility [ok] * Starting System V runlevel compatibility [ok] * Starting crash report submission daemon [ok] * Starting automatic crash report generation [ok] ... ... * Starting LightDM Display Manager [ok] Nothing works after that, no Esc, etc, except restart. Also I've observed the following: Inactivity of Hard-drive (Led doesn't glows). Flashing, or blinking, of Caps-lock and Scroll-lock On restart, Ubuntu seem to load successfully. However, the loading screen has somewhat basic graphics. This problem started after I installed Additional drivers: NVIDIA accelerated graphics driver Also, most of the times Ubuntu loads without any problem. However, it is annoying to restart everytime it fails. So my question is: Why this happens and what is the solution?

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• Slow boot on Ubuntu 12.04, probable cause the network connection

  - by Ravi S Ghosh

  I have been having rather slow boot on Ubuntu 12.04. Lately, I tried to figure out the reason and it seems to be the network connection which does not get connected and requires multiple attempts. Here is part of dmesg [ 2.174349] EXT4-fs (sda2): INFO: recovery required on readonly filesystem [ 2.174352] EXT4-fs (sda2): write access will be enabled during recovery [ 2.308172] firewire_core: created device fw0: GUID 384fc00005198d58, S400 [ 2.333457] usb 7-1.2: new low-speed USB device number 3 using uhci_hcd [ 2.465896] EXT4-fs (sda2): recovery complete [ 2.466406] EXT4-fs (sda2): mounted filesystem with ordered data mode. Opts: (null) [ 2.589440] usb 7-1.3: new low-speed USB device number 4 using uhci_hcd **[ 18.292029] ADDRCONF(NETDEV_UP): eth0: link is not ready** [ 18.458958] udevd[377]: starting version 175 [ 18.639482] Adding 4200960k swap on /dev/sda5. Priority:-1 extents:1 across:4200960k [ 19.314127] wmi: Mapper loaded [ 19.426602] r592 0000:09:01.2: PCI INT B -> GSI 18 (level, low) -> IRQ 18 [ 19.426739] r592: driver successfully loaded [ 19.460105] input: Dell WMI hotkeys as /devices/virtual/input/input5 [ 19.493629] lp: driver loaded but no devices found [ 19.497012] cfg80211: Calling CRDA to update world regulatory domain [ 19.535523] ACPI Warning: _BQC returned an invalid level (20110623/video-480) [ 19.539457] acpi device:03: registered as cooling_device2 [ 19.539520] input: Video Bus as /devices/LNXSYSTM:00/device:00/PNP0A08:00/device:01/LNXVIDEO:00/input/input6 [ 19.539568] ACPI: Video Device [M86] (multi-head: yes rom: no post: no) [ 19.578060] Linux video capture interface: v2.00 [ 19.667708] dcdbas dcdbas: Dell Systems Management Base Driver (version 5.6.0-3.2) [ 19.763171] r852 0000:09:01.3: PCI INT B -> GSI 18 (level, low) -> IRQ 18 [ 19.763258] r852: driver loaded successfully [ 19.854769] input: Microsoft Comfort Curve Keyboard 2000 as /devices/pci0000:00/0000:00:1d.1/usb7/7-1/7-1.2/7-1.2:1.0/input/input7 [ 19.854864] generic-usb 0003:045E:00DD.0001: input,hidraw0: USB HID v1.11 Keyboard [Microsoft Comfort Curve Keyboard 2000] on usb-0000:00:1d.1-1.2/input0 [ 19.878605] input: Microsoft Comfort Curve Keyboard 2000 as /devices/pci0000:00/0000:00:1d.1/usb7/7-1/7-1.2/7-1.2:1.1/input/input8 [ 19.878698] generic-usb 0003:045E:00DD.0002: input,hidraw1: USB HID v1.11 Device [Microsoft Comfort Curve Keyboard 2000] on usb-0000:00:1d.1-1.2/input1 [ 