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mysql row locking via php

- by deezee

I am helping a friend with a web based form that is for their business. I am trying to get it ready to handle multiple users. I have set it up so that just before the record is displayed for editing I am locking the record with the following code. $query = "START TRANSACTION;"; mysql_query($query); $query = "SELECT field FROM table WHERE ID = \"$value\" FOR UPDATE;"; mysql_query($query); (okay that is greatly simplified but that is the essence of the mysql) It does not appear to be working. However, when I go directly to mysql from the command line, logging in with the same user and execute START TRANSACTION; SELECT field FROM table WHERE ID = "40" FOR UPDATE; I can effectively block the web form from accessing record "40" and get the timeout warning. I have tried using BEGIN instead of START TRANSACTION. I have tried doing SET AUTOCOMMIT=0 first and starting the transaction after locking but I cannot seem to lock the row from the PHP code. Since I can lock the row from the command line I do not think there is a problem with how the database is set up. I am really hoping that there is some simple something that I have missed in my reading. FYI, I am developing on XAMPP version 1.7.3 which has Apache 2.2.14, MySQL 5.1.41 and PHP 5.3.1. Thanks in advance. This is my first time posting but I have gleaned alot of knowledge from this site in the past.

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Drawbacks with using Class Methods in Objective C.

- by RickiG

Hi I was wondering if there are any memory/performance drawbacks, or just drawbacks in general, with using Class Methods like: + (void)myClassMethod:(NSString *)param { // much to be done... } or + (NSArray*)myClassMethod:(NSString *)param { // much to be done... return [NSArray autorelease]; } It is convenient placing a lot of functionality in Class Methods, especially in an environment where I have to deal with memory management(iPhone), but there is usually a catch when something is convenient? An example could be a thought up Web Service that consisted of a lot of classes with very simple functionality. i.e. TomorrowsXMLResults; TodaysXMLResults; YesterdaysXMLResults; MondaysXMLResults; TuesdaysXMLResults; . . . n I collect a ton of these in my Web Service Class and just instantiate the web service class and let methods on this class call Class Methods on the 'Results' Classes. The classes are simple but they handle large amount of Xml, instantiate lots of objects etc. I guess I am asking if Class Methods lives or are treated different on the stack and in memory than messages to instantiated objects? Or are they just instantiated and pulled down again behind the scenes and thus, just a way of saving a few lines of code?

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How can I design a custom control in Javascript (possibly using jQuery)

- by Mathieu Pagé

I'd like to create a custom control in javascript. The goal is to create a building block that has methods, properties and events and render into a div. An example of one such control would be a calendar. It would render into a div, it would have properties that would define how it's displayed and what date is selected or highlighted, it would have methods to change the current month or to select some date and it would raise events when a day is clicked or the current month is changed by a user input. I can think of lots of way to implement this and I'm not sure what is the best way. I seem to remember that it's a bad thing to augment a DOM elements with properties and method, so I ruled that out. A jQuery plugin seems like a good idea, however I'm not sure if it's appropriate to create a plugin for each and every method my control would have so I could then use it like : $('#control').method1(); $('#control').method2(); And if I do use jQuery, where do I store the private data of my control? Another idea I got was to create a new kind of object that would have a reference to a div in which it could render it's elements. So what is the prefered way to do this. If I can I would like to do this as a jQuery plugin, but I'd need guidlines on how to create methods and where to store private data. I've loked at Plugins/Authoring on jQuery website and it did not helped that much in this regard.

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Why two subprocesses created by Java behave differently?

