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  • ServerControl randomly null

    - by Sascha
    Hi, I got a master page with a server control in it. Randomly the server control is inaccessible from codebehind. This doesn't happen on a specific action (eg a Button click or so). Currently I have no clue what this could be. I don't think it's output caching since this is not explcitly activated and the error happens far to seldom for that. But I'm going to disable caching in the master page explicitly with next deployment. Anyone an idea how to find more info to find what's happening? Or has someone had a similar error? Thanks. sa

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  • JQuery.ajax success function returns empty

    - by viatropos
    I have a very basic AJAX function in JQuery: $.ajax({ url: "http://www.google.com", dataType: "html", success: function(data) { alert(data); } }); But the data is always an empty string, no matter what url I go to... Why is that? I am running this locally at http://localhost:3000, and am using JQuery 1.4.2. If I make a local response, however, like this: $.ajax({ url: "http://localhost:3000/test", dataType: "html", success: function(data) { alert(data); } }); ...it returns the html page at that address. What am I missing here?

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  • Var null and not an object when using document.getElementById

    - by Dean
    Hi, I'm doing some work in HTML and JQuery. I have a problem of my textarea and submit button not appearing after the radio button is selected. My HTML looks like this: <html> <head><title>Publications Database | Which spotlight for Publications</title> <script type="text/javascript" src="./jquery.js"></script> <script src="./addSpotlight.js" type="text/javascript" charset="utf-8"></script> </head> <body> <div class="wrapper"> <div class="header"> <div class="headerText">Which spotlight for Publications</div> </div> <div class="mainContent"> <p>Please select the publication that you would like to make the spotlight of this month:</p> <form action="addSpotlight" method="POST" id="form" name="form"> <div class="div29" id="div29"><input type="radio" value="29" name="publicationIDs" >A System For Dynamic Server Allocation in Application Server Clusters, IEEE International Symposium on Parallel and Distributed Processsing with Applications, 2008 </div> <div class="div30" id="div30"><input type="radio" value="30" name="publicationIDs" >Analysing BitTorrent's Seeding Strategies, 7th IEEE/IFIP International Conference on Embedded and Ubiquitous Computing (EUC-09), 2009 </div> <div class="div31" id="div31"><input type="radio" value="31" name="publicationIDs" >The Effect of Server Reallocation Time in Dynamic Resource Allocation, UK Performance Engineering Workshop 2009, 2009 </div> <div class="div32" id="div32"><input type="radio" value="32" name="publicationIDs" >idk, hello, 1992 </div> <div class="div33" id="div33"><input type="radio" value="33" name="publicationIDs" >sad, safg, 1992 </div> <div class="abstractWriteup" id="abstractWriteup"><textarea name="abstract"></textarea> <input type="submit" value="Add Spotlight"></div> </form> </div> </div> </body> </html> My javascript looks like this: $(document).ready( function() { $('.abstractWriteup').hide(); addAbstract(); }); function addAbstract() { var abstractWU = document.getElementById('.abstractWriteup'); $("input[name='publicationIDs']").change(function() { var abstractWU = document.getElementById('.abstractWriteup'); var classNameOfSelected = $("input[name='publicationIDs']").val(); var radioSelected = document.getElementById("div"+classNameOfSelected); var parentDiv = radioSelected.parentNode; parentDiv.insertBefore(radioSelected, abstractWU.nextSibling); $('.abstractWriteup').show(); });}; I have developed this by using Node#insertBefore. When I have had it working it has been rearranging the radio buttons. Thanks in Advance Dean

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  • polymorphism pass instantiated base to deriver

    - by Eric
    I was wondering how to do this, consider the following classes public class Fruit { public string Name { get; set; } public Color Color { get; set; } } public class Apple : Fruit { public Apple() { } } How can I instantiate a new fruit but upcast to Apple, is there a way to instantiate a bunch of Fruit and make them apples with the name & color set. Do I need to manually deep copy? Of course this fails Fruit a = new Fruit(); a.Name = "FirstApple"; a.Color = Color.Red; Apple wa = a as Apple; System.Diagnostics.Debug.Print("Apple name: " + wa.Name); Do I need to pass in a Fruit to the AppleCTor and manually set the name and color( or 1-n properties) Is there an better design to do this?