19.902779] input: DELL DELL USB Laser Mouse as /devices/pci0000:00/0000:00:1d.1/usb7/7-1/7-1.3/7-1.3:1.0/input/input9 [ 19.925034] generic-usb 0003:046D:C063.0003: input,hidraw2: USB HID v1.10 Mouse [DELL DELL USB Laser Mouse] on usb-0000:00:1d.1-1.3/input0 [ 19.925057] usbcore: registered new interface driver usbhid [ 19.925059] usbhid: USB HID core driver [ 19.942362] uvcvideo: Found UVC 1.00 device Laptop_Integrated_Webcam_2M (0c45:63ea) [ 19.947004] input: Laptop_Integrated_Webcam_2M as /devices/pci0000:00/0000:00:1a.7/usb1/1-6/1-6:1.0/input/input10 [ 19.947075] usbcore: registered new interface driver uvcvideo [ 19.947077] USB Video Class driver (1.1.1) [ 20.145232] Intel(R) Wireless WiFi Link AGN driver for Linux, in-tree: [ 20.145235] Copyright(c) 2003-2011 Intel Corporation [ 20.145327] iwlwifi 0000:04:00.0: PCI INT A -> GSI 17 (level, low) -> IRQ 17 [ 20.145357] iwlwifi 0000:04:00.0: setting latency timer to 64 [ 20.145402] iwlwifi 0000:04:00.0: pci_resource_len = 0x00002000 [ 20.145404] iwlwifi 0000:04:00.0: pci_resource_base = ffffc90000674000 [ 20.145407] iwlwifi 0000:04:00.0: HW Revision ID = 0x0 [ 20.145531] iwlwifi 0000:04:00.0: irq 46 for MSI/MSI-X [ 20.145613] iwlwifi 0000:04:00.0: Detected Intel(R) WiFi Link 5100 AGN, REV=0x54 [ 20.145720] iwlwifi 0000:04:00.0: L1 Enabled; Disabling L0S [ 20.167535] iwlwifi 0000:04:00.0: device EEPROM VER=0x11f, CALIB=0x4 [ 20.167538] iwlwifi 0000:04:00.0: Device SKU: 0Xf0 [ 20.167567] iwlwifi 0000:04:00.0: Tunable channels: 13 802.11bg, 24 802.11a channels [ 20.172779] fglrx: module license 'Proprietary. (C) 2002 - ATI Technologies, Starnberg, GERMANY' taints kernel. [ 20.172783] Disabling lock debugging due to kernel taint [ 20.250115] [fglrx] Maximum main memory to use for locked dma buffers: 3759 MBytes. [ 20.250567] [fglrx] vendor: 1002 device: 9553 count: 1 [ 20.251256] [fglrx] ioport: bar 1, base 0x2000, size: 0x100 [ 20.251271] pci 0000:01:00.0: PCI INT A -> GSI 16 (level, low) -> IRQ 16 [ 20.251277] pci 0000:01:00.0: setting latency timer to 64 [ 20.251559] [fglrx] Kernel PAT support is enabled [ 20.251578] [fglrx] module loaded - fglrx 8.96.4 [Mar 12 2012] with 1 minors [ 20.310385] iwlwifi 0000:04:00.0: loaded firmware version 8.83.5.1 build 33692 [ 20.310598] Registered led device: phy0-led [ 20.310628] cfg80211: Ignoring regulatory request Set by core since the driver uses its own custom regulatory domain [ 20.372306] ieee80211 phy0: Selected rate control algorithm 'iwl-agn-rs' [ 20.411015] psmouse serio1: synaptics: Touchpad model: 1, fw: 7.2, id: 0x1c0b1, caps: 0xd04733/0xa40000/0xa0000 [ 20.454232] input: SynPS/2 Synaptics TouchPad as /devices/platform/i8042/serio1/input/input11 [ 20.545636] cfg80211: Ignoring regulatory request Set by core since the driver uses its own custom regulatory domain [ 20.545640] cfg80211: World regulatory domain updated: [ 20.545642] cfg80211: (start_freq - end_freq @ bandwidth), (max_antenna_gain, max_eirp) [ 20.545644] cfg80211: (2402000 KHz - 2472000 KHz @ 40000 KHz), (300 mBi, 2000 mBm) [ 20.545647] cfg80211: (2457000 KHz - 2482000 KHz @ 20000 KHz), (300 mBi, 2000 mBm) [ 20.545649] cfg80211: (2474000 KHz - 2494000 KHz @ 20000 KHz), (300 mBi, 2000 mBm) [ 20.545652] cfg80211: (5170000 KHz - 5250000 KHz @ 40000 KHz), (300 mBi, 2000 mBm) [ 20.545654] cfg80211: (5735000 