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  • gcc, strict-aliasing, and casting through a union

    - by Joseph Quinsey
    About a year ago the following paragraph was added to the GCC Manual, version 4.3.4, regarding -fstrict-aliasing: Similarly, access by taking the address, casting the resulting pointer and dereferencing the result has undefined behavior [emphasis added], even if the cast uses a union type, e.g.: union a_union { int i; double d; }; int f() { double d = 3.0; return ((union a_union *)&d)->i; } Does anyone have an example to illustrate this undefined behavior? Note this question is not about what the C99 standard says, or does not say. It is about the actual functioning of gcc, and other existing compilers, today. My simple, naive, attempt fails. For example: #include <stdio.h> union a_union { int i; double d; }; int f1(void) { union a_union t; t.d = 3333333.0; return t.i; // gcc manual: 'type-punning is allowed, provided ...' } int f2(void) { double d = 3333333.0; return ((union a_union *)&d)->i; // gcc manual: 'undefined behavior' } int main(void) { printf("%d\n", f1()); printf("%d\n", f2()); return 0; } works fine, giving on CYGWIN: -2147483648 -2147483648 Also note that taking addresses is obviously wrong (or right, if you are trying to illustrate undefined behavior). For example, just as we know this is wrong: extern void foo(int *, double *); union a_union t; t.d = 3.0; foo(&t.i, &t.d); // UD behavior so is this wrong: extern void foo(int *, double *); double d = 3.0; foo(&((union a_union *)&d)->i, &d); // UD behavior For background discussion about this, see for example: http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1422.pdf http://gcc.gnu.org/ml/gcc/2010-01/msg00013.html http://davmac.wordpress.com/2010/02/26/c99-revisited/ http://cellperformance.beyond3d.com/articles/2006/06/understanding-strict-aliasing.html http://stackoverflow.com/questions/98650/what-is-the-strict-aliasing-rule http://stackoverflow.com/questions/2771023/c99-strict-aliasing-rules-in-c-gcc/2771041#2771041 The first link, draft minutes of an ISO meeting seven months ago, notes in section 4.16: Is there anybody that thinks the rules are clear enough? No one is really able to interpret tham.

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  • PHP use of undefined constant error