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  • My first c# app and first null object exception

    - by Fresheyeball
    Total noob here. This is my first c# attempt, its a console application that simulates a drinking game called 'Left Right Center'. In the console I receive the following: CONSOLE Unhandled Exception: System.NullReferenceException: Object reference not set to an instance of an object at LeftRightCenter.MainClass.Main (System.String[] args) [0x00038] in /Users/apple/Projects/LearningC/LearningC/Main.cs:80 [ERROR] FATAL UNHANDLED EXCEPTION: System.NullReferenceException: Object reference not set to an instance of an object at LeftRightCenter.MainClass.Main (System.String[] args) [0x00038] in /Users/apple/Projects/LearningC/LearningC/Main.cs:80 C# using System; namespace LeftRightCenter { class Player { //fields private int _quarters = 4; public int Quarters { get{ return _quarters; } set{ _quarters += value; } } public Player (string name) { } } class Dice { Random random = new Random(); public int Roll () { random = new Random (); int diceSide; diceSide = random.Next (0, 6); diceSide = (diceSide > 2) ? 3 : diceSide; return diceSide; } } class MainClass { static int activePlayer = 0; static int theCup = 0; static Player[] thePlayers = { new Player ("Jessica"), new Player ("Isaac"), new Player ("Ed"), new Player ("Bella"), new Player ("Elisa"), new Player ("Fake RedHead"), new Player ("Linda"), new Player ("MJ"), new Player ("Irene"), new Player("Devin") }; static Dice[] theDice = new Dice[2]; private static void MoveQuarter (int direction) { int numberOfPlayers = thePlayers.Length - 1; switch (direction) { case 0: thePlayers [activePlayer].Quarters = -1; theCup++; break; case 1: thePlayers [activePlayer].Quarters = -1; int leftPlayer = (activePlayer == 0) ? numberOfPlayers : activePlayer - 1; thePlayers [leftPlayer].Quarters = +1; break; case 2: thePlayers [activePlayer].Quarters = -1; int rightPlayer = (activePlayer == numberOfPlayers) ? 0 : activePlayer + 1; thePlayers [rightPlayer].Quarters = +1; break; } } public static void Main (string[] args) { int cupEndPoint = thePlayers.Length * 4 - 1; while (theCup < cupEndPoint) { foreach (Dice rattle in theDice) { if (thePlayers [activePlayer].Quarters > 0) { MoveQuarter (rattle.Roll ()); // this line seems to be the problem } } Console.WriteLine ("{0} Quarters In the Cup", theCup); } } } } I have no idea what the problem is or why, and my googling have proven more use confusing than helpful.

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  • rails check_box_tag value is NULL

    - by looloobs
    Hi I am not sure why I am having this problem, maybe I am using the check_box_tag incorrectly. I have a form that is used to send an email message. You are supposed to be able to choose one or more boxes that represent different groups of people. <%= check_box_tag (:bcc_email, value = @spouses) %> <%= f.label :bcc_email, "Company Spouses" %><br /> <%= check_box_tag (:bcc_email, value = @soldiers) %> <%= f.label :bcc_email, "Company Soldiers" %><br /> The values are an array of email addresses. Those work fine, I have had them functioning as drop down menus for sometime. When I look at the HTML page source the values are there, they are just not being passed along with the create method. Any ideas?