KHz - 5835000 KHz @ 40000 KHz), (300 mBi, 2000 mBm) [ 20.609484] type=1400 audit(1340502633.160:2): apparmor="STATUS" operation="profile_load" name="/sbin/dhclient" pid=693 comm="apparmor_parser" [ 20.609494] type=1400 audit(1340502633.160:3): apparmor="STATUS" operation="profile_replace" name="/sbin/dhclient" pid=642 comm="apparmor_parser" [ 20.609843] type=1400 audit(1340502633.160:4): apparmor="STATUS" operation="profile_load" name="/usr/lib/NetworkManager/nm-dhcp-client.action" pid=693 comm="apparmor_parser" [ 20.609852] type=1400 audit(1340502633.160:5): apparmor="STATUS" operation="profile_replace" name="/usr/lib/NetworkManager/nm-dhcp-client.action" pid=642 comm="apparmor_parser" [ 20.610047] type=1400 audit(1340502633.160:6): apparmor="STATUS" operation="profile_load" name="/usr/lib/connman/scripts/dhclient-script" pid=693 comm="apparmor_parser" [ 20.610060] type=1400 audit(1340502633.160:7): apparmor="STATUS" operation="profile_replace" name="/usr/lib/connman/scripts/dhclient-script" pid=642 comm="apparmor_parser" [ 20.610476] type=1400 audit(1340502633.160:8): apparmor="STATUS" operation="profile_replace" name="/sbin/dhclient" pid=814 comm="apparmor_parser" [ 20.610829] type=1400 audit(1340502633.160:9): apparmor="STATUS" operation="profile_replace" name="/usr/lib/NetworkManager/nm-dhcp-client.action" pid=814 comm="apparmor_parser" [ 20.611035] type=1400 audit(1340502633.160:10): apparmor="STATUS" operation="profile_replace" name="/usr/lib/connman/scripts/dhclient-script" pid=814 comm="apparmor_parser" [ 20.661912] snd_hda_intel 0000:00:1b.0: PCI INT A -> GSI 22 (level, low) -> IRQ 22 [ 20.661982] snd_hda_intel 0000:00:1b.0: irq 47 for MSI/MSI-X [ 20.662013] snd_hda_intel 0000:00:1b.0: setting latency timer to 64 [ 20.770289] input: HDA Intel Mic as /devices/pci0000:00/0000:00:1b.0/sound/card0/input12 [ 20.770689] snd_hda_intel 0000:01:00.1: PCI INT B -> GSI 17 (level, low) -> IRQ 17 [ 20.770786] snd_hda_intel 0000:01:00.1: irq 48 for MSI/MSI-X [ 20.770815] snd_hda_intel 0000:01:00.1: setting latency timer to 64 [ 20.994040] HDMI status: Codec=0 Pin=3 Presence_Detect=0 ELD_Valid=0 [ 20.994189] input: HDA ATI HDMI HDMI/DP,pcm=3 as /devices/pci0000:00/0000:00:01.0/0000:01:00.1/sound/card1/input13 [ 21.554799] vesafb: mode is 1024x768x32, linelength=4096, pages=0 [ 21.554802] vesafb: scrolling: redraw [ 21.554804] vesafb: Truecolor: size=0:8:8:8, shift=0:16:8:0 [ 21.557342] vesafb: framebuffer at 0xd0000000, mapped to 0xffffc90011800000, using 3072k, total 3072k [ 21.557498] Console: switching to colour frame buffer device 128x48 [ 21.557516] fb0: VESA VGA frame buffer device [ 21.987338] EXT4-fs (sda2): re-mounted. Opts: errors=remount-ro [ 22.184693] EXT4-fs (sda6): mounted filesystem with ordered data mode. Opts: (null) [ 27.362440] iwlwifi 0000:04:00.0: RF_KILL bit toggled to disable radio. [ 27.436988] init: failsafe main process (986) killed by TERM signal [ 27.970112] ppdev: user-space parallel port driver [ 28.198917] Bluetooth: Core ver 2.16 [ 28.198935] NET: Registered protocol family 31 [ 28.198937] Bluetooth: HCI device and connection manager initialized [ 28.198940] Bluetooth: HCI socket layer initialized [ 28.198941] Bluetooth: L2CAP socket layer initialized [ 28.198947] Bluetooth: SCO socket layer initialized [ 28.226135] Bluetooth: RFCOMM