    - by user272899
    Using a great script to grab details from imdb, I would like to thank Fabian Beiner. Just one error i have encountered with it is: Use of undefined constant sys_get_temp_dir assumed 'sys_get_temp_dir' in '/path/to/directory' on line 49 This is the complete script <?php /** * IMDB PHP Parser * * This class can be used to retrieve data from IMDB.com with PHP. This script will fail once in * a while, when IMDB changes *anything* on their HTML. Guys, it's time to provide an API! * * @link http://fabian-beiner.de * @copyright 2010 Fabian Beiner * @author Fabian Beiner (mail [AT] fabian-beiner [DOT] de) * @license MIT License * * @version 4.1 (February 1st, 2010) * */ class IMDB { private $_sHeader = null; private $_sSource = null; private $_sUrl = null; private $_sId = null; public $_bFound = false; private $_oCookie = '/tmp/imdb-grabber-fb.tmp'; const IMDB_CAST = '#<a href="/name/(\w+)/" onclick="\(new Image\(\)\)\.src=\'/rg/castlist/position-(\d|\d\d)/images/b\.gif\?link=/name/(\w+)/\';">(.*)</a>#Ui'; const IMDB_COUNTRY = '#<a href="/Sections/Countries/(\w+)/">#Ui'; const IMDB_DIRECTOR = '#<a href="/name/(\w+)/" onclick="\(new Image\(\)\)\.src=\'/rg/directorlist/position-(\d|\d\d)/images/b.gif\?link=name/(\w+)/\';">(.*)</a><br/>#Ui'; const IMDB_GENRE = '#<a href="/Sections/Genres/(\w+|\w+\-\w+)/">(\w+|\w+\-\w+)</a>#Ui'; const IMDB_MPAA = '#<h5><a href="/mpaa">MPAA</a>:</h5>\s*<div class="info-content">\s*(.*)\s*</div>#Ui'; const IMDB_PLOT = '#<h5>Plot:</h5>\s*<div class="info-content">\s*(.*)\s*<a#Ui'; const IMDB_POSTER = '#<a name="poster" href="(.*)" title="(.*)"><img border="0" alt="(.*)" title="(.*)" src="(.*)" /></a>#Ui'; const IMDB_RATING = '#<b>(\d\.\d/10)</b>#Ui'; const IMDB_RELEASE_DATE = '#<h5>Release Date:</h5>\s*\s*<div class="info-content">\s*(.*) \((.*)\)#Ui'; const IMDB_RUNTIME = '#<h5>Runtime:</h5>\s*<div class="info-content">\s*(.*)\s*</div>#Ui'; const IMDB_SEARCH = '#<b>Media from&nbsp;<a href="/title/tt(\d+)/"#i'; const IMDB_TAGLINE = '#<h5>Tagline:</h5>\s*<div class="info-content">\s*(.*)\s*</div>#Ui'; const IMDB_TITLE = '#<title>(.*) \((.*)\)</title>#Ui'; const IMDB_URL = '#http://(.*\.|.*)imdb.com/(t|T)itle(\?|/)(..\d+)#i'; const IMDB_VOTES = '#&nbsp;&nbsp;<a href="ratings" class="tn15more">(.*) votes</a>#Ui'; const IMDB_WRITER = '#<a href="/name/(\w+)/" onclick="\(new Image\(\)\)\.src=\'/rg/writerlist/position-(\d|\d\d)/images/b\.gif\?link=name/(\w+)/\';">(.*)</a>#Ui'; const IMDB_REDIRECT = '#Location: (.*)#'; /** * Public constructor. * * @param string $sSearch */ public function __construct($sSearch) { if (function_exists(sys_get_temp_dir)) { $this->_oCookie = tempnam(sys_get_temp_dir(), 'imdb'); } $sUrl = $this->findUrl($sSearch); if ($sUrl) { $bFetch = $this->fetchUrl($this->_sUrl); $this->_bFound = true; } } /** * Little REGEX helper. * * @param string $sRegex * @param string $sContent * @param int $iIndex; */ private function getMatch($sRegex, $sContent, $iIndex = 1) { preg_match($sRegex, $sContent, $aMatches); if ($iIndex > count($aMatches)) return; if ($iIndex == null) { return $aMatches; } return $aMatches[(int)$iIndex]; } /** * Little REGEX helper, I should find one that works for both... ;/ * * @param string $sRegex * @param int $iIndex; */ private function getMatches($sRegex, $iIndex = null) { preg_match_all($sRegex, $this->_sSource, $aMatches); if ((int)$iIndex) return $aMatches[$iIndex]; return $aMatches; } /** * Save an image. * * @param string $sUrl */ private function saveImage($sUrl) { $sUrl = trim($sUrl); $bolDir = false; if (!is_dir(getcwd() . '/posters')) { if (mkdir(getcwd() . '/posters', 0777)) { $bolDir = true; } } $sFilename = getcwd() . '/posters/' . preg_replace("#[^0-9]#", "", basename($sUrl)) . '.jpg'; if (file_exists($sFilename)) { return 'posters/' . basename($sFilename); } if (is_dir(getcwd() . '/posters') OR $bolDir) { if (function_exists('curl_init')) { $oCurl = curl_init($sUrl); curl_setopt_array($oCurl, array ( CURLOPT_VERBOSE => 0, CURLOPT_HEADER => 0, CURLOPT_RETURNTRANSFER => 1, CURLOPT_TIMEOUT => 5, CURLOPT_CONNECTTIMEOUT => 5, CURLOPT_REFERER => $sUrl, CURLOPT_BINARYTRANSFER => 1)); $sOutput = curl_exec($oCurl); curl_close($oCurl); $oFile = fopen($sFilename, 'x'); fwrite($oFile, $sOutput); fclose($oFile); return 'posters/' . basename($sFilename); } else { $oImg = imagecreatefromjpeg($sUrl); imagejpeg($oImg, $sFilename); return 'posters/' . basename($sFilename); } return false; } return false; } /** * Find a valid Url out of the passed argument. * * @param string $sSearch */ private function findUrl($sSearch) { $sSearch = trim($sSearch); if ($aUrl = $this->getMatch(self::IMDB_URL, $sSearch, 4)) { $this->_sId = 'tt' . preg_replace('[^0-9]', '', $aUrl); $this->_sUrl = 'http://www.imdb.com/title/' . $this->_sId .'/'; return true; } else { $sTemp = 'http://www.imdb.com/find?s=all&q=' . str_replace(' ', '+', $sSearch) . '&x=0&y=0'; $bFetch = $this->fetchUrl($sTemp); if( $this->isRedirect() ) { return true; } else if ($bFetch) { if ($strMatch = $this->getMatch(self::IMDB_SEARCH, $this->_sSource)) { $this->_sUrl = 'http://www.imdb.com/title/tt' . $strMatch . '/'; unset($this->_sSource); return true; } } } return false; } /** * Find if result is redirected directly to exact movie. */ private function isRedirect() { if ($strMatch = $this->getMatch(self::IMDB_REDIRECT, $this->_sHeader)) { $this->_sUrl = $strMatch; unset($this->_sSource); unset($this->_sHeader); return true; } return false; } /** * Fetch data from given Url. * Uses cURL if installed, otherwise falls back to file_get_contents. * * @param string $sUrl * @param int $iTimeout; */ private function fetchUrl($sUrl, $iTimeout = 15) { $sUrl = trim($sUrl); if (function_exists('curl_init')) { $oCurl = curl_init($sUrl); curl_setopt_array($oCurl, array ( CURLOPT_VERBOSE => 0, CURLOPT_HEADER => 1, CURLOPT_FRESH_CONNECT => true, CURLOPT_RETURNTRANSFER => 1, CURLOPT_TIMEOUT => (int)$iTimeout, CURLOPT_CONNECTTIMEOUT => (int)$iTimeout, CURLOPT_REFERER => $sUrl, CURLOPT_FOLLOWLOCATION => 0, CURLOPT_COOKIEFILE => $this->_oCookie, CURLOPT_COOKIEJAR => $this->_oCookie, CURLOPT_USERAGENT => 'Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2) Gecko/20100115 Firefox/3.6' )); $sOutput = curl_exec($oCurl); if ($sOutput === false) { return false; } $aInfo = curl_getinfo($oCurl); if ($aInfo['http_code'] != 200 && $aInfo['http_code'] != 302) { return false; } $sTmpHeader = strpos($sOutput, "\r\n\r\n"); $this->_sHeader = substr($sOutput, 0, $sTmpHeader); $this->_sSource = str_replace("\n", '', substr($sOutput, $sTmpHeader+1)); curl_close($oCurl); return true; } else { $sOutput = @file_get_contents($sUrl, 0); if (strpos($http_response_header[0], '200') === false){ return false; } $this->_sSource = str_replace("\n", '', (string)$sOutput); return true; } return false; } /** * Returns the cast. */ public function getCast($iOutput = null, $bMore = true) { if ($this->_sSource) { $sReturned = $this->getMatches(self::IMDB_CAST, 4); if (is_array($sReturned)) { if ($iOutput) { foreach ($sReturned as $i => $sName) { if ($i >= $iOutput) break; $sReturn[] = $sName; } return implode(' / ', $sReturn) . (($bMore) ? '&hellip;' : ''); } return implode(' / ', $sReturned); } return $sReturned; } return 'n/A'; } /** * Returns the cast as links. */ public function getCastAsUrl($iOutput = null, $bMore = true) { if ($this->_sSource) { $sReturned1 = $this->getMatches(self::IMDB_CAST, 4); $sReturned2 = $this->getMatches(self::IMDB_CAST, 3); if (is_array($sReturned1)) { if ($iOutput) { foreach ($sReturned1 as $i => $sName) { if ($i >= $iOutput) break; $aReturn[] = '<a href="http://www.imdb.com/name/' . $sReturned2[$i] . '/">' . $sName . '</a>';; } return implode(' / ', $aReturn) . (($bMore) ? '&hellip;' : ''); } return implode(' / ', $sReturned); } return '<a href="http://www.imdb.com/name/' . $sReturned2 . '/">' . $sReturned1 . '</a>';; } return 'n/A'; } /** * Returns the countr(y|ies). */ public function getCountry() { if ($this->_sSource) { $sReturned = $this->getMatches(self::IMDB_COUNTRY, 1); if (is_array($sReturned)) { return implode(' / ', $sReturned); } return $sReturned; } return 'n/A'; } /** * Returns the countr(y|ies) as link(s). */ public function getCountryAsUrl() { if ($this->_sSource) { $sReturned = $this->getMatches(self::IMDB_COUNTRY, 1); if (is_array($sReturned)) { foreach ($sReturned as $sCountry) { $aReturn[] = '<a href="http://www.imdb.com/Sections/Countries/' . $sCountry . '/">' . $sCountry . '</a>'; } return implode(' / ', $aReturn); } return '<a href="http://www.imdb.com/Sections/Countries/' . $sReturned . '/">' . $sReturned . '</a>'; } return 'n/A'; } /** * Returns the director(s). */ public function getDirector() { if ($this->_sSource) { $sReturned = $this->getMatches(self::IMDB_DIRECTOR, 4); if (is_array($sReturned)) { return implode(' / ', $sReturned); } return $sReturned; } return 'n/A'; } /** * Returns the director(s) as link(s). */ public function getDirectorAsUrl() { if ($this->_sSource) { $sReturned1 = $this->getMatches(self::IMDB_DIRECTOR, 4); $sReturned2 = $this->getMatches(self::IMDB_DIRECTOR, 1); if (is_array($sReturned1)) { foreach ($sReturned1 as $i => $sDirector) { $aReturn[] = '<a href="http://www.imdb.com/name/' . $sReturned2[$i] . '/">' . $sDirector . '</a>'; } return implode(' / ', $aReturn); } return '<a href="http://www.imdb.com/name/' . $sReturned2 . '/">' . $sReturned1 . '</a>'; } return 'n/A'; } /** * Returns the genre(s). */ public function getGenre() { if ($this->_sSource) { $sReturned = $this->getMatches(self::IMDB_GENRE, 1); if (is_array($sReturned)) { return implode(' / ', $sReturned); } return $sReturned; } return 'n/A'; } /** * Returns the genre(s) as link(s). */ public function getGenreAsUrl() { if ($this->_sSource) { $sReturned = $this->getMatches(self::IMDB_GENRE, 1); if (is_array($sReturned)) { foreach ($sReturned as $i => $sGenre) { $aReturn[] = '<a href="http://www.imdb.com/Sections/Genres/' . $sGenre . '/">' . $sGenre . '</a>'; } return implode(' / ', $aReturn); } return '<a href="http://www.imdb.com/Sections/Genres/' . $sReturned . '/">' . $sReturned . '</a>'; } return 'n/A'; } /** * Returns the mpaa. */ public function getMpaa() { if ($this->_sSource) { return implode('' , $this->getMatches(self::IMDB_MPAA, 1)); } return 'n/A'; } /** * Returns the plot. */ public function getPlot() { if ($this->_sSource) { return implode('' , $this->getMatches(self::IMDB_PLOT, 1)); } return 'n/A'; } /** * Download the poster, cache it and return the local path to the image. */ public function getPoster() { if ($this->_sSource) { if ($sPoster = $this->saveImage(implode("", $this->getMatches(self::IMDB_POSTER, 5)), 'poster.jpg')) { return $sPoster; } return implode('', $this->getMatches(self::IMDB_POSTER, 5)); } return 'n/A'; } /** * Returns the rating. */ public function getRating() { if ($this->_sSource) { return implode('', $this->getMatches(self::IMDB_RATING, 1)); } return 'n/A'; } /** * Returns the release date. */ public function getReleaseDate() { if ($this->_sSource) { return implode('', $this->getMatches(self::IMDB_RELEASE_DATE, 1)); } return 'n/A'; } /** * Returns the runtime of the current movie. */ public function getRuntime() { if ($this->_sSource) { return implode('', $this->getMatches(self::IMDB_RUNTIME, 1)); } return 'n/A'; } /** * Returns the tagline. */ public function getTagline() { if ($this->_sSource) { return implode('', $this->getMatches(self::IMDB_TAGLINE, 1)); } return 'n/A'; } /** * Get the release date of the current movie. */ public function getTitle() { if ($this->_sSource) { return implode('', $this->getMatches(self::IMDB_TITLE, 1)); } return 'n/A'; } /** * Returns the url. */ public function getUrl() { return $this->_sUrl; } /** * Get the votes of the current movie. */ public function getVotes() { if ($this->_sSource) { return implode('', $this->getMatches(self::IMDB_VOTES, 1)); } return 'n/A'; } /** * Get the year of the current movie. */ public function getYear() { if ($this->_sSource) { return implode('', $this->getMatches(self::IMDB_TITLE, 2)); } return 'n/A'; } /** * Returns the writer(s). */ public function getWriter() { if ($this->_sSource) { $sReturned = $this->getMatches(self::IMDB_WRITER, 4); if (is_array($sReturned)) { return implode(' / ', $sReturned); } return $sReturned; } return 'n/A'; } /** * Returns the writer(s) as link(s). */ public function getWriterAsUrl() { if ($this->_sSource) { $sReturned1 = $this->getMatches(self::IMDB_WRITER, 4); $sReturned2 = $this->getMatches(self::IMDB_WRITER, 1); if (is_array($sReturned1)) { foreach ($sReturned1 as $i => $sWriter) { $aReturn[] = '<a href="http://www.imdb.com/name/' . $sReturned2[$i] . '/">' . $sWriter . '</a>'; } return implode(' / ', $aReturn); } return '<a href="http://www.imdb.com/name/' . $sReturned2 . '/">' . $sReturned1 . '</a>'; } return 'n/A'; } } ?>

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  • Simplest way to flatten document to a view in RavenDB

    - by degorolls
    Given the following classes: public class Lookup { public string Code { get; set; } public string Name { get; set; } } public class DocA { public string Id { get; set; } public string Name { get; set; } public Lookup Currency { get; set; } } public class ViewA // Simply a flattened version of the doc { public string Id { get; set; } public string Name { get; set; } public string CurrencyName { get; set; } // View just gets the name of the currency } I can create an index that allows client to query the view as follows: public class A_View : AbstractIndexCreationTask<DocA, ViewA> { public A_View() { Map = docs => from doc in docs select new ViewA { Id = doc.Id, Name = doc.Name, CurrencyName = doc.Currency.Name }; Reduce = results => from result in results group on new ViewA { Id = result.Id, Name = result.Name, CurrencyName = result.CurrencyName } into g select new ViewA { Id = g.Key.Id, Name = g.Key.Name, CurrencyName = g.Key.CurrencyName }; } } This certainly works and produces the desired result of a view with the data transformed to the structure required at the client application. However, it is unworkably verbose, will be a maintenance nightmare and is probably fairly inefficient with all the redundant object construction. Is there a simpler way of creating an index with the required structure (ViewA) given a collection of documents (DocA)? FURTHER INFORMATION The issue appears to be that in order to have the index hold the data in the transformed structure (ViewA), we have to do a Reduce. It appears that a Reduce must have both a GROUP ON and a SELECT in order to work as expected so the following are not valid: INVALID REDUCE CLAUSE 1: Reduce = results => from result in results group on new ViewA { Id = result.Id, Name = result.Name, CurrencyName = result.CurrencyName } into g select g.Key; This produces: System.InvalidOperationException: Variable initializer select must have a lambda expression with an object create expression Clearly we need to have the 'select new'. INVALID REDUCE CLAUSE 2: Reduce = results => from result in results select new ViewA { Id = result.Id, Name = result.Name, CurrencyName = result.CurrencyName }; This prduces: System.InvalidCastException: Unable to cast object of type 'ICSharpCode.NRefactory.Ast.IdentifierExpression' to type 'ICSharpCode.NRefactory.Ast.InvocationExpression'. Clearly, we also need to have the 'group on new'. Thanks for any assistance you can provide. (Note: removing the type (ViewA) from the constructor calls has no effect on the above)

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  • Should I add try/catch around when casting on an attribute of JSP implicit object?

