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  • Practical non-image based CAPTCHA approaches?

    - by Jeff Atwood
    It looks like we'll be adding CAPTCHA support to Stack Overflow. This is necessary to prevent bots, spammers, and other malicious scripted activity. We only want human beings to post or edit things here! We'll be using a JavaScript (jQuery) CAPTCHA as a first line of defense: http://docs.jquery.com/Tutorials:Safer_Contact_Forms_Without_CAPTCHAs The advantage of this approach is that, for most people, the CAPTCHA won't ever be visible! However, for people with JavaScript disabled, we still need a fallback and this is where it gets tricky. I have written a traditional CAPTCHA control for ASP.NET which we can re-use. However, I'd prefer to go with something textual to avoid the overhead of creating all these images on the server with each request. I've seen things like.. ASCII text captcha: \/\/(_)\/\/ math puzzles: what is 7 minus 3 times 2? trivia questions: what tastes better, a toad or a popsicle? Maybe I'm just tilting at windmills here, but I'd like to have a less resource intensive, non-image based <noscript> compatible CAPTCHA if possible. Ideas?

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  • What is the best way to solve an Objective-C namespace collision?

    - by Mecki
    Objective-C has no namespaces; it's much like C, everything is within one global namespace. Common practice is to prefix classes with initials, e.g. if you are working at IBM, you could prefix them with "IBM"; if you work for Microsoft, you could use "MS"; and so on. Sometimes the initials refer to the project, e.g. Adium prefixes classes with "AI" (as there is no company behind it of that you could take the initials). Apple prefixes classes with NS and says this prefix is reserved for Apple only. So far so well. But appending 2 to 4 letters to a class name in front is a very, very limited namespace. E.g. MS or AI could have an entirely different meanings (AI could be Artificial Intelligence for example) and some other developer might decide to use them and create an equally named class. Bang, namespace collision. Okay, if this is a collision between one of your own classes and one of an external framework you are using, you can easily change the naming of your class, no big deal. But what if you use two external frameworks, both frameworks that you don't have the source to and that you can't change? Your application links with both of them and you get name conflicts. How would you go about solving these? What is the best way to work around them in such a way that you can still use both classes? In C you can work around these by not linking directly to the library, instead you load the library at runtime, using dlopen(), then find the symbol you are looking for using dlsym() and assign it to a global symbol (that you can name any way you like) and then access it through this global symbol. E.g. if you have a conflict because some C library has a function named open(), you could define a variable named myOpen and have it point to the open() function of the library, thus when you want to use the system open(), you just use open() and when you want to use the other one, you access it via the myOpen identifier. Is something similar possible in Objective-C and if not, is there any other clever, tricky solution you can use resolve namespace conflicts? Any ideas? Update: Just to clarify this: answers that suggest how to avoid namespace collisions in advance or how to create a better namespace are certainly welcome; however, I will not accept them as the answer since they don't solve my problem. I have two libraries and their class names collide. I can't change them; I don't have the source of either one. The collision is already there and tips on how it could have been avoided in advance won't help anymore. I can forward them to the developers of these frameworks and hope they choose a better namespace in the future, but for the time being I'm searching a solution to work with the frameworks right now within a single application. Any solutions to make this possible?

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  • Taking my ASP.NET from my local comp to the server

    - by Andrew G. Johnson
    Hi All, So I have been developing a small ASP.NET web app in C# for my company over the past few weeks and now I am trying to push it onto our Rackspace server. First step was to create a virtual directory because we want it to be www.ourdomain.com/appname/ and most of the stuff on ourdomain.com is currently in classic ASP. So I did this and then uploaded my stuff to the new folder. I *think* I did this at least semi-right because the error message I am getting is that nice puke color (ASP.NET style instead of classic ASP style) -- problem is it is generic and just saying runtime error. I tried just copy/pasting <customErrors mode="On" /> into the web.config file in the /appname/ directory but nothing changed So the actual questions are: How can I get a more descriptive error, when I was developing locally I just pushed the "play button" in VS2010 and it would either show me the app or tell me where I screwed up Is there anything else I'm doing wrong that may be causing this? If there's things I need to check lemme know!

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  • Using WordPress as a CMS

    - by tonsils
    Hi, Hoping someone can assist but I am currently teaching myself WordPress and working on my own CMS site. My site will consist of approx 5 pages where the header/sidebar menu/footer will be seen on all these 5 pages. Newbie here and questions are as follows: 1) All these 5 pages will consist of different content, for example, every page will have a image banner representing the menu option just clicked, for example, "About Us" on page 5, "Promotions" on page 4 etc and then some text beneath that and then possibly some images inside a carousel set up. Within WordPress, how would I tackle this, i.e. do I just create a page in WordPress, position the banner image at the top of the page, then have a few breaks and then insert the carousel of images - is this correct? If not, do I need to create a separate php file called aboutUs.php that has this markup and then somehow link it to a WordPress page? 2) On my landing page of my site ONLY (page 1), just above the footer, I want to display a div section that displays all the sponsors of the website along with a URL to click to their websites - how would I go about doing this in WordPress? If there are any sites that people know that will somehow answer my queries, pls pass them on. Thanks.

