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• Eclipse (Aptana) Typing Lag

  - by Zack

  Hello SO, I've been using Aptana for some time now, and as of recent I've been dealing with files that are really, really big (500+ lines of code, which is huge for me, being a novice developer). Whenever I deal with smaller files, I get that weird sensation that I'm "in front of" what's typing, but now I'm quite sure of it--there is a significant lag between when I type something and when I see the text appear on screen. I don't have this issue with Dreamweaver CS3, so I know my computer has the capability to edit these files without this happening, but Eclipse still lags. I also don't see when something is being deleted if I hold down backspace, I see the first few characters get deleted, but then everything "hangs." Once I release the backspace key, the characters that would've been shown deleting instantly vanish all at once. The same thing happens with the forward delete key. I'm beginning to think this is an issue with Java, since I have the same feeling that everything is slightly "behind me" when I'm using -any- Java application. The computer is an intel Pentium 4 3.2 GHz Prescott, with 2GB's of DDR400 RAM and a Radeon HD3650 graphics card. If anyone knows how to fix this lagging issue, I'm all ears (eyes?); if anyone can recommend a different IDE with capabilities similar to Aptana (I do Python, HTML, CSS and JS; I use Git for SCM), I'd be glad to give it a try. Thanks!

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• hdfs configuration

  - by Ananymous

  I am a newbie. Trying to setup a hdfs system to serve my data (I don't plan to use mapreduce) at my lab. So far I have read, cluster setup in but I am still confused. Several questions: Do I need to have a secondary namenode? There are 2 files, masters and slaves. Do I really need these 2 files eventhough I just want hdfs? If I need them, what should go in there? I assume my namenode in masters and datanodes as slaves? Do I need slaves nodes What configuration files are needed for namenode, secondary namenode, datanode and client? (I assume core-site.xml is needed for all 4)? In addition, can someone suggest a good configuration model? sample configuration for namenode, secondary namenode, datanode, and the client would be very helpful. I am getting confused because it seems most of the documentation assumes I want to use map-reduce which isn't the case.

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• Possible to host CentOS netinstall files on a local HTTP/FTP?

  - by garlicman

  I'm running XenServer on an Dell R610 and am running into a catch-22. During install from DVD, CentOS can't find the DVD package catalogue. It's a reported error for some, XenServer + CentOS6 + DVD install in some hardware configurations = failed install. Yes, I checked the MD5 and let the disc test pass. In every reported case, the netinstall was the solution. The issue is my net access is required to go through a web proxy that prompts before you can download a file. This naturally breaks any download automation. I've been waiting on our IT to put in an exception rule to allow my lab to bypass the prompt, but it's been over 3 weeks now and they don't seem responsive. (I've been working on this a day or two a week) I want to try and host the netinstall files local in my Xen network. Right now I only have a bunch of Windows based VMs, CentOS won't install so I don't have any Linux tools. I had tried simply hosting all the DVD contents off one of the Windows servers using Mongoose. (I didn't want to setup IIS) I copied them to a hosted sub-directory similar to all the mirrors out there (e.g. http:///centos/6.2/os/i386/) with no auth or anything. Then in the netinstall I correctly pointed to it. I now realize just copying the DVD files over won't work. The repodata will point to a local device, not the site I'm hosting. (e.g. the DVD repodata includes xml that points to where the packages are) Clearly I'm hosting them over HTTP, not from a DVD. Is there an easy way to sort this out? I'm just trying to install CentOS6 on Xen. If there's a turnkey downloadable Xen image with CentOS 6.2 on it, or a downloadable repo image, I'll take that too! Thank you in advance!

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• How to combine twill and python into one code that could be run on "Google App Engine"?

