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• How to handle alpha in a manual "Overlay" blend operation?

  - by quixoto

  I'm playing with some manual (walk-the-pixels) image processing, and I'm recreating the standard "overlay" blend. I'm looking at the "Photoshop math" macros here: http://www.nathanm.com/photoshop-blending-math/ (See also here for more readable version of Overlay) Both source images are in fairly standard RGBA (8 bits each) format, as is the destination. When both images are fully opaque (alpha is 1.0), the result is blended correctly as expected: But if my "blend" layer (the top image) has transparency in it, I'm a little flummoxed as to how to factor that alpha into the blending equation correctly. I expect it to work such that transparent pixels in the blend layer have no effect on the result, opaque pixels in the blend layer do the overlay blend as normal, and semitransparent blend layer pixels have some scaled effect on the result. Can someone explain to me the blend equations or the concept behind doing this? Bonus points if you can help me do it such that the resulting image has correctly premultiplied alpha (which only comes into play for pixels that are not opaque in both layers, I think.) Thanks! // factor in blendLayerA, (1-blendLayerA) somehow? resultR = ChannelBlend_Overlay(baseLayerR, blendLayerR); resultG = ChannelBlend_Overlay(baseLayerG, blendLayerG); resultB = ChannelBlend_Overlay(baseLayerB, blendLayerB); resultA = 1.0; // also, what should this be??

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• Why does one of these statements compile in Scala but not the other?

  - by Jeff

  (Note: I'm using Scala 2.7.7 here, not 2.8). I'm doing something pretty simple -- creating a map based on the values in a simple, 2-column CSV file -- and I've completed it easily enough, but I'm perplexed at why my first attempt didn't compile. Here's the code: // Returns Iterator[String] private def getLines = Source.fromFile(csvFilePath).getLines // This doesn't compile: def mapping: Map[String,String] = { Map(getLines map { line: String => val pairArr = line.split(",") pairArr(0) -> pairArr(1).trim() }.toList:_*) } // This DOES compile def mapping: Map[String,String] = { def strPair(line: String): (String,String) = { val pairArr = line.split(",") pairArr(0) -> pairArr(1).trim() } Map(getLines.map( strPair(_) ).toList:_*) } The compiler error is CsvReader.scala:16: error: value toList is not a member of (St ring) = (java.lang.String, java.lang.String) [scalac] possible cause: maybe a semicolon is missing before `value toList'? [scalac] }.toList:_*) [scalac] ^ [scalac] one error found So what gives? They seem like they should be equivalent to me, apart from the explicit function definition (vs. anonymous in the nonworking example) and () vs. {}. If I replace the curly braces with parentheses in the nonworking example, the error is "';' expected, but 'val' found." But if I remove the local variable definition and split the string twice AND use parens instead of curly braces, it compiles. Can someone explain this difference to me, preferably with a link to Scala docs explaining the difference between parens and curly braces when used to surround method arguments?

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• Why do my CouchDB databases grow so fast?

  - by konrad

  I was wondering why my CouchDB database was growing to fast so I wrote a little test script. This script changes an attributed of a CouchDB document 1200 times and takes the size of the database after each change. After performing these 1200 writing steps the database is doing a compaction step and the db size is measured again. In the end the script plots the databases size against the revision numbers. The benchmarking is run twice: The first time the default number of document revision (=1000) is used (_revs_limit). The second time the number of document revisions is set to 1. The first run produces the following plot The second run produces this plot For me this is quite an unexpected behavior. In the first run I would have expected a linear growth as every change produces a new revision. When the 1000 revisions are reached the size value should be constant as the older revisions are discarded. After the compaction the size should fall significantly. In the second run the first revision should result in certain database size that is then keeps during the following writing steps as every new revision leads to the deletion of the previous one. I could understand if there is a little bit of overhead needed to manage the changes but this growth behavior seems weird to me. Can anybody explain this phenomenon or correct my assumptions that lead to the wrong expectations?