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  • WCFExtras SOAP headers support returns null reference exception

    - by jlp
    I use WCFExtras to add headers to my service. I set up everything according to http://wcfextras.codeplex.com/wikipage?title=HowToUse&referringTitle=Home My WCF client works but throws NullReferenceException on both: client.InnerChannel.SetHeader("myHeader", new local.Header()); and var header = client.InnerChannel.GetHeader<local.Header>("myHeader"); I wonder if web.config element <wsdlExtensions location="noidea" singleFile="True"/> might cause a problem because I don't know what type in location attribute. I simply tried to type service address but it didn't fix anything.

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  • How does multiple implementing multiple COM interfaces work in C++?

    - by Martin
    I am trying to understand this example code regarding Browser Helper Objects. Inside, the author implements a single class which exposes multiple interfaces (IObjectWithSite, IDispatch). His QueryInterface function performs the following: if(riid == IID_IUnknown) *ppv = static_cast<BHO*>(this); else if(riid == IID_IObjectWithSite) *ppv = static_cast<IObjectWithSite*>(this); else if (riid == IID_IDispatch) *ppv = static_cast<IDispatch*>(this); I have learned that from a C perspective, interface pointers are just pointers to VTables. So I take it to mean that C++ is capable of returning the VTable of any implemented interface using static_cast. Does this mean that a class constructed in this way has a bunch of VTables in memory (IObjectWithSite, IDispatch, etc)? What does C++ do with the name collisions on the different interfaces (they each have a QueryInterface, AddRef and Release function), can I implement different methods for each of these?

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  • Null Exception RelativeLayout

    - by theblixguy
    I am trying to remove objects from my relative layout and replace the background with another image but I get a java.lang.NullPointerException on this line: RelativeLayout ths = (RelativeLayout)findViewById(R.layout.activity_main); Below is my code: package com.ssrij.qrmag; import android.app.Activity; import android.content.Intent; import android.net.Uri; import android.os.Bundle; import android.view.View; import android.view.animation.Animation; import android.view.animation.TranslateAnimation; import android.view.animation.Animation.AnimationListener; import android.widget.Button; import android.widget.RelativeLayout; import android.widget.TextView; public class MainActivity extends Activity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); // Initialize animations Animation a = new TranslateAnimation(1000,0,0,0); Animation a1 = new TranslateAnimation(1000,0,0,0); Animation a2 = new TranslateAnimation(1000,0,0,0); Animation a3 = new TranslateAnimation(1000,0,0,0); // Set animation durations (ms) a.setDuration(1200); a1.setDuration(1400); a2.setDuration(1600); a3.setDuration(1800); // Get a reference to the objects we want to apply the animation to final TextView v = (TextView)findViewById(R.id.textView1); final TextView v1 = (TextView)findViewById(R.id.textView2); final TextView v2 = (TextView)findViewById(R.id.TextView3); final Button v3 = (Button)findViewById(R.id.tap_scan); // Clear existing animations, just in case... v.clearAnimation(); v1.clearAnimation(); v2.clearAnimation(); v3.clearAnimation(); // Start animating v.startAnimation(a); v1.startAnimation(a1); v2.startAnimation(a2); v3.startAnimation(a3); a1.setAnimationListener(new AnimationListener() { @Override public void onAnimationStart(Animation animation) { // TODO Auto-generated method stub } @Override public void onAnimationRepeat(Animation animation) { // TODO Auto-generated method stub } @Override public void onAnimationEnd(Animation animation) { v.setVisibility(View.INVISIBLE); v1.setVisibility(View.INVISIBLE); v2.setVisibility(View.INVISIBLE); v3.setVisibility(View.INVISIBLE); RelativeLayout ths = (RelativeLayout)findViewById(R.layout.activity_main); ths.setBackgroundResource(R.drawable.blurbg); } }); } public void ScanQr(View v) { // Open the QR Scan page Intent a = new Intent(MainActivity.this, ScanActivity.class); startActivity(a); } } Is there anything that I am doing wrong?