  - by brilliant

  Hello everybody!!! I have installed twill on my computer (having previously installed Python 2.5) and have been using it recently. Python is installed on disk C on my computer: C:\Python25 And the twill folder (“twill-0.9”) is located here: E:\tmp\twill-0.9 Here is a code that I’ve been using in twill: go “some website’s sign-in page URL” formvalue 2 userid “my login” formvalue 2 pass “my password” submit go “URL of some other page from that website” save_html result.txt This code helps me to log in to one website, in which I have an account, record the HTML code of some other page of that website (that I can access only after logging in), and store it in a file named “result.txt” (of course, before using this code I firstly need to replace “my login” with my real login, “my password” with my real password, “some website’s sign-in page URL” and “URL of some other page from that website” with real URLs of that website, and number 2 with the number of the form on that website that is used as a sign-in form on that website’s log-in page) This code I store in “test.twill” file that is located in my “twill-0.9” folder: E:\tmp\twill-0.9\test.twill I run this file from my command prompt: python twill-sh test.twill Now, I also have installed “Google App Engine SDK” from “Google App Engine” and have also been using it for awhile. For example, I’ve been using this code: import hashlib m = hashlib.md5() m.update("Nobody inspects") m.update(" the spammish repetition ") print m.hexdigest() This code helps me transform the phrase “Nobody inspects the spammish repetition” into md5 digest. Now, how can I put these two pieces of code together into one python script that I could run on “Google App Engine”? Let’s say, I want my code to log in to a website from “Google App Engine”, go to another page on that website, record its HTML code (that’s what my twill code does) and than transform this HTML code into its md5 digest (that’s what my second code does). So, how can I combine those two codes into one python code? I guess, it should be done somehow by importing twill, but how can it be done? Can a python code - the one that is being run by “Google App Engine” - import twill from somewhere on the internet? Or, perhaps, twill is already installed on “Google App Engine”?

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• VMWare converter performance

  - by bellocarico

  Hello, I have a question about my test lab. It's more to understand the concept more than apply this into production: I have an ESXi with few VMs linux/windows configured and I'd like to use VMWare converter to create backups. To speedup the process I decided to create a Windows VM on the same ESXi host where I've installed Windows 7 and VMWare Converter. The Host has a gigabit card but it's currently connected to a 100Mb FD port. Windows 7 sees a 1gb card connected. When I do the backup using VMWare converter I specify the host IP as source and destination, so I thought the copy could be faster then use my laptop across the network. Well, to cut a long sotry short: I get dreadful performance (4Mb/sec). I'm a buit confused on this because despite the fact that the host is running 100Mb communication between VMs and hosts shouldn't (correct me if I'm wrong) have any limitation instead. I did tweak windows 7 to optimise network performane but I got just a little improvement. i still need 4 hours to back up a 50Gb (thin) VM. Additionally I wanted to ask: Would jumbo frame help in this? I know that jumbo frame have to be supported end to end, and the network switch where the host is currently connected doesn't support this, but I was wondering: 1) Does ESXi host support jumbo frames at all? 2) Can I enable it somehow? 3) If I do so, I guess bulk transfert between VMs and host would improve, but would this affect the communication going through the real switch as this doesn't do jumbo? Thanks for reading

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• CentOS Latency High Troubleshooting

  - by Sarah Weinberger

  I have two CentOS servers connected via a 10 Gb fiber optic cable with a network emulator connected between them. All three units sit on a desk in the lab. There is also a regular 1 Gbit Ethernet cable connected to each of the machines, which provide internet connectivity. When I set the latency to something roughly below 30 ms, all is fine. When the latency gets to 70ms and above, and definitely 130ms, the network layer suspends. For instance, if I set the latency (delay) to 70ms, then launching TeamViewer (or any other application that uses network connectivity) never happens or does not work. There is no timeout message, simply no response. I have to lower to latency back down to zero to see any response and have the box start working. What is the problem and how would I go about fixing it? It seems to me some sort of setting in Linux causes one of the CentOS networking drivers to sit in an infinite loop or something. eth0 is the connection to the internet, all settings are default eth2 is the 10 Gbit fiber optic connection to the other computer with the MTU set to 9600 with all other parameters at default values.