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  • Can't write to dynamic iframe using jQuery

    - by Fremont Troll
    My goal is to dynamically create an iframe and write ad JavaScript into it using jQuery (e.g. Google AdSense script). My code works on Chrome, but fails intermittently in Firefox i.e. sometimes the ad script runs and renders the ad, and other times it doesn't. When it doesn't work, the script code itself shows up in the iframe. My guess is these intermittent failures occur because the iframe is not ready by the time I write to it. I have tried various iterations of *iframe_html* (my name for the function which is supposed to wait for the iframe to be ready), but no luck. Any help appreciated! PS: I have read various threads (e.g. http://stackoverflow.com/questions/205087/jquery-ready-in-a-dynamically-inserted-iframe). Just letting everyone know that I've done my research on this, but I'm stuck :) Iteration 1: function iframe_html(html){ $('<iframe name ="myiframe" id="myiframe"/>').appendTo('#maindiv'); $('#myiframe').load( function(){ $('#myiframe').ready( function(){ var d = $("#myiframe")[0].contentWindow.document; d.open(); d.close(); d.write(html); }); } ); }; Iteration 2: function iframe_html(html){ $('<iframe id="myiframe"/>').appendTo('#maindiv').ready( function(){ $("#myiframe").contents().get(0).write(html); } ); };

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  • What Do You Need To Write Your Own Blog Engine?

    - by deworde
    I've been messing around with basic websites for a few years, using companies like www.Fasthosts.co.uk to do my web hosting. But I'd like to expand my skills from C++ and Java app programming into Web-based programming, and I think the best way to do that is with a project. I've chosen to go with a blog engine because it's a relative comprehensive yet non-complex project. I'm aware that you can just go to Blogger and bam! One blog. I've done that, so that I can at least have some content, and work out what I want to do with this blog. At the moment, I'm thinking I'll use it to chart my progress creating the blogging engine. But I have some questions. Do you need to be running your own server? Or is it more sensible in the short-term to use a hosting company? What types of language are worth considering? What's important to focus on from a design perspective? What unexpected problems might I encounter?

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  • How to prevent my C# winforms application from stealing focus when I set the visible properly to tru

    - by Fopedush
    I've got a C# winforms application that runs in the background, listening for hotkeys to be pressed. When a hotkey is pressed, my form makes a brief appearance. The form is always running, but set to hidden until I receive a hotkey event, at which time I set the visible property to true. The code looks like this: void hook_volumeDown(object sender, KeyPressedEventArgs e) { this.Visible = true; } It should be noted that the topmost property of this form is set to true. The really odd part is, after my C# app has stolen focus from another application, it will never do it again. For example: I launch my app, then launch some fullscreep app like Team Fortress 2. Then I press my hotkey. Team Fortress 2 minimizes, and I see my form. Then, however, I can restore TF2, and press my hotkey again all I want (with the desired effect), and TF2 will remain focused. At any rate, I'm looking for a way to fix this. I've found a lot of questions here covering similar problems, but all of them are related to creating/launching a new form, not making an existing one visible (unless I missed something). I could rework the application to create a new form every time I need one, but that would entail creating yet another form to be invisible all the time just to wait for hotkey events, so I'd rather leave it as it is. Any ideas?

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  • Behavior of <- NULL on lists versus data.frames for removing data

    - by Ananda Mahto
    Many R users eventually figure out lots of ways to remove elements from their data. One way is to use NULL, particularly when you want to do something like drop a column from a data.frame or drop an element from a list. Eventually, a user comes across a situation where they want to drop several columns from a data.frame at once, and they hit upon <- list(NULL) as the solution (since using <- NULL will result in an error). A data.frame is a special type of list, so it wouldn't be too tough to imagine that the approaches for removing items from a list should be the same as removing columns from a data.frame. However, they produce different results, as can be seen in the example below. ## Make some small data--two data.frames and two lists cars1 <- cars2 <- head(mtcars)[1:4] cars3 <- cars4 <- as.list(cars2) ## Demonstration that the `list(NULL)` approach works cars1[c("mpg", "cyl")] <- list(NULL) cars1 # disp hp # Mazda RX4 160 110 # Mazda RX4 Wag 160 110 # Datsun 710 108 93 # Hornet 4 Drive 258 110 # Hornet Sportabout 360 175 # Valiant 225 105 ## Demonstration that simply using `NULL` does not work cars2[c("mpg", "cyl")] <- NULL # Error in `[<-.data.frame`(`*tmp*`, c("mpg", "cyl"), value = NULL) : # replacement has 0 items, need 12 Switch to applying the same concept to a list, and compare the difference in behavior. ## Does not fully drop the items, but sets them to `NULL` cars3[c("mpg", "cyl")] <- list(NULL) # $mpg # NULL # # $cyl # NULL # # $disp # [1] 160 160 108 258 360 225 # # $hp # [1] 110 110 93 110 175 105 ## *Does* drop the `list` items while this would ## have produced an error with a `data.frame` cars4[c("mpg", "cyl")] <- NULL # $disp # [1] 160 160 108 258 360 225 # # $hp # [1] 110 110 93 110 175 105 The main questions I have are, if a data.frame is a list, why does it behave so differently in this scenario? Is there a foolproof way of knowing when an element will be dropped, when it will produce an error, and when it will simply be given a NULL value? Or do we depend on trial-and-error for this?