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  • Casting array of pointers to objects

    - by ritmbo
    If B is subclass of A. And I have in main(): B** b = new B*[10]; ... some algorithm that do b[i] = new B(..); ... So I have an array of pointers to objets B. Then I have a function: void f(A** foo); If in main, I do: f(b); I get a warning, but obviously if I do: f((A**)b);, i dont. The (A**) its a bit nasty. I was wondering if there's a more elegant way in C++ that at least do type checking as dynamic_cast.

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  • How Can i Create This Complicated Query ?

    - by mTuran
    Hi, I have 3 tables: projects, skills and project_skills. In projects table i hold project's general data. Second table skills i hold skill id and skill name also i have projects_skills table which is hold project's skill relationships. Here is scheme of tables: CREATE TABLE IF NOT EXISTS `project_skills` ( `project_id` int(11) NOT NULL, `skill_id` int(11) NOT NULL, KEY `project_id` (`project_id`), KEY `skill_id` (`skill_id`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_turkish_ci; CREATE TABLE IF NOT EXISTS `projects` ( `id` int(11) NOT NULL AUTO_INCREMENT, `employer_id` int(11) NOT NULL, `project_title` varchar(100) COLLATE utf8_turkish_ci NOT NULL, `project_description` text COLLATE utf8_turkish_ci NOT NULL, `project_budget` int(11) NOT NULL, `project_allowedtime` int(11) NOT NULL, `project_deadline` datetime NOT NULL, `total_bids` int(11) NOT NULL, `average_bid` int(11) NOT NULL, `created` datetime NOT NULL, `active` tinyint(1) NOT NULL, PRIMARY KEY (`id`), KEY `created` (`created`), KEY `employer_id` (`employer_id`), KEY `active` (`active`), FULLTEXT KEY `project_title` (`project_title`,`project_description`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_turkish_ci AUTO_INCREMENT=3 ; CREATE TABLE IF NOT EXISTS `skills` ( `id` int(11) NOT NULL AUTO_INCREMENT, `category` int(11) NOT NULL, `name` varchar(100) COLLATE utf8_turkish_ci NOT NULL, `seo_name` varchar(100) COLLATE utf8_turkish_ci NOT NULL, `total_projects` int(11) NOT NULL, PRIMARY KEY (`id`), KEY `seo_name` (`seo_name`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_turkish_ci AUTO_INCREMENT=224 ; I want to select projects with related skill names. I think i have to use JOIN but i don't know how can i do. Thanks

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  • XMLHttpRequst return null on Chrome

    - by BoltBait
    I have the following code that works fine in IE: <HTML> <BODY> <script language="JavaScript"> text=""; req = new XMLHttpRequest(); if (req) { req.onreadystatechange = processStateChange; req.open("GET", "http://www.boltbait.com", true); req.send(); } function processStateChange() { // is the data ready for use? if (req.readyState == 4) { // process my data alert(req.status); alert(req.responseText); } } </script> </BODY> </HTML> In IE, the first alert returns 200, the second returns the web page. However, in Chrome the first alert returns 0 and the second returns the empty string. My intent is to grab a web page into a string for processing. If I'm not doing this right, how should I be doing this? Thanks.

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  • dijit.form.FilteringSelectinitial initial value always null.

    - by jiggs
    I'm using QueryReadStore as data and displaying the widget using the declarative way. My store looks like this: <div style="display:none" jsId="role_store" url="some/url/here" requestMethod="post" dojoType="dojox.data.QueryReadStore"></div> My widget is like this: <input dojoType="dijit.form.FilteringSelect" id="role_id" name="role_name" required="false" store="role_store" value="100" searchAttr="description"> Scenario: store is declared inside the HTML page. widget is loaded using parse.parse in the javascript. Issue: At first click no displayed value on the widget. But at the second click, values are displayed right.

