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  • In Safari, using jQuery a Form Input Text Field does not receive focus after alert is displayed. Why

    - by Rob
    I have an ASPX web form. I use jQuery to simply my Javascript. I use a Javascript validation script to validate each of the form fields' values. If an error occurs, I popup an alert with an error message. Then I transfer focus to the underlying element. Here are examples I have tried. Using jQuery: var Form_FieldDef = function(name) { this.name = name; this.SetFocus = function() { $('#' + this.name)[0].focus(); } this.Validate = function() { var isvalid = true; if ( $.trim($('#' + this.name).val()) == '') { alert("Your entry is empty"); this.SetFocus(); isvalid = false; } return isvalid; } } This works on IE7, IE8, Opera, Chrome, and Firefox. It does not work on Safari 4 on PC. I don't have a Mac. So I changed the SetFocus method to this. this.SetFocus = function() { var fld = document.getElementById(this.name); if (fld != null) fld.focus(); } This works on IE7, IE8, Opera, Chrome, and Firefox. It does not work on Safari 4 on PC. I stepped through the code with VS 2008 debugger, and I'm calling the focus method on the underlying element.

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  • What are the linkage of the following functions?

    - by Derui Si
    When I was reading the c++ 03 standard (7.1.1 Storage class specifiers [dcl.stc]), there are some examples as below, I'm not able to tell how the linkage of each successive declarations is determined? Could anyone help here? Thanks in advance! static char* f(); // f() has internal linkage char* f() { /* ... */ } // f() still has internal linkage char* g(); // g() has external linkage static char* g() { /* ... */ } // error: inconsistent linkage void h(); inline void h(); // external linkage inline void l(); void l(); // external linkage inline void m(); extern void m(); // external linkage static void n(); inline void n(); // internal linkage static int a; // a has internal linkage int a; // error: two definitions static int b; // b has internal linkage extern int b; // b still has internal linkage int c; // c has external linkage static int c; // error: inconsistent linkage extern int d; // d has external linkage static int d; // error: inconsistent linkage UPD: Additionally, how can I understand the statement in the standard, " The linkages implied by successive declarations for a given entity shall agree. That is, within a given scope, each declaration declaring the same object name or the same overloading of a function name shall imply the same linkage. Each function in a given set of overloaded functions can have a different linkage, however."

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  • HTML Table: How to resize data cells when already specified "colspan"?

    - by Jenny
    I have tabular data to display, which has a meaning to both rows and columns. Columns are time blocks, rows are days. A particular datacell is confined to a single day, but can be in multiple time block. To show this, I am using the colspan tag. <div id = "GuideTable"> <table> <tr> <td colspan = 3> </td></tr></table> </div> Or Whatever. I'm trying to apply CSS formating to the entire table, and for changing colors, etc, things are fine, but wanting to have a consistent width is where I am running into problems. Right now, each data cell's width seems tied to the maximum width in its column (everything auto lines up). Some columns are itty bitty, others are huge. I'm trying to make columns consistently sized (even if that means every column is as big as the biggest column needs to be), but setting an individual datacells width (either via css or in the tag itself) is getting me nowhere. I'm thinking maybe the colspan tag is overriding my manual width? If that's the case, how can I change the width of a column as a whole, especially since they aren't explicitly defined? (CAN you explicitly define columns?) Examples of the CSS I'm using: #GuideTable td{ background:#ffffff; border-style: solid; border-width: 1px; width: 100px; }

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  • When to use pointer to a class and when to just instantiate it as a variable

    - by Enders
    Im sort of confused by it. The best I could find was reading through the cplusplus.com tutorial and all they have to say about pointers to classes. "It is perfectly valid to create pointers that point to classes. We simply have to consider that once declared, a class becomes a valid type, so we can use the class name as the type for the pointer" Which tells me nothing about when to use them over the normal instantiation. I've seen the - operator many times, and looked at some codes but cant really decipher why they did it. Generic examples will be appreciated; but more specifically related to gui programming. Its where I encountered it first. QGridLayout *mainLayout = new QGridLayout; mainLayout->addWidget(nameLabel, 0, 0); mainLayout->addWidget(nameLine, 0, 1); mainLayout->addWidget(addressLabel, 1, 0, Qt::AlignTop); mainLayout->addWidget(addressText, 1, 1); Why not QGridLayout mainLayout mainLayout.addWidget ... (It doesnt compile if I change the sample code to that and try it but you get the point) Thanks in advance