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  • Secure web module for paid subscribtion

    - by DarkJaff
    Hello everyone, I'm building a website (a community web site like digg) but we will soon release a new feature that people will need to pay for. Right now, our website is in pure C# in .NET, very simple pages with some AJAX. When the member log in, there is no HTTPS. Everything is check with session and the internal validation that I do. What we need, is that when the people are logged in, they can click on a link a proceed to a payment (Paypal, credit card, etc). After the payment is done, the "billing module" will return a value to my site to validate that the payment is done so the account will be flagged as "paying member". I'm guessing this is the way to do, maybe I'm wrong! So my questions are: -What is the name of this kind of billing module? (I will do some research on that) -Do you know any ready to go module that does this kind of thing? -(I push my luck) Do you know any FREE module that do this kind of things. If something is not clear, don't hesitate to ask question :) Thanks a lot! DarkJaff

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  • iphone coredata fetch-request sorting

    - by satyam
    I'm using core data and fetching the results successfully. I've few questions regarding core data 1. When I add a record, will it be added at the end or at the start of entity. 2. I'm using following code to fetch the data. Array is being populated with all the records. But they are not in the same order as I entered records into entity. why? on what basis default sorting is used? NSFetchRequest* allLatest = [[NSFetchRequest alloc] init]; [allLatest setEntity:[NSEntityDescription entityForName:@"Latest" inManagedObjectContext:[self managedObjectContext]]]; NSError* error = nil; NSArray* records = [managedObjectContext executeFetchRequest:allLatest error:&error]; [allLatest release]; 3. The way that I enter the records, 1,2,3,4......... after some time, I want to delete the records that I entered first(i mean oldest data). Something like delete oldest two records. How to do it?

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  • Do you have suggestions for these assembly mnemonics?

    - by Noctis Skytower
    Greetings! Last semester in college, my teacher in the Computer Languages class taught us the esoteric language named Whitespace. In the interest of learning the language better with a very busy schedule (midterms), I wrote an interpreter and assembler in Python. An assembly language was designed to facilitate writing programs easily, and a sample program was written with the given assembly mnemonics. Now that it is summer, a new project has begun with the objective being to rewrite the interpreter and assembler for Whitespace 0.3, with further developments coming afterwards. Since there is so much extra time than before to work on its design, you are presented here with an outline that provides a revised set of mnemonics for the assembly language. This post is marked as a wiki for their discussion. Have you ever had any experience with assembly languages in the past? Were there some instructions that you thought should have been renamed to something different? Did you find yourself thinking outside the box and with a different paradigm than in which the mnemonics were named? If you can answer yes to any of those questions, you are most welcome here. Subjective answers are appreciated! Stack Manipulation (IMP: [Space]) Stack manipulation is one of the more common operations, hence the shortness of the IMP [Space]. There are four stack instructions. hold N Push the number onto the stack copy Duplicate the top item on the stack copy N Copy the nth item on the stack (given by the argument) onto the top of the stack swap Swap the top two items on the stack drop Discard the top item on the stack drop N Slide n items off the stack, keeping the top item Arithmetic (IMP: [Tab][Space]) Arithmetic commands operate on the top two items on the stack, and replace them with the result of the operation. The first item pushed is considered to be left of the operator. add Addition sub Subtraction mul Multiplication div Integer Division mod Modulo Heap Access (IMP: [Tab][Tab]) Heap access commands look at the stack to find the address of items to be stored or retrieved. To store an item, push the address then the value and run the store command. To retrieve an item, push the address and run the retrieve command, which will place the value stored in the location at the top of the stack. save Store load Retrieve Flow Control (IMP: [LF]) Flow control operations are also common. Subroutines are marked by labels, as well as the targets of conditional and unconditional jumps, by which loops can be implemented. Programs must be ended by means of [LF][LF][LF] so that the interpreter can exit cleanly. L: Mark a location in the program call L Call a subroutine goto L Jump unconditionally to a label if=0 L Jump to a label if the top of the stack is zero if<0 L Jump to a label if the top of the stack is negative return End a subroutine and transfer control back to the caller halt End the program I/O (IMP: [Tab][LF]) Finally, we need to be able to interact with the user. There are IO instructions for reading and writing numbers and individual characters. With these, string manipulation routines can be written. The read instructions take the heap address in which to store the result from the top of the stack. print chr Output the character at the top of the stack print int Output the number at the top of the stack input chr Read a character and place it in the location given by the top of the stack input int Read a number and place it in the location given by the top of the stack Question: How would you redesign, rewrite, or rename the previous mnemonics and for what reasons?

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  • Interpreting java.lang.NoSuchMethodError message

    - by Doog
    I get the following runtime error message (along with the first line of the stack trace, which points to line 94). I'm trying to figure out why it says no such method exists. java.lang.NoSuchMethodError: com.sun.tools.doclets.formats.html.SubWriterHolderWriter.printDocLinkForMenu( ILcom/sun/javadoc/ClassDoc;Lcom/sun/javadoc/MemberDoc; Ljava/lang/String;Z)Ljava/lang/String; at com.sun.tools.doclets.formats.html.AbstractExecutableMemberWriter.writeSummaryLink( AbstractExecutableMemberWriter.java:94) Line 94 of writeSummaryLink is shown below. QUESTIONS What does "ILcom" or "Z" mean? Why there are four types in parentheses (ILcom/sun/javadoc/ClassDoc;Lcom/sun/javadoc/MemberDoc;Ljava/lang/String;Z) and one after the parentheses Ljava/lang/String; when the method printDocLinkForMenu clearly has five parameters? CODE DETAIL The writeSummaryLink method is: protected void writeSummaryLink(int context, ClassDoc cd, ProgramElementDoc member) { ExecutableMemberDoc emd = (ExecutableMemberDoc)member; String name = emd.name(); writer.strong(); writer.printDocLinkForMenu(context, cd, (MemberDoc) emd, name, false); // 94 writer.strongEnd(); writer.displayLength = name.length(); writeParameters(emd, false); } Here's the method line 94 is calling: public void printDocLinkForMenu(int context, ClassDoc classDoc, MemberDoc doc, String label, boolean strong) { String docLink = getDocLink(context, classDoc, doc, label, strong); print(deleteParameterAnchors(docLink)); }