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• Cache consistency & spawning a thread

  - by Dave Keck

  Background I've been reading through various books and articles to learn about processor caches, cache consistency, and memory barriers in the context of concurrent execution. So far though, I have been unable to determine whether a common coding practice of mine is safe in the strictest sense. Assumptions The following pseudo-code is executed on a two-processor machine: int sharedVar = 0; myThread() { print(sharedVar); } main() { sharedVar = 1; spawnThread(myThread); sleep(-1); } main() executes on processor 1 (P1), while myThread() executes on P2. Initially, sharedVar exists in the caches of both P1 and P2 with the initial value of 0 (due to some "warm-up code" that isn't shown above.) Question Strictly speaking – preferably without assuming any particular CPU – is myThread() guaranteed to print 1? With my newfound knowledge of processor caches, it seems entirely possible that at the time of the print() statement, P2 may not have received the invalidation request for sharedVar caused by P1's assignment in main(). Therefore, it seems possible that myThread() could print 0. References These are the related articles and books I've been reading. (It wouldn't allow me to format these as links because I'm a new user - sorry.) Shared Memory Consistency Models: A Tutorial hpl.hp.com/techreports/Compaq-DEC/WRL-95-7.pdf Memory Barriers: a Hardware View for Software Hackers rdrop.com/users/paulmck/scalability/paper/whymb.2009.04.05a.pdf Linux Kernel Memory Barriers kernel.org/doc/Documentation/memory-barriers.txt Computer Architecture: A Quantitative Approach amazon.com/Computer-Architecture-Quantitative-Approach-4th/dp/0123704901/ref=dp_ob_title_bk

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• I have two choices of Master's classes this fall. Which is the most useful?

  - by ahplummer

  (For background purposes and context): I am a Software Engineer, and manage other Software Engineers currently. I kind of wear two hats right now: one of a programmer, and one as a 'team lead'. In this regard, I've started going back to school to get my Master's degree with an emphasis in Computer Science. I already have a Bachelor's in Computer Science, and have been working in the field for about 13 years. Our primary development environment is a Windows environment, writing in .NET, Delphi, and SQL Server. Choice #1: CST 798 DATA VISUALIZATION Course Description: Basically, this is a course on the "Processing" language: http://processing.org/ Choice #2: CST 711 INFORMATICS Course Description: (From catalog): Informatics is the science of the use and processing of data, information, and knowledge. This course covers a variety of applied issues from information technology, information management at a variety of levels, ranging from simple data entry, to the creation, design and implementation of new information systems, to the development of models. Topics include basic information representation, processing, searching, and organization, evaluation and analysis of information, Internet-based information access tools, ethics and economics of information sharing.

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• Query Access and VB.NET

  - by yae

  Hi all: I have 2 tables: "products" and "pieces" PRODUCTS idProd product price PIECES id idProdMain idProdChild quant idProdMain and idProdChild are vinculated with the table: "products". Other considerations is that 1 product can have some pieces and 1 product can be a piece. Price product equal a sum of quantity * price of all their pieces. EXAMPLE: TABLE PRODUCTS (idProd - product - price) 1 - Computer - 300€ 2 - Hard Disk - 100€ 3 - Memory - 50€ 4 - Main Board - 100€ 5 - Software - 50€ 6 - CDroms 100 un. - 30€ TABLE PIECES (id - idProdMain - idProdChild - Quant.) 1 - 1 - 2 - 1 2 - 1 - 3 - 2 3 - 1 - 4 - 1 WHAT I NEED? I need update the price of the main product when the price of the product child (piece) is changed. Following the previous example, if I change the price of this product "memory" (is a piece too) to 60€, then product "Computer" will must change his price to 320€ How I can do it using queries? Already I have tried this to obatin the price of the main product, but not runs. This query not returns any value SELECT Sum(products.price*pieces.quant) AS Expr1 FROM products LEFT JOIN pieces ON (products.idProd = pieces.idProdChild) AND (products.idProd = pieces.idProdChild) AND (products.idProd = pieces.idProdMain) WHERE (((pieces.idProdMain)=5));

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• Problems getting Cron to run processes tagged @reboot for LDAP users

  - by Ben Torell

  I have a lab of computers running Ubuntu 9.10. Most of the people who log on to these computers are users from an LDAP server, and not local users. We discovered that if an LDAP user has a crontab with an entry marked to be run @reboot, the command will not actually run upon the reboot of a machine. I'm pretty sure that this is because the cron daemon starts before networking is fully up, so the crontabs of any LDAP users aren't loaded and run or checked for @reboot. In fact, cron will ignore LDAP users' crontabs entirely after a reboot until that user runs crontab -e again and saves, or until the cron daemon is rebooted. We were able to fix one part of this problem by adding the following line to /etc/crontab: @reboot root /bin/sleep 45 && /etc/init.d/cron restart Thus, when cron starts back up upon a reboot, it waits for networking to get up, then restarts the cron daemon. That fixes the problem of crontabs not being read at all for LDAP users. However, since it's the cron daemon being restarted and not the computer, @reboot entries are ignored. Is there a way for a user to make a command run upon restarting the daemon, rather than a reboot? Or is there a better solution to this overall problem? Thanks.