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• Reading a Wordpress function description

  - by Casebash

  I want to be able to understand the standard function description that is provided for Wordpress functions. In particular, could someone explain the following example from here: Usage <?php wp_list_categories( $args ); ?> Default Usage <?php $args = array( 'show_option_all' => , 'orderby' => 'name', 'order' => 'ASC', 'show_last_update' => 0, 'style' => 'list', 'show_count' => 0, 'hide_empty' => 1, 'use_desc_for_title' => 1, 'child_of' => 0, 'feed' => , 'feed_type' => , 'feed_image' => , 'exclude' => , 'exclude_tree' => , 'include' => , 'current_category' => 0, 'hierarchical' => true, 'title_li' => __( 'Categories' ), 'number' => NULL, 'echo' => 1, 'depth' => 0 ); ?> I can guess most of it, but in particular I can't guess: What does blank after the comma mean? Empty string? What is the __? How do I call the function? Keyword like python, positional arguments or do I have to pass an array? Is there anything else about Wordpress function descriptions which isn't covered in this example? Thanks, Chris

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• General JDBC Setup

  - by AeroDroid

  So I have a MySQL database set up on a Debian server and it works fine from a phpMyAdmin client. I'm currently working on a project to write a Java server that would be able to use the MySQL database that is already on this server through a JDBC connection. I've looked at many tutorials and documentations but all of them seem to just explain how to do client-side code, but I have yet to figure out how to even successfully open a JDBC connection to the server. As far as I am concerned, I believe that program has the drivers properly set up because it's not crashing anymore (I simply direct the Java Build Path of my program to the Connector/J provided by MySQL). As far as my program goes, this is what it looks like... import java.sql.*; public class JDBCTest { public static void main(String[] args) { System.out.println("Started!"); try { DriverManager.registerDriver(new com.mysql.jdbc.Driver()); System.out.println("Driver registered. Connecting..."); Connection conn = DriverManager.getConnection("jdbc:mysql://localhost/", "root", "password"); System.out.println("Connected!"); conn.close(); } catch (SQLException e) { System.out.println("Error!"); e.printStackTrace(); } } } This is what's printed... Started! Driver registered. Connecting... It's as if the DriverManager.getConnection(String) just freezes there. I'm sure this is a problem with the server because when I intentionally misspell localhost, or an IP address, the program crashes within 20 seconds. This just hangs there forever. Sorry about this wall of text, but my final question is if anyone has any information what I should do or install on the server to get this to work? Thank you so much!

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• Increment non unique field during SQL insert

  - by phill

  I'm not sure how to word this cause I am a little confused at the moment, so bare with me while I attempt to explain, I have a table with the following fields: OrderLineID, OrderID, OrderLine, and a few other unimportant ones. OrderLineID is the primary key and is always unique(which isn't a problem), OrderID is a foreign key that isn't unique(also not a problem), and OrderLine is a value that is not unique in the table, but should be unique for any OrderIDs that are the same...so if that didn't make sense, perhaps a picture OrderLineID, OrderID, OrderLine 1 1 1 2 1 2 3 1 3 4 2 1 5 2 2 For all OrderIDs there is a unique OrderLine. I am trying to create an insert statement that gets the max OrderLine value for a specific OrderId so I can increment it, but it's not working so well and I could use a little help. What I have right now is below, I build the sql statement in a program and replace OrderID # with an actual value. I am pretty sure the problem is with the nested select statement, and incrementing the result, but I can't find any examples that do this since my google skills are weak apparently.... INSERT INTO tblOrderLine (OrderID, OrderLine) VALUES (<OrderID #>, (SELECT MAX(OrderLine) FROM tblOrderLine WHERE orderID = <same OrderID #>)+1) any help would be nice.

