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• Security review of an authenticated Diffie Hellman variant

  - by mtraut

  EDIT I'm still hoping for some advice on this, i tried to clarify my intentions... When i came upon device pairing in my mobile communication framework i studied a lot of papers on this topic and and also got some input from previous questions here. But, i didn't find a ready to implement protocol solution - so i invented a derivate and as i'm no crypto geek i'm not sure about the security caveats of the final solution: The main questions are Is SHA256 sufficient as a commit function? Is the addition of the shared secret as an authentication info in the commit string safe? What is the overall security of the 1024 bit group DH I assume at most 2^-24 bit probability of succesful MITM attack (because of 24 bit challenge). Is this plausible? What may be the most promising attack (besides ripping the device out off my numb, cold hands) This is the algorithm sketch For first time pairing, a solution proposed in "Key agreement in peer-to-peer wireless networks" (DH-SC) is implemented. I based it on a commitment derived from: A fix "UUID" for the communicating entity/role (128 bit, sent at protocol start, before commitment) The public DH key (192 bit private key, based on the 1024 bit Oakley group) A 24 bit random challenge Commit is computed using SHA256 c = sha256( UUID || DH pub || Chall) Both parties exchange this commitment, open and transfer the plain content of the above values. The 24 bit random is displayed to the user for manual authentication DH session key (128 bytes, see above) is computed When the user opts for persistent pairing, the session key is stored with the remote UUID as a shared secret Next time devices connect, commit is computed by additionally hashing the previous DH session key before the random challenge. For sure it is not transfered when opening. c = sha256( UUID || DH pub || DH sess || Chall) Now the user is not bothered authenticating when the local party can derive the same commitment using his own, stored previous DH session key. After succesful connection the new DH session key becomes the new shared secret. As this does not exactly fit the protocols i found so far (and as such their security proofs), i'd be very interested to get an opinion from some more crypto enabled guys here. BTW. i did read about the "EKE" protocol, but i'm not sure what the extra security level is.

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• mysql: can't set max_allowed_package to anything grater than 16MB

  - by sas

  I'm not sure if this is the right place to post these kind of questions, if it's not so, please (politely) let me know... :-) I need to save files greater than 16MB on a mysql database from a php site... I've already changed the c:\xampp\mysql\bin\my.cnf and set max_allowed_packet to 16 MB, and everything worked fine then I set it to 32 MB but there´s no way I can handle a file bigger than 16 MB I get the following error: 'MySQL server has gone away' (the same error I had when max_allowed_packet was set to 1MB) there must be some other setting that doesn´t allow me to handle files bigger than 16MB maybe the php client, I guess, but I don't know where to edit it this is the code I'm running when file.txt is smaller than 16.776.192 bytes long, it works fine, but if file.txt has 16.777.216 bytes i get the aforementioned error oh, and the field download.content is a longblob... $file = 'file.txt'; $file_handle = fopen( $file, 'r' ); $content = fread( $file_handle, filesize( $file ) ); fclose( $file_handle ); db_execute( 'truncate table download', true ); $sql = "insert into download( code, title, name, description, original_name, mime_type, size, content, user_insert_id, date_insert, user_update_id, date_update ) values ( 'new file', 'new file', 'sas.jpg', 'new file', '$file', 'mime', " . filesize( $file ) . ", '" . addslashes( $content ) . "', 0, " . db_char_to_sql( now_char(), 'datetime' ) . ", 0, " . db_char_to_sql( now_char(), 'datetime' ) . " )"; db_execute( $sql, true ); (the db_execute funcion just opens the connections and executes the sql stuff) running on windows XP sp2 server version: 5.0.67-community PHP Version 4.4.9 mysql client API version: 3.23.49 using: ApacheFriends XAMPP (Basispaket) version 1.6.8 that comes with + Apache 2.2.9 + MySQL 5.0.67 (Community Server) + PHP 5.2.6 + PHP 4.4.9 + PEAR + phpMyAdmin 2.11.9.2 ... this is part of the content of c:\xampp\mysql\bin\my.cnf # The MySQL server [mysqld] port= 3306 socket= "C:/xampp/mysql/mysql.sock" basedir="C:/xampp/mysql" tmpdir="C:/xampp/tmp" datadir="C:/xampp/mysql/data" skip-locking key_buffer = 16M # max_allowed_packet = 1M max_allowed_packet = 32M table_cache = 128 sort_buffer_size = 512K net_buffer_length = 8K read_buffer_size = 256K read_rnd_buffer_size = 512K myisam_sort_buffer_size = 8M