- by Lily

I use Java Runtime.getRuntime().exec(command) to create a subprocess and print its pid as follows: public static void main(String[] args) { Process p2; try { p2 = Runtime.getRuntime().exec(cmd); Field f2 = p2.getClass().getDeclaredField("pid"); f2.setAccessible(true); System.out.println( f2.get( p2 ) ); } catch (Exception ie) { System.out.println("Yikes, you are not supposed to be here"); } } I tried both C++ executable and Java executable (.jar file). Both executables will continuously print out "Hello World" to stdout. When cmd is the C++ executable, the pid is printed out to console but the subprocess gets killed as soon as main() returns. However, when I call the .jar executable in cmd, the subprocess does not get killed, which is the desired behavior. I don't understand why same Java code, with different executables can behave so differently. How should I modify my code so that I could have persistent subprocesses in Java. Newbie in this field. Any suggestion is welcomed. Lily

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Click outside menu to close in jquery

- by George

So I have a drop-down menu that shows on a click, as per business requirements. The menu becomes hidden again after you mouse away from it. But now I am being asked to have it stay in place until user clicks anywhere on the document. How can this be accomplished? This is a simplified version of what I have now: $(document).ready(function() { $("ul.opMenu li").click(function(){ $('#MainOptSubMenu',this).css('visibility', 'visible'); }); $("ul.opMenu li").mouseleave(function(){ $('#MainOptSubMenu',this).css('visibility', 'hidden'); }); }); <ul class="opMenu"> <li id="footwo" class=""> <span id="optImg" style="display: inline-block;"> <img src="http://localhost.vmsinfo.com:8002/insight/images/options-hover2.gif"/> </span> <ul id="MainOptSubMenu" style="visibility: hidden; top: 25px; border-top: 0px solid rgb(217, 228, 250); background-color: rgb(217, 228, 250); padding-bottom: 15px;"> <li>some</li> <li>nav</li> <li>links</li> </ul> </li> </ul> I tried something like this $('document[id!=MainOptSubMenu]').click(function() thinking it would trigger on anything that wasnt the menu, but it didnt work.

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Multiple UIWebViewNavigationTypeBackForward not only false but make inferring the actual url impossi

- by SG1

I have a UIWebView and a UITextField for the url. Naturally, I want the textField to always show the current document url. This works fine for urls directly input in the field, but I also have some buttons attached to the view for reload, back, and forward. So I've added all the UIWebViewDelegate methods to my controller, so it can listen to whenever the webView navigates and change the url in the textField as needed. Here's how I'm using the shouldStartLoadWithRequest: method: - (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType { NSLog(@"navigated via %d", navigationType); //loads the user cares about if ( navigationType == UIWebViewNavigationTypeLinkClicked || navigationType == UIWebViewNavigationTypeBackForward ) { //URL setting [self setUrlQuietly:request.URL]; } return YES; } Now, my problem here is that an actual click will generate a single navigation of type "LinkClicked" followed by a dozen type "Other" (redirects and ad loads I assume), which gets handled correctly by the code, but a back/forward action will generate all its requests as back/forward requests. In other words, a click calls setUrlQuietly: once, but a back/forward calls it multiple times. I am trying to use this method to determine if the user actually initiated the action (and I'd like to catch page redirects too). But if the method has no way of distinguishing between an actual "back" and a "load initiated as a result of a back", how can I make this assessment? Without this, I am completely stumped as to how I can only show the actual url and not intermediate urls. Thank you!

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Wrapper Classes for Backward compatibility in Java

- by Casebash

There is an interesting article here on maintaing backwards compatibility for Java. In the wrapper class section, I can't actually understand what the wrapper class accomplishes. In the following code from MyApp, WrapNewClass.checkAvailable() could be replaced by Class.forName("NewClass"). static { try { WrapNewClass.checkAvailable(); mNewClassAvailable = true; } catch (Throwable ex) { mNewClassAvailable = false; } } Consider when NewClass is unavailable. In the code where we use the wrapper (see below), all we have done is replace a class that doesn't exist, with one that exists, but which can't be compiled as it uses a class that doesn't exist. public void diddle() { if (mNewClassAvailable) { WrapNewClass.setGlobalDiv(4); WrapNewClass wnc = new WrapNewClass(40); System.out.println("newer API is available - " + wnc.doStuff(10)); }else { System.out.println("newer API not available"); } } Can anyone explain why this makes a difference? I assume it has something to do with how Java compiles code - which I don't know much about.