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• ASP.Net MVC 2 - How to set up a Cancel button with client side navigation

  - by arame3333

  Thanks to a previous question I found a useful link on multiple buttons. http://weblogs.asp.net/dfindley/archive/2009/05/31/asp-net-mvc-multiple-buttons-in-the-same-form.aspx What I want to do is have a cancel button on my page, similar to this; <button name="button" type="button" onclick="document.location.href=$('#cancelUrl').attr('href')">Cancel</button> <a id="cancelUrl" href="<%: Url.Action("Index", "Home") %>" style="display:none;"></a> However although this code works, I really want to go back to the previous page. For Web Forms I could use the javascript Back() or Go(-1) functions, but they relied on postbacks. I could of course hard code the previous page and controller as I have done above. However I am struggling to find links that explain to me how Url.Action works. Because if I do this, I also need to include an index parameter, and I am not clear how the syntax works for that. It seems odd the amount of coding to do this. Out of curiosity, I am also wondering how you TDD client side code like this.

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• Please help optimizing a long running query (left outer join, with 2 subqueries)

  - by 46and2

  Hi all. The query I need help with is: SELECT d.bn, d.4700, d.4500, ... , p.`Activity Description` FROM ( SELECT temp.bn, temp.4700, temp.4500, .... FROM `tdata` temp GROUP BY temp.bn HAVING (COUNT(temp.bn) = 1) ) d LEFT OUTER JOIN ( SELECT temp2.bn, max(temp2.FPE) AS max_fpe, temp2.`Activity Description` FROM `pdata` temp2 GROUP BY temp2.bn ) p ON p.bn = d.bn; The ... represents other fields that aren't really important to solving this problem. The issue is on the the second subquery - it is not using the index I have created and I am not sure why, it seems to be because of the way TEXT fields are handled. The first subquery uses the index I have created and runs quite snappy, however an explain on the second shows a 'Using temporary; Using filesort'. Please see the indexes I have created in the below table create statements. Can anyone help me optimize this? By way of quick explanation the first subquery is meant to only select records that have unique bn's, the second, while it looks a bit wacky (with the max function there which is not being used in the result set) is making sure that only one record from the right part of the join is included in the result set. My table create statements are CREATE TABLE `tdata` ( `BN` varchar(15) DEFAULT NULL, `4000` varchar(3) DEFAULT NULL, `5800` varchar(3) DEFAULT NULL, .... KEY `BN` (`BN`), KEY `idx_t3010`(`BN`,`4700`,`4500`,`4510`,`4520`,`4530`,`4570`,`4950`,`5000`,`5010`,`5020`,`5050`,`5060`,`5070`,`5100`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8 CREATE TABLE `pdata` ( `BN` varchar(15) DEFAULT NULL, `FPE` datetime DEFAULT NULL, `Activity Description` text, .... KEY `BN` (`BN`), KEY `idx_programs_2009` (`BN`,`FPE`,`Activity Description`(100)) ) ENGINE=MyISAM DEFAULT CHARSET=utf8 Thanks!

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• Why slim reader/writer exclusive lock outperformance the shared one?

  - by Jichao

  I have tested the performance of slim reader/writer lock under windows 7 using the codefrom Windows Via C/C++. The result surprised me that the exclusive lock out performance the shared one. Here are the code and the result. unsigned int __stdcall slim_reader_writer_exclusive(void *arg) { //SRWLOCK srwLock; //InitializeSRWLock(&srwLock); for (int i = 0; i < 1000000; ++i) { AcquireSRWLockExclusive(&srwLock); g_value = 0; ReleaseSRWLockExclusive(&srwLock); } _endthreadex(0); return 0; } unsigned int __stdcall slim_reader_writer_shared(void *arg) { int b; for (int i = 0; i < 1000000; ++i) { AcquireSRWLockShared(&srwLock); //b = g_value; g_value = 0; ReleaseSRWLockShared(&srwLock); } _endthreadex(0); return 0; } g_value is a global int volatile variable. Could you kindly explain why this could happen?