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• Race condition for thread startup

  - by Ozzah

  A similar question was asked here, but the answers generally all seem to relate to the lambda notation. I get a similar result without the lambda so I thought I'd ask for some clarification: Say I have something like this: for (int i = 0; i < 5; i++) (new Thread(new ThreadStart(delegate() { Console.WriteLine("Thread " + i); }))).Start(); One would expect the following output: Thread 0 Thread 1 Thread 2 Thread 3 Thread 4 Now I realise that the threads aren't started in any particular order, so let's just assume that the above lines can come out in any order. But that is not what happens. What instead happens: Thread 3 Thread 4 Thread 4 Thread 4 Thread 4 or something similar, which leads me to believe that rather than passing the value if i, it is passing the reference. (Which is weird, since an int is a value type). Doing something like this: for (int i = 0; i < 5; i++) (new Thread(new ThreadStart(delegate() { int j = i; Console.WriteLine("Thread " + j); }))).Start(); does not help either, even though we have made a copy of i. I am assuming the reason is that it hasn't made a copy of i in time. Doing something like this: for (int i = 0; i < 5; i++) { (new Thread(new ThreadStart(delegate() { Console.WriteLine("Thread " + i); }))).Start(); Thread.Sleep(50); } seems to fix the problem, however it is extremely undesirable as we're wasting 50ms on each iteration, not to mention the fact that if the computer is heavily loaded then maybe 50ms may not be enough. Here is a sample with my current, specific problem: Thread t = new Thread(new ThreadStart(delgate() { threadLogic(param1, param2, param3, param4); })); t.Start(); param1 = param2 = param3 = param4 = null; with: void threadLogic(object param1, object param2, object param3, object param4) { // Do some stuff here... } I want threadLogic() to run in its own thread, however the above code gives a null reference exception. I assume this is because the values are set to null before the thread has had a chance to start. Again, putting a Thread.Sleep(100) works, but it is an awful solution from every aspect. What do you guys recommend for this particular type of race condition?

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• Displaying xaml resources dynamically?

  - by Robert

  I used Mike Swanson's illustrator to xaml converter to convert some of my images to xaml. The convert creates a viewbox that contains the image. These viewboxes I made resource files in my program. The code below shows what I'm trying to do: I have a viewmodel that has an enum variable called PrimaryWinding of type Windings. The values PrimD and PrimY of the enum select the respective PrimD and PrimY xaml files in the resources. <UserControl.Resources> <DataTemplate x:Key="PrimTrafo" DataType="{x:Type l:Windings}"> <Frame Source="{Binding}" x:Name="PART_Image" NavigationUIVisibility="Hidden"> <Frame.LayoutTransform> <ScaleTransform ScaleX="0.5" ScaleY="0.5"/> </Frame.LayoutTransform> </Frame> <DataTemplate.Triggers> <DataTrigger Binding="{Binding}" Value="PrimD"> <Setter TargetName="PART_Image" Property="Source" Value="Resources\PrimD.xaml" /> </DataTrigger> <DataTrigger Binding="{Binding}" Value="PrimY"> <Setter TargetName="PART_Image" Property="Source" Value="Resources\PrimY.xaml" /> </DataTrigger> </DataTemplate.Triggers> </DataTemplate> </UserControl.Resources> <!--The contentcontrol that holds the datatemplate defined above--> <Grid > <Grid.ColumnDefinitions> <ColumnDefinition Width="2*"></ColumnDefinition> <ColumnDefinition Width="2*"></ColumnDefinition> <ColumnDefinition Width="1*"></ColumnDefinition> </Grid.ColumnDefinitions> <ContentControl Grid.Column="0" Content="{Binding PrimaryWinding}" ContentTemplate="{StaticResource PrimTrafo}"/> </Grid> This code works. Only I can't resize the drawings to the size of the grid cell. I added the ScaleTransform class to resize the image. Is a Frame the wrong class to hold the drawings? Should I use the ScaleTransform class to resize the drawing to the size of the cell? And how can I do that dynamically?

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• User has many computers, computers have many attributes in different tables, best way to JOIN?