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• How do I find Microsoft APIs?

  - by Stephen

  I'm a java programmer, and if I see something that: I don't know about or just want to find a method description without opening an ide or am on support I type java [classname] into google, and there it is. If I try this crazy stunt for C# I'll come up with a whole heap of tutorials (how do I use it etc). If I manage to get to MSDN, I have to wade through a page describing every .net technology to see how their syntax references the same object, and then I have to find the appropriate page from there ([class name] Constructor) for example. This is even more pronounced, because I don't have Visual Studio, so I've got nothing to make it easier. There must be something I'm missing or don't know... how does this situation work for Microsoft developers? how can I make my life easier/searches better? are there techniques that work no matter what computer I'm on (e.g. require no computer setup/downloads) Notes It could be thought that java is just "java", but it's just that the java apis are only referenced/defined in the core language. For all the other languages on the JVM, it's assumed that you will just learn the correct syntax to use the java apis. I presume that .Net only lists a whole heap of languages as the api classes are actually different and have different interfaces capabilities (or some approximation of this presumption). Edit While searching msdn works... in the java space I can type 'java [anyclass]' and it will generally be found... whether it's a java core api or a third party library

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• Registry remotley hacked win 7 need help tracking the perp

  - by user577229

  I was writing some .VBS code at thhe office that would allow certain file extensions to be downloaded without a warning dialog on a w7x32 system. The system I was writing this on is in a lab on a segmented subnet. All web access is via a proxy server. The only means of accessing my machine is via the internet or from within the labs MSFT AD domain. While writing and testing my code I found a message of sorts. Upon refresing the registry to verify my code changed a dword, instead the message HELLO was written and visible in regedit where the dword value wass called for. I took a screen shot and proceeded to edit my code. This same weird behavior occurred last time I was writing registry code except on another internal server. I understand that remote registry access exists for windows systems. I will block this immediately once I return to the office. What I want to know is, can I trace who made this connection? How would I do this? I suspect the cause of this is the cause of other "odd" behaviors I'm experiencing at work such as losing control of my input director master control for over an hour and unchanged code that all of a sudden fails for no logical region. These failures occur at funny times, whenver I'm about to give a demonstration of my test code. I know this sounds crazy however knowledge of the registry component makes this believable. Once the registry can be accessed, the entire system is compromised. Any help or sanity checking is appreciated.

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• Windows service hangs

  - by Ram

  Hi, I have a webdav client-server application. I'm using Cassini webserver to host the webdav server. One important thing here is that I start and Stop my webserver using a windows service. Now, I start my windows service and I attach my webdav server application's debugger to the windows service. Everything used to go fine, that is I could connect to the server using my webdav client, debug the server code. However, a couple of days back, when I tried to debug my webdav server application, which in turn is attached to a windows service, my computer freezes while I'm in the midst of debugging the server app. The freeze does not occur at the same line every time and is therefore not predictable. Every time this happens, I would not be able to do anything at all with my computer except to reboot the system using the power button. What could be the problem? Could it be the service that is freezing or something else? Any help? Thanks, Ram

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• How can I get back my privilege to create a new database in MySQL?

  - by Steven

  I can not use MySQL. MySQL is on my local computer. Currently I added skip-grant-tables in My.ini so I can use MySQL. But I have no privilege to create a new database. My problem is tough, although I asked related questions on SO, but no answer can resolve my problem. I almost give up. So I lower my expectation. I am developing a website, so I need to create database, tables and operate tables. You don't have to consider security. Is there a simple solution that can give me privilege to create a new database? Maybe by adding some command in my.ini or something? You won't need to completely resolve my problem. Maybe after the development, I will upload the database and tables to another server(The current database server is my personal computer, windows XP) so I can uninstall and reinstall MySQL. The root of problem is that I lack privileges.