    - by Michael Mao
    Hi all: Basically what I mean is like this: List<String[]> routes = (List<String[]>)application.getAttribute("routes"); For the above code, it tries to get an attribute named "routes" from the JSP implicit object - application. But as everyone knows, after this line of code, routes may very well contains a null - which means this application hasn't got an attribute named "routes". Is this "casting on null" good programming practice in Java or not? Basically I try to avoid exceptions such as java.io.InvalidCastException I reckon things like this are more as "heritage" of Java 1.4 when generic types were not introduced to this language. So I guess everything stored in application attributes as Objects (Similar to traditional ArrayList). And when you do "downcast", there might be invalid casts. What would you do in this case? Update: Just found that although in the implicit object application I did store a List of String arrays, when I do this : List<double[]> routes = (List<double[]>)application.getAttribute("routes"); It doesn't produce any error... And I felt not comfortable already... And even with this code: out.print(routes.get(0)); It does print out something strange : [Ljava.lang.String;@18b352f Am I printing a "pointer to String"? I can finally get an exception like this: out.print(routes.get(0)[1]); with error : java.lang.ClassCastException: [Ljava.lang.String; Because it was me to add the application attribute, I know which type should it be cast to. I feel this is not "good enough", what if I forget the exact type? I know there are still some cases where this sort of thing would happen, such as in JSP/Servlet when you do casting on session attributes. Is there a better way to do this? Before you say:"OMG, why you don't use Servlets???", I should justify my reason as this: - because my uni sucks, its server can only work with Servlets generated by JSP, and I don't really want to learn how to fix issues like that. look at my previous question on this , and this is uni homework, so I've got no other choice, forget all about war, WEB-INF,etc, but "code everything directly into JSP" - because the professors do that too. :)

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  • Stored procedure error when use computed column for ID

    - by Hari
    I got the error: Procedure or function usp_User_Info3 has too many arguments specified When I run the program. I don't know the error in SP or in C# code. I have to display the Vendor_ID after the user clicks the submit button. Where the thing going wrong here ? Table structure : CREATE TABLE User_Info3 ( SNo int Identity (2000,1) , Vendor_ID AS 'VEN' + CAST(SNo as varchar(16)) PERSISTED PRIMARY KEY, UserName VARCHAR(16) NOT NULL, User_Password VARCHAR(12) NOT NULL, User_ConPassword VARCHAR(12) NOT NULL, User_FirstName VARCHAR(25) NOT NULL, User_LastName VARCHAR(25) SPARSE NULL, User_Title VARCHAR(35) NOT NULL, User_EMail VARCHAR(35) NOT NULL, User_PhoneNo VARCHAR(14) NOT NULL, User_MobileNo VARCHAR(14)NOT NULL, User_FaxNo VARCHAR(14)NOT NULL, UserReg_Date DATE DEFAULT GETDATE() ) Stored Procedure : ALTER PROCEDURE [dbo].[usp_User_Info3] @SNo INT OUTPUT, @Vendor_ID VARCHAR(10) OUTPUT, @UserName VARCHAR(30), @User_Password VARCHAR(12), @User_ConPassword VARCHAR(12), @User_FirstName VARCHAR(25), @User_LastName VARCHAR(25), @User_Title VARCHAR(35), @User_OtherEmail VARCHAR(30), @User_PhoneNo VARCHAR(14), @User_MobileNo VARCHAR(14), @User_FaxNo VARCHAR(14) AS BEGIN SET NOCOUNT ON; INSERT INTO User_Info3 (UserName,User_Password,User_ConPassword,User_FirstName, User_LastName,User_Title,User_OtherEmail,User_PhoneNo,User_MobileNo,User_FaxNo) VALUES (@UserName,@User_Password,@User_ConPassword,@User_FirstName,@User_LastName, @User_Title,@User_OtherEmail,@User_PhoneNo,@User_MobileNo,@User_FaxNo) SET @SNo = Scope_Identity() SELECT Vendor_ID From User_Info3 WHERE SNo = @SNo END C# Code : protected void BtnUserNext_Click(object sender, EventArgs e) { cmd.CommandType = CommandType.StoredProcedure; cmd.CommandText = "usp_User_Info3"; System.Data.SqlClient.SqlParameter SNo=cmd.Parameters.Add("@SNo",System.Data.SqlDbType.Int); System.Data.SqlClient.SqlParameter Vendor_ID=cmd.Parameters.Add("@Vendor_ID", System.Data.SqlDbType.VarChar,10); cmd.Parameters.Add("@UserName", SqlDbType.VarChar).Value = txtUserName.Text; cmd.Parameters.Add("@User_Password", SqlDbType.VarChar).Value = txtRegPassword.Text; cmd.Parameters.Add("@User_ConPassword", SqlDbType.VarChar).Value = txtRegConPassword.Text; cmd.Parameters.Add("@User_FirstName", SqlDbType.VarChar).Value = txtRegFName.Text; cmd.Parameters.Add("@User_LastName", SqlDbType.VarChar).Value = txtRegLName.Text; cmd.Parameters.Add("@User_Title", SqlDbType.VarChar).Value = txtRegTitle.Text; cmd.Parameters.Add("@User_OtherEmail", SqlDbType.VarChar).Value = txtOtherEmail.Text; cmd.Parameters.Add("@User_PhoneNo", SqlDbType.VarChar).Value =txtRegTelephone.Text; cmd.Parameters.Add("@User_MobileNo", SqlDbType.VarChar).Value =txtRegMobile.Text; cmd.Parameters.Add("@User_FaxNo", SqlDbType.VarChar).Value =txtRegFax.Text; cmd.Connection = SqlCon; try { Vendor_ID.Direction = System.Data.ParameterDirection.Output; SqlCon.Open(); cmd.ExecuteNonQuery(); string VendorID = cmd.ExecuteScalar() as string; } catch (Exception ex) { throw new Exception(ex.Message); } finally { string url = "../CompanyBasicInfo.aspx?Parameter=" + Server.UrlEncode(" + VendorID + "); SqlCon.Close(); } }

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  • Changing backgroundcolor in listview (expandable listview)

    - by Stofke
    I'm trying to dynamically change a backgroundcolor in a part of a listview, I have on example that works fine in a listview when I try to replicate it in another part with an expandable listview it fails This piece of code works and displays a different color if a student is online or not ... map.put(KEY_FIRSTNAME, temp.firstName); map.put(KEY_NAME, temp.name); map.put(KEY_EMAIL, temp.email); map.put(KEY_ISONLINE, temp.isOnLine); // change image if student is online or not Log.d("demo", "is on line= " + temp.isOnLine); if (temp.isOnLine.equalsIgnoreCase("1")) { map.put(KEY_IMAGE_ISONLINE, R.color.greenColor); } else { map.put(KEY_IMAGE_ISONLINE, R.color.greyColor); } listItem.add(map); } myListView = (ListView) findViewById(R.id.listViewTabLeerlingen); SimpleAdapter adapter = new SimpleAdapter(StudentTab.this, listItem, R.layout.list_item_student, new String[] { KEY_FIRSTNAME, KEY_NAME, KEY_IMAGE_ISONLINE }, new int[] { R.id.firstNameTextView, R.id.lastNameTextView, R.id.logo }); myListView.setAdapter(adapter); the xml that goes along with it <ImageView android:id="@+id/logo" android:layout_width="85dp" android:layout_height="match_parent" android:background="@color/greenColor" android:contentDescription="Image if student is online or not" android:src="@drawable/transparent_pixel" /> The above works fine however the following code (just part of the code) ... ArrayList<Map<String, Object>> children = new ArrayList<Map<String, Object>>(); for (int i = 0; i < _data.length(); i++) { try { JSONArray tmp = _data.getJSONArray(i); HashMap<String, Object> map = new HashMap<String, Object>(); // change image if student is online or not if (tmp.getString(3).equalsIgnoreCase("0")) { map.put(KEY_POINTS,R.color.redColor); }else{ map.put(KEY_POINTS,R.color.greenColor); } map.put(KEY_QUESTIONTEXT, tmp.getString(1)); map.put(KEY_ANSWER, tmp.getString(2)); children.add(map); } catch (JSONException e) { e.printStackTrace(); } childData.add(children); ... ... ArrayList<ArrayList<Map<String, Object>>> childData) { SimpleExpandableListAdapter listAdapter = new SimpleExpandableListAdapter( this, groupData, R.layout.list_item_results_students, new String[] { KEY_FIRSTNAME, KEY_NAME, KEY_ISJUIST }, new int[] { R.id.firstnameResults, R.id.nameResults, R.id.resultsTextView }, childData, R.layout.list_item_results_results, new String[] { KEY_QUESTIONTEXT, KEY_ANSWER, KEY_POINTS }, new int[] { R.id.questionTextView, R.id.answerTextTextView, R.id.score }); ExpandableListView myListView = (ExpandableListView) findViewById(R.id.listViewTabResultaten); myListView.setAdapter(listAdapter); with xml: <ImageView android:id="@+id/score" android:layout_width="16dp" android:layout_height="match_parent" android:background="@color/greenColor" android:contentDescription="Image if student has correct answer" android:src="@drawable/transparent_pixel" /> I will get this error: 06-09 10:35:21.490: E/AndroidRuntime(4406): java.lang.ClassCastException: android.widget.ImageView cannot be cast to android.widget.TextView

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  • Linq query challenge - can this be done?