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• using volatile keyword

  - by sap

  As i understand, if we declare a variable as volatile, then it will not be stored in the local cache. Whenever thread are updating the values, it is updated to the main memory. So, other threads can access the updated value. But in the following program both volatile and non-volatile variables are displaying same value. The volatile variable is not updated for the second thread. Can anybody plz explain this why testValue is not changed. class ExampleThread extends Thread { private int testValue1; private volatile int testValue; public ExampleThread(String str){ super(str); } public void run() { if (getName().equals("Thread 1 ")) { testValue = 10; testValue1= 10; System.out.println( "Thread 1 testValue1 : " + testValue1); System.out.println( "Thread 1 testValue : " + testValue); } if (getName().equals("Thread 2 ")) { System.out.println( "Thread 2 testValue1 : " + testValue1); System.out.println( "Thread 2 testValue : " + testValue); } } } public class VolatileExample { public static void main(String args[]) { new ExampleThread("Thread 1 ").start(); new ExampleThread("Thread 2 ").start(); } } output: Thread 1 testValue1 : 10 Thread 1 testValue : 10 Thread 2 testValue1 : 0 Thread 2 testValue : 0

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• Output reformatted text within a file included in a JSP

  - by javanix

  I have a few HTML files that I'd like to include via tags in my webapp. Within some of the files, I have pseudo-dynamic code - specially formatted bits of text that, at runtime, I'd like to be resolved to their respective bits of data in a MySQL table. For instance, the HTML file might include a line that says: Welcome, [username]. I want this resolved to (via a logged-in user's data): Welcome, [email protected]. This would be simple to do in a JSP file, but requirements dictate that the files will be created by people who know basic HTML, but not JSP. Simple text-tags like this should be easy enough for me to explain to them, however. I have the code set up to do resolutions like that for strings, but can anyone think of a way to do it across files? I don't actually need to modify the file on disk - just load the content, modify it, and output it w/in the containing JSP file. I've been playing around with trying to load the files into strings via the apache readFileToString, but I can't figure out how to load files from a specific folder within the webapp's content directory without hardcoding it in and having to worry about it breaking if I deploy to a different system in the future.

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• Emulating Visual Studio's Web Application "publish" at the command line

  - by cbp

  Hi, I am trying to automate my deployment process and am now thoroughly confused. I know that there are many questions on stackoverflow about this, but they all have different solutions and none of them work. I have a Web Application project which I usually publish by right-clicking and selecting "Publish". I get a dialog box where I use the following options: Build configuration: Release Publish method: File system Target location: C:\Deployments\MyWebsite Replace matching files with local copies I should mention that in the properties of the project I have "Items to deploy" set to "Only files needed to run this application". After running this, my entire solution is built, dependencies are resolved, build events are run, web.config transformations are applied and the website is copied to C:\Deployments\MyWebsite, although non-required files such as code-behind files are not copied. I have not been able to replicate this... in fact at this stage I'm not even sure which command line tool am I supposed to be using - msbuild, msdeploy or aspnet_compiler? This guy asks almost the same question but his solution doesn't work at all. For example, build events do not run correctly because the macros are not resolved. Whats more, the files do not get copied into the correct directory at all... I can't even begin to explain what happens!

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• PHPMailer with GMail: SMTP Error

  - by Abs

  Hello all, I am making use of PHPMailer to send mail through GMail. The code I use is straight from a tutorial and it works perfectly on my laptop. However, testing this on a Windows 2003 Server - it seems to always return an SMPT error: SMTP Error: Could not connect to SMTP host. Mailer Error: SMTP Error: Could not connect to SMTP host. Here is the settings I use in PHPMailer: include("phpmailer/class.phpmailer.php"); $mail = new PHPMailer(); $mail->IsSMTP(); $mail->SMTPAuth = true; // enable SMTP authentication $mail->SMTPSecure = "ssl"; // use ssl $mail->Host = "smtp.gmail.com"; // GMAIL's SMTP server $mail->Port = 465; // SMTP port used by GMAIL server Can I say with confidence that this isn't a port issue, since I am connecting to another server on port 465 and it is sending mail. If not, please explain. How can I resolve this issue? Thanks all for any help

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• are projects with high developer turn over rate really a bad thing?