TTY layer initialized [ 28.226141] Bluetooth: RFCOMM socket layer initialized [ 28.226143] Bluetooth: RFCOMM ver 1.11 [ 28.445620] Bluetooth: BNEP (Ethernet Emulation) ver 1.3 [ 28.445623] Bluetooth: BNEP filters: protocol multicast [ 28.524578] type=1400 audit(1340502641.076:11): apparmor="STATUS" operation="profile_load" name="/usr/lib/cups/backend/cups-pdf" pid=1052 comm="apparmor_parser" [ 28.525018] type=1400 audit(1340502641.076:12): apparmor="STATUS" operation="profile_load" name="/usr/sbin/cupsd" pid=1052 comm="apparmor_parser" [ 28.629957] type=1400 audit(1340502641.180:13): apparmor="STATUS" operation="profile_replace" name="/sbin/dhclient" pid=1105 comm="apparmor_parser" [ 28.630325] type=1400 audit(1340502641.180:14): apparmor="STATUS" operation="profile_replace" name="/usr/lib/NetworkManager/nm-dhcp-client.action" pid=1105 comm="apparmor_parser" [ 28.630535] type=1400 audit(1340502641.180:15): apparmor="STATUS" operation="profile_replace" name="/usr/lib/connman/scripts/dhclient-script" pid=1105 comm="apparmor_parser" [ 28.645266] type=1400 audit(1340502641.196:16): apparmor="STATUS" operation="profile_load" name="/usr/lib/lightdm/lightdm/lightdm-guest-session-wrapper" pid=1104 comm="apparmor_parser" **[ 28.751922] ADDRCONF(NETDEV_UP): wlan0: link is not ready** [ 28.753653] tg3 0000:08:00.0: irq 49 for MSI/MSI-X **[ 28.856127] ADDRCONF(NETDEV_UP): eth0: link is not ready [ 28.857034] ADDRCONF(NETDEV_UP): eth0: link is not ready** [ 28.871080] type=1400 audit(1340502641.420:17): apparmor="STATUS" operation="profile_load" name="/usr/lib/telepathy/mission-control-5" pid=1108 comm="apparmor_parser" [ 28.871519] type=1400 audit(1340502641.420:18): apparmor="STATUS" operation="profile_load" name="/usr/lib/telepathy/telepathy-*" pid=1108 comm="apparmor_parser" [ 28.874905] type=1400 audit(1340502641.424:19): apparmor="STATUS" operation="profile_replace" name="/usr/lib/cups/backend/cups-pdf" pid=1113 comm="apparmor_parser" [ 28.875354] type=1400 audit(1340502641.424:20): apparmor="STATUS" operation="profile_replace" name="/usr/sbin/cupsd" pid=1113 comm="apparmor_parser" [ 30.477976] tg3 0000:08:00.0: eth0: Link is up at 100 Mbps, full duplex [ 30.477979] tg3 0000:08:00.0: eth0: Flow control is on for TX and on for RX **[ 30.478390] ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready** [ 31.110269] fglrx_pci 0000:01:00.0: irq 50 for MSI/MSI-X [ 31.110859] [fglrx] Firegl kernel thread PID: 1327 [ 31.111021] [fglrx] Firegl kernel thread PID: 1329 [ 31.111408] [fglrx] Firegl kernel thread PID: 1330 [ 31.111543] [fglrx] IRQ 50 Enabled [ 31.712938] [fglrx] Gart USWC size:1224 M. [ 31.712941] [fglrx] Gart cacheable size:486 M. [ 31.712945] [fglrx] Reserved FB block: Shared offset:0, size:1000000 [ 31.712948] [fglrx] Reserved FB block: Unshared offset:fc2b000, size:3d5000 [ 31.712950] [fglrx] Reserved FB block: Unshared offset:1fffb000, size:5000 [ 41.312020] eth0: no IPv6 routers present As you can see I get multiple instances of [ 28.856127] ADDRCONF(NETDEV_UP): eth0: link is not ready and then finally it becomes read and I get the message [ 30.478390] ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready. I searched askubuntun, ubuntuforum, and the web but couldn't find a solution. Any help would be very much appreciated. Here is the bootchart