  - by krismeld

  I have a table for users: USERS: ID | NAME | ---------------- 1 | JOHN | 2 | STEVE | a table for computers: COMPUTERS: ID | USER_ID | ------------------ 13 | 1 | 14 | 1 | a table for processors: PROCESSORS: ID | NAME | --------------------------- 27 | PROCESSOR TYPE 1 | 28 | PROCESSOR TYPE 2 | and a table for harddrives: HARDDRIVES: ID | NAME | ---------------------------| 35 | HARDDRIVE TYPE 25 | 36 | HARDDRIVE TYPE 90 | Each computer can have many attributes from the different attributes tables (processors, harddrives etc), so I have intersection tables like this, to link the attributes to the computers: COMPUTER_PROCESSORS: C_ID | P_ID | --------------| 13 | 27 | 13 | 28 | 14 | 27 | COMPUTER_HARDDRIVES: C_ID | H_ID | --------------| 13 | 35 | So user JOHN, with id 1 owns computer 13 and 14. Computer 13 has processor 27 and 28, and computer 13 has harddrive 35. Computer 14 has processor 27 and no harddrive. Given a user's id, I would like to retrieve a list of that user's computers with each computers attributes. I have figured out a query that gives me a somewhat of a result: SELECT computers.id, processors.id AS p_id, processors.name AS p_name, harddrives.id AS h_id, harddrives.name AS h_name, FROM computers JOIN computer_processors ON (computer_processors.c_id = computers.id) JOIN processors ON (processors.id = computer_processors.p_id) JOIN computer_harddrives ON (computer_harddrives.c_id = computers.id) JOIN harddrives ON (harddrives.id = computer_harddrives.h_id) WHERE computers.user_id = 1 Result: ID | P_ID | P_NAME | H_ID | H_NAME | ----------------------------------------------------------- 13 | 27 | PROCESSOR TYPE 1 | 35 | HARDDRIVE TYPE 25 | 13 | 28 | PROCESSOR TYPE 2 | 35 | HARDDRIVE TYPE 25 | But this has several problems... Computer 14 doesnt show up, because it has no harddrive. Can I somehow make an OUTER JOIN to make sure that all computers show up, even if there a some attributes they don't have? Computer 13 shows up twice, with the same harddrive listet for both. When more attributes are added to a computer (like 3 blocks of ram), the number of rows returned for that computer gets pretty big, and it makes it had to sort the result out in application code. Can I somehow make a query, that groups the two returned rows together? Or a query that returns NULL in the h_name column in the second row, so that all values returned are unique? EDIT: What I would like to return is something like this: ID | P_ID | P_NAME | H_ID | H_NAME | ----------------------------------------------------------- 13 | 27 | PROCESSOR TYPE 1 | 35 | HARDDRIVE TYPE 25 | 13 | 28 | PROCESSOR TYPE 2 | 35 | NULL | 14 | 27 | PROCESSOR TYPE 1 | NULL | NULL | Or whatever result that make it easy to turn it into an array like this [13] => [P_NAME] => [0] => PROCESSOR TYPE 1 [1] => PROCESSOR TYPE 2 [H_NAME] => [0] => HARDDRIVE TYPE 25 [14] => [P_NAME] => [0] => PROCESSOR TYPE 1

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• Not allowing characters after Space. Mysql Insert With PHP