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• Analyzing Web Application Speed

  - by Amy

  I'm a bit confused because the logical/programmer brain in me says that if all things are constant, the speed of a function must be constant. I am working on a PHP web application with jqGrid as a front end for showing the data. I am testing on my personal computer, so network traffic does not apply. I make an HTTP request to a PHP function, it returns the data, and then jqGrid renders it. What has me befuddled is that sometimes, Firebug reports that this is taking 300-600 milliseconds sometimes, and sometimes, it's taking 3.68 seconds. I can run the request over and over again, with very radically different response times. The query is the same. The number of users on the system is the same. No network latency. Same code. I'm not running other applications on the computer while testing. I could understand query caching improving performance on subsequent requests, but the speed is just fluctuating wildly with no rhyme or reason. So, my question is, what else can cause such variability in the response time? How can I determine what's doing it? More importantly, is there any way to get things more consistent?

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• Building a CMS in PHP: Development tools

  - by TRiG

  I'm planning to build a CMS in PHP and MySQL, mainly for my own amusement and education. (Though who knows, I may come up with something useful and cool. Anything's possible.) I'll be asking questions about code architecture etc. later. For now, I'm more interested in development tools. So far, all my playing with code has been done on a web server, and I've edited over FTP. I was thinking it might be quicker to use a localhost. Also, that way, I could use version control (which I've never done before). So, A. How do I set up a localhost server with many subdomains on an Ubuntu 9.10 computer. Is XAMPP for Linux the way to go, or should I use a standard Apache distro? (Or another webserver altogether?) For that matter, is it possible to set up more than one webserver on the same computer, and to use them for different localhost subdomains? B. How do I set up a version control thingy covering all the code (which will be on several subdomains of localhost, and in a few shared folders)? I've read Joel Spolsky's HgInt tutorial, and it makes Mercurial look good. And simple, especially if you're working on your own. C. Should I continue to use gEdit to write HTML/CSS/JS/PHP, or is there a better free editor out there for these languages?

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• Trouble extending event log messages

  - by Matt H

  Hi. I'm trying to add some extended error codes to the event log but I get the following error. The description for Event ID ( 109 ) in Source ( PumpServer ) cannot be found. The local computer may not have the necessary registry information or message DLL files to display messages from a remote computer. You may be able to use the /AUXSOURCE= flag to retrieve this description; see Help and Support for details. The following information is part of the event: The event log file is corrupt.. The message file looks like this and I added the one on the end:- <---snip---> MessageId= SymbolicName=EVMSG_BADREQUEST Language=English The service received an unsupported request. . MessageId= SymbolicName=EVMSG_DEBUG Language=English %1 . MessageId= SymbolicName=EVMSG_STOPPED Language=English The service was stopped. . MessageId= SymbolicName=EVMSG_INVALIDLICENCE Language=English The service does not have a valid licence. Initialization failed. . It compiles fine. The mc program is running over this file and producing a header file of the same name with my new message id showing. // // MessageId: EVMSG_INVALIDLICENCE // // MessageText: // // The service does not have a valid licence. Initialization failed. // #define EVMSG_INVALIDLICENCE 0x0000006DL Any ideas why it's not finding my message? All the others work.

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• Unable to ping server from client B but able to ping from client A. Please help

  - by Soundar Rajan

  This is not really a programming question, but I am at my wit's end ... I am trying to configure a IIS 6.0/Windows Server 2003 web server with a ASP.net application. When I try to ping the server from client computer A I get the following: PING 74.208.192.xxx ==> Ping fails PING 74.208.192.xxx:80 ==> Ping succeeds! From client computer B, BOTH the pings fail. PING 74.208.192.xxx ==> Ping fails PING 74.208.192.xxx:80 ==> Ping fails with a message "Ping request could not find host 74.208.192.xxx:80" Both clients A and B are on the same subnet. The server is outside (a virtual server hosted by an ISP) I have an ASP.NET application in a virtual directory on the server. In IE or firefox, if I enter http://74.208.192.xxx/subdir/subdir/../Default.aspx, it works from both the clients! The server has default firewall settings but web server enabled (Port 80 is open).

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• How does a client find the port number of a server?