  - by John

  I've inherited a lot of web projects that experienced high developer turn over rates. Sometimes these web projects are a horrible patchwork of band aid solutions. Other times they can be somewhat maintainable mozaics of half-done features each built with a different architectural style. Everytime I inherit these projects, I wish the previous developers could explain to me why things got so bad. What puzzles me is the reaction of the owners (either a manager, a middle man company, or a client). They seem to think, "Well, if you leave, I'll just find another developer." Or they think, "Oh, it costs that much money to refactor the system? I know another developer who can do it at half the price. I'll hire him if I can't afford you." I'm guessing that the high developer turn over rate is related to the owner's mentality of "If you think it's a bad idea to build this, I'll just find another (possibly cheaper) developer to do what I want". For the owners, the approach seems to work because their business is thriving. Unfortunately, it's no fun for the developers that go AWOL 3-4 months after working with poor code, strict timelines, and little feedback. So my question is the following: Are the following symptoms of a project really such a bad thing for business? high developer turn over rate poorly built technology - often a patchwork of different and inappropriately used architectural styles owners without a clear roadmap for their web project, and they request features on a whim I've seen numerous businesses prosper while experiencing the symptoms above. So as a programmer, even though my instincts tell me the above points are terrible, I'm forced to take a step back and ask, "are things really that bad in the grand scheme of things?" If not, I will re-evaluate my approach to these projects.

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• Why would a script not like using MySQLi but is fine with MySQL?

  - by Taylor

  I'm having some issues using mysqli to execute a script with SELECT,DELETE,INSERT and UPDATE querys. They work when using norm mysql such as mysql_connect but im getting strange results when using mysqli. It works fine with a lot of the SELECT querys in other scripts but when it comes to some admin stuff it messes up. Its difficult to explain without attaching the whole script. This is the function for modifying... function database_queryModify($sql,&$insertId) { global $databaseServer; global $databaseName; global $databaseUsername; global $databasePassword; global $databaseDebugMode; $link = @mysql_connect($databaseServer,$databaseUsername,$databasePassword); @mysql_select_db($databaseName,$link); $result = mysql_query($sql,$link); if (!$result && $databaseDebugMode) { print "[".$sql."][".mysql_error()."]"; } $insertId = mysql_insert_id(); return mysql_affected_rows(); } and heres what I changed it to for mysqli function database_queryModify($sql,&$insertId) { global $databaseServer; global $databaseName; global $dbUser_feedadmin; global $dbUser_feedadmin_pw; global $databaseDebugMode; $link = @mysqli_connect($databaseServer,$dbUser_feedadmin,$dbUser_feedadmin_pw,$databaseName); $result = mysqli_query($link, $sql); if (!$result && $databaseDebugMode) { print "[".$sql."][".mysqli_error()."]"; } $insertId = mysqli_insert_id(); return mysqli_affected_rows(); } Does that look right? It isn't actually producing an error but its not functioning in the same way as when using mysql. any ideas?

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• java annotations - problem with calling a locator class from a Vaadin Project