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  • status update error (null field)

    - by ejah85
    hai guys... i .ve the problem that i cannot be recovered yet... i have one form where admin need to approve or reject the booking request... i've set the b_status field in table usage IN PROCESS default value... i want to update the b_status value BOOKING APPROVED when user click APPROVE button.. otherwise, the b_status will update the value as BOOKING REJECTED when user click on the REJECT button here's is the form code: <?php $db = mysql_connect('localhost','root') or die ("unable to connect"); mysql_select_db('fyp',$db) or die ("able to select"); $sql="SELECT * FROM vehicle WHERE v_status='READY'"; $result = mysql_query($sql) or die ("Query failed!"); ?> <tr><td>&nbsp;</td></tr> <tr> <tr> <td width="200"><font face="Arial" size="2" font color="#000000">Registration Number </font></td> <td><select name="regno"> <option value="" selected>--Registration No--</option> <?php while($row = mysql_fetch_array($result)){?> <option value="<?php echo $row['regno']; ?>"><?php echo $row['regno']; ?></option> <?php } ?> </select></td> <td><font face="Arial" size="2" font color="#000000">Reason</font></td> <td><textarea name="reason" rows="3" cols="50 "value = ""></textarea></td> </tr> <?php $db = mysql_connect('localhost','root') or die ("unable to connect"); mysql_select_db('fyp',$db) or die ("able to select"); $sql="SELECT * FROM driver WHERE d_status='READY'"; $result = mysql_query($sql) or die ("Query failed!"); ?> <tr> <td><font face="Arial" size="2" font color="#000000">Driver</font></td> <td><select id = "d_name" name="d_name"> <option value="" selected>--Driver Name--</option> <?php while($row = mysql_fetch_array($result)){?> <option value="<?php echo $row['d_name']; ?>"><?php echo $row['d_name']; ?></option> <?php } ?> </select></td> </tr> <tr> <?php mysql_close($db); ?> </table> <p></p> <center><input name="APPROVED" type="submit" id="APPROVED" value="APPROVED"> <input name="REJECT" type="submit" id="REJECT" value="REJECT"> </center> </div> </center> and this is the process page code: <?php $db = mysql_connect('localhost','root') or die ("unable to connect"); mysql_select_db('fyp',$db) or die ("able to select"); $bookingno=mysql_real_escape_string($_POST['bookingno']); $username=mysql_real_escape_string($_POST['username']); $name=mysql_real_escape_string($_POST['name']); $department=mysql_real_escape_string($_POST['department']); $g_date=mysql_real_escape_string($_POST['g_date']); $g_time=mysql_real_escape_string($_POST['g_time']); $r_date=mysql_real_escape_string($_POST['r_date']); $r_time=mysql_real_escape_string($_POST['r_time']); $destination=mysql_real_escape_string($_POST['destination']); $pass_num=mysql_real_escape_string($_POST['pass_num']); $trip_purpose=mysql_real_escape_string($_POST['trip_purpose']); $regno=mysql_real_escape_string($_POST['regno']); $d_name=mysql_real_escape_string($_POST['d_name']); $reason=mysql_real_escape_string($_POST['reason']); $b_status=mysql_real_escape_string($_POST['b_status']); $sql = "INSERT INTO `usage` VALUES('$bookingno','$username','$name','$department','$g_date','$g_time','$r_date','$r_time','$destination', '$pass_num','$trip_purpose','$regno','$d_name','$reason','$b_status')"; $query = "INSERT INTO `usage` VALUES b_status ='BOOKING APPROVED'"; $result = @mysql_query($query); $query1 = "UPDATE driver SET d_status ='OUT' WHERE '$d_name'=d_name"; $result1 = @mysql_query($query1); if(isset($_POST['APPROVED'])) { $query2 = "UPDATE `usage` SET b_status ='BOOKING APPROVED' WHERE '$b_status'='IN PROCESS'"; $result2 = @mysql_query($query2); } if (isset($_POST['REJECT'])) { $query3 = "UPDATE `usage` SET b_status ='BOOKING REJECTED' WHERE '$b_status'='IN PROCESS'"; $result3 = @mysql_query($query3); } //$result = mysql_query($sql) or die ("error!"); $result = mysql_query($sql) or trigger_error (mysql_error().' in '.$sql); i.ve the problem on the b_status field.. plz guys... help me ya :-)