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  • SQL Server find and replace in TEXT field

    - by incubushead
    I have a database in SQL Server 2005 that was brought up from SQL Server 2000 and is still using TEXT type fields instead of varchar(max). I need to find and replace a string of characters in the text field but all of the examples of how to do this that I have found don't seem like they would work for me. It seems the UPDATETEXT command requires that the two parameters "insert_offset" and "delete_length" be set explicitly but the string i am searching for could show up in the text at any point or even at several points in the same cell. My understanding of these two parameters is that the string im searching for will always be in the same place, so that insert_offset is the number of spaces into the text that the UPDATETEXT command will start replacing text. Example: Need to find: &lt;u&gt; and Replace it with: <u> Text field example: *Everyone in the room was <b>&lt;u&gt;tired&lt;/u&gt;.</b><br>Then they woke <b>&lt;u&gt;up&lt;/u&gt;. Can anyone help me out with this? THANKS!

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  • Any workarounds for non-static member array initialization?

    - by TomiJ
    In C++, it's not possible to initialize array members in the initialization list, thus member objects should have default constructors and they should be properly initialized in the constructor. Is there any (reasonable) workaround for this apart from not using arrays? [Anything that can be initialized using only the initialization list is in our application far preferable to using the constructor, as that data can be allocated and initialized by the compiler and linker, and every CPU clock cycle counts, even before main. However, it is not always possible to have a default constructor for every class, and besides, reinitializing the data again in the constructor rather defeats the purpose anyway.] E.g. I'd like to have something like this (but this one doesn't work): class OtherClass { private: int data; public: OtherClass(int i) : data(i) {}; // No default constructor! }; class Foo { private: OtherClass inst[3]; // Array size fixed and known ahead of time. public: Foo(...) : inst[0](0), inst[1](1), inst[2](2) {}; }; The only workaround I'm aware of is the non-array one: class Foo { private: OtherClass inst0; OtherClass inst1; OtherClass inst2; OtherClass *inst[3]; public: Foo(...) : inst0(0), inst1(1), inst2(2) { inst[0]=&inst0; inst[1]=&inst1; inst[2]=&inst2; }; }; Edit: It should be stressed that OtherClass has no default constructor, and that it is very desirable to have the linker be able to allocate any memory needed (one or more static instances of Foo will be created), using the heap is essentially verboten. I've updated the examples above to highlight the first point.

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  • Importing a Mercurial repository automatically (e.g. SVN Externals)

    - by dawmail333
    I have a project that I am developing built off CodeIgniter. The main part of the project is a private system I am creating, but I want to add it to source control, to gain all the associated goodies. Now I'm using Mercurial, so I did the whole hg init bit, so I've got the repository set up. Now, one of the things I've done is to make a library for CodeIgniter, which I use in this project. Now I want to make this library open, so I need a separate repo for that. For anyone unfamiliar with CodeIgniter library development, here's a reference: application /config <- configuration files /libraries <- library logic in here Now I will probably develop a few more libraries in the course of this project, so I can't just dump a repo in the application folder without clumping them all together. What I did was this: dev/ci/library <- library here dev/project <- project here Now in both of those folders, I have made a repository. What I want to do is make the project repository automatically reference the library repository, so I can have a private and a public repository, as I explained earlier. The main way to do this, I have read, is to use subrepositories, but I can only find examples on nested ones (which are unclear anyway, I find). How do I make it reference another repository like svn:externals?

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  • php facebook delete feeds

    - by meAtStackOverflow
    Hi there, I have manage to grab all the photos posted to my app wall. Now I am trying to add a function to my facebook app where it will delete all the feeds posted on the wall. <?php include_once 'facebook.php'; include_once 'config.php'; $feed = $facebook->api('/me/feed'); foreach($feed['data'] as $feeds) { echo "Feeds secion", "<br />"; echo $feeds["picture"], "<br />"; echo "<img src='{$feeds['picture']}' />", "<br />"; $target_path = "uploads/"; $target_path = $target_path . basename($feeds["picture"]); $content = file_get_contents($feeds["picture"]); file_put_contents($target_path, $content); } ? This is how i grab the photos and push them into my server. Please guide me on how i could delete all the feeds. I have went through some online examples but i could not figure out how to go about doing it. I kept receving errors. Thanks!