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  • java 6 web services share domain specific classes between server and client

    - by user173446
    Hi all, Context: Considering below defined Engine class being parameter of some webservice method. As we have both server and client in java we may have some benefits (???) in sharing Engine class between server and client ( i.e we may put in a common jar file to be added to both client and server classpath ) Some benefits would be : we keep specific operations like 'brushEngine' in same place build is faster as we do not need in our case to generate java code for client classes but to use them from the server build) if we later change server implementation for 'brushEngine' this is reflected automatically in client . Questions: How to share below detailed Engine class using java 6 tools ( i.e wsimport , wsgen etc )? Is there other tools for java that can achieve this sharing ? Is sharing a case that java 6 web services support is missing ? Can this case be reduced to other web service usage patterns? Thanks. Code: public class Engine { private String engineData; public String getData(){ return data; } public setData(String value){ this.data = value; } public void brushEngine(){ engineData = "BrushedEngine"+engineData; } }

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  • How to Load external Div that has a dynamic content using ajax and jsp/servlets ?

    - by A.S al-shammari
    I need to use ajax feature to load external div element ( external jsp file) into the current page. That JSP page contains a dynamic content - e.g. content that is based on values received from the current session. I solved this problem , but I'm in doubt because I think that my solution is bad , or maybe there is better solution since I'm not expert. I have three files: Javascript function that is triggered when a element is clicked, it requests html data from a servlet: $("#inboxtable tbody tr").click(function(){ var trID = $(this).attr('id'); $.post("event?view=read",{id:trID}, function(data){ $("#eventContent").html(data); // load external file },"html"); // type }); The servlet "event" loads the data and generates HTML content using include method : String id = request.getParameter("id"); if (id != null) { v.add("Test"); v.add(id); session.setAttribute("readMessageVector", v); request.getRequestDispatcher("readMessage.jsp").include(request, response); } The readMessage jsp file looks like this: <p> Text: ${readMessageVector[0]} </p> <p> ID: ${readMessageVector[1]} </p> My questions Is this solution good enough to solve this problem - loading external jsp that has dynamic content ? Is there better solution ?

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  • dual boot install--no GRUB

    - by Jim Syyap
    My computer recently had a hardware upgrade and now runs on Windows 7. I decided to install Ubuntu 11.04 as dual boot using the ISO I got from ubuntu.com downloaded onto my USB stick. Restarting with the USB stick, I was able to install Ubuntu 11.04 choosing the option: Install Ubuntu 11.04 side by side with Windows 7 (or something like that). No errors were encountered on installation. However on restarting, there was no GRUB; the system went straight into Windows 7. Looking for answers, I found these: http://essayboard.com/2011/07/12/how-to-dual-boot-ubuntu-11-04-and-windows-7-the-traditional-way-through-grub-2/ http://ubuntuforums.org/showthread.php?t=1774523 Following their instructions, I got: Boot Info Script 0.60 from 17 May 2011 ============================= Boot Info Summary: =============================== => Windows is installed in the MBR of /dev/sda. => Syslinux MBR (3.61-4.03) is installed in the MBR of /dev/sdb. => Grub2 (v1.99) is installed in the MBR of /dev/sdc and looks at sector 1 of the same hard drive for core.img. core.img is at this location and looks for (,msdos7)/boot/grub on this drive. sda1: __________________________________________________ ________________________ File system: ntfs Boot sector type: Windows Vista/7 Boot sector info: No errors found in the Boot Parameter Block. Operating System: Boot files: /grldr /bootmgr /Boot/BCD /grldr sda2: __________________________________________________ ________________________ File system: ntfs Boot sector type: Windows Vista/7 Boot sector info: No errors found in the Boot Parameter Block. Operating System: Windows 7 Boot files: /Windows/System32/winload.exe sdb1: __________________________________________________ ________________________ File system: vfat Boot sector type: SYSLINUX 4.02 debian-20101016 ...........>...r>....... ......0...~.k...~...f...M.f.f....f..8~....>2} Boot sector info: Syslinux looks at sector 1437504 of /dev/sdb1 for its second stage. SYSLINUX is installed in the directory. The integrity check of the ADV area failed. According to the info in the boot sector, sdb1 starts at sector 0. But according to the info from fdisk, sdb1 starts at sector 62. Operating System: Boot files: /boot/grub/grub.cfg /syslinux/syslinux.cfg /ldlinux.sys sdc1: __________________________________________________ ________________________ File system: ntfs Boot sector type: Windows XP Boot sector info: No errors found in the Boot Parameter Block. Operating System: Boot files: sdc2: __________________________________________________ ________________________ File system: Extended Partition Boot sector type: - Boot sector info: sdc5: __________________________________________________ ________________________ File system: swap Boot sector type: - Boot sector info: sdc6: __________________________________________________ ________________________ File system: swap Boot sector type: - Boot sector info: sdc7: __________________________________________________ ________________________ File system: ext4 Boot sector type: - Boot sector info: Operating System: Ubuntu 11.04 Boot files: /boot/grub/grub.cfg /etc/fstab /boot/grub/core.img sdc8: __________________________________________________ ________________________ File system: swap Boot sector type: - Boot sector info: Going back into Ubuntu and running sudo fdisk -l , I got these: ubuntu@ubuntu:~$ sudo fdisk -l Disk /dev/sda: 160.0 GB, 160041885696 bytes 255 heads, 63 sectors/track, 19457 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x0002f393 Device Boot Start End Blocks Id System /dev/sda1 * 1 13 102400 7 HPFS/NTFS Partition 1 does not end on cylinder boundary. /dev/sda2 13 19458 156185600 7 HPFS/NTFS Disk /dev/sdb: 2011 MB, 2011168768 bytes 62 heads, 62 sectors/track, 1021 cylinders Units = cylinders of 3844 * 512 = 1968128 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x000f2ab9 Device Boot Start End Blocks Id System /dev/sdb1 * 1 1021 1962331 c W95 FAT32 (LBA) Disk /dev/sdc: 1000.2 GB, 1000202043392 bytes 255 heads, 63 sectors/track, 121600 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00261ddd Device Boot Start End Blocks Id System /dev/sdc1 * 1 60657 487222656+ 7 HPFS/NTFS /dev/sdc2 60657 121600 489527681 5 Extended /dev/sdc5 120563 121600 8337703+ 82 Linux swap / Solaris /dev/sdc6 120073 120562 3930112 82 Linux swap / Solaris /dev/sdc7 60657 119584 473328640 83 Linux /dev/sdc8 119584 120072 3923968 82 Linux swap / Solaris Should I proceed and do the following? Assuming Ubuntu 11.04 was installed on device sdb1, do this: sudo mount /dev/sdb1 /mnt Then do this: sudo grub-install--root-directory=/mnt /dev/sdb Notice there are two dashes in front of the root directory, and I'm not using sdb1 but sdb. Since the command in step 15 had reinstalled Grub 2, now we need to unmount the /mnt (i.e. sdb1) to clean up. Do this: sudo umount /mnt Reboot and remove Ubuntu 11.04 CD/DVD from disk tray. Log into Ubuntu 11.04 (you have no choice but it will make you log into Ubuntu 11.04 at this point). Open up a terminal in Ubuntu 11.04 (using real installation, not live CD/DVD). Execute this command: sudo update-grub Reboot the machine.