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Server returns 500 error only when called by Java client using urlConnection/httpUrlConnection

- by user455889

Hi - I'm having a very strange problem. I'm trying to call a servlet (JSP) with an HTTP GET and a few parameters (http://mydomain.com/method?param1=test&param2=123). If I call it from the browser or via WGET in a bash session, it works fine. However, when I make the exact same call in a Java client using urlConnection or httpURLConnection, the server returns a 500 error. I've tried everything I have found online including: urlConn.setRequestProperty("Accept-Language", "en-us,en;q=0.5"); Nothing I've tried, however, has worked. Unfortunately, I don't have access to the server I'm calling so I can't see the logs. Here's the latest code: private String testURLConnection() { String ret = ""; String url = "http://localhost:8080/TestService/test"; String query = "param1=value1&param2=value2"; try { URLConnection connection = new URL(url + "?" + query).openConnection(); connection.setRequestProperty("Accept-Charset", "UTF-8"); connection.setRequestProperty("Accept-Language", "en-us,en;q=0.5"); BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(connection.getInputStream())); String line; StringBuilder content = new StringBuilder(); while ((line = bufferedReader.readLine()) != null) { content.append(line + "\n"); } bufferedReader.close(); metaRet = content.toString(); log.debug(methodName + " return = " + metaRet); } catch (Exception ex) { log.error("Exception: " + ex); log.error("stack trace: " + getStackTrace(ex)); } return metaRet; } Any help would be greatly appreciated!

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How to populate a listview in ASP.NET 3.5 through a dataset?

- by EasyDot

Is it possible to populate a listview with a dataset? I have a function that returns a dataset. Why im asking this is because my SQL is quite complicated and i can't convert it to a SQLDataSource... Public Function getMessages() As DataSet Dim dSet As DataSet = New DataSet Dim da As SqlDataAdapter Dim cmd As SqlCommand Dim SQL As StringBuilder Dim connStr As StringBuilder = New StringBuilder("") connStr.AppendFormat("server={0};", ConfigurationSettings.AppSettings("USERserver").ToString()) connStr.AppendFormat("database={0};", ConfigurationSettings.AppSettings("USERdb").ToString()) connStr.AppendFormat("uid={0};", ConfigurationSettings.AppSettings("USERuid").ToString()) connStr.AppendFormat("pwd={0};", ConfigurationSettings.AppSettings("USERpwd").ToString()) Dim conn As SqlConnection = New SqlConnection(connStr.ToString()) Try SQL = New StringBuilder cmd = New SqlCommand SQL.Append("SELECT m.MESSAGE_ID, m.SYSTEM_ID, m.DATE_CREATED, m.EXPIRE_DATE, ISNULL(s.SYSTEM_DESC,'ALL SYSTEMS') AS SYSTEM_DESC, m.MESSAGE ") SQL.Append("FROM MESSAGE m ") SQL.Append("LEFT OUTER JOIN [SYSTEM] s ") SQL.Append("ON m.SYSTEM_ID = s.SYSTEM_ID ") SQL.AppendFormat("WHERE m.SYSTEM_ID IN ({0}) ", sSystems) SQL.Append("OR m.SYSTEM_ID is NULL ") SQL.Append("ORDER BY m.DATE_CREATED DESC; ") SQL.Append("SELECT mm.MESSAGE_ID, mm.MODEL_ID, m.MODEL_DESC ") SQL.Append("FROM MESSAGE_MODEL mm ") SQL.Append("JOIN MODEL m ") SQL.Append(" ON m.MODEL_ID = mm.MODEL_ID ") cmd.CommandText = SQL.ToString cmd.Connection = conn da = New SqlDataAdapter(cmd) da.Fill(dSet) dSet.Tables(0).TableName = "BASE" dSet.Tables(1).TableName = "MODEL" Return dSet Catch ev As Exception cLog.EventLog.logError(ev, cmd) Finally 'conn.Close() End Try End Function