    - by vdh_ant
    My table structure is as follows: Person 1-M PesonAddress Person 1-M PesonPhone Person 1-M PesonEmail Person 1-M Contract Contract M-M Program Contract M-1 Organization At the end of this query I need a populated object graph where each person has their: PesonAddress's PesonPhone's PesonEmail's PesonPhone's Contract's - and this has its respective Program's Now I had the following query and I thought that it was working great, but it has a couple of problems: from people in ctx.People.Include("PersonAddress") .Include("PersonLandline") .Include("PersonMobile") .Include("PersonEmail") .Include("Contract") .Include("Contract.Program") where people.Contract.Any( contract => (param.OrganizationId == contract.OrganizationId) && contract.Program.Any( contractProgram => (param.ProgramId == contractProgram.ProgramId))) select people; The problem is that it filters the person to the criteria but not the Contracts or the Contract's Programs. It brings back all Contracts that each person has not just the ones that have an OrganizationId of x and the same goes for each of those Contract's Programs respectively. What I want is only the people that have at least one contract with an OrgId of x with and where that contract has a Program with the Id of y... and for the object graph that is returned to have only the contracts that match and programs within that contract that match. I kinda understand why its not working, but I don't know how to change it so it is working... This is my attempt thus far: from people in ctx.People.Include("PersonAddress") .Include("PersonLandline") .Include("PersonMobile") .Include("PersonEmail") .Include("Contract") .Include("Contract.Program") let currentContracts = from contract in people.Contract where (param.OrganizationId == contract.OrganizationId) select contract let currentContractPrograms = from contractProgram in currentContracts let temp = from x in contractProgram.Program where (param.ProgramId == contractProgram.ProgramId) select x where temp.Any() select temp where currentContracts.Any() && currentContractPrograms.Any() select new Person { PersonId = people.PersonId, FirstName = people.FirstName, ..., ...., MiddleName = people.MiddleName, Surname = people.Surname, ..., ...., Gender = people.Gender, DateOfBirth = people.DateOfBirth, ..., ...., Contract = currentContracts, ... }; //This doesn't work But this has several problems (where the Person type is an EF object): I am left to do the mapping by myself, which in this case there is quite a lot to map When ever I try to map a list to a property (i.e. Scholarship = currentScholarships) it says I can't because IEnumerable is trying to be cast to EntityCollection Include doesn't work Hence how do I get this to work. Keeping in mind that I am trying to do this as a compiled query so I think that means anonymous types are out.

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  • ASP.NET MVC: How can I explain an invalid type violation to an end-user with Html.ValidationSummary?

    - by Terminal Frost
    Serious n00b warning here; please take mercy! So I finished the Nerd Dinner MVC Tutorial and I'm now in the process of converting a VB.NET application to ASP.NET MVC using the Nerd Dinner program as a sort of rough template. I am using the "IsValid / GetRuleViolations()" pattern to identify invalid user input or values that violate business rules. I am using LINQ to SQL and am taking advantage of the "OnValidate()" hook that allows me to run the validation and throw an application exception upon trying to save changes to the database via the CustomerRepository class. Anyway, everything works well, except that by the time the form values reach my validation method invalid types have already been converted to a default or existing value. (I have a "StreetNumber" property that is an integer, though I imagine this would be a problem for DateTime or any other non-strings as well.) Now, I am guessing that the UpdateModel() method throws an exception and then alters the value because the Html.ValidationMessage is displayed next to the StreetNumber field but my validation method never sees the original input. There are two problems with this: While the Html.ValidationMessage does signal that something is wrong, there is no corresponding entry in the Html.ValidationSummary. If I could even get the exception message to show up there indicating an invalid cast or something that would be better than nothing. My validation method which resides in my Customer partial class never sees the original user input so I do not know if the problem is a missing entry or an invalid type. I can't figure out how I can keep my validation logic nice and neat in one place and still get access to the form values. I could of course write some logic in the View that processes the user input, however that seems like the exact opposite of what I should be doing with MVC. Do I need a new validation pattern or is there some way to pass the original form values to my model class for processing? CustomerController Code // POST: /Customers/Edit/[id] [AcceptVerbs(HttpVerbs.Post)] public ActionResult Edit(int id, FormCollection formValues) { Customer customer = customerRepository.GetCustomer(id); try { UpdateModel(customer); customerRepository.Save(); return RedirectToAction("Details", new { id = customer.AccountID }); } catch { foreach (var issue in customer.GetRuleViolations()) ModelState.AddModelError(issue.PropertyName, issue.ErrorMessage); } return View(customer); }

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  • using dictionaries with WebServices

    - by umit-alba
    Hi! I tried to pass a dictionary via WebServices. However it is not serializeable. So i wrote an Own Class that makes it serializeable: using System; using System.Net; using System.Windows; using System.Collections.Generic; using System.Xml.Serialization; using System.Xml; using System.Xml.Schema; namespace Platform { public class SaDictionary<TKey, TValue> : Dictionary<TKey, TValue>, IXmlSerializable { #region Constructors public SaDictionary() : base() { } public SaDictionary(IDictionary<TKey, TValue> dictionary) : base(dictionary) { } public SaDictionary(IEqualityComparer<TKey> comparer) : base(comparer) { } public SaDictionary(int capacity) : base(capacity) { } public SaDictionary(IDictionary<TKey, TValue> dictionary, IEqualityComparer<TKey> comparer) : base(dictionary, comparer) { } public SaDictionary(int capacity, IEqualityComparer<TKey> comparer) : base(capacity, comparer) { } //protected SaDictionary(SerializationInfo info, StreamingContext context) // : base(info, context) //{ //} #endregion public XmlSchema GetSchema() { return null; } public void ReadXml(XmlReader reader) { XmlSerializer keySerializer = new XmlSerializer(typeof(TKey)); XmlSerializer valueSerializer = new XmlSerializer(typeof(TValue)); bool wasEmpty = reader.IsEmptyElement; reader.Read(); if (wasEmpty) return; while (reader.NodeType != XmlNodeType.EndElement) { reader.ReadStartElement("item"); reader.ReadStartElement("key"); TKey key = (TKey)keySerializer.Deserialize(reader); reader.ReadEndElement(); //key reader.ReadStartElement("value"); TValue value = (TValue)valueSerializer.Deserialize(reader); reader.ReadEndElement(); //value this.Add(key, value); reader.ReadEndElement(); //item // reader.MoveToContent(); } reader.ReadEndElement(); } public void WriteXml(XmlWriter writer) { XmlSerializer keySerializer = new XmlSerializer(typeof(TKey)); XmlSerializer valueSerializer = new XmlSerializer(typeof(TValue)); foreach (TKey key in this.Keys) { writer.WriteStartElement("item"); writer.WriteStartElement("key"); keySerializer.Serialize(writer, key); writer.WriteEndElement(); //key writer.WriteStartElement("value"); TValue value = this[key]; valueSerializer.Serialize(writer, value); writer.WriteEndElement(); //value writer.WriteEndElement(); //item } } } } However i get an ArrayOfXElement back. Is there a way to cast it back to a Dictionary? greets

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  • Rails Tutorial Chapter 4 2nd Ed. Title Helper not being called with out argument.

    - by SuddenlyAwakened
    I am running through the Rails Tutorial by Michael Hartl (Screen Cast). Ran into the and issue in chapter 4 on the title helper. I have been putting my own twist on the code as I go to make sure I understand it all. However on this one I it is very similar and I am not quite sure why it is acting the way it is. Here is the code: Application.html.erb <!DOCTYPE html> <html> <head> <%- Rails.logger.info("Testing: #{yield(:title)}") %> <title><%= full_title(yield(:title)) %></title> <%= stylesheet_link_tag "application", :media => "all" %> <%= javascript_include_tag "application" %> <%= csrf_meta_tags %> </head> <body> <%= yield %> </body> </html> Application_helper.rb module ApplicationHelper def full_title(page_title) full_title = "Ruby on Rails Tutorial App" full_title += " | #{page_title}" unless page_title.blank? end end Home.html.erb <h1><%= t(:sample_app) %></h1> <p> This is the home page for the <a href="http://railstutorial.org/">Ruby on Rails Tutorial</a> sample application </p> about.html.erb <% provide(:title, t(:about_us)) %> <h1><%= t(:about_us) %></h1> <p> The <a href="http://railstutorial.org/">Ruby on Rails Tutorial</a> is a project to make a book and screencast to teach web development with <a href="http://railstutorial.org/">Ruby on Rails</a>. This is the sample application for the tutorial. </p> What Happens: The code works fine when I set the provide method like on the about page. However when I do not it does not seem to even call the helper. I am assuming that because no title is passed back. Any ideas on what I am doing wrong? Thank you all for your help.