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  • get distinct items in a collection if other item is not null

    - by Anurag Sharma
    I have a collection like this { Country : 'XYZ' Books : [ {"name" : "book1", "url" : "book1url", "auth_email" : "emailid1"}, {"name" : "book2", "url" : "book2url", "auth_email" : "emailid2"}, {"name" : "book3", "url" : "book3url", "auth_email" : "emailid3"}, {"name" : "book4", "url" : "book4url", "auth_email" : "emailid4"} .......................................... ] } I want to extract distinct 'Books.name' and corresponding 'Books.email' only if 'Books.email' is not = ''

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  • How to null a translation in gettext system?

    - by Evgeny
    Suppose a simple phrase "In" in English needs to be interpreted as "" - empty string in Russian. Is is possible to specify that in the .po file? What normally happens if you set msgstr "" - you'll get the untranslated key, but I want to get nothing in that specific case. Here is a use case: I have underneath a giant search bar a set of buttons to select questions (for a Q&A site) from particular scopes - like so: (in English) In: [all] [unanswered] [my own] (in Russian I want) [???] [??? ???????] [???] It just sounds more natural. Yes I can leave out In for english, but I don't want to and I do not want to put button (things in [] are buttons) html into the 'po' file. Thanks!

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  • SQL CASE WHEN NULL - question

    - by cc0
    Ok, so I'm trying to select an amount of rows from a column that holds the value 3, but only if there are no rows containing 10 or 4, if there are rows containing 10 or 4 I only want to show those. What would be a good syntax to do that? So far I've been attempting a CASE WHEN statement, but I can't seem to figure it out. Any help would be greatly appreciated. (My database is in an MS SQL 2008 server)

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  • Force external function to be const

    - by vanna
    Here is my problem. I made a class with a member function declared as const that uses an external function that I cannot modify (declared in someone else's code) and that is not declared const. More precisely Someone else's code class B { public: void foo(); }; My code class A : public B { public: void bar() const { this->foo(); } }; I know that for member data we can force const-correctness by using mutable or const_cast. How can I 'hack' foo such that my compiler understands that I would like to use it as if it was const even if it is not declared in someone else's code ?

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  • Why does an EXE file that does *nothing* contain so many dummy zero bytes?

    - by Lambert
    Hi, I've compiled a C file that does absolutely nothing (just a main that returns... not even a "Hello, world" gets printed), and I've compiled it with various compilers (MinGW GCC, Visual C++, Windows DDK, etc.). All of them link with the C runtime, which is standard. But what I don't get is: When I open up the file in a hex editor (or a disassembler), why do I see that almost half of the 16 KB is just huge sections of either 0x00 bytes or 0xCC bytes? It seems rather ridiculous to me... is there any way to prevent these from occurring? And why are they there in the first place? Thank you!

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  • C++ Stringstream int to string but returns null

    - by jumm
    Hi below is my function: string Employee::get_print(void) { string out_string; stringstream ss; ss << e_id << " " << type << endl; out_string = ss.str(); return out_string; } e_id and type are int and they contain values from the class Employee. But when I pass them into the stringstream they just clear the string when I try to out put it. But if I don't have a int in the ss << "Some text" << endl; this output fine. What am I doing wrong =S

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  • Make interchangeable class types via pointer casting only, without having to allocate any new objects?