  - by George

  Hello, I'm not sure how to explain this without writing several pages so I hope the actual code is more expressive. I've made a jar containing multiple annotation declaration similar to the following: @Target(ElementType.PACKAGE) @Retention(RetentionPolicy.RUNTIME) public @interface MarkedPackage { } then I have made a test jar containing several classes in several packages and marked just one package with the above annotation (with package-info.java) like below: @myPackage.MarkedPackage package package.test.jar; this jar had in its build path the jar containing the annotations. then I made a static class that has a method (LoadPlugins) that retrieves a list with all the jars of a directory. Then it searches through the jars for the 'package-info' class and checks if that classes package contains the MarkedPackage annotation. by calling this: if (checkPackageAnnotation(thisClass.getPackage())) where thisClass is the package-info class retrieved via a classloader. and: public static boolean checkPackageAnnotation(AnnotatedElement elem) { System.out.println(elem.getAnnotations().length); if (elem == null || !elem.isAnnotationPresent(MarkedPackage.class)) return false; return true; } the elem.getAnnotatios().length is there for debug purposes. And the problem appears when I call the method from the static class: if I call it from a main function: public class MyMain { public static void main(String[] args){ PluginUtils.LoadPlugins(); } } everything works perfectly it displays '1' from that System.out.println(elem.getAnnotations().length); But if I call it from a button from my Vaadin project: header.addComponent(new Button("CallThat", new Button.ClickListener() { public void buttonClick(ClickEvent event) { PluginUtils.LoadPlugins(); } })); It displays '0' from that System.out.println(elem.getAnnotations().length); Also I should mention that I created the main inside my Vaadin project so it would have the exact same build path and resources. Is there a problem with web applications and that "@Retention(RetentionPolicy.RUNTIME)" ? hope I was clear enough... Hope someone has a solution for me... If you need more information - let me know. Thank you.

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• Why my events aren't registered after postback?

  - by lucian.jp

  I have a problem where I have a page with a checkbox : <asp:CheckBox runat="server" ID="chkSelectAll" OnCheckedChanged="chkSelectAll_CheckedChanged" EnableViewState="true" Text='<%# CommonFunctions.GetText(Page, "CreateTask", "chkSelectAll.text") %>' AutoPostBack="true" /> First I had the problem that when the event was raised the checkbox wasn't keeping the checked property value. This is still strange because nowhere in the application we set the EnableViewState to false and by default it should be true. Well this behavior was fixed by puting EnableViewState="true". So now, I have a checkbox that when I first load the page, wworks correctly. I check the box, the event is raised Checked property valu is good and the method is executed. Postback completes and renders the page. I check the box back to false, the event is not triggered and the page is reloaded with the previous data but the Checked Property stays at true. So after the first postback I seem to loose behavior of event and ViewState. We suspect the fact that we move dynamically the controls in the page (See answer here) But this suspicion doesn't explain why everything works perfectly after the first load and stops working after first PostBack. EDIT CODE SAMPLE I created a test project where you can experience my problem. At load if you check any checkbox both raise their respective event. After postback only the second raise both events. I seem to have a problem when I register the events after moving control.

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• how to ignore ivy revision number?

  - by user315228

  Guys, I have certain jar files without revision number. But as rev is mandatory attribute for ivy dependency, i am providing the revision attribute. But i have something like (-[revision]) in url resolver. but its taking the module number instead of ignoring the revision attribute. I know it wont ignore the revision attribute as its not null. Following is the output that i get default-cache: no cached resolved revision for perltools#perltools;latest.integration [ivy:retrieve] tried [ivy:retrieve] listing all in [ivy:retrieve] using privateRepo to list all in [ivy:retrieve] ApacheURLLister found URL=[httP://myrepo/ivyRepository/perltools/jars/perltools.jar]. [ivy:retrieve] found 1 resources [ivy:retrieve] found revs: [perltools.jar] [ivy:retrieve] HTTP response status: 404 url=httP://myrepo/ivyRepository/perltools/jars/perltools.jar/perltools-perltools.jar.jar [ivy:retrieve] CLIENT ERROR: Not Found url=httP://myrepo/ivyRepository/perltools/jars/perltools.jar/perltools-perltools.jar.jar Can somebody please explain why its taking module.ext as revision where revision i specified is latest.integration and in myrepo, i dont have revision attribute. its just has [http://myrepo/ivyRepository/perltools/jars//perltools.jar] Can somebody please help me so that i can avoid revision attribute?

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• CSS ] how to automatically resize the wrapper div.