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Customers angry, fighting unknown DLL dependencies

- by wheaties

I'm a one man show developing a C++ Windows application for a customer. Over the past several months we've been running to the same problems with missing DLL dependencies on customer machines. Despite my best efforts something keeps going wrong and we get angry emails back. My boss and my boss's boss are angry with me and the customers aren't happy. I'm hoping you guys can help out and give suggestions/ideas on how to get the deliverables in order. Before some of the obvious: I have no test machine. That is, I can't replicate the customer environment nor attempt to install the app on a "clean" system to catch gotchas before shipping. I've tried using depends.exe to track down what versions of the DLLs my project is dependent upon. I'm shipping our code with the redistributables I've been able to find that way. After that it's an angry customer email waiting game. I'm required to use a third-party DLL which can not be registered (it's buggy as hell.) I'm not supposed to use Install Shield, any other automated installer, or write an install script. I provide written instructions on how to get the app installed (unzip, double click exe file.) I'm tired of taking heat for this stuff. What am I missing that I could be doing? What should I ask in terms of support from my employer? How should I ask for that support in a way that they'll provide it?

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Indenting Paragraph With cout

- by Eric

Given a string of unknown length, how can you output it using cout so that the entire string displays as an indented block of text on the console? (so that even if the string wraps to a new line, the second line would have the same level of indentation) Example: cout << "This is a short string that isn't indented." << endl; cout << /* Indenting Magic */ << "This is a very long string that will wrap to the next line because it is a very long string that will wrap to the next line..." << endl; And the desired output: This is a short string that isn't indented. This is a very long string that will wrap to the next line because it is a very long string that will wrap to the next line... Edit: The homework assignment I'm working on is complete. The assignment has nothing to do with getting the output to format as in the above example, so I probably shouldn't have included the homework tag. This is just for my own enlightment. I know I could count through the characters in the string, see when I get to the end of a line, then spit out a newline and output -x- number of spaces each time. I'm interested to know if there is a simpler, idiomatic C++ way to accomplish the above.

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HttpWebResonse hangs on multiple request

- by Ehsan

I've an application that create many web request to donwload the news pages of a web site (i've tested for many web sites) after a while I find out that the application slows down in fetching the html source then I found out that HttpWebResonse fails getting the response. I post only the function that do this job. public PageFetchResult Fetch() { PageFetchResult fetchResult = new PageFetchResult(); try { HttpWebRequest req = (HttpWebRequest)HttpWebRequest.Create(URLAddress); HttpWebResponse resp = (HttpWebResponse)req.GetResponse(); Uri requestedURI = new Uri(URLAddress); Uri responseURI = resp.ResponseUri; if (Uri.Equals(requestedURI, responseURI)) { string resultHTML = ""; byte[] reqHTML = ResponseAsBytes(resp); if (!string.IsNullOrEmpty(FetchingEncoding)) resultHTML = Encoding.GetEncoding(FetchingEncoding).GetString(reqHTML); else if (!string.IsNullOrEmpty(resp.CharacterSet)) resultHTML = Encoding.GetEncoding(resp.CharacterSet).GetString(reqHTML); resp.Close(); fetchResult.IsOK = true; fetchResult.ResultHTML = resultHTML; } else { URLAddress = responseURI.AbsoluteUri; relayPageCount++; if (relayPageCount > 5) { fetchResult.IsOK = false; fetchResult.ErrorMessage = "Maximum page redirection occured."; return fetchResult; } return Fetch(); } } catch (Exception ex) { fetchResult.IsOK = false; fetchResult.ErrorMessage = ex.Message; } return fetchResult; } any solution would greatly appreciate

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Deobfuscating Javascript

- by David Murdoch

What is this monstrosity? Anyone know of a way to make it readable? <script type="text/javascript"> //<![CDATA[  //]]> </script>

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2D Histogram in R: Converting from Count to Frequency within a Column