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  • Is it possible to wrap an asynchronous event and its callback in a function that returns a boolean?

    - by Rob Flaherty
    I'm trying to write a simple test that creates an image element, checks the image attributes, and then returns true/false. The problem is that using the onload event makes the test asynchronous. On it own this isn't a problem (using a callback as I've done in the code below is easy), but what I can't figure out is how to encapsulate this into a single function that returns a boolean. I've tried various combinations of closures, recursion, and self-executing functions but have had no luck. So my question: am I being dense and overlooking something simple, or is this in fact not possible, because, no matter what, I'm still trying to wrap an asynchronous function in synchronous expectations? Here's the code: var supportsImage = function(callback) { var img = new Image(); img.onload = function() { //Check attributes and pass true or false to callback callback(true); }; img.src = 'data:image/gif;base64,R0lGODlhAQABAAD/ACwAAAAAAQABAAACADs='; }; supportsImage(function(status){ console.log(status); }); To be clear, what I want is to be able to wrap this in something such that it can be used like: if (supportsImage) { //Do some crazy stuff } Thanks! (Btw, I know there are a ton of SO questions regarding confusion about synchronous vs. asynchronous. Apologies if this can be reduced to something previously answered.)

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  • Remove redundant SQL code

    - by Dave Jarvis
    Code The following code calculates the slope and intercept for a linear regression against a slathering of data. It then applies the equation y = mx + b against the same result set to calculate the value of the regression line for each row. Can the two separate sub-selects be joined so that the data and its slope/intercept are calculated without executing the data gathering part of the query twice? SELECT AVG(D.AMOUNT) as AMOUNT, Y.YEAR * ymxb.SLOPE + ymxb.INTERCEPT as REGRESSION_LINE, Y.YEAR as YEAR, MAKEDATE(Y.YEAR,1) as AMOUNT_DATE FROM CITY C, STATION S, YEAR_REF Y, MONTH_REF M, DAILY D, (SELECT ((avg(t.AMOUNT * t.YEAR)) - avg(t.AMOUNT) * avg(t.YEAR)) / (stddev( t.AMOUNT ) * stddev( t.YEAR )) as CORRELATION, ((sum(t.YEAR) * sum(t.AMOUNT)) - (count(1) * sum(t.YEAR * t.AMOUNT))) / (power(sum(t.YEAR), 2) - count(1) * sum(power(t.YEAR, 2))) as SLOPE, ((sum( t.YEAR ) * sum( t.YEAR * t.AMOUNT )) - (sum( t.AMOUNT ) * sum(power(t.YEAR, 2)))) / (power(sum(t.YEAR), 2) - count(1) * sum(power(t.YEAR, 2))) as INTERCEPT FROM ( SELECT AVG(D.AMOUNT) as AMOUNT, Y.YEAR as YEAR, MAKEDATE(Y.YEAR,1) as AMOUNT_DATE FROM CITY C, STATION S, YEAR_REF Y, MONTH_REF M, DAILY D WHERE $X{ IN, C.ID, CityCode } AND SQRT( POW( C.LATITUDE - S.LATITUDE, 2 ) + POW( C.LONGITUDE - S.LONGITUDE, 2 ) ) < $P{Radius} AND S.STATION_DISTRICT_ID = Y.STATION_DISTRICT_ID AND Y.YEAR BETWEEN 1900 AND 2009 AND M.YEAR_REF_ID = Y.ID AND M.CATEGORY_ID = $P{CategoryCode} AND M.ID = D.MONTH_REF_ID AND D.DAILY_FLAG_ID <> 'M' GROUP BY Y.YEAR ) t ) ymxb WHERE $X{ IN, C.ID, CityCode } AND SQRT( POW( C.LATITUDE - S.LATITUDE, 2 ) + POW( C.LONGITUDE - S.LONGITUDE, 2 ) ) < $P{Radius} AND S.STATION_DISTRICT_ID = Y.STATION_DISTRICT_ID AND Y.YEAR BETWEEN 1900 AND 2009 AND M.YEAR_REF_ID = Y.ID AND M.CATEGORY_ID = $P{CategoryCode} AND M.ID = D.MONTH_REF_ID AND D.DAILY_FLAG_ID <> 'M' GROUP BY Y.YEAR Question How do I execute the duplicate bits only once per query, instead of twice? The duplicate bit is the WHERE clause: $X{ IN, C.ID, CityCode } AND SQRT( POW( C.LATITUDE - S.LATITUDE, 2 ) + POW( C.LONGITUDE - S.LONGITUDE, 2 ) ) < $P{Radius} AND S.STATION_DISTRICT_ID = Y.STATION_DISTRICT_ID AND Y.YEAR BETWEEN 1900 AND 2009 AND M.YEAR_REF_ID = Y.ID AND M.CATEGORY_ID = $P{CategoryCode} AND M.ID = D.MONTH_REF_ID AND D.DAILY_FLAG_ID <> 'M' Related http://stackoverflow.com/questions/1595659/how-to-eliminate-duplicate-calculation-in-sql Thank you!