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  • Values of generated column not appearing in table

    - by msh210
    I'm using mysql version 5.1.41-3ubuntu12.10 (Ubuntu). mysql> show create table tt\G *************************** 1. row *************************** Table: tt Create Table: CREATE TABLE `tt` ( `pz` int(8) DEFAULT NULL, `os` varchar(8) DEFAULT NULL, `uz` int(11) NOT NULL, `p` bigint(21) NOT NULL DEFAULT '0', `c` decimal(23,0) DEFAULT NULL, KEY `pz` (`pz`), KEY `uz` (`uz`), KEY `os` (`os`), KEY `pz_2` (`pz`,`uz`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 1 row in set (0.00 sec) mysql> select pz,uz,pz*uz, -> if(pz*uz,1,.5), -> left(pz,2) pl,left(lpad(uz,5,0),2) ul, -> p from tt limit 10; +-------+----+-------+----------------+--------+----+--------+ | pz | uz | pz*uz | if(pz*uz,1,.5) | pl | ul | p | +-------+----+-------+----------------+--------+----+--------+ | NULL | 0 | NULL | 0.5 | NULL | 00 | 4080 | | NULL | 0 | NULL | 0.5 | NULL | 00 | 323754 | | 89101 | 0 | 0 | 0.5 | 89 | 00 | 6880 | | 0 | 0 | 0 | 0.5 | 0 | 00 | 11591 | | 89110 | 0 | 0 | 0.5 | 89 | 00 | 72 | | 78247 | 0 | 0 | 0.5 | 78 | 00 | 27 | | 90062 | 0 | 0 | 0.5 | 90 | 00 | 5 | | 63107 | 0 | 0 | 0.5 | 63 | 00 | 4 | | NULL | 0 | NULL | 0.5 | NULL | 00 | 54561 | | 94102 | 0 | 0 | 0.5 | 94 | 00 | 12499 | +-------+----+-------+----------------+--------+----+--------+ So far so good. As you see, 0.5 appears as a value of if(pz*uz,1,.5). The problem is: mysql> select os, -> if(pz*uz,left(pz,2)<=>left(lpad(uz,5,0),2),.5) uptwo, -> if(pz*uz,left(pz,3)<=>left(lpad(uz,5,0),3),.5) upthree, -> sum(p) p,sum(c) c -> from tt t -> group by os,uptwo,upthree order by null; +----+-------+---------+---------+-------+ | os | uptwo | upthree | p | c | +----+-------+---------+---------+-------+ | u | 1 | 1 | 52852 | 318 | | i | 1 | 1 | 7046563 | 21716 | | m | 1 | 1 | 1252166 | 7337 | | i | 0 | 0 | 1830284 | 4033 | | m | 0 | 0 | 294612 | 1714 | | i | 1 | 0 | 911486 | 3560 | | m | 1 | 0 | 145182 | 1136 | | u | 0 | 0 | 12144 | 23 | | u | 1 | 0 | 1571 | 8 | +----+-------+---------+---------+-------+ Although I group by uptwo, 0.5 doesn't appear in that column. What happened to the 0.5 values? Edit: As noted in the comments to Todd Gibson's answer, I also tried it with if(pz*uz,cast(left(pz,2)<=>left(lpad(uz,5,0),2) as decimal),.5) instead of if(pz*uz,left(pz,2)<=>left(lpad(uz,5,0),2),.5), but it, too, didn't work.

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  • how to update an Android ListActivity on changing data of the connected SimpleCursorAdapter

    - by 4485670
    I have the following code. What I want to achieve is to update the shown list when I click an entry so I can traverse through the list. I found the two uncommented ways to do it here on stackoverflow, but neither works. I also got the advice to create a new ListActivity on the data update, but that sounds like wasting resources? EDIT: I found the solution myself. All you need to do is call "SimpleCursorAdapter.changeCursor(new Cursor);". No notifying, no things in UI-Thread or whatever. import android.app.ListActivity; import android.database.Cursor; import android.os.Bundle; import android.util.Log; import android.view.View; import android.widget.ListView; import android.widget.SimpleCursorAdapter; public class MyActivity extends ListActivity { private DepartmentDbAdapter mDbHelper; private Cursor cursor; private String[] from = new String[] { DepartmentDbAdapter.KEY_NAME }; private int[] to = new int[] { R.id.text1 }; private SimpleCursorAdapter notes; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.departments_list); mDbHelper = new DepartmentDbAdapter(this); mDbHelper.open(); // Get all of the departments from the database and create the item list cursor = mDbHelper.fetchSubItemByParentId(1); this.startManagingCursor(cursor); // Now create an array adapter and set it to display using our row notes = new SimpleCursorAdapter(this, R.layout.department_row, cursor, from, to); this.setListAdapter(notes); } @Override protected void onListItemClick(ListView l, View v, int position, long id) { super.onListItemClick(l, v, position, id); // get new data and update the list this.updateData(safeLongToInt(id)); } /** * update data for the list * * @param int departmentId id of the parent department */ private void updateData(int departmentId) { // close the old one, get a new one cursor.close(); cursor = mDbHelper.fetchSubItemByParentId(departmentId); // change the cursor of the adapter to the new one notes.changeCursor(cursor); } /** * safely convert long to in to save memory * * @param long l the long variable * * @return integer */ public static int safeLongToInt(long l) { if (l < Integer.MIN_VALUE || l > Integer.MAX_VALUE) { throw new IllegalArgumentException (l + " cannot be cast to int without changing its value."); } return (int) l; } }

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  • Specializating a template function that takes a universal reference parameter

    - by David Stone
    How do I specialize a template function that takes a universal reference parameter? foo.hpp: template<typename T> void foo(T && t) // universal reference parameter foo.cpp template<> void foo<Class>(Class && class) { // do something complicated } Here, Class is no longer a deduced type and thus is Class exactly; it cannot possibly be Class &, so reference collapsing rules will not help me here. I could perhaps create another specialization that takes a Class & parameter (I'm not sure), but that implies duplicating all of the code contained within foo for every possible combination of rvalue / lvalue references for all parameters, which is what universal references are supposed to avoid. Is there some way to accomplish this? To be more specific about my problem in case there is a better way to solve it: I have a program that can connect to multiple game servers, and each server, for the most part, calls everything by the same name. However, they have slightly different versions for a few things. There are a few different categories that these things can be: a move, an item, etc. I have written a generic sort of "move string to move enum" set of functions for internal code to call, and my server interface code has similar functions. However, some servers have their own internal ID that they communicate with, some use strings, and some use both in different situations. Now what I want to do is make this a little more generic. I want to be able to call something like ServerNamespace::server_cast<Destination>(source). This would allow me to cast from a Move to a std::string or ServerMoveID. Internally, I may need to make a copy (or move from) because some servers require that I keep a history of messages sent. Universal references seem to be the obvious solution to this problem. The header file I'm thinking of right now would expose simply this: namespace ServerNamespace { template<typename Destination, typename Source> Destination server_cast(Source && source); } And the implementation file would define all legal conversions as template specializations.

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  • casting doubles to integers in order to gain speed

    - by antirez
    Hello all, in Redis (http://code.google.com/p/redis) there are scores associated to elements, in order to take this elements sorted. This scores are doubles, even if many users actually sort by integers (for instance unix times). When the database is saved we need to write this doubles ok disk. This is what is used currently: snprintf((char*)buf+1,sizeof(buf)-1,"%.17g",val); Additionally infinity and not-a-number conditions are checked in order to also represent this in the final database file. Unfortunately converting a double into the string representation is pretty slow. While we have a function in Redis that converts an integer into a string representation in a much faster way. So my idea was to check if a double could be casted into an integer without lost of data, and then using the function to turn the integer into a string if this is true. For this to provide a good speedup of course the test for integer "equivalence" must be fast. So I used a trick that is probably undefined behavior but that worked very well in practice. Something like that: double x = ... some value ... if (x == (double)((long long)x)) use_the_fast_integer_function((long long)x); else use_the_slow_snprintf(x); In my reasoning the double casting above converts the double into a long, and then back into an integer. If the range fits, and there is no decimal part, the number will survive the conversion and will be exactly the same as the initial number. As I wanted to make sure this will not break things in some system, I joined #c on freenode and I got a lot of insults ;) So I'm now trying here. Is there a standard way to do what I'm trying to do without going outside ANSI C? Otherwise, is the above code supposed to work in all the Posix systems that currently Redis targets? That is, archs where Linux / Mac OS X / *BSD / Solaris are running nowaday? What I can add in order to make the code saner is an explicit check for the range of the double before trying the cast at all. Thank you for any help.

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  • JAXB doesn't unmarshal list of interfaces

    - by Joker_vD
    It seems JAXB can't read what it writes. Consider the following code: interface IFoo { void jump(); } @XmlRootElement class Bar implements IFoo { @XmlElement public String y; public Bar() { y = ""; } public Bar(String y) { this.y = y; } @Override public void jump() { System.out.println(y); } } @XmlRootElement class Baz implements IFoo { @XmlElement public int x; public Baz() { x = 0; } public Baz(int x) { this.x = x; } @Override public void jump() { System.out.println(x); } } @XmlRootElement public class Holder { private List<IFoo> things; public Holder() { things = new ArrayList<>(); } @XmlElementWrapper @XmlAnyElement public List<IFoo> getThings() { return things; } public void addThing(IFoo thing) { things.add(thing); } } // ... try { JAXBContext context = JAXBContext.newInstance(Holder.class, Bar.class, Baz.class); Holder holder = new Holder(); holder.addThing(new Bar("1")); holder.addThing(new Baz(2)); holder.addThing(new Baz(3)); for (IFoo thing : holder.getThings()) { thing.jump(); } StringWriter s = new StringWriter(); context.createMarshaller().marshal(holder, s); String data = s.toString(); System.out.println(data); StringReader t = new StringReader(data); Holder holder2 = (Holder)context.createUnmarshaller().unmarshal(t); for (IFoo thing : holder2.getThings()) { thing.jump(); } } catch (Exception e) { System.err.println(e.getMessage()); } It's a simplified example, of course. The point is that I have to store two very differently implemented classes, Bar and Baz, in one collection. Well, I observed that they have pretty similar public interface, so I created an interface IFoo and made them two to implement it. Now, I want to have tools to save and load this collection to/from XML. Unfortunately, this code doesn't quite work: the collection is saved, but then it cannot be loaded! The intended output is 1 2 3 some xml 1 2 3 But unfortunately, the actual output is 1 2 3 some xml com.sun.org.apache.xerces.internal.dom.ElementNSImpl cannot be cast to testapplication1.IFoo Apparently, I need to use the annotations in a different way? Or to give up on JAXB and look for something else? I, well, can write "XMLNode toXML()" method for all classes I wan't to (de)marshal, but...