- by Jac

Would appreciate help with generating a 2D histogram of frequencies, where frequencies are calculated within a column. My main issue: converting from counts to column based frequency. Here's my starting code: # expected packages library(ggplot2) library(plyr) # generate example data corresponding to expected data input x_data = sample(101:200,10000, replace = TRUE) y_data = sample(1:100,10000, replace = TRUE) my_set = data.frame(x_data,y_data) # define x and y interval cut points x_seq = seq(100,200,10) y_seq = seq(0,100,10) # label samples as belonging within x and y intervals my_set$x_interval = cut(my_set$x_data,x_seq) my_set$y_interval = cut(my_set$y_data,y_seq) # determine count for each x,y block xy_df = ddply(my_set, c("x_interval","y_interval"),"nrow") # still need to convert for use with dplyr # convert from count to frequency based on formula: freq = count/sum(count in given x interval) ################ TRYING TO FIGURE OUT ################# # plot results fig_count <- ggplot(xy_df, aes(x = x_interval, y = y_interval)) + geom_tile(aes(fill = nrow)) # count fig_freq <- ggplot(xy_df, aes(x = x_interval, y = y_interval)) + geom_tile(aes(fill = freq)) # frequency I would appreciate any help in how to calculate the frequency within a column. Thanks! jac EDIT: I think the solution will require the following steps 1) Calculate and store overall counts for each x-interval factor 2) Divide the individual bin count by its corresponding x-interval factor count to obtain frequency. Not sure how to carry this out though. .

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Getting a Specified Cast is not valid while importing data from Excel using Linq to SQL

- by niceoneishere

This is my second post. After learning from my first post how fantastic is to use Linq to SQL, I wanted to try to import data from a Excel sheet into my SQL database. First My Excel Sheet: it contains 4 columns namely ItemNo ItemSize ItemPrice UnitsSold I have a created a database table with the following fields table name ProductsSold Id int not null identity --with auto increment set to true ItemNo VarChar(10) not null ItemSize VarChar(4) not null ItemPrice Decimal(18,2) not null UnitsSold int not null Now I created a dal.dbml file based on my database and I am trying to import the data from excel sheet to db table using the code below. Everything is happening on click of a button. private const string forecast_query = "SELECT ItemNo, ItemSize, ItemPrice, UnitsSold FROM [Sheet1$]"; protected void btnUpload_Click(object sender, EventArgs e) { var importer = new LinqSqlModelImporter(); if (fileUpload.HasFile) { var uploadFile = new UploadFile(fileUpload.FileName); try { fileUpload.SaveAs(uploadFile.SavePath); if(File.Exists(uploadFile.SavePath)) { importer.SourceConnectionString = uploadFile.GetOleDbConnectionString(); importer.Import(forecast_query); gvDisplay.DataBind(); pnDisplay.Visible = true; } } catch (Exception ex) { Response.Write(ex.Source.ToString()); lblInfo.Text = ex.Message; } finally { uploadFile.DeleteFileNoException(); } } } // Now here is the code for LinqSqlModelImporter public class LinqSqlModelImporter : SqlImporter { public override void Import(string query) { // importing data using oledb command and inserting into db using LINQ to SQL using (var context = new WSDALDataContext()) { using (var myConnection = new OleDbConnection(base.SourceConnectionString)) using (var myCommand = new OleDbCommand(query, myConnection)) { myConnection.Open(); var myReader = myCommand.ExecuteReader(); while (myReader.Read()) { context.ProductsSolds.InsertOnSubmit(new ProductsSold() { ItemNo = myReader.GetString(0), ItemSize = myReader.GetString(1), ItemPrice = myReader.GetDecimal(2), UnitsSold = myReader.GetInt32(3) }); } } context.SubmitChanges(); } } } can someone please tell me where am I making the error or if I am missing something, but this is driving me nuts. When I debugged I am getting this error when casting from a number the value must be a number less than infinity I really appreciate it

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drupal themes: .info file: how do I add more than 1 css file / js file to my theme?