  - by Jake

  Ok so I think this is easy but I dont know (I'm a novice to PHP and MySQL). I have a select that is getting data from a table in the database. I am simply taking whatever options the user selects and putting it into a separate table with a php mysql insert statement. But I am having a problem. When I hit submit, everything is submitted properly except for any select options that have spaces don't submit after the first space. For example if the option was COMPUTER REPAIR, all that would get sent is COMPUTER. I will post code if needed, and any help would be greatly appreciated. Thanks! Ok here is my select code: <?php include("./config.php"); $query="SELECT id,name FROM category_names ORDER BY name"; $result = mysql_query ($query); echo"<div style='overflow:auto;width:100%'><label>Categories (Pick three that describe your business)</label><br/><select name='select1'><option value='0'>Please Select A Category</option>"; // printing the list box select command while($catinfo=mysql_fetch_array($result)){//Array or records stored in $nt echo "<option>$catinfo[name]</option><br/> "; } echo"</select></div>"; ?> And here is my insert code ( Just to let you know its got everything not just the select!) ?php require("./config.php"); $companyname = mysql_real_escape_string(addslashes(trim($_REQUEST['name']))); $phone = mysql_real_escape_string(addslashes($_REQUEST['phone'])); $zipcode = mysql_real_escape_string(addslashes($_REQUEST['zipcode'])); $city = mysql_real_escape_string(addslashes($_REQUEST['city'])); $description = mysql_real_escape_string(addslashes($_REQUEST['description'])); $website = mysql_real_escape_string(addslashes($_REQUEST['website'])); $address = mysql_real_escape_string(addslashes($_REQUEST['address'])); $other = mysql_real_escape_string(addslashes($_REQUEST['other'])); $payment = mysql_real_escape_string(addslashes($_REQUEST['payment'])); $products = mysql_real_escape_string(addslashes($_REQUEST['products'])); $email = mysql_real_escape_string(addslashes($_REQUEST['email'])); $select1 = mysql_real_escape_string(addslashes($_REQUEST['select1'])); $select2 = mysql_real_escape_string(addslashes($_REQUEST['select2'])); $select3 = mysql_real_escape_string(addslashes($_REQUEST['select3'])); $save=$_POST['save']; if(!empty($save)){ $sql="INSERT INTO gj (name, phone, city, zipcode, description, dateadded, website, address1, other2, payment_options, Products, email,cat1,cat2,cat3) VALUES ('$companyname','$phone','$city','$zipcode','$description',curdate(),'$website','$address','$other','$payment','$products','$email','$select1','$select2','$select3')"; if (!mysql_query($sql,$link)) { die('Error: ' . mysql_error()); } echo "<br/><h2><font color='green' style='font-size:15px'>1 business added</font></h2>"; mysql_close($link); } ?>

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• .NET Extension Objects with XSLT -- how to iterate over a collection?

  - by Pandincus

  Help me, Stackoverflow! I have a simple .NET 3.5 console app that reads some data and sends emails. I'm representing the email format in an XSLT stylesheet so that we can easily change the wording of the email without needing to recompile the app. We're using Extension Objects to pass data to the XSLT when we apply the transformation: <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:msxsl="urn:schemas-microsoft-com:xslt" exclude-result-prefixes="msxsl" xmlns:EmailNotification="ext:EmailNotification"> -- this way, we can have statements like: <p> Dear <xsl:value-of select="EmailNotification:get_FullName()" />: </p> The above works fine. I pass the object via code like this (some irrelevant code omitted for brevity): // purely an example structure public struct EmailNotification { public string FullName { get; set; } } // Somewhere in some method ... var notification = new Notification("John Smith"); // ... XsltArgumentList xslArgs = new XsltArgumentList(); xslArgs.AddExtensionObject("ext:EmailNotification", notification); // ... // The part where it breaks! (This is where we do the transformation) xslt.Transform(fakeXMLDocument.CreateNavigator(), xslArgs, XmlWriter.Create(transformedXMLString)); So, all of the above code works. However, I wanted to get a little fancy (always my downfall) and pass a collection, so that I could do something like this: <p>The following accounts need to be verified:</p> <xsl:for-each select="EmailNotification:get_SomeCollection()"> <ul> <li> <xsl:value-of select="@SomeAttribute" /> </li> </ul> <xsl:for-each> When I pass the collection in the extension object and attempt to transform, I get the following error: "Extension function parameters or return values which have Clr type 'String[]' are not supported." or List, or IEnumerable, or whatever I try to pass in. So, my questions are: How can I pass in a collection to my XSLT? What do I put for the xsl:value-of select="" inside the xsl:for-each ? Is what I am trying to do impossible?

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• jQuery reports incorrect element height in Firefox iframe

  - by Augustus

  Here a short test to demonstrate my problem. I have a page that loads an iframe: <html> <head> <title></title> <script src="http://ajax.googleapis.com/ajax/libs/jquery/1.3.2/jquery.js"></script> </head> <body> <iframe id="iframe" src="box.html" style="width: 100px; height: 100px"></iframe> <script> $('#iframe').bind('load', function () { var div = $(this).contents().find('div'); alert(div.height()); alert(div.innerHeight()); alert(div.outerHeight()); alert(div.outerHeight(true)); }); </script> </body> </html> The iframe (box.html) contains a single styled div: <html> <head> <title></title> <style> div { height: 50px; width: 50px; margin: 5px; padding: 5px; border: 2px solid #00f; background-color: #f00; } </style> </head> <body> <div></div> </body> </html> The four alerts should return 50, 60, 64 and 74, respectively. This works as expected in Safari and Chrome. In FF 3.5.1, they all return 64. This is wrong. Does anyone know how I can force FF/jQuery to return the correct values?

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• Symfony2 Forms: is it possible to bind a form in an "unconventional way"?