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  • Simplifying const Overloading?

    - by templatetypedef
    Hello all- I've been teaching a C++ programming class for many years now and one of the trickiest things to explain to students is const overloading. I commonly use the example of a vector-like class and its operator[] function: template <typename T> class Vector { public: T& operator[] (size_t index); const T& operator[] (size_t index) const; }; I have little to no trouble explaining why it is that two versions of the operator[] function are needed, but in trying to explain how to unify the two implementations together I often find myself wasting a lot of time with language arcana. The problem is that the only good, reliable way that I know how to implement one of these functions in terms of the other is with the const_cast/static_cast trick: template <typename T> const T& Vector<T>::operator[] (size_t index) const { /* ... your implementation here ... */ } template <typename T> T& Vector<T>::operator[] (size_t index) { return const_cast<T&>(static_cast<const Vector&>(*this)[index]); } The problem with this setup is that it's extremely tricky to explain and not at all intuitively obvious. When you explain it as "cast to const, then call the const version, then strip off constness" it's a little easier to understand, but the actual syntax is frightening,. Explaining what const_cast is, why it's appropriate here, and why it's almost universally inappropriate elsewhere usually takes me five to ten minutes of lecture time, and making sense of this whole expression often requires more effort than the difference between const T* and T* const. I feel that students need to know about const-overloading and how to do it without needlessly duplicating the code in the two functions, but this trick seems a bit excessive in an introductory C++ programming course. My question is this - is there a simpler way to implement const-overloaded functions in terms of one another? Or is there a simpler way of explaining this existing trick to students? Thanks so much!

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  • Passing enums to functions in C++

    - by rocknroll
    Hi all, I have a header file with all the enums listed (#ifndef #define #endif construct has been used to avoid multiple inclusion of the file) that I use in multiple cpp files in my application.One of the enums in the files is enum StatusSubsystem {ENABLED,INCORRECT_FRAME,INVALID_DATA,DISABLED}; There are functions in the application delcared as ShowStatus(const StatusSubsystem&); Earlier in the application when I made calls to the above function like ShowStatus(INCORRECT_FRAME); my application used to compile perfectly. But after some code was added The compilation halts giving the following error: File.cpp:71: error: invalid conversion from `int' to `StatusSubsystem' File.cpp:71: error: initializing argument 1 of `void Class::ShowStatus(const StatusSubsystem&) I checked the code for any conflicting enums in the new code and it looked fine. My Question is what is wrong with the function call that compiler shows as erroneous? For your reference the function definition is: void Class::ShowStatus(const StatusSubsystem& eStatus) { QPalette palette; mStatus=eStatus;//store current Communication status of system if(eStatus==DISABLED) { //select red color for label, if it is to be shown disabled palette.setColor(QPalette::Window,QColor(Qt::red)); mLabel->setText("SYSTEM"); } else if(eStatus==ENABLED) { //select green color for label,if it is to be shown enabled palette.setColor(QPalette::Window,QColor(Qt::green)); mLabel->setText("SYSTEM"); } else if(eStatus==INCORRECT_FRAME) { //select yellow color for label,to show that it is sending incorrect frames palette.setColor(QPalette::Window,QColor(Qt::yellow)); mLabel->setText("SYSTEM(I)"); } //Set the color on the Label mLabel->setPalette(palette); } A strange side effect of this situation is it compiles when I cast all the calls to ShowStatus() as ShowStatus((StatusSubsystem)INCORRECT_FRAME); Though this removes any compilation error, but a strange thing happens. Though I make call to INCORRECT_FRAME above but in function definition it matches with ENABLED. How on earth is that possible? Its like while passing INCORRECT_FRAME by reference, it magically converts to ENABLED, which should be impossible. This is driving me nuts. Can you find any flaw in what I am doing? or is it something else? The application is made using C++,Qt-4.2.1 on RHEL4. Thanks.

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  • This code appears to achieve the return of a null reference in C++

    - by Chuck
    Hi folks, My C++ knowledge is somewhat piecemeal. I was reworking some code at work. I changed a function to return a reference to a type. Inside, I look up an object based on an identifier passed in, then return a reference to the object if found. Of course I ran into the issue of what to return if I don't find the object, and in looking around the web, many people claim that returning a "null reference" in C++ is impossible. Based on this advice, I tried the trick of returning a success/fail boolean, and making the object reference an out parameter. However, I ran into the roadblock of needing to initialize the references I would pass as actual parameters, and of course there is no way to do this. I retreated to the usual approach of just returning a pointer. I asked a colleague about it. He uses the following trick quite often, which is accepted by both a recent version of the Sun compiler and by gcc: MyType& someFunc(int id) { // successful case here: // ... // fail case: return *static_cast<MyType*>(0); } // Use: ... MyType& mt = somefunc(myIdNum); if (&mt) // test for "null reference" { // whatever } ... I have been maintaining this code base for a while, but I find that I don't have as much time to look up the small details about the language as I would like. I've been digging through my reference book but the answer to this one eludes me. Now, I had a C++ course a few years ago, and therein we emphasized that in C++ everything is types, so I try to keep that in mind when thinking things through. Deconstructing the expression: "*static_cast(0);", it indeed seems to me that we take a literal zero, cast it to a pointer to MyType (which makes it a null pointer), and then apply the dereferencing operator in the context of assigning to a reference type (the return type), which should give me a reference to the same object pointed to by the pointer. This sure looks like returning a null reference to me. Any advice in explaining why this works (or why it shouldn't) would be greatly appreciated. Thanks, Chuck

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  • RequestFactoryEditorDriver getting edited data after flush

    - by Deanna
    Let me start with I have a solution, but I don't really think it is elegant. So, I am looking for a cleaner way to do this. I have an EntityProxy displayed in a view panel. The view panel is a RequestFactoryEditorDriver only using display mode. The user clicks on a data element and opens a popup editor to edit a data element of the EntityProxy with a few more bits of data than is displayed in the view panel. When the user saves the element I need the view panel to update the display. I ran into a problem because the RequestFactoryEditorDriver of the popup editor flow doesn't let you get to the edited data. The driver uses the passed in context and sends it to the server. The context returned out of flush only allows a Receiver even if you cast it to the type of context you stored in the editor driver in the edit() call. It doesn't appear to send and EntityProxyChanged event either, so I couldn't listen for that and update the display view. The solution I found was to change my domain object persist to return the newly saved entity. Then create the popup editor like this editor.getSaveButtonClickHandler().addClickHandler(createSaveHandler(driver, editor)); // initialize the Driver and edit the given text. driver.initialize(rf, editor); PlayerProfileCtx ctx = rf.playerProfile(); ctx.persist().using(playerProfile).with(driver.getPaths()) .to(new Receiver<PlayerProfileProxy>(){ @Override public void onSuccess(PlayerProfileProxy profile) { editor.hide(); playerProfile = profile; viewDriver.display(playerProfile); } }); driver.edit(playerProfile, ctx); editor.centerAndShow(); Then in the save handler I just fire the context I get from the flush. While this approach works, it doesn't seem right. It would seem I should subscribe to the entitychanged event in the display view and update the entity and the view from there. Also this approach saves the complete entity, not just the changed bits, which will increase bandwidth usage. What I would think should happen, is when you flush the entity it should 'optimistically' update the rf managed version of the entity and fire the entity proxy changed event. Only reverting the entity if something went wrong in the save. The actual save should only send the changed bits. In this way there isn't a need to refetch the whole entity and send that complete data over the wire twice. Is there a better solution?