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  • How can I log any login operation in case of "Remember Me" option ?

    - by Space Cracker
    I have an asp.net login web form that have ( username textBox - password textBox ) plus Remember Me CheckBox option When user login i do the below code if (provider.ValidateUser(username, password)) { int timeOut = 0x13; DateTime expireDate = DateTime.Now.AddMinutes(19.0); if (rememberMeCheckBox.Checked) { timeOut = 0x80520; expireDate = DateTime.Now.AddYears(1); } FormsAuthenticationTicket ticket = new FormsAuthenticationTicket(username, true, timeOut); string cookieValue = FormsAuthentication.Encrypt(ticket); HttpCookie cookie = new HttpCookie(FormsAuthentication.FormsCookieName, cookieValue); cookie.Expires = expireDate; HttpContext.Current.Response.Cookies.Add(cookie); AddForLogin(username); Response.Redirect("..."); } as in code after user is authenticated i log that he login in db by calling method AddForLogin(username); But if user choose remember me in login and then he try to go to site any time this login method isn't executed as it use cookies ... so i have many questions: 1- Is this the best way to log login operation or is there any other better ? 2- In my case how to log login operation in case of remember me chosen by user ?

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  • Unable to persist objects in GAE JDO

    - by Basil Dsouza
    Hello Guys, I am completely fresh to both JDO and GAE, and have been struggling to get my data layer to persist any code at all! The issues I am facing may be very simple, but I just cant seem to find any a way no matter what solution I try. Firstly the problem: (Slightly simplified, but still contains all the info necessary) My data model is as such: User: (primary key) String emailID String firstName Car: (primary key) User user (primary key) String registration String model This was the initial datamodel. I implemented a CarPK object to get a composite primary key of the User and the registration. However that ran into a variety of issues. (Which i will save for another time/question) I then changed the design as such: User: (Unchanged) Car: (primary key) String fauxPK (here fauxPK = user.getEmailID() + SEP + registration) User user String registration String model This works fine for the user, and it can insert and retrieve user objects. However when i try to insert a Car Object, i get the following error: "Cannot have a java.lang.String primary key and be a child object" Found the following helpful link about it: http://stackoverflow.com/questions/2063467/persist-list-of-objects Went to the link suggested there, that explains how to create Keys, however they keep talking about "Entity Groups" and "Entity Group Parents". But I cant seem to find any articles or sites that explain what are "Entity Group"s or an "Entity Group Parents" I could try fiddling around some more to figure out if i can store an object somehow, But I am running sort on patience and also would rather understand and implement than vice versa. So i would appreciate any docs (even if its huge) that covers all these points, and preferably has some examples that go beyond the very basic data modeling. And thanks for reading such a long post :)

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  • How to implement rank structure