  - by DonCallisto

  Imagine this scenario: in our company there is an employee that "play" around graphic,css,html and so on. Our new project will born under symfony2 so we're trying some silly - but "real" - stuff (like authentication from db, submit data from a form and persist it to db and so on..) The problem As far i know, learnt from symfony2 "book" that i found on the site (you can find it here), there is an "automated" way for creating and rendering forms: 1) Build the form up into a controller in this way $form = $this->createFormBuilder($task) ->add('task','text'), ->add('dueDate','date'), ->getForm(); return $this->render('pathToBundle:Controller:templateTwig', array('form'=>$form->createview()); 2) Into templateTwig render the template {{ form_widget(form) }} // or single rows method 3) Into a controller (the same that have a route where you can submit data), take back submitted information if($rquest->getMethod()=='POST'){ $form->bindRequest($request); /* and so on */ } Return to scenario Our graphic employee don't want to access controllers, write php and other stuff like those. So he'll write a twig template with a "unconventional" (from symfony2 point of view, but conventional from HTML point of view) method: /* into twig template */ <form action="{{ path('SestanteUserBundle_homepage') }}" method="post" name="userForm"> <div> USERNAME: <input type="text" name="user_name" value="{{ user.username}}"/> </div> <div> EMAIL: <input type="text" name="user_mail" value="{{ user.email }}"/> </div> <input type="hidden" name="user_id" value="{{ id }}" /> <input type="submit" value="modifica i dati"> </form> Now, if into the controller that handle the submission of data we do something like that public function indexAction(Request $request) { if($request->getMethod() == 'POST'){ // sono arrivato per via di un submit, quindi devo modificare i dati prima di farli vedere a video $defaultData = array('message'=>'ho visto questa cosa in esempio, ma non capisco se posso farne a meno'); $form = $this->createFormBuilder($defaultData) ->add('user_name','text') ->add('user_mail','email') ->add('user_id','integer') ->getForm(); $form->bindRequest($request); //bindo la form ad una request $data = $form->getData(); //mi aspetto un'array chiave=>valore /* .... */ We expected that $data will contain an array with key,value from the submitted form. We found that it isn't true. After googling for a while and try with other "bad" ideas, we're frozen into that. So, if you have a "graphic office" that can't handle directly php code, how can we interface from form(s) to controller(s) ? UPDATE It seems that Symfony2 use a different convention for form's field name and lookup once you've submitted that. In particular, if my form's name is addUser and a field is named userName, the field's name will be AddUser[username] so maybe it have a "dynamic" lookup method that will extract form's name, field's name, concat them and lookup for values. Is it possible?

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• C++ include statement required if defining a map in a headerfile.

  - by Justin

  I was doing a project for computer course on programming concepts. This project was to be completed in C++ using Object Oriented designs we learned throughout the course. Anyhow, I have two files symboltable.h and symboltable.cpp. I want to use a map as the data structure so I define it in the private section of the header file. I #include <map> in the cpp file before I #include "symboltable.h". I get several errors from the compiler (MS VS 2008 Pro) when I go to debug/run the program the first of which is: Error 1 error C2146: syntax error : missing ';' before identifier 'table' c:\users\jsmith\documents\visual studio 2008\projects\project2\project2\symboltable.h 22 Project2 To fix this I had to #include <map> in the header file, which to me seems strange. Here are the relevant code files: // symboltable.h #include <map> class SymbolTable { public: SymbolTable() {} void insert(string variable, double value); double lookUp(string variable); void init(); // Added as part of the spec given in the conference area. private: map<string, double> table; // Our container for variables and their values. }; and // symboltable.cpp #include <map> #include <string> #include <iostream> using namespace std; #include "symboltable.h" void SymbolTable::insert(string variable, double value) { table[variable] = value; // Creates a new map entry, if variable name already exist it overwrites last value. } double SymbolTable::lookUp(string variable) { if(table.find(variable) == table.end()) // Search for the variable, find() returns a position, if thats the end then we didnt find it. throw exception("Error: Uninitialized variable"); else return table[variable]; } void SymbolTable::init() { table.clear(); // Clears the map, removes all elements. }

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• Can someone who understands C code help me understand this code?