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  • Refactor the following two C++ methods to move out duplicate code

    - by ossandcad
    I have the following two methods that (as you can see) are similar in most of its statements except for one (see below for details) unsigned int CSWX::getLineParameters(const SURFACE & surface, vector<double> & params) { VARIANT varParams; surface->getPlaneParams(varParams); // this is the line of code that is different SafeDoubleArray sdParams(varParams); for( int i = 0 ; i < sdParams.getSize() ; ++i ) { params.push_back(sdParams[i]); } if( params.size() > 0 ) return 0; return 1; } unsigned int CSWX::getPlaneParameters(const CURVE & curve, vector<double> & params) { VARIANT varParams; curve->get_LineParams(varParams); // this is the line of code that is different SafeDoubleArray sdParams(varParams); for( int i = 0 ; i < sdParams.getSize() ; ++i ) { params.push_back(sdParams[i]); } if( params.size() > 0 ) return 0; return 1; } Is there any technique that I can use to move the common lines of code of the two methods out to a separate method, that could be called from the two variations - OR - possibly combine the two methods to a single method? The following are the restrictions: The classes SURFACE and CURVE are from 3rd party libraries and hence unmodifiable. (If it helps they are both derived from IDispatch) There are even more similar classes (e.g. FACE) that could fit into this "template" (not C++ template, just the flow of lines of code) I know the following could (possibly?) be implemented as solutions but am really hoping there is a better solution: I could add a 3rd parameter to the 2 methods - e.g. an enum - that identifies the 1st parameter (e.g. enum::input_type_surface, enum::input_type_curve) I could pass in an IDispatch and try dynamic_cast< and test which cast is NON_NULL and do an if-else to call the right method (e.g. getPlaneParams() vs. get_LineParams()) The following is not a restriction but would be a requirement because of my teammates resistance: Not implement a new class that inherits from SURFACE/CURVE etc. (They would much prefer to solve it using the enum solution I stated above)

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  • Several C# Language Questions

    - by Water Cooler v2
    1) What is int? Is it any different from the struct System.Int32? I understand that the former is a C# alias (typedef or #define equivalant) for the CLR type System.Int32. Is this understanding correct? 2) When we say: IComparable x = 10; Is that like saying: IComparable x = new System.Int32(); But we can't new a struct, right? or in C like syntax: struct System.In32 *x; x=>someThing = 10; 3) What is String with a capitalized S? I see in Reflector that it is the sealed String class, which, of course, is a reference type, unlike the System.Int32 above, which is a value type. What is string, with an uncapitalized s, though? Is that also the C# alias for this class? Why can I not see the alias definitions in Reflector? 4) Try to follow me down this subtle train of thought, if you please. We know that a storage location of a particular type can only access properties and members on its interface. That means: Person p = new Customer(); p.Name = "Water Cooler v2"; // legal because as Name is defined on Person. but // illegal without an explicit cast even though the backing // store is a Customer, the storage location is of type // Person, which doesn't support the member/method being // accessed/called. p.GetTotalValueOfOrdersMade(); Now, with that inference, consider this scenario: int i = 10; // obvious System.object defines no member to // store an integer value or any other value in. // So, my question really is, when the integer is // boxed, what is the *type* it is actually boxed to. // In other words, what is the type that forms the // backing store on the heap, for this operation? object x = i; Update Thank you for your answers, Eric Gunnerson and Aaronought. I'm afraid I haven't been able to articulate my questions well enough to attract very satisfying answers. The trouble is, I do know the answers to my questions on the surface, and I am, by no means, a newbie programmer. But I have to admit, a deeper understanding to the intricacies of how a language and its underlying platform/runtime handle storage of types has eluded me for as long as I've been a programmer, even though I write correct code.

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  • Error reading values from dynamically created table rows in Android

    - by jaymo
    So I have a couple of dynamically created tablerows.Each TableRow has a couple of Textviews.I have a button that on clicked should get all the values of the second and third textviews in each Tablerow in the Table. I have tried to do this using the code below mSubmitOrders.setOnClickListener(new View.OnClickListener() { public void onClick(View v) { if(mTable.getChildCount()>1){ for(int i = 0; i < mTable.getChildCount(); i++){ TableRow tr = (TableRow)mTable.getChildAt(i); TextView code = (TextView) tr.getChildAt(1); TextView quantity = (TextView) tr.getChildAt(2); String Scode = code.getText().toString(); Log.i("TAG", Scode); String Squantity = quantity.getText().toString(); Log.i("TAG", Squantity); } } But I get the below errors (Logcat below). Assistance required 10-22 09:00:16.345: E/AndroidRuntime(4495): FATAL EXCEPTION: main 10-22 09:00:16.345: E/AndroidRuntime(4495): java.lang.ClassCastException: android.widget.LinearLayout cannot be cast to android.widget.TextView 10-22 09:00:16.345: E/AndroidRuntime(4495): at com.symetry.myitprovider.ui.actual$4.onClick(actual.java:173) 10-22 09:00:16.345: E/AndroidRuntime(4495): at android.view.View.performClick(View.java:3131) 10-22 09:00:16.345: E/AndroidRuntime(4495): at android.view.View$PerformClick.run(View.java:12035) 10-22 09:00:16.345: E/AndroidRuntime(4495): at android.os.Handler.handleCallback(Handler.java:587) 10-22 09:00:16.345: E/AndroidRuntime(4495): at android.os.Handler.dispatchMessage(Handler.java:92) 10-22 09:00:16.345: E/AndroidRuntime(4495): at android.os.Looper.loop(Looper.java:132) 10-22 09:00:16.345: E/AndroidRuntime(4495): at android.app.ActivityThread.main(ActivityThread.java:4123) 10-22 09:00:16.345: E/AndroidRuntime(4495): at java.lang.reflect.Method.invokeNative(Native Method) 10-22 09:00:16.345: E/AndroidRuntime(4495): at java.lang.reflect.Method.invoke(Method.java:491) 10-22 09:00:16.345: E/AndroidRuntime(4495): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:844) 10-22 09:00:16.345: E/AndroidRuntime(4495): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:602) 10-22 09:00:16.345: E/AndroidRuntime(4495): at dalvik.system.NativeStart.main(Native Method) EDIT: I have modified my code and now there is no error..but its not working as needed.. The new code is as below.. mSubmitOrders.setOnClickListener(new View.OnClickListener() { public void onClick(View v) { if(mTable.getChildCount()>1){ for(int i = 0; i < mTable.getChildCount(); i++){ //TODO: Figure out how to do this well LinearLayout LL = (LinearLayout)mTable.getChildAt(i); View x = ((View)(LL.getParent()).getParent()); Log.i("TAG", "Past view"); TextView code = (TextView)((ViewGroup) x).getChildAt(2); String Scode = code.getText().toString(); Log.i("TAG", Scode); } But thing is its not getting the texview from TableLayout's Table Row..its getting a different one...the one I have circled in the picture ![Error]:http://semasoftltd.com/error.png

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  • Handling Model Inheritance in ASP.NET MVC2

    - by enth
    I've gotten myself stuck on how to handle inheritance in my model when it comes to my controllers/views. Basic Model: public class Procedure : Entity { public Procedure() { } public int Id { get; set; } public DateTime ProcedureDate { get; set; } public ProcedureType Type { get; set; } } public ProcedureA : Procedure { public double VariableA { get; set; } public int VariableB { get; set; } public int Total { get; set; } } public ProcedureB : Procedure { public int Score { get; set; } } etc... many of different procedures eventually. So, I do things like list all the procedures: public class ProcedureController : Controller { public virtual ActionResult List() { IEnumerable<Procedure> procedures = _repository.GetAll(); return View(procedures); } } but now I'm kinda stuck. Basically, from the list page, I need to link to pages where the specific subclass details can be viewed/edited and I'm not sure what the best strategy is. I thought I could add an action on the ProcedureController that would conjure up the right subclass by dynamically figuring out what repository to use and loading the subclass to pass to the view. I had to store the class in the ProcedureType object. I had to create/implement a non-generic IRepository since I can't dynamically cast to a generic one. public virtual ActionResult Details(int procedureID) { Procedure procedure = _repository.GetById(procedureID, false); string className = procedure.Type.Class; Type type = Type.GetType(className, true); Type repositoryType = typeof (IRepository<>).MakeGenericType(type); var repository = (IRepository)DependencyRegistrar.Resolve(repositoryType); Entity procedure = repository.GetById(procedureID, false); return View(procedure); } I haven't even started sorting out how the view is going to determine which partial to load to display the subclass details. I'm wondering if this is a good approach? This makes determining the URL easy. It makes reusing the Procedure display code easy. Another approach is specific controllers for each subclass. It simplifies the controller code, but also means many simple controllers for the many procedure subclasses. Can work out the shared Procedure details with a partial view. How to get to construct the URL to get to the controller/action in the first place? Time to not think about it. Hopefully someone can show me the light. Thanks in advance.

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  • Creating a dynamic proxy generator with c# – Part 2 – Interceptor Design