    - by Luke101
    What is the best way to implement a rank system: here is the code i will use public class MyRank { private int LevelOneMaxPoints = 100; private int LevelTwoMinPoints = 200; private int LevelTwoMaxPoints = 299; private int LevelThreeMinPoints = 300; private int LevelThreeMaxPoints = 399; private int LevelFourMinPoints = 400; private int LevelFourMaxPoints = 599; private int LevelFourPlusMinPoints = 600; private int LevelFourPlusMaxPoints = 999; private int LevelFiveMinPoints = 1000; private int LevelFiveMaxPoints = 1299; private int LevelSixMinPoints = 1300; private int LevelSixMaxPoints = 2699; private int LevelSevenMinPoints = 2700; private int LevelSevenMaxPoints = 3999; private int LevelEightMinPoints = 4000; private int LevelEightMaxPoints = 5499; private int LevelEightPlusMinPoints = 5500; private int LevelEightPlusMaxPoints = 7499; private int LevelNineMinPoints = 7500; private int LevelNineMaxPoints = 9999; private int LevelTenMinPoints = 10000; private string LevelOneName = "Private"; private string LevelTwoName = "PV2"; private string LevelThreeName = "Private Fist Class"; private string LevelFourName = "Specialist"; private string LevelFourPlusName = "Corporal"; private string LevelFiveName = "Sergeant"; //private string LevelSixName = "Staff Sergeant"; private string LevelSevenName = "Sergeant First Class"; private string LevelEightName = "Master Sergeant"; private string LevelEightPlusName = "First Sergeant"; private string LevelNineName = "Sergeant Major"; //private string LevelTenName = "Sergeant Major of the Answers"; private int points = 0; public string RankName { get; private set; } public MyRank(int points) { this.points = points; RankName = GetRankName(); } private string GetRankName() { if (points >= Int32.MinValue && points <= LevelOneMaxPoints) return LevelOneName; else if (points >= LevelTwoMinPoints && points <= LevelTwoMaxPoints) return LevelTwoName; else if (points >= LevelThreeMinPoints && points <= LevelThreeMaxPoints) return LevelThreeName; else if (points >= LevelFourMinPoints && points <= LevelFourMaxPoints) return LevelFourName; else if (points >= LevelFourPlusMinPoints && points <= LevelFourPlusMaxPoints) return LevelFourPlusName; else if (points >= LevelFiveMinPoints && points <= LevelFiveMaxPoints) return LevelFiveName; else if (points >= LevelSixMinPoints && points <= LevelSixMaxPoints) return LevelFiveName; else if (points >= LevelSevenMinPoints && points <= LevelSevenMaxPoints) return LevelSevenName; else if (points >= LevelEightMinPoints && points <= LevelEightMaxPoints) return LevelEightName; else if (points >= LevelEightPlusMinPoints && points <= LevelEightPlusMaxPoints) return LevelEightPlusName; else if (points >= LevelNineMinPoints && points <= LevelNineMaxPoints) return LevelNineName; else if (points >= LevelNineMinPoints && points <= LevelNineMaxPoints) return LevelNineName; else if (points >= LevelTenMinPoints) return LevelFourName; else return "No Rank"; } } Do you think this is the most efficient way to do this?

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  • jQuery gallery scrolling effect with ease

    - by Sebastian Otarola
    So, I got this page from a friend and I think the gallery is amazingly done. Too bad it's in Flash ; http://selected.com/en/#/collection/homme/ Now, I'm trying to replicate the effect with jQuery. I've made all the loco searches on google one could think of. Zooming the picture is not a problem, the problem lies within the scrolling, how they come together at the ease part. I'm looking for solution in how to make the thumbnail animate when you scroll the page, they drag behind and infront of each other in a very subtle way - I've got (With a lot of help from Whirl3d in the jQuery-irc channel) this for the scrollup/down part of the mouse but the scrolling goes haywire; I Thought I post it here where I've come many times to get answers to a lot of questions and code-errors. This is my first post in stackoverflow and I know you guys are geniuses! Give it a shot! Thanks in advance! jQuery Part $(document).ready(function() { var fronts=$(".front"); var backs=$(".back"); var tempScrollTop, currentScrollTop = 0; $(document).scroll(function () { currentScrollTop = $(document).scrollTop(); if (tempScrollTop < currentScrollTop) { //Scroll down fronts.animate({marginTop:"-=100"},{duration:500, queue:false, easing:"easeOutBack"}); backs.animate({marginTop:"-=100"}, {duration:300, queue:false, easing:"easeOutBack"}); console.log('scroll down'); } else if (tempScrollTop > currentScrollTop) { //scroll up fronts.animate({marginTop:"+=100"},{duration:500, queue:false, easing:"easeOutBack"}); backs.animate({marginTop:"+=100"}, {duration:300, queue:false, easing:"easeOutBack"}); console.log('scroll up'); } tempScrollTop = currentScrollTop ;}) ;}); The HTML <html> <head> <link rel="stylesheet" type="text/css" href="style.css" /> <script type="text/javascript" src="http://code.jquery.com/jquery-1.7.2.min.js"></script> <script type="text/javascript" src="http://www.paigeharvey.net/assets/js/jquery.easing.js"></script> <script type="text/javascript" src="gallery.js"></script> <title>Parallax testing image gallery</title> </head> <body> <div class="container"> <div class='box front'>First Group</div> <div class='box back'>First Group</div> <div class='box front'>First Group</div> <div class='box back'>First Group</div> <br style="clear:both"/> <div class='box front'>Second Group</div> <div class='box back'>Second Group</div> <div class='box front'>Second Group</div> <div class='box back'>Second Group</div> <br style="clear:both"/> <div class='box front'>Third Group</div> <div class='box back'>Third Group</div> <div class='box front'>Third Group</div> <br style="clear:both"/> </div> </body> And finally the CSS Part .container {margin: auto; width: 410px; border: 1px solid red;} .box.front{border: 1px solid red;background-color:Black;color:white;z-Index:500;} .box.back {border: 1px solid green;z-Index:300;background-color:white;} .box {float:left; text-align:center; width:100px; height:100px;}

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  • How to check if two records have a self-referencing relation?