  - by Jonathan

  Hello all, I am currently learning about basic networking in java. I have been playing around with the server and client relationship between two of my computers. However, I cannot figure out how distributed programs (say, a videogame), can not only find the 'host' computer, but also the port number on which the server is running in order to create a Socket between the two computers. The only way I really see to create a Socket is with an already known IP Address, and with a known port number. How do you search a LAN network for another computer (host) searching for clients? How do you determine what port the server is located on without 'pinging' all available ports for a response (which, I understand, is bad form... Something about 'server attack'...)? In such a situation as a video game, there can be any number of computers on the same network, and any number of them might be attempting to host, or otherwise running the application. Any other important information, or perhaps reference to a more detailed tutorial than the one I am using, regarding making connections on so very little information on the client side would be appreciated. Many thanks, Jonathan

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• Tablet interface for the physically disabled?

  - by Glenn

  My sister has Cerebral Palsy, which in her case means she has only gross motor control and her speech is slurred. Implications should be obvious: traditional computer/phone/tablet interfaces won't work for her and she can't speak clearly enough for speech recognition software to help her at all. She enjoys reading but has difficulty holding the book and/or turning a page. There are a few options for helping her use a computer, but nothing for tablets or eReaders. That's where you come in. I would like to make (or buy, if such a thing exists) a better interface to an Android tablet that would work for someone with little to no physical dexterity or speech ability. I'd also be interested in work on the Kindle or iPad, but I'm most familiar with Android so I'm starting there. I know Android has Bluetooth capability. Is it possible to interface a joystick to control the Android device? By "control", I mean the entire operating system - selecting an app, launching it, controlling the menus, etc. I want to give her control over the whole thing, not just a specific app. On a PC this can be accomplished by creating a generic USB HID interface and an arcade joystick to move the mouse over the screen and click on thigns. Is it possible to do something like that in Android? Any help you can offer would be greatly appreciated. Thanks!

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• Help Me With This Access Query

  - by yae

  I have 2 tables: "products" and "pieces" PRODUCTS idProd product price PIECES id idProdMain idProdChild quant idProdMain and idProdChild are related with the table: "products". Other considerations is that 1 product can have some pieces and 1 product can be a piece. Price product equal a sum of quantity * price of all their pieces. "Products" table contains all products (p EXAMPLE: TABLE PRODUCTS (idProd - product - price) 1 - Computer - 300€ 2 - Hard Disk - 100€ 3 - Memory - 50€ 4 - Main Board - 100€ 5 - Software - 50€ 6 - CDroms 100 un. - 30€ TABLE PIECES (id - idProdMain - idProdChild - Quant.) 1 - 1 - 2 - 1 2 - 1 - 3 - 2 3 - 1 - 4 - 1 WHAT I NEED? I need update the price of the main product when the price of the product child (piece) is changed. Following the previous example, if I change the price of this product "memory" (is a piece too) to 60€, then product "Computer" will must change his price to 320€ How I can do it using queries? Already I have tried this to obatin the price of the main product, but not runs. This query not returns any value: SELECT Sum(products.price*pieces.quant) AS Expr1 FROM products LEFT JOIN pieces ON (products.idProd = pieces.idProdChild) AND (products.idProd = pieces.idProdChild) AND (products.idProd = pieces.idProdMain) WHERE (((pieces.idProdMain)=5)); MORE INFO The table "products" contains all the products to sell that it is in the shop. The table "pieces" is to take a control of the compound products. To know those who are the products children. For example of compound product: computers. This product is composed by other products (motherboard, hard disk, memory, cpu, etc.)

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• How to calculate this string-dissimilarity function efficiently?

  - by ybungalobill

  Hello, I was looking for a string metric that have the property that moving around large blocks in a string won't affect the distance so much. So "helloworld" is close to "worldhello". Obviously Levenshtein distance and Longest common subsequence don't fulfill this requirement. Using Jaccard distance on the set of n-grams gives good results but has other drawbacks (it's a pseudometric and higher n results in higher penalty for changing single character). [original research] As I thought about it, what I'm looking for is a function f(A,B) such that f(A,B)+1 equals the minimum number of blocks that one have to divide A into (A1 ... An), apply a permutation on the blocks and get B: f("hello", "hello") = 0 f("helloworld", "worldhello") = 1 // hello world -> world hello f("abba", "baba") = 2 // ab b a -> b ab a f("computer", "copmuter") = 3 // co m p uter -> co p m uter This can be extended for A and B that aren't necessarily permutations of each other: any additional character that can't be matched is considered as one additional block. f("computer", "combuter") = 3 // com uter -> com uter, unmatched: p and b. Observing that instead of counting blocks we can count the number of pairs of indices that are taken apart by a permutation, we can write f(A,B) formally as: f(A,B) = min { C(P) | P:|A|?|B|, P is bijective, ?i?dom(P) A[P(i)]=B[P(i)] } C(P) = |A| + |B| - |dom(P)| - |{ i | i,i+1?dom(P) and P(i)+1=P(i+1) }| - 1 The problem is... guess what... ... that I'm not able to calculate this in polynomial time. Can someone suggest a way to do this efficiently? Or perhaps point me to already known metric that exhibits similar properties?