  - by Phrixus

  Hi, I've been struggling with this problem.. There is a wrapper div and it contains 3 vertical column divs with full of texts, and this wrapper div has red background color so that it can be a background of the entire texts. <div id="content_wrapper"> <div id="cside_a"> // massive texts goes here </div> ... // two more columns go here. </div> And here is the CSS code for them. #content_wrapper { background-color:#DB0A00; background-repeat:no-repeat; min-height:400px; } #cside_a, #cside_b, #cside_c { float: left; width: 33%; } And this code gives me a background that covers only 400px height box.. My expectation was the wrapper div automatically resizes depending on the size of the divs in it. Somehow putting "overflow:hidden" with wrapper CSS code makes everything work fine. I have no idea why "overflow:hidden" works.. shouldn't this hide all the overflowed texts..? Could anyone explain me why? Is is the correct way to do it anyway?

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• Redirecting from an update action to the referrer of the edit

  - by Mark Westling

  My Rails 2.3 application has a User model and the usual controller actions. The edit form can be reached two ways: when a user edits his own profile from the home page, or when an admin user edits someone else's profile from users collection. What I'd like to do is have the update action redirect back to the referred of the edit action, not the update action. If I do a simple redirect_to(:back) within update, it goes back to the edit form -- not good. One solution is to forget entirely about referrers and redirect based on the current_user and the updated user: if they're the same, go back to the home page, else go to the users collection page. This will break if I ever add a third path to the edit form. It's doubtful I'll ever do this but I'd prefer a solution that's not so brittle. Another solution is to store the referrer of edit form in a hidden field and then redirect to this value from inside the update action. This doesn't feel quite right, though I can't explain why. Are there any better approaches? Or, should I stop worrying and go with one of the two I've mentioned?

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• Does this language feature already exists?

  - by Pindatjuh

  I'm currently developing a new language for programming in a continuous environment (compare it to electrical engineering), and I've got some ideas on a certain language construction. Let me explain the feature by explanation and then by definition; x = a | b; Where x is a variable and a and b are other variables (or static values). if(x == a) { // all references to "x" are essentially references to "a". } if(x == b) { // same but with "b" } if(x != a) { // ... } if(x == a | b) { // guaranteed that "x" is '"a" | "b"'; interacting with "x" // will interact with both "a" and "b". } // etc. In the above, all code-blocks are executed, but the "scope" changes in each block how x is interpreted. In the first block, x is guaranteed to be a: thus interacting with x inside that block will interact on a. The second and the third code-block are only equal in this situation (because not b only remains a). The last block guarantees that x is at least a or b. Further more; | is not the "bitwise or operator", but I've called it the "and/or"-operator. It's definition is: "|" = "and" | "or" (On my blog, http://cplang.wordpress.com/2009/12/19/binop-and-or/, is more (mathematical) background information on this operator. It's loosely based on sets.) I do not know if this construction already exists, so that's my question: does this language feature already exists?

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• Concurrent WCF calls via shared channel

  - by Kent Boogaart

  I have a web tier that forwards calls onto an application tier. The web tier uses a shared, cached channel to do so. The application tier services in question are stateless and have concurrency enabled. But they are not being called concurrently. If I alter the web tier to create a new channel on every call, then I do get concurrent calls onto the application tier. But I wanted to avoid that cost since it is functionally unnecessary for my scenario. I have no session state, and nor do I need to re-authenticate the caller each time. I understand that the creation of the channel factory is far more expensive than than the creation of the channels, but it is still a cost I'd like to avoid if possible. I found this article on MSDN that states: While channels and clients created by the channels are thread-safe, they might not support writing more than one message to the wire concurrently. If you are sending large messages, particularly if streaming, the send operation might block waiting for another send to complete. Firstly, I'm not sending large messages (just a lot of small ones since I'm doing load testing) but am still seeing the blocking behavior. Secondly, this is rather open-ended and unhelpful documentation. It says they "might not" support writing more than one message but doesn't explain the scenarios under which they would support concurrent messages. Can anyone shed some light on this?