  - by Benjamin

  INT GetTree (HWND hWnd, HTREEITEM hItem, HKEY *pRoot, TCHAR *pszKey, INT nMax) { TV_ITEM tvi; TCHAR szName[256]; HTREEITEM hParent; HWND hwndTV = GetDlgItem (hWnd, ID_TREEV); memset (&tvi, 0, sizeof (tvi)); hParent = TreeView_GetParent (hwndTV, hItem); if (hParent) { // Get the parent of the parent of the... GetTree (hWnd, hParent, pRoot, pszKey, nMax); // Get the name of the item. tvi.mask = TVIF_TEXT; tvi.hItem = hItem; tvi.pszText = szName; tvi.cchTextMax = dim(szName); TreeView_GetItem (hwndTV, &tvi); //send the TVM_GETITEM message? lstrcat (pszKey, TEXT ("\\")); lstrcat (pszKey, szName); } else { *pszKey = TEXT ('\0'); szName[0] = TEXT ('\0'); // Get the name of the item. tvi.mask = TVIF_TEXT | TVIF_PARAM; tvi.hItem = hItem; tvi.pszText = szName; tvi.cchTextMax = dim(szName); if (TreeView_GetItem (hwndTV, &tvi)) //*pRoot = (HTREEITEM)tvi.lParam; //original hItem = (HTREEITEM)tvi.lParam; else { INT rc = GetLastError(); } } return 0; } The block of code that begins with the comment "Get the name of the item" does not make sense to me. If you are getting the listview item why does the code set the parameters of the item being retrieved, because if you already had the values there would be no need to retrieve them. Secondly near the comment "original" is the original line of code which will compile with a varning under embedded visual c++, but if you copy the exact same code into visual studio 2008 it will not compile. Since I did not write any of this code and am trying to learn is it possible the original author made a mistake on this line, since the *pRoot should point to and HKEY type yet he is casting to an HTREEITEM type which should never work since the data types don't match? (Side note someone with a better reputation should add a windows ce tag to SO since windows mobile is not the same as windows ce.)

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• Java replacement for C macros

  - by thkala

  Recently I refactored the code of a 3rd party hash function from C++ to C. The process was relatively painless, with only a few changes of note. Now I want to write the same function in Java and I came upon a slight issue. In the C/C++ code there is a C preprocessor macro that takes a few integer variables names as arguments and performs a bunch of bitwise operations with their contents and a few constants. That macro is used in several different places, therefore its presence avoids a fair bit of code duplication. In Java, however, there is no equivalent for the C preprocessor. There is also no way to affect any basic type passed as an argument to a method - even autoboxing produces immutable objects. Coupled with the fact that Java methods return a single value, I can't seem to find a simple way to rewrite the macro. Avenues that I considered: Expand the macro by hand everywhere: It would work, but the code duplication could make things interesting in the long run. Write a method that returns an array: This would also work, but it would repeatedly result into code like this: long tmp[] = bitops(k, l, m, x, y, z); k = tmp[0]; l = tmp[1]; m = tmp[2]; x = tmp[3]; y = tmp[4]; z = tmp[5]; Write a method that takes an array as an argument: This would mean that all variable names would be reduced to array element references - it would be rather hard to keep track of which index corresponds to which variable. Create a separate class e.g. State with public fields of the appropriate type and use that as an argument to a method: This is my current solution. It allows the method to alter the variables, while still keeping their names. It has the disadvantage, however, that the State class will get more and more complex, as more macros and variables are added, in order to avoid copying values back and forth among different State objects. How would you rewrite such a C macro in Java? Is there a more appropriate way to deal with this, using the facilities provided by the standard Java 6 Development Kit (i.e. without 3rd party libraries or a separate preprocessor)?

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• Correlation formula explanation needed d3.js