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  • Prolog Beginner: How to unify with arithmentic cmparison operators or how to get a set var to range

    - by sixtyfootersdude
    I am new to prolog. I need to write an integer adder that will add numbers between 0-9 to other numbers 0-9 and produce a solution 0-18. This is what I want to do: add(in1, in2, out) :- in1 < 10, in2 < 10, out < 18. I would like to be able to call it like this: To Check if it is a valid addition: ?- add(1,2,3). true ?- add(1,2,4). false With one missing variable: ?- add(X,2,3). 1 ?- add(1,4,X). 5 With multiple missing variables: ?-add(X,Y,Z). % Some output that would make sense. Some examples could be: X=1, Y=1, Z=2 ; X=2, Y=1, Z=3 ...... I realize that this is probably a pretty simplistic question and it is probably very straightforward. However cording to the prolog tutorial I am using: "Unlike unification Arithmetic Comparison Operators operators cannot be used to give values to a variable. The can only be evaluated when every term on each side have been instantiated."

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  • How do I call a variable from another class?

    - by squeezemylime
    I have a class called 'Constants' that I am storing a String variable in. This class contains a few global variables used in my app. I want to be able to reference this class and call the variable (called profileId) in other Views of my app. I looked around and found a few examples, but am not sure how to do this. Currently my setup is: Constants.h @interface Constants : UIViewController { NSString *profileId; } @property (nonatomic, retain) NSString *profileId; @end Constants.m #import "Constants.h" @implementation Constants @synthesize profileId; - (void)dealloc { [profileId release]; [super dealloc]; } And I am trying to call the variable profileId in a new View via this way: NewView.h file @class Constants; NewView.m file NSLog(@"ProfileId is:", [myConstants profileId]); Is there something I'm missing? It is coming up null, even though I am properly storing a value in it in another function via this way: Constants *Constant; Constant = [[Constants alloc] init]; Constant.profileId = userId;

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  • regexp to match string with (comma-separated) number at start and to split into number and rest?

    - by mix
    Given a string such as: 23,234,456 first second third How can I split string this into two parts, where part 1 contains the number at the beginning and part 2 contains the rest---but only if the string STARTS with a number, and the number can be comma-separated or not? In other words, I want two results: 23,234,456 and first second third. If there's a number in that string that isn't part of the first number then it should be in the second result. My best stab at this so far, to grab the number at the beginning, is something like this: ^[0-9]+(,[0-9]{3})* Which seems to grab a comma-separated or non-comma-separated number that starts the line. However, when I run this in the Javascript console I get not only the full number, but also a match on just the last 3 digits with their preceeding ,. (e.g. 23,234,456 and ,456). As for getting the rest into another var I'm having trouble. I tried working with \b, etc., but I think I must be missing something fundamental about grabbing the rest of the line. I'm doing this in Javascript in case it matters. More examples of what to match and what not to match. 2 one two three should return 2 and one two three 2345 one two three should return 2345 and one two three 2 one 2 three should return 2 and one 2 three 2,234 one two 3,000 should return 2,234 and one two 3,000 The space between parts 1 and two could be included in the beginning of part 2.

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  • How to reference input elements within a specific scope when there are multiple input elements of same kind?

    - by Will Merydith
    How do I select data for input elements within a specific scope? I have the same form multiple times (class "foo-form), and want to ensure I get the values for the hidden inputs within the scope of the form being submitted. Is the scope "this" implied? If not, what is the syntax for selecting input class "foo-text" within the scope of this? Feel free to point me to examples in the jquery docs - I could not find what I was looking for. $('.foo-form').submit(function() { // Store a reference to this form var $thisForm = $(this); }); <form class="foo-form"> <input type="hidden" class="foo-text"/> <input type="submit" class="button" /> </form> <form class="foo-form"> <input type="hidden" class="foo-text"/> <input type="submit" class="button" /> </form> <form class="foo-form"> <input type="hidden" class="foo-text"/> <input type="submit" class="button" /> // user clicks this submit button </form>

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  • Validating a phone number in Android PreferenceScreen