- by egarcia

I'm creating a new Drupal theme. Until now, I only needed to include a single css file and a single js file. So my theme.info file had something like this: stylesheets[all][] = css/style.css scripts[] = js/script.js Now I must include jquery and jquery-ui in order to use a calendar date. These come with 2 new javascript files, and 1 additonal css file that I must add to the site. The calendar input form is going to be used in all pages (on a side block) so it is ok for me to load the extra css/javascript on all pages. I think the easiest thing would be to reference them on the .info file itself. At first I tried to just put them there with separate spaces: stylesheets[all][] = css/style.css css/ui-lightness/jquery-ui-1.8.1.custom.css scripts[] = js/jquery-1.4.2.min.js js/jquery-ui-1.8.1.custom.min.js js/reservations.js I emptied drupal's cache and... none of them loaded. I then tried separating each file with a comma, and flushing the cache again. Same result. I've browsed some drupal pages, but could not find how to add several javascript/css files on one theme (they always seem to add just 1 of each). So, how do I include several css/javascript files on the .info file?

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Java: creating objects of arrays with different names at runtime and accessing/updating them

- by scriptingalias

Hello, I'm trying to create a class that can instantiate arrays at runtime by giving each array a "name" created by the createtempobjectname() method. I'm having trouble making this program run. I would also like to see how I could access specific objects that were created during runtime and accessing those arrays by either changing value or accessing them. This is my mess so far, which compiles but gets a runtime exception. import java.lang.reflect.Array; public class arrays { private static String temp; public static int name = 0; public static Object o; public static Class c; public static void main(String... args) { assignobjectname(); //getclassname();//this is supposed to get the name of the object and somehow //allow the arrays to become updated using more code? } public static void getclassname() { String s = c.getName(); System.out.println(s); } public static void assignobjectname()//this creates the object by the name returned { //createtempobjectname() try { String object = createtempobjectname(); c = Class.forName(object); o = Array.newInstance(c, 20); } catch (ClassNotFoundException exception) { exception.printStackTrace(); } } public static String createtempobjectname() { name++; temp = Integer.toString(name); return temp; } }

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What is happening in this T-SQL code? (Concatenting the results of a SELECT statement)

- by Ben McCormack

I'm just starting to learn T-SQL and could use some help in understanding what's going on in a particular block of code. I modified some code in an answer I received in a previous question, and here is the code in question: DECLARE @column_list AS varchar(max) SELECT @column_list = COALESCE(@column_list, ',') + 'SUM(Case When Sku2=' + CONVERT(varchar, Sku2) + ' Then Quantity Else 0 End) As [' + CONVERT(varchar, Sku2) + ' - ' + Convert(varchar,Description) +'],' FROM OrderDetailDeliveryReview Inner Join InvMast on SKU2 = SKU and LocationTypeID=4 GROUP BY Sku2 , Description ORDER BY Sku2 Set @column_list = Left(@column_list,Len(@column_list)-1) Select @column_list ---------------------------------------- 1 row is returned: ,SUM(Case When Sku2=157 Then Quantity Else 0 End) As [157 -..., SUM(Case ... The T-SQL code does exactly what I want, which is to make a single result based on the results of a query, which will then be used in another query. However, I can't figure out how the SELECT @column_list =... statement is putting multiple values into a single string of characters by being inside a SELECT statement. Without the assignment to @column_list, the SELECT statement would simply return multiple rows. How is it that by having the variable within the SELECT statement that the results get "flattened" down into one value? How should I read this T-SQL to properly understand what's going on?