    - by Machine
    Consider the following schema with users and their collegues (friends): Users User: columns: user_id: name: user_id as userId type: integer(8) unsigned: 1 primary: true autoincrement: true first_name: name: first_name as firstName type: string(45) notnull: true last_name: name: last_name as lastName type: string(45) notnull: true email: type: string(45) notnull: true unique: true relations: Collegues: class: User local: invitor foreign: invitee refClass: CollegueStatus equal: true onDelete: CASCADE onUpdate: CASCADE Join table: CollegueStatus: columns: invitor: type: integer(8) unsigned: 1 primary: true invitee: type: integer(8) unsigned: 1 primary: true status: type: enum(8) values: [pending, accepted, denied] default: pending notnull: true Now, let's say I two records, one for the user making a HTTP request (the logged in user), and one record for a user he wants to send a message to. I want to check if these users are collegues. Questions: Does Doctrine have any pre-build functionality to check if two records with with self-relations are related? If not, how would you write a method to check this? Where would you put said method? (In the User-class, UserTable-class etc) I could probably do something like this: public function (User $user1, User $user2) { // Ensure we load collegues if $user1 was fetched with DQL that // doesn't load this relation $collegues = $user1->get('Collegues'); $areCollegues = false; foreach($collegues as $collegue) { if($collegue['userId'] === $user2['userId']) { $areCollegues = true; break; } } return $areCollegues; } But this looks a neither efficient nor pretty. I just feel that it should be solved already for self-referencing relations to be nice to use.

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  • Beginner Question: For extract a large subset of a table from MySQL, how does Indexing, order of tab

    - by chongman
    Sorry if this is too simple, but thanks in advance for helping. This is for MySQL but might be relevant for other RDMBSs tblA has 4 columns: colA, colB, colC, mydata, A_id It has about 10^9 records, with 10^3 distinct values for colA, colB, colC. tblB has 3 columns: colA, colB, B_id It has about 10^4 records. I want all the records from tblA (except the A_id) that have a match in tblB. In other words, I want to use tblB to describe the subset that I want to extract and then extract those records from tblA. Namely: SELECT a.colA, a.colB, a.colC, a.mydata FROM tblA as a INNER JOIN tblB as b ON a.colA=b.colA a.colB=b.colB ; It's taking a really long time (more than an hour) on a newish computer (4GB, Core2Quad, ubuntu), and I just want to check my understanding of the following optimization steps. ** Suppose this is the only query I will ever run on these tables. So ignore the need to run other queries. Now my questions: 1) What indexes should I create to optimize this query? I think I just need a multiple index on (colA, colB) for both tables. I don't think I need separate indexes for colA and colB. Another stack overflow article (that I can't find) mentioned that when adding new indexes, it is slower when there are existing indexes, so that might be a reason to use the multiple index. 2) Is INNER JOIN correct? I just want results where a match is found. 3) Is it faster if I join (tblA to tblB) or the other way around, (tblB to tblA)? This previous answer says that the optimizer should take care of that. 4) Does the order of the part after ON matter? This previous answer say that the optimizer also takes care of the execution order.

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  • I'm trying to grasp the concept of creating a program that uses a SQL Server database, but I'm used

    - by Sergio Tapia
    How can I make a program use a SQL Server database, and have that program work on whatever computer it's installed on. If you've been following my string of questions today, you'd know that I'm making an open source and free Help Desk suite for small and medium businesses. The client application. The client application is a Windows Forms app. On installation and first launch on every client machine, it'll ask for the address of the main Help Desk server. The server. Here I plan to handle all incoming help requests, show them to the IT guys, and provide WCF services for the Client application to consume. My dilemma lies in that, I know how to make the program run on my local machine; but I'm really stumped on how to make this work for everyone who wants to download and install the server bit on their Windows Server. Would I have to make an SQL Script and have it run on the MS SQL server when a user wants to install the 'server' application? Many thanks to all for your valuable time and effort to teach me. It's really really appreciated. :) Edit: To clarify, each business will have their server completely separate from me. I will have no access whatsoever to them nor will they be in any way connected to me. (I don't know why I should clarify this :P ) So, assuming the have ABSOLUTELY NO DATABASE SERVER installed; what can I do?

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  • Web development scheme for staging and production servers using Git Push

    - by ServAce85
    I am using git to manage a dynamic website (PHP + MySQL) and I want to send my files from my localhost to my staging and development servers in the most efficient and hassle-free way. I am currently convinced that the best way for me to approach this problem is to use this git branching model to organize my local git repo. From there, I will use the release branches to push to my staging server for testing. Once I am happy that the release code works on the staging server, I can then merge with my master branch and push that to my production server. Pushing to Staging Server: As noted in many introductory git posts, I could run into problems pushing into a non-bare repo, so, as suggested in this response, I plan to push the release branch to a bare repo on the server and have a post-receive hook that clones the bare repo to a non-bare repo that also acts as the web-hosted directory. Pushing to Production Server: Here's my newest source of confusion... In the response that I cited above, it made me curious as to why @Paul states that it's a completely different story when pushing to a live, development server. I guess I don't see the problem. Would it be safe and hassle-free to follow the same steps as above, but for the master branch? Where are the potential pit-falls? Config Files: With respect to configuration files that are unique to each environment (.htaccess, config.php, etc), it seems simplest to .gitignore each of those files in their respective repos on their respective servers. Can you see anything immediately wrong with this? Better solutions? Accessing Data: Finally, as I initially stated, the site uses MySQL databases to store data. How would you suggest I access that data (for testing purposes) from the staging server and localhost? I realize that I may have asked way too many questions for a single post, but since they're all related to the best way to set up this development scheme, I thought it was necessary.

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