    - by SeanMcAlinden
    Creating a dynamic proxy generator – Part 1 – Creating the Assembly builder, Module builder and caching mechanism For the latest code go to http://rapidioc.codeplex.com/ Before getting too involved in generating the proxy, I thought it would be worth while going through the intended design, this is important as the next step is to start creating the constructors for the proxy. Each proxy derives from a specified type The proxy has a corresponding constructor for each of the base type constructors The proxy has overrides for all methods and properties marked as Virtual on the base type For each overridden method, there is also a private method whose sole job is to call the base method. For each overridden method, a delegate is created whose sole job is to call the private method that calls the base method. The following class diagram shows the main classes and interfaces involved in the interception process. I’ll go through each of them to explain their place in the overall proxy.   IProxy Interface The proxy implements the IProxy interface for the sole purpose of adding custom interceptors. This allows the created proxy interface to be cast as an IProxy and then simply add Interceptors by calling it’s AddInterceptor method. This is done internally within the proxy building process so the consumer of the API doesn’t need knowledge of this. IInterceptor Interface The IInterceptor interface has one method: Handle. The handle method accepts a IMethodInvocation parameter which contains methods and data for handling method interception. Multiple classes that implement this interface can be added to the proxy. Each method override in the proxy calls the handle method rather than simply calling the base method. How the proxy fully works will be explained in the next section MethodInvocation. IMethodInvocation Interface & MethodInvocation class The MethodInvocation will contain one main method and multiple helper properties. Continue Method The method Continue() has two functions hidden away from the consumer. When Continue is called, if there are multiple Interceptors, the next Interceptors Handle method is called. If all Interceptors Handle methods have been called, the Continue method then calls the base class method. Properties The MethodInvocation will contain multiple helper properties including at least the following: Method Name (Read Only) Method Arguments (Read and Write) Method Argument Types (Read Only) Method Result (Read and Write) – this property remains null if the method return type is void Target Object (Read Only) Return Type (Read Only) DefaultInterceptor class The DefaultInterceptor class is a simple class that implements the IInterceptor interface. Here is the code: DefaultInterceptor namespace Rapid.DynamicProxy.Interception {     /// <summary>     /// Default interceptor for the proxy.     /// </summary>     /// <typeparam name="TBase">The base type.</typeparam>     public class DefaultInterceptor<TBase> : IInterceptor<TBase> where TBase : class     {         /// <summary>         /// Handles the specified method invocation.         /// </summary>         /// <param name="methodInvocation">The method invocation.</param>         public void Handle(IMethodInvocation<TBase> methodInvocation)         {             methodInvocation.Continue();         }     } } This is automatically created in the proxy and is the first interceptor that each method override calls. It’s sole function is to ensure that if no interceptors have been added, the base method is still called. Custom Interceptor Example A consumer of the Rapid.DynamicProxy API could create an interceptor for logging when the FirstName property of the User class is set. Just for illustration, I have also wrapped a transaction around the methodInvocation.Coninue() method. This means that any overriden methods within the user class will run within a transaction scope. MyInterceptor public class MyInterceptor : IInterceptor<User<int, IRepository>> {     public void Handle(IMethodInvocation<User<int, IRepository>> methodInvocation)     {         if (methodInvocation.Name == "set_FirstName")         {             Logger.Log("First name seting to: " + methodInvocation.Arguments[0]);         }         using (TransactionScope scope = new TransactionScope())         {             methodInvocation.Continue();         }         if (methodInvocation.Name == "set_FirstName")         {             Logger.Log("First name has been set to: " + methodInvocation.Arguments[0]);         }     } } Overridden Method Example To show a taster of what the overridden methods on the proxy would look like, the setter method for the property FirstName used in the above example would look something similar to the following (this is not real code but will look similar): set_FirstName public override void set_FirstName(string value) {     set_FirstNameBaseMethodDelegate callBase =         new set_FirstNameBaseMethodDelegate(this.set_FirstNameProxyGetBaseMethod);     object[] arguments = new object[] { value };     IMethodInvocation<User<IRepository>> methodInvocation =         new MethodInvocation<User<IRepository>>(this, callBase, "set_FirstName", arguments, interceptors);          this.Interceptors[0].Handle(methodInvocation); } As you can see, a delegate instance is created which calls to a private method on the class, the private method calls the base method and would look like the following: calls base setter private void set_FirstNameProxyGetBaseMethod(string value) {     base.set_FirstName(value); } The delegate is invoked when methodInvocation.Continue() is called within an interceptor. The set_FirstName parameters are loaded into an object array. The current instance, delegate, method name and method arguments are passed into the methodInvocation constructor (there will be more data not illustrated here passed in when created including method info, return types, argument types etc.) The DefaultInterceptor’s Handle method is called with the methodInvocation instance as it’s parameter. Obviously methods can have return values, ref and out parameters etc. in these cases the generated method override body will be slightly different from above. I’ll go into more detail on these aspects as we build them. Conclusion I hope this has been useful, I can’t guarantee that the proxy will look exactly like the above, but at the moment, this is pretty much what I intend to do. Always worth downloading the code at http://rapidioc.codeplex.com/ to see the latest. There will also be some tests that you can debug through to help see what’s going on. Cheers, Sean.

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  • HttpContext.Items and Server.Transfer/Execute

    - by Rick Strahl
    A few days ago my buddy Ben Jones pointed out that he ran into a bug in the ScriptContainer control in the West Wind Web and Ajax Toolkit. The problem was basically that when a Server.Transfer call was applied the script container (and also various ClientScriptProxy script embedding routines) would potentially fail to load up the specified scripts. It turns out the problem is due to the fact that the various components in the toolkit use request specific singletons via a Current property. I use a static Current property tied to a Context.Items[] entry to handle this type of operation which looks something like this: /// <summary> /// Current instance of this class which should always be used to /// access this object. There are no public constructors to /// ensure the reference is used as a Singleton to further /// ensure that all scripts are written to the same clientscript /// manager. /// </summary> public static ClientScriptProxy Current { get { if (HttpContext.Current == null) return new ClientScriptProxy(); ClientScriptProxy proxy = null; if (HttpContext.Current.Items.Contains(STR_CONTEXTID)) proxy = HttpContext.Current.Items[STR_CONTEXTID] as ClientScriptProxy; else { proxy = new ClientScriptProxy(); HttpContext.Current.Items[STR_CONTEXTID] = proxy; } return proxy; } } The proxy is attached to a Context.Items[] item which makes the instance Request specific. This works perfectly fine in most situations EXCEPT when you’re dealing with Server.Transfer/Execute requests. Server.Transfer doesn’t cause Context.Items to be cleared so both the current transferred request and the original request’s Context.Items collection apply. For the ClientScriptProxy this causes a problem because script references are tracked on a per request basis in Context.Items to check for script duplication. Once a script is rendered an ID is written into the Context collection and so considered ‘rendered’: // No dupes - ref script include only once if (HttpContext.Current.Items.Contains( STR_SCRIPTITEM_IDENTITIFIER + fileId ) ) return; HttpContext.Current.Items.Add(STR_SCRIPTITEM_IDENTITIFIER + fileId, string.Empty); where the fileId is the script name or unique identifier. The problem is on the Transferred page the item will already exist in Context and so fail to render because it thinks the script has already rendered based on the Context item. Bummer. The workaround for this is simple once you know what’s going on, but in this case it was a bitch to track down because the context items are used in many places throughout this class. The trick is to determine when a request is transferred and then removing the specific keys. The first issue is to determine if a script is in a Trransfer or Execute call: if (HttpContext.Current.CurrentHandler != HttpContext.Current.Handler) Context.Handler is the original handler and CurrentHandler is the actual currently executing handler that is running when a Transfer/Execute is active. You can also use Context.PreviousHandler to get the last handler and chain through the whole list of handlers applied if Transfer calls are nested (dog help us all for the person debugging that). For the ClientScriptProxy the full logic to check for a transfer and remove the code looks like this: /// <summary> /// Clears all the request specific context items which are script references /// and the script placement index. /// </summary> public void ClearContextItemsOnTransfer() { if (HttpContext.Current != null) { // Check for Server.Transfer/Execute calls - we need to clear out Context.Items if (HttpContext.Current.CurrentHandler != HttpContext.Current.Handler) { List<string> Keys = HttpContext.Current.Items.Keys.Cast<string>().Where(s => s.StartsWith(STR_SCRIPTITEM_IDENTITIFIER) || s == STR_ScriptResourceIndex).ToList(); foreach (string key in Keys) { HttpContext.Current.Items.Remove(key); } } } } along with a small update to the Current property getter that sets a global flag to indicate whether the request was transferred: if (!proxy.IsTransferred && HttpContext.Current.Handler != HttpContext.Current.CurrentHandler) { proxy.ClearContextItemsOnTransfer(); proxy.IsTransferred = true; } return proxy; I know this is pretty ugly, but it works and it’s actually minimal fuss without affecting the behavior of the rest of the class. Ben had a different solution that involved explicitly clearing out the Context items and replacing the collection with a manually maintained list of items which also works, but required changes through the code to make this work. In hindsight, it would have been better to use a single object that encapsulates all the ‘persisted’ values and store that object in Context instead of all these individual small morsels. Hindsight is always 20/20 though :-}. If possible use Page.Items ClientScriptProxy is a generic component that can be used from anywhere in ASP.NET, so there are various methods that are not Page specific on this component which is why I used Context.Items, rather than the Page.Items collection.Page.Items would be a better choice since it will sidestep the above Server.Transfer nightmares as the Page is reloaded completely and so any new Page gets a new Items collection. No fuss there. So for the ScriptContainer control, which has to live on the page the behavior is a little different. It is attached to Page.Items (since it’s a control): /// <summary> /// Returns a current instance of this control if an instance /// is already loaded on the page. Otherwise a new instance is /// created, added to the Form and returned. /// /// It's important this function is not called too early in the /// page cycle - it should not be called before Page.OnInit(). /// /// This property is the preferred way to get a reference to a /// ScriptContainer control that is either already on a page /// or needs to be created. Controls in particular should always /// use this property. /// </summary> public static ScriptContainer Current { get { // We need a context for this to work! if (HttpContext.Current == null) return null; Page page = HttpContext.Current.CurrentHandler as Page; if (page == null) throw new InvalidOperationException(Resources.ERROR_ScriptContainer_OnlyWorks_With_PageBasedHandlers); ScriptContainer ctl = null; // Retrieve the current instance ctl = page.Items[STR_CONTEXTID] as ScriptContainer; if (ctl != null) return ctl; ctl = new ScriptContainer(); page.Form.Controls.Add(ctl); return ctl; } } The biggest issue with this approach is that you have to explicitly retrieve the page in the static Current property. Notice again the use of CurrentHandler (rather than Handler which was my original implementation) to ensure you get the latest page including the one that Server.Transfer fired. Server.Transfer and Server.Execute are Evil All that said – this fix is probably for the 2 people who are crazy enough to rely on Server.Transfer/Execute. :-} There are so many weird behavior problems with these commands that I avoid them at all costs. I don’t think I have a single application that uses either of these commands… Related Resources Full source of ClientScriptProxy.cs (repository) Part of the West Wind Web Toolkit Static Singletons for ASP.NET Controls Post © Rick Strahl, West Wind Technologies, 2005-2010Posted in ASP.NET  

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