    - by djechelon
    I have a PreferenceScreen in which the user is capable, if system can't autodetect it, to enter the device's phone number. I'm still learning this part of Android but I managed to understand a bit of PreferenceScreens by examples provided by Android SDK itself and a few tutorials. What I want is that the user can save the phone number only if null or valid, where by "valid" I mean running a generic validation logic (ie. an anonymous method that returns true or false, that can be reused in any possible situation*) or better, just to simplify things, ^(\+39)?3[0-9]{9}$ For now I have the following XML snip <EditTextPreference android:inputType="phone" android:key="@string/preference_phoneNo" android:selectAllOnFocus="true" android:singleLine="true" android:summary="@string/pref_phoneNumber_description" android:title="@string/pref_phoneNumber" /> and following code by courtesy of Eclipse New Activity wizard: private void setupSimplePreferencesScreen() { if (!isSimplePreferences(this)) { return; } addPreferencesFromResource(R.xml.pref_general); bindPreferenceSummaryToValue(findPreference(getString(R.string.preference_phoneNo))); } addPreferenceFromResource is supposed to load the XML node and add the preference to the screen, while binPreferenceSummaryToValue is supposed to make description text change when preference is updated. Just for sake of completeness for those who don't like code courtesy of the IDE, the second method is provided by Eclipse who also provides a private class in the code file that is /** * A preference value change listener that updates the preference's summary * to reflect its new value. */ In the general case, what should I do to perform validation logic before the preference gets saved when I click OK on the preference editor? Where is the validation logic to be put in a PreferenceScreen? *Aren't we all here to learn?

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  • Isotope.js help: Changing item image after sorting

    - by user3643081
    This is a general question on how to go about building a project I have in mind, and the best way to set off on the right foot. I am fairly new to JS, please be gentle. I want to use isotope.js (or a similar script) to display a page with multiple items (about 30 different plants found in a garden) and the ability to sort them by seasons of the year + "what is most beautiful now" + and "view all" (a total of 6 categories) . On load, or when sorted by either "what is beautiful now" or "view all", I need each item to reflect the image of the current season we are in. When sorted by season, I need those "current" images to switch over to a designated seasonal image of that plant. Therefore, each sortable item will ultimately have 4 different versions with 4 different images in the background ready to surface when plants are sorted. (perhaps 5 if it makes more sense to have a "current" version besides the 4 seasonal versions.) My question: what approach can I take to achieve this effect in a manageable way? Can isotope apply a class to items sorted? Assuming it can: Should each item have 4 inline images, each with a css class, that I then control by using display:inline; and display:none; properties from my stylesheets? (I worry that this approach would significantly increase load times) Would it make more sense to create a blank dummy div who's background I control similarly to the example above -relying mostly on CSS. Or is there some other way involving JS I am overlooking? Any help would be appreciated. Examples of what you suggest would be immensely helpful.

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  • How can I create a .jar file?

    - by Roman
    In the tutorial I found out that jar files can be created in the following way: jar cf jar-file input-file(s) However, it was not clear what are the input-file(s). Is that .java files or .class files? From the examples on the same page I can assume that should be .class files. But now it is not clear which .class files should I put there. After the compilation of .java files I have a lot of .class files. One of the reason of that is that I have a lot files like that: GameWindow$2$10class, GameWindow$2$7.class and so on. Should I include all of them into the command line for the creation of the .jar file? To run my application I use java Game. So, my be I need to use only Game.class file when I create a .jar file? On the other hand other class files corresponds to classes used by the application. My software use external libraries (during compilation I specify .jar files of these libraries). Will .jar file of my application be able to run on the computer which does not contain the .jar file of used library?

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  • Multithreading for loop while maintaining order