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• how to apply iddata into calculation?

  - by Sam

  I am trying to figure out how to combine the input and output data into the ARX model and then apply it into the BIC (Bayesian Information Criterion) formula. Below is the code that I am currently working on: for i=1:30; %% Set Model Order data=iddata(output,input,1); model = arx(data,[8 9 i]); yp = predict(model,data); ye = regress(data,yp{1,1}(1:4018,1)); M(i) = var(yp); BIC(i)=(N+i*(log(N)-1))/(N-i)*log(M(i)); end But it does not work. It keep on giving me an error something like below: "The syntax "Data{...}" is not supported. Use the "getexp" command to extract individual experiments from an IDDATA object." I did not understand what does that mean. Can someone explain it to me and where do I do wrong on my piece of code? Thanks in advance. Sam.

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• Windows Service doesn't start process with different credentials

  - by Marcus

  I have a Windows Service, running as a user, that should start several processes under different user credentials. I'm using the following code to start a process: Dim winProcess As New System.Diagnostics.Process With winProcess .StartInfo.Arguments = "some_args" .StartInfo.CreateNoWindow = True .StartInfo.ErrorDialog = False .StartInfo.FileName = "C:\TEMP\ProcessFromService\ProcessFromService\bin\Debug\ProcessFromService.exe" .StartInfo.UseShellExecute = False .StartInfo.WindowStyle = ProcessWindowStyle.Hidden 'Opgave WorkingDirectory kan soms tot problemen leiden, indien betreffende directory 'niet bereikbaar (rechten) is voor opgegeven gebruiker. 'Beter dus om deze niet op te geven. '.StartInfo.WorkingDirectory = My.Computer.FileSystem.SpecialDirectories.Temp .StartInfo.Domain = "" .StartInfo.UserName = "MyUserId" Dim strPassword As String = "MyPassword" Dim ssPassword As New Security.SecureString For Each chrPassword As Char In strPassword.ToCharArray ssPassword.AppendChar(chrPassword) Next .StartInfo.Password = ssPassword .Start() End With The process is correctly started when I use the same credentials as of which the Windows Service is running under. The process is not started, without any error, when I use different credentials. In other words: If the Windows Service is running as UserA then I can start a process running as UserA. If the Windows Service is running as UserB then I can not start a process running as UserA. I have created a test project in which I can reproduce this problem. If you put this project in C:\Temp then the used paths will be correct. You can download this test project here: https://dl.dropboxusercontent.com/u/5391091/ProcessFromService.zip NB: I hope this info is enough to explain it. If you need more info, please let me know and I will add it.

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• How should I progressively enhance this content with JavaScript?

  - by Sean Dunwoody

  The background to this problem is that I'm doing a computing project which involves Some drop down boxes for input, and a text input where the user can input a date. I've used YUI to enhance the form, so the calendar input uses the YUI calendar widget and the drop down list is converted into a horizontal list of inputs where the user only has to click once to select any input as opposed to two clicks with the drop down box (hope that makes sense, not sure how to explain it clearly) The problem is, that in the design section of my project I stated that I would follow the progressive enhancement principles. I am struggling however to ensure that users without JavaScript are able to view the drop down box / text input on said page. This is not because I do not necessarily know how, but the two methods I've tried seem unsatisfactory. Method 1 - I tried using YUI to hide the text box and drop down list, this seemed like the ideal solution however there was quite a noticeable lag when loading the page (especially for the first time), the text box and drop down list where visibile for at least a second. I included the script for this just before the end of the body tag, is there any way that I can run it onload with YUI? Would that help? Method 2 - Use the noscript tag . . . however I am loathed to do this as while it would be a simple solution, I have read various bad things about the noscript tag. Is there a way of making mehtod one work? Or is there a better way of doing this that I am yet to encounter?

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