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Adding an unknown number of JComponents to a JPanel

- by Matthew

Good day, I am building an Applet (JApplet to be exact) and I sub divided that into two panels. The top panel is called DisplayPanel which is a custom class that extends JPanel. The bottom panel is called InputPanel which also extends JPanel. As mentioned above, I can add those two Panel's to the applet and they display fine. The next thing that I would like to do is have the InputPanel be able to hold a random number of JComponent Objects all listed veritcally. This means that the InputPanel should be able to have JButtons, JLabels, JTextFields etc thrown at it. I then want the InputPanel to display some sort of scrolling capability. The catch is that since these two panels are already inside my applet, I need the InputPanel to stay the same size as it was given when added to the Applet. So for example, if my applet (from the web-browser html code) was given the size 700,700, and then the DisplayPanel was 700 by 350, and the InputPanel was below it with the same dimensions, I want to then be able to add lots of JComponents like buttons, to the InputPanel and the panel would stay 700 x 350 in the same position that it is at, only the panel would have scroll bars if needed. I've played with many different combinations of JScrollPane, but just cannot get it. Thank you.

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Image appearing in the wrong place.

- by Luke

I have a list that I want to precede on each line with a small image. The CSS: .left div.arrow{background-image: url(../images/design/box.png); float:left; height:15px; width:15px; margin-right:2px;} .left a.list:link, a:visited, a:active {color:black; font-size:0.8em; text-decoration:none; display:block; float:left;} The HTML: <div class="panel">My quick links</div> <div class="arrow"></div> <a href="/messages.php?p=new" class="list">Send a new message</a> <br /> <div class="arrow"></div> <a href="/settings.php#password" class="list">Change my password</a> <br /> <div class="arrow"></div> <a href="/settings.php#picture" class="list">Upload a new site image</a> <br /> As you can see, each image should go before the writing. On the first line, the text "Send a new message" has the preceeding image. However, each line afterwards has the image at the end. So "Send a new message" has an image at the start and finish. It is like the images are staying at the end of the previous line. Any ideas?

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Dynamic Auto updating (to UI, Grid) binding list in C# Winform?

- by Dhana

I'm not even sure if i'm doing this correctly. But basically I have a list of objects that are built out of a class/interface. From there, I am binding the list to a datagrid view that is on a Windows Form (C#) Here the list is a Sync list which will auto update the UI, in this case datagridview. Every thing works fine now, but now i would like to have the List should have an dynamic object, that is the object will have by default two static property (ID, Name), and at run time user will select remaining properties. These should be bind to the data grid. Any update on the list should be auto reflected in the grid. I am aware that, we can use dynamic objects, but i would like to know , how to approach for solution, datagridview.DataSource = myData; // myData is AutoUpdateList<IPersonInfo> Now IPersonInfo is the type of object, need to add dynamic properties for this type at runtime. public class AutoUpdateList<T> : System.ComponentModel.BindingList<T> { private System.ComponentModel.ISynchronizeInvoke _SyncObject; private System.Action<System.ComponentModel.ListChangedEventArgs> _FireEventAction; public AutoUpdateList() : this(null) { } public AutoUpdateList(System.ComponentModel.ISynchronizeInvoke syncObject) { _SyncObject = syncObject; _FireEventAction = FireEvent; } protected override void OnListChanged(System.ComponentModel.ListChangedEventArgs args) { try { if (_SyncObject == null) { FireEvent(args); } else { _SyncObject.Invoke(_FireEventAction, new object[] { args }); } } catch (Exception) { // TODO: Log Here } } private void FireEvent(System.ComponentModel.ListChangedEventArgs args) { base.OnListChanged(args); } } Could you help out on this?

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template files in python

- by saminny

I am trying to use python for translating a set of templates to a set of configuration files based on values taken from a main configuration file. However, I am having certain issues. Consider the following example of a template file. file1.cfg.template %(CLIENT1)s %(HOST1)s %(PORT1)d C %(COMPID1)s %(CLIENT2)s %(HOST2)s %(PORT2)d C %(COMPID2)s This file contains an entry for each client. There are hundreds of config files like this and I don't want to have logic for each type of config file. Python should do the replacements and generate config files automatically given a set of global values read from a main xml config file. However, in the above example, if CLIENT2 does not exist, how do I delete that line? I expect Python would generate the config file using the following simple code: os.open("file1.cfg.template").read() & myhash where myhash is hash of all configuration parameters which may not contain CLIENT2 at all. In the case it does not contain CLIENT2, I want that line to disappear from the file. Is it possible to insert some 'IF' block in the file and have python evaluate it? Thanks for your help. Any suggestions most welcome.