    - by David
    I started messing around with multithreading for a CPU intensive batch process I'm running. Essentially I'm trying to condense multiple single page tiffs into single PDF documents. This works fine with a foreach loop or standard iteration but can be very slow for several 100 page documents. I tried the following based on a some examples I found to use multithreading and it has significant performance improvements however it obliterates the page order instead of 1,2,3,4 it will be 1,3,4,2,6,5 on what thread completes first. My question is how would I utilize this technique while maintaining the page order and if I can will it negate the performance benefit of the multithreading? Thank you in advance. PdfDocument doc = new PdfDocument(); string mail = textBox1.Text; string[] split = mail.Split(new string[] { Environment.NewLine }, StringSplitOptions.None); int counter = split.Count(); // Source must be array or IList. var source = Enumerable.Range(0, 100000).ToArray(); // Partition the entire source array. var rangePartitioner = Partitioner.Create(0, counter); double[] results = new double[counter]; // Loop over the partitions in parallel. Parallel.ForEach(rangePartitioner, (range, loopState) => { // Loop over each range element without a delegate invocation. for (int i = range.Item1; i < range.Item2; i++) { f_prime = split[i].Replace(" " , ""); PdfPage page = doc.AddPage(); XGraphics gfx = XGraphics.FromPdfPage(page); XImage image = XImage.FromFile(f_prime); double x = 0; gfx.DrawImage(image, x, 0); } });

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  • Best ways to format LINQ queries.

    - by Aren B
    Before you ignore / vote-to-close this question, I consider this a valid question to ask because code clarity is an important topic of discussion, it's essential to writing maintainable code and I would greatly appreciate answers from those who have come across this before. I've recently run into this problem, LINQ queries can get pretty nasty real quick because of the large amount of nesting. Below are some examples of the differences in formatting that I've come up with (for the same relatively non-complex query) No Formatting var allInventory = system.InventorySources.Select(src => new { Inventory = src.Value.GetInventory(product.OriginalProductId, true), Region = src.Value.Region }).GroupBy(i => i.Region, i => i.Inventory); Elevated Formatting var allInventory = system.InventorySources .Select(src => new { Inventory = src.Value.GetInventory(product.OriginalProductId, true), Region = src.Value.Region }) .GroupBy( i => i.Region, i => i.Inventory); Block Formatting var allInventory = system.InventorySources .Select( src => new { Inventory = src.Value.GetInventory(product.OriginalProductId, true), Region = src.Value.Region }) .GroupBy( i => i.Region, i => i.Inventory ); List Formatting var allInventory = system.InventorySources .Select(src => new { Inventory = src.Value.GetInventory(product.OriginalProductId, true), Region = src.Value.Region }) .GroupBy(i => i.Region, i => i.Inventory); I want to come up with a standard for linq formatting so that it maximizes readability & understanding and looks clean and professional. So far I can't decide so I turn the question to the professionals here.

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  • Setting pixel values in Nvidia NPP ImageCPU objects?

    - by solvingPuzzles
    In the Nvidia Performance Primitives (NPP) image processing examples in the CUDA SDK distribution, images are typically stored on the CPU as ImageCPU objects, and images are stored on the GPU as ImageNPP objects. boxFilterNPP.cpp is an example from the CUDA SDK that uses these ImageCPU and ImageNPP objects. When using a filter (convolution) function like nppiFilter, it makes sense to define a filter as an ImageCPU object. However, I see no clear way setting the values of an ImageCPU object. npp::ImageCPU_32f_C1 hostKernel(3,3); //allocate space for 3x3 convolution kernel //want to set hostKernel to [-1 0 1; -1 0 1; -1 0 1] hostKernel[0][0] = -1; //this doesn't compile hostKernel(0,0) = -1; //this doesn't compile hostKernel.at(0,0) = -1; //this doesn't compile How can I manually put values into an ImageCPU object? Notes: I didn't actually use nppiFilter in the code snippet; I'm just mentioning nppiFilter as a motivating example for writing values into an ImageCPU object. The boxFilterNPP.cpp example doesn't involve writing directly to an ImageCPU object, because nppiFilterBox is a special case of nppiFilter that uses a built-in gaussian smoothing filter (probably something like [1 1 1; 1 1 1; 1 1 1]).