    - by HostileFork
    UPDATE: I do appreciate "don't want that, want this instead" suggestions. They are useful, especially when provided in context of the motivating scenario. Still...regardless of goodness/badness, I've become curious to find a hard-and-fast "yes that can be done legally in C++11" vs "no it is not possible to do something like that". I want to "alias" an object pointer as another type, for the sole purpose of adding some helper methods. The alias cannot add data members to the underlying class (in fact, the more I can prevent that from happening the better!) All aliases are equally applicable to any object of this type...it's just helpful if the type system can hint which alias is likely the most appropriate. There should be no information about any specific alias that is ever encoded in the underlying object. Hence, I feel like you should be able to "cheat" the type system and just let it be an annotation...checked at compile time, but ultimately irrelevant to the runtime casting. Something along these lines: Node<AccessorFoo>* fooPtr = Node<AccessorFoo>::createViaFactory(); Node<AccessorBar>* barPtr = reinterpret_cast< Node<AccessorBar>* >(fooPtr); Under the hood, the factory method is actually making a NodeBase class, and then using a similar reinterpret_cast to return it as a Node<AccessorFoo>*. The easy way to avoid this is to make these lightweight classes that wrap nodes and are passed around by value. Thus you don't need casting, just Accessor classes that take the node handle to wrap in their constructor: AccessorFoo foo (NodeBase::createViaFactory()); AccessorBar bar (foo.getNode()); But if I don't have to pay for all that, I don't want to. That would involve--for instance--making a special accessor type for each sort of wrapped pointer (AccessorFooShared, AccessorFooUnique, AccessorFooWeak, etc.) Having these typed pointers being aliased for one single pointer-based object identity is preferable, and provides a nice orthogonality. So back to that original question: Node<AccessorFoo>* fooPtr = Node<AccessorFoo>::createViaFactory(); Node<AccessorBar>* barPtr = reinterpret_cast< Node<AccessorBar>* >(fooPtr); Seems like there would be some way to do this that might be ugly but not "break the rules". According to ISO14882:2011(e) 5.2.10-7: An object pointer can be explicitly converted to an object pointer of a different type.70 When a prvalue v of type "pointer to T1" is converted to the type "pointer to cv T2", the result is static_cast(static_cast(v)) if both T1 and T2 are standard-layout types (3.9) and the alignment requirements of T2 are no stricter than those of T1, or if either type is void. Converting a prvalue of type "pointer to T1" to the type "pointer to T2" (where T1 and T2 are object types and where the alignment requirements of T2 are no stricter than those of T1) and back to its original type yields the original pointer value. The result of any other such pointer conversion is unspecified. Drilling into the definition of a "standard-layout class", we find: has no non-static data members of type non-standard-layout-class (or array of such types) or reference, and has no virtual functions (10.3) and no virtual base classes (10.1), and has the same access control (clause 11) for all non-static data members, and has no non-standard-layout base classes, and either has no non-static data member in the most-derived class and at most one base class with non-static data members, or has no base classes with non-static data members, and has no base classes of the same type as the first non-static data member. Sounds like working with something like this would tie my hands a bit with no virtual methods in the accessors or the node. Yet C++11 apparently has std::is_standard_layout to keep things checked. Can this be done safely? Appears to work in gcc-4.7, but I'd like to be sure I'm not invoking undefined behavior.

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  • How to check for a null object reference when validating forms in MVC

    - by quakkels
    Hello SO, I'm experimenting with validating forms in the asp.net MVC framework. I'm focusing on server side validation for the time being. I've come across an error that I'm not sure how to rectify. System.NullReferenceException: Object reference not set to an instance of an object. The code that throws the error is: [AcceptVerbs(HttpVerbs.Post)] public ActionResult Create([Bind(Exclude="ID")] MembersCreate mc ) { mc.Modules = ModuleListDataContext.GetModuleList(); ViewData.Model = mc; //Validation using ModelState // // //line below errors when form field is empty // if ((string)mc.Member.Username.Trim() == "") ModelState.AddModelError("Member.Username", "Username is required."); if (!ModelState.IsValid) return View(); try { // TODO: Add insert logic here return RedirectToAction("Index","Home"); } catch { return View(); } } When I put spaces in the field it performs exactly as i want, but if I leave the field blank and press submit I get the error. What's the best way to avoid this error and still validate blank form fields? Thanks all -

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