  - by divakar

  function getCorrelation(xArray, yArray) { alert(xArray); alert(yArray); function sum(m, v) {return m + v;} function sumSquares(m, v) {return m + v * v;} function filterNaN(m, v, i) {isNaN(v) ? null : m.push(i); return m;} // clean the data (because we know that some values are missing) var xNaN = _.reduce(xArray, filterNaN , []); var yNaN = _.reduce(yArray, filterNaN , []); var include = _.intersection(xNaN, yNaN); var fX = _.map(include, function(d) {return xArray[d];}); var fY = _.map(include, function(d) {return yArray[d];}); var sumX = _.reduce(fX, sum, 0); var sumY = _.reduce(fY, sum, 0); var sumX2 = _.reduce(fX, sumSquares, 0); var sumY2 = _.reduce(fY, sumSquares, 0); var sumXY = _.reduce(fX, function(m, v, i) {return m + v * fY[i];}, 0); var n = fX.length; var ntor = ( ( sumXY ) - ( sumX * sumY / n) ); var dtorX = sumX2 - ( sumX * sumX / n); var dtorY = sumY2 - ( sumY * sumY / n); var r = ntor / (Math.sqrt( dtorX * dtorY )); // Pearson ( http://www.stat.wmich.edu/s216/book/node122.html ) var m = ntor / dtorX; // y = mx + b var b = ( sumY - m * sumX ) / n; // console.log(r, m, b); return {r: r, m: m, b: b}; } I have finding correlation between the points i plot using this function which is not written by me. my xarray=[120,110,130,132,120,118,134,105,120,0,0,0,0,137,125,120,127,120,160,120,148] yarray=[80,70,70,80,70,62,69,70,70,62,90,42,80,72,0,0,0,0,78,82,68,60,58,82,60,76,86,82,70] I can t able to understand the function perfectly. Can anybody explain it with the data i pasted here. I also wanted to remove the zeros getting calculated from this function.

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• Having trouble doing an Update with a Linq to Sql object

  - by Pure.Krome

  Hi folks, i've got a simple linq to sql object. I grab it from the database and change a field then save. No rows have been updated. :( When I check the full Sql code that is sent over the wire, I notice that it does an update to the row, not via the primary key but on all the fields via the where clause. Is this normal? I would have thought that it would be easy to update the field(s) with the where clause linking on the Primary Key, instead of where'ing (is that a word :P) on each field. here's the code... using (MyDatabase db = new MyDatabase()) { var boardPost = (from bp in db.BoardPosts where bp.BoardPostId == boardPostId select bp).SingleOrDefault(); if (boardPost != null && boardPost.BoardPostId > 0) { boardPost.ListId = listId; // This changes the value from 0 to 'x' db.SubmitChanges(); } } and here's some sample sql.. exec sp_executesql N'UPDATE [dbo].[BoardPost] SET [ListId] = @p6 WHERE ([BoardPostId] = @p0) AND .... <snip the other fields>',N'@p0 int,@p1 int,@p2 nvarchar(9),@p3 nvarchar(10),@p4 int,@p5 datetime,@p6 int',@p0=1276,@p1=212787,@p2=N'ttreterte',@p3=N'ttreterte3',@p4=1,@p5='2009-09-25 12:32:12.7200000',@p6=72 Now, i know there's a datetime field in this update .. and when i checked the DB it's value was/is '2009-09-25 12:32:12.720' (less zero's, than above) .. so i'm not sure if that is messing up the where clause condition... but still! should it do a where clause on the PK's .. if anything .. for speed! Yes / no ? UPDATE After reading nitzmahone's reply, I then tried playing around with the optimistic concurrency on some values, and it still didn't work :( So then I started some new stuff ... with the optimistic concurrency happening, it includes a where clause on the field it's trying to update. When that happens, it doesn't work. so.. in the above sql, the where clause looks like this ... WHERE ([BoardPostId] = @p0) AND ([ListId] IS NULL) AND ... <rest snipped>) This doesn't sound right! the value in the DB is null, before i do the update. but when i add the ListId value to the where clause (or more to the point, when L2S add's it because of the optomistic concurrecy), it fails to find/match the row. wtf?

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• Problem in suspending 2 threads at the same time in MFC!