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  • image transistion

    - by Jeff Main
    Hi all. I've gotten stuck again. I've got an image (album cover) that I'll be changing in code behind, and wish to basicaly do the following. When a new album cover image is determine and aquired, I want the current image in the image control to fade out, get updated with the new cover, and then fade back in. I'm not seeing very many good examples on how to accomplish this in code behind. The following was my latest failed attempt... if (currentTrack != previousTrack) { BitmapImage image = new BitmapImage(); image.BeginInit(); image.CacheOption = BitmapCacheOption.OnLoad; image.CreateOptions = BitmapCreateOptions.IgnoreImageCache; image.UriSource = new Uri(Address, UriKind.Absolute); image.EndInit(); Storyboard MyStoryboard = new Storyboard(); DoubleAnimation FadeOut = new DoubleAnimation(); FadeOut.From = 1.0; FadeOut.To = 0.0; FadeOut.Duration = new Duration(TimeSpan.FromSeconds(.5)); MyStoryboard.Children.Add(FadeOut); Storyboard.SetTargetName(FadeOut, CoverArt.Name); Storyboard.SetTargetProperty(FadeOut, new PropertyPath(Rectangle.OpacityProperty)); CoverArt.Source = image; DoubleAnimation Fadein = new DoubleAnimation(); Fadein.From = 0.0; Fadein.To = 1.0; Fadein.Duration = new Duration(TimeSpan.FromSeconds(.5)); MyStoryboard.Children.Add(Fadein); Storyboard.SetTargetName(Fadein, CoverArt.Name); Storyboard.SetTargetProperty(Fadein, new PropertyPath(Rectangle.OpacityProperty)); MyStoryboard.Begin(this); } I'd prefer to do this in code behind simply because that is where I'm aquiring the image. Otherwise, I'm not sure how I'd trigger it. An example would be greatly appriciated. Thanks.

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  • Convert IIS / Tomcat Web Application to a multi-server environment.

    - by bill_the_loser
    I have an existing web application built in .Net, running on IIS that leverages a java servlet that we have running on Tomcat 5.5. We need to scale the application and I'm confused about what relates to our situation and what we need to do to get the servlet running on multiple servers. Right now I have 4 servers that can each individually process results, it almost seems like all I should have to do is add the ajp13 worker processes from three additional machines to the machine hosting the load balancer worker. But I can't imagine it should be that easy. What do I need to do to distribute the Tomcat load to the extra three machines? Thanks. Update: The current configuration is using a workers2.properties configuration file. From all of the documentation online I have not been able to determine the distinction between the workers.properties and the workers2.properties. Most of the examples that I have found are configuring the workers.properties and revolve around adding workers and registering them in the worker.list element. The workers2.properties does not appears to have a worker.list element and the syntax is different enough between the workers.properties and the workers2.properties that I'm doubtful that I can add that element. If I just add my multiple AJP workers to the workers2.properties file do I need to worry about the apparent lack of a worker.list element? [ajp13:localhost:8009] channel=channel.socket:localhost:8009 group=lb [ajp13:host2.mydomain.local:8009] channel=channel.socket:host2.mydomain.local:8009 group=lb [ajp13:host3.mydomain.local:8009] channel=channel.socket:host3.mydomain.local:8009 group=lb A couple of side notes... One I've noticed that sometime Tomcat doesn't seem to reload my changes and I don't know why. Also, I have no idea why this configuration has a workers2.properties and not a workers.properties. I've been assuming that it's based on version but I haven't seen anything to back up that assumption.

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  • Write out to text file using T-SQL

    - by sasfrog
    I am creating a basic data transfer task using TSQL where I am retrieving certain records from one database that are more recent than a given datetime value, and loading them into another database. This will happen periodically throughout the day. It's such a small task that SSIS seems like overkill - I want to just use a scheduled task which runs a .sql file. Where I need guidance is that I need to persist the datetime from the last run of this task, then use this to filter the records next time the task runs. My initial thought is to just store the datetime in a text file, and update (overwrite) it as part of the task each time it runs. I can read the file in without problems using T-SQL, but writing back out has got me stuck. I've seen plenty of examples which make use of a dynamically-built bcp command, which is then executed using xp_cmdshell. Trouble is, security on the server I'm deploying to precludes the use of xp_cmdshell. So, my question is, are there other ways to simply write a datetime value to a file using TSQL, or should I be thinking about a different approach? EDIT: happy to be corrected about SSIS being "overkill"...

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  • When to use basic types (Integer, String), and when to write a new class?

    - by belgarat
    Stackoverflow users: A lot of things can be represented in programs by using the basic types, or we can create a new class for it. Example: A social security number can be a number, string or its own object. (Other common examples: Phone numbers, names, zip codes, user id, order id and other id's.) My question is: When should the basic types be used, and when should we write ourselves a new class? I see that when you need to add behavior, you'll want to create a class (example, social security number parsing, validation, formatting, etc). But is this the only criteria? I have come across cases where many of these things are represented as java Integers and/or Strings. We loose the benefit of type-checking, and I have often seen bugs caused by parameters being mixed in calls to function(Intever, Integer, Integer, Integer). On the other hand, some programmers are opposed to over-designing by creating classes for "eveything". Obviously, the answer is "it depends". But, what do you think, and what do you normally do?