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• Oracle Enterprise Manager 12c Anniversary at Open World General Session and Twitter Chat using #em12c on October 2nd

  - by Anand Akela

  As most of you will remember, Oracle Enterprise Manager 12c was announced last year at Open World. We are celebrating first anniversary of Oracle Enterprise Manager 12c next week at Open world. During the last year, Oracle customers have seen the benefits of federated self-service access to complete application stacks, elastic scalability, automated metering, and charge-back from capabilities of Oracle Enterprise manager 12c. In this session you will learn how customers are leveraging Oracle Enterprise Manager 12c to build and operate their enterprise cloud. You will also hear about Oracle’s IT management strategy and some new capabilities inside the Oracle Enterprise Manager product family. In this anniversary general session of Oracle Enterprise Manager 12c, you will also watch an interactive role play ( similar to what some of you may have seen at "Zero to Cloud" sessions at the Oracle Cloud Builder Summit ) depicting a fictional company in the throes of deploying a private cloud. Watch as the CIO and his key cloud architects battle with misconceptions about enterprise cloud computing and watch how Oracle Enterprise Manager helps them address the key challenges of planning, deploying and managing an enterprise private cloud. The session will be led by Sushil Kumar, Vice President, Product Strategy and Business Development, Oracle Enterprise Manager. Jeff Budge, Director, Global Oracle Technology Practice, CSC Consulting, Inc. will join Sushil for the general session as well. Following the general session, Sushil Kumar ( Twitter user name @sxkumar ) will join us for a Twitter Chat on Tuesday at 1:00 PM to 2:00 PM.  Sushil will answer any follow-up questions from the general session or any question related to Oracle Enterprise Manager and Oracle Private Cloud . You can participate in the chat using hash tag #em12c on Twitter.com or by going to  tweetchat.com/room/em12c (Needs Twitter credential for participating).  You could pre-submit your questions for Sushil using any of the social media channels mentioned below. Stay Connected: Twitter |  Face book |  You Tube |  Linked in |  Newsletter

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• 12.10 wants to install multiarch :i386-packages

  - by gspr

  I have an AMD64 system without any i386 multiarch packages. After successfully upgrading to 12.10, aptitude seems to want to install a few, and I can't tell why: $ sudo aptitude safe-upgrade Resolving dependencies... The following NEW packages will be installed: gcc-4.7-base:i386{a} libarmadillo3{a} libboost-date-time1.49-dev{a} libboost-serialization1.49-dev{a} libboost-serialization1.49.0{a} libboost-thread1.49-dev{a} libboost1.49-dev{a} libc6:i386{a} libgcc1:i386{a} libgdal1{a} libhdf5-7{a} libltdl7:i386{a} libnetcdfc7{a} libodbc1:i386{a} libreadline6:i386{a} libtinfo5:i386{a} odbcinst1debian2:i386{a} unixodbc:i386{a} Why libc6:i386, for example? I ask.. $ aptitude why libc6:i386 p icoutils:i386 Provides icoutils p icoutils:i386 Depends libc6:i386 (>= 2.8) ... alright, but why icoutils:i386? $ aptitude why icoutils:i386 p icoutils:i386 Provides icoutils But I already have the AMD64 version of icoutils: $ aptitude search icoutils i icoutils - Create and extract MS Windows icons and cursors p icoutils:i386 - Create and extract MS Windows icons and cursors Has some multiarch behavior changed recently, or am I just overlooking something? Addendum: Chasing down from gcc-4.7-base:i386, I'm led to qdbus:i386, which is up for installation since it provides qdbus... which I already have.

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• Matching the superclass's constructor's parameter list, is treating a null default value as a non-null value within a constructor a violation of LSP?

  - by Panzercrisis

  I kind of ran into this when messing around with FlashPunk, and I'm going to use it as an example. Essentially the main sprite class is pretty much class Entity. Entity's constructor has four parameters, each with a default value. One of them is graphic, whose default value is null. Entity is designed to be inherited from, with many such subclasses providing their own graphic within their own internal workings. Normally these subclasses would not have graphic in their constructor's parameter lists, but would simply pick something internally and go with it. However I was looking into possibly still adhering to the Liskov Substitution Principal. Which led me to the following example: package com.blank.graphics { import net.flashpunk.*; import net.flashpunk.graphics.Image; public class SpaceGraphic extends Entity { [Embed(source = "../../../../../../assets/spaces/blank.png")] private const BLANK_SPACE:Class; public function SpaceGraphic(x:Number = 0, y:Number = 0, graphic:Graphic = null, mask:Mask = null) { super(x, y, graphic, mask); if (!graphic) { this.graphic = new Image(BLANK_SPACE); } } } } Alright, so now there's a parameter list in the constructor that perfectly matches the one in the super class's constructor. But if the default value for graphic is used, it'll exhibit two different behaviors, depending on whether you're using the subclass or the superclass. In the superclass, there won't be a graphic, but in the subclass, it'll choose the default graphic. Is this a violation of the Liskov Substitution Principal? Does the fact that subclasses are almost intended to use different parameter lists have any bearing on this? Would minimizing the parameter list violate it in a case like this? Thanks.

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