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• Using boost asio for pub/sub style tcp in a game loop

  - by unohoo

  I have been reading through the boost asio documentation for a couple of hours now, and while I think the documentation is really great, I am still left a bit confused on how to implement the system that I need. I have to stream info, from a game engine, to a list of computers over tcp. One snag is that, unlike traditional pub/sub, the computer that does the distribution of info is actually the computer that has to connect to the subscribers as well (instead of the subscribers registering with the publisher). This is done via a config file - a list of ip's/ports along with the data that they each require. The subscribers listen, but do not know the ip of the publisher. (As a side note, I'm quite new to network programming, so maybe I'm missing something .. but it's strange that I do not find much information regarding this style of "inverted" client-server model..) I am looking for suggestions for the implementation of such a system using boost asio. Of course I have to integrate the networking into an already existing engine, so with regards to that: What would be a good way to handle messages being sent to multiple computers every frame? Use async_write, call io_service.run and then reset every frame? Would having io_service.run have its own thread be better? Or should I just use threads and use blocking writes?

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• Downloading a picture via urllib and python.

  - by Mike

  So I'm trying to make a Python script that downloads webcomics and puts them in a folder on my desktop. I've found a few similar programs on here that do something similar, but nothing quite like what I need. The one that I found most similar is right here (http://bytes.com/topic/python/answers/850927-problem-using-urllib-download-images). I tried using this code: >>> import urllib >>> image = urllib.URLopener() >>> image.retrieve("http://www.gunnerkrigg.com//comics/00000001.jpg","00000001.jpg") ('00000001.jpg', <httplib.HTTPMessage instance at 0x1457a80>) I then searched my computer for a file "00000001.jpg", but all I found was the cached picture of it. I'm not even sure it saved the file to my computer. Once I understand how to get the file downloaded, I think I know how to handle the rest. Essentially just use a for loop and split the string at the '00000000'.'jpg' and increment the '00000000' up to the largest number, which I would have to somehow determine. Any reccomendations on the best way to do this or how to download the file correctly? Thanks!

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• What are Code Smells? What is the best way to correct them?

  - by Rob Cooper

  OK, so I know what a code smell is, and the Wikipedia Article is pretty clear in its definition: In computer programming, code smell is any symptom in the source code of a computer program that indicates something may be wrong. It generally indicates that the code should be refactored or the overall design should be reexamined. The term appears to have been coined by Kent Beck on WardsWiki. Usage of the term increased after it was featured in Refactoring. Improving the Design of Existing Code. I know it also provides a list of common code smells. But I thought it would be great if we could get clear list of not only what code smells there are, but also how to correct them. Some Rules Now, this is going to be a little subjective in that there are differences to languages, programming style etc. So lets lay down some ground rules: ** ONE SMELL PER ANSWER PLEASE! & ADVISE ON HOW TO CORRECT! ** See this answer for a good display of what this thread should be! DO NOT downmod if a smell doesn't apply to your language or development methodology We are all different. DO NOT just quickly smash in as many as you can think of Think about the smells you want to list and get a good idea down on how to work around. DO downmod answers that just look rushed For example "dupe code - remove dupe code". Let's makes it useful (e.g. Duplicate Code - Refactor into separate methods or even classes, use these links for help on these common.. etc. etc.). DO upmod answers that you would add yourself If you wish to expand, then answer with your thoughts linking to the original answer (if it's detailed) or comment if its a minor point. DO format your answers! Help others to be able to read it, use code snippets, headings and markup to make key points stand out!

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