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  • Parallelize or vectorize all-against-all operation on a large number of matrices?

    - by reve_etrange
    I have approximately 5,000 matrices with the same number of rows and varying numbers of columns (20 x ~200). Each of these matrices must be compared against every other in a dynamic programming algorithm. In this question, I asked how to perform the comparison quickly and was given an excellent answer involving a 2D convolution. Serially, iteratively applying that method, like so list = who('data_matrix_prefix*') H = cell(numel(list),numel(list)); for i=1:numel(list) for j=1:numel(list) if i ~= j eval([ 'H{i,j} = compare(' char(list(i)) ',' char(list(j)) ');']); end end end is fast for small subsets of the data (e.g. for 9 matrices, 9*9 - 9 = 72 calls are made in ~1 s). However, operating on all the data requires almost 25 million calls. I have also tried using deal() to make a cell array composed entirely of the next element in data, so I could use cellfun() in a single loop: # who(), load() and struct2cell() calls place k data matrices in a 1D cell array called data. nextData = cell(k,1); for i=1:k [nextData{:}] = deal(data{i}); H{:,i} = cellfun(@compare,data,nextData,'UniformOutput',false); end Unfortunately, this is not really any faster, because all the time is in compare(). Both of these code examples seem ill-suited for parallelization. I'm having trouble figuring out how to make my variables sliced. compare() is totally vectorized; it uses matrix multiplication and conv2() exclusively (I am under the impression that all of these operations, including the cellfun(), should be multithreaded in MATLAB?). Does anyone see a (explicitly) parallelized solution or better vectorization of the problem?

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  • Use of Java [Interfaces / Abstract classes]

    - by Samuel
    Hello, Lately i decided to take a look at Java so i am still pretty new to it and also to the approach of OO programming, so i wanted to get some things straight before learning more, (i guess it's never to soon to start with good practices). I am programming a little 2D game for now but i think my question applies to any non trivial project. For the simplicity i'll provide examples from my game. I have different kinds of zombies, but they all have the same attributes (x, y, health, attack etc) so i wrote an interface Zombie which i implement by WalkingZombie, RunningZombie TeleportingZombie etc. Is this the best thing to do? Am i better of with an abstract class? Or with a super class? (I am not planning to partially implement functions - therefor my choice for an interface instead of an abstract class) I have one class describing the main character (Survivor) and since it is pretty big i wanted to write an interface with the different functions, so that i can easily see and share the structure of it. Is it good practice? Or is it simply a waste of space and time? I hope this question will not be rated as subjective because i thought that experienced programmers won't disagree about this kind of topic since the use of interfaces / super classes / abstract classes follows logical rules and is thereby not simply a personal choice. Thank you for your time -Samuel

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  • How to parse mathematical expressions involving parentheses

    - by Rob P.
    Please forgive my title, I really don't know how to phrase it better. This isn't a school assignment or anything, but I realize it's a mostly academic question. But, what I've been struggling to do is parse 'math' text and come up with an answer. For Example - I can figure out how to parse '5 + 5' or '3 * 5' - but I fail when I try to correctly chain operations together. (5 + 5) * 3 It's mostly just bugging me that I can't figure it out. If anyone can point me in a direction, I'd really appreciate it. EDIT Thanks for all of the quick responses. I'm sorry I didn't do a better job of explaining. First - I'm not using regular expressions. I also know there are already libraries available that will take, as a string, a mathematical expression and return the correct value. So, I'm mostly looking at this because, sadly, I don't "get it". Second - What I've tried doing (is probably misguided) but I was counting '(' and ')' and evaluating the deepest items first. In simple examples, this worked; but my code is not pretty and more complicated stuff crashes. When I 'calculated' the lowest level, I was modifying the string. So... (5 + 5) * 3 Would turn into 10 * 3 Which would then evaluate to 30 But it just felt 'wrong'. I hope that helps clarify things. I'll certainly check out the links provided.

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