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Is Stream.Write thread-safe?

- by Mike Spross

I'm working on a client/server library for a legacy RPC implementation and was running into issues where the client would sometimes hang when waiting to a receive a response message to an RPC request message. It turns out the real problem was in my message framing code (I wasn't handling message boundaries correctly when reading data off the underlying NetworkStream), but it also made me suspicious of the code I was using to send data across the network, specifically in the case where the RPC server sends a large amount of data to a client as the result of a client RPC request. My send code uses a BinaryWriter to write a complete "message" to the underlying NetworkStream. The RPC protocol also implements a heartbeat algorithm, where the RPC server sends out PING messages every 15 seconds. The pings are sent out by a separate thread, so, at least in theory, a ping can be sent while the server is in the middle of streaming a large response back to a client. Suppose I have a Send method as follows, where stream is a NetworkStream: public void Send(Message message) { //Write the message to a temporary stream so we can send it all-at-once MemoryStream tempStream = new MemoryStream(); message.WriteToStream(tempStream); //Write the serialized message to the stream. //The BinaryWriter is a little redundant in this //simplified example, but here because //the production code uses it. byte[] data = tempStream.ToArray(); BinaryWriter bw = new BinaryWriter(stream); bw.Write(data, 0, data.Length); bw.Flush(); } So the question I have is, is the call to bw.Write (and by implication the call to the underlying Stream's Write method) atomic? That is, if a lengthy Write is still in progress on the sending thread, and the heartbeat thread kicks in and sends a PING message, will that thread block until the original Write call finishes, or do I have to add explicit synchronization to the Send method to prevent the two Send calls from clobbering the stream?

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sqlite3 'database is locked' won't go away with retries

- by Azarias

I have a sqlite3 database that is accessed by a few threads (3-4). I am aware of the general limitations of sqlite3 with regards to concurrency as stated http://www.sqlite.org/faq.html#q6 , but I am convinced that is not the problem. All of the threads both read and write from this database. Whenever I do a write, I have the following construct: try: Cursor.execute(q, params) Connection.commit() except sqlite3.IntegrityError: Notify except sqlite3.OperationalError: print sys.exc_info() print("DATABASE LOCKED; sleeping for 3 seconds and trying again") time.sleep(3) Retry On some runs, I won't even hit this block, but when I do, it never comes out of it (keeps retrying, but I keep getting the 'database is locked' error from exc_info. If I understand the reader/writer lock usage correctly, some amount of waiting should help with the contention. What this sounds like is deadlock, but I do not use any transactions in my code, and every SELECT or INSERT is simply a one off. Some threads, however, keep the same connection when they do their operation (which includes a mix of SELECTS and INSERTS and other modifiers). I would appericiate it if you could shade a light on this, and also ways around fixing it (besides using a different database engine.)

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Preserving order when copying elements using Deliverance / XPath

- by Jon Hadley

How would I, using Deliverance & XPath (or CSS) selectors, select and copy list items .one and .three from each list below, but display them in the order of their parent list? <ul id="a-wrapper"> <li class="one"></li> <li class="two"></li> <li class="three"></li> <li class="four"></li> </li> <ul id="b-wrapper"> <li class="one"></li> <li class="two"></li> <li class="three"></li> <li class="four"></li> </ul> c,d,e,f,g etc.... The catch is it needs to use a href rule, eg: <prepend href="/blah/deblah" content="#x" theme="#y" /> Using the following just lists all the .one elements, then all the .three elements. <prepend href="/blah/deblah" content=".one" theme="#y" /> <prepend href="/blah/deblah" content=".three" theme="#y" />

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