  - by kiddo

  I am learning about threading and multithreading..so i just created a small application in which i will update the progressbar and a static text using threading.I vl get two inputs from the user, start and end values for how long the loop should rotate.I have 2threads in my application. Thread1- to update the progressbar(according to the loop) the static text which will show the count(loop count). Thread2 - to update the another static text which will just diplay a name Basically if the user clicks start, the progressbar steps up and at the same time filecount and the name are displayed parallely. There's is another operation where if the user clicks pause it(thread) has to suspend until the user clicks resume. The problem is,the above will not work(will not suspend and resume) for both thread..but works for a singlw thread. Please check the code to get an idea and reply me what can done! on button click start void CThreadingEx3Dlg::OnBnClickedStart() { m_ProgressBar.SetRange(start,end); myThread1 = AfxBeginThread((AFX_THREADPROC)MyThreadFunction1,this); myThread2 = AfxBeginThread((AFX_THREADPROC)MyThreadFunction2,this); } thread1 UINT MyThreadFunction1(LPARAM lparam) { CThreadingEx3Dlg* pthis = (CThreadingEx3Dlg*)lparam; for(int intvalue =pthis->start;intvalue<=pthis->end; ++intvalue) { pthis->SendMessage(WM_MY_THREAD_MESSAGE1,intvalue); } return 0; } thread1 function LRESULT CThreadingEx3Dlg::OnThreadMessage1(WPARAM wparam,LPARAM lparam) { int nProgress= (int)wparam; m_ProgressBar.SetPos(nProgress); CString strStatus; strStatus.Format(L"Thread1:Processing item: %d", nProgress); m_Static.SetWindowText(strStatus); Sleep(100); return 0; } thread2 UINT MyThreadFunction2(LPARAM lparam) { CThreadingEx3Dlg* pthis = (CThreadingEx3Dlg*)lparam; for(int i =pthis->start;i<=pthis->end;i++) { pthis->SendMessage(WM_MY_THREAD_MESSAGE2,i); } return 0; } thread2 function LRESULT CThreadingEx3Dlg::OnThreadMessage2(WPARAM wparam,LPARAM lparam) { m_Static1.GetDlgItem(IDC_STATIC6); m_Static1.SetWindowTextW(L"Thread2 Running"); Sleep(100); m_Static1.SetWindowTextW(L""); Sleep(100); return TRUE; } void CThreadingEx3Dlg::OnBnClickedPause() { // TODO: Add your control notification handler code here if(!m_Track) { m_Track = TRUE; GetDlgItem(IDCANCEL)->SetWindowTextW(L"Resume"); myThread1->SuspendThread(); WaitForSingleObject(myThread1->m_hThread,INFINITE); myThread2->SuspendThread(); m_Static.SetWindowTextW(L"Paused.."); } else { m_Track = FALSE; GetDlgItem(IDCANCEL)->SetWindowTextW(L"Pause"); myThread1->ResumeThread(); myThread2->ResumeThread(); /*myEventHandler.SetEvent(); WaitForSingleObject(myThread1->m_hThread,INFINITE);*/ } }

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• Avoiding explicit recursion in Haskell

  - by Travis Brown

  The following simple function applies a given monadic function iteratively until it hits a Nothing, at which point it returns the last non-Nothing value. It does what I need, and I understand how it works. lastJustM :: (Monad m) => (a -> m (Maybe a)) -> a -> m a lastJustM g x = g x >>= maybe (return x) (lastJustM g) As part of my self-education in Haskell I'm trying to avoid explicit recursion (or at least understand how to) whenever I can. It seems like there should be a simple non-explicitly recursive solution in this case, but I'm having trouble figuring it out. I don't want something like a monadic version of takeWhile, since it could be expensive to collect all the pre-Nothing values, and I don't care about them anyway. I checked Hoogle for the signature and nothing shows up. The m (Maybe a) bit makes me think a monad transformer might be useful here, but I don't really have the intuitions I'd need to come up with the details (yet). It's probably either embarrassingly easy to do this or embarrassingly easy to see why it can't or shouldn't be done, but this wouldn't be the first time I've used self-embarrassment as a pedagogical strategy. Background: Here's a simplified working example for context: suppose we're interested in random walks in the unit square, but we only care about points of exit. We have the following step function: randomStep :: (Floating a, Ord a, Random a) => a -> (a, a) -> State StdGen (Maybe (a, a)) randomStep s (x, y) = do (a, gen') <- randomR (0, 2 * pi) <$> get put gen' let (x', y') = (x + s * cos a, y + s * sin a) if x' < 0 || x' > 1 || y' < 0 || y' > 1 then return Nothing else return $ Just (x', y') Something like evalState (lastJustM (randomStep 0.01) (0.5, 0.5)) <$> newStdGen will give us a new data point.

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• How do I call a function name that is stored in a hash in Perl?

  - by Ether

  I'm sure this is covered in the documentation somewhere but I have been unable to find it... I'm looking for the syntactic sugar that will make it possible to call a method on a class whose name is stored in a hash (as opposed to a simple scalar): use strict; use warnings; package Foo; sub foo { print "in foo()\n" } package main; my %hash = (func => 'foo'); Foo->$hash{func}; If I copy $hash{func} into a scalar variable first, then I can call Foo->$func just fine... but what is missing to enable Foo->$hash{func} to work? (EDIT: I don't mean to do anything special by calling a method on class Foo -- this could just as easily be a blessed object (and in my actual code it is); it was just easier to write up a self-contained example using a class method.) EDIT 2: Just for completeness re the comments below, this is what I'm actually doing (this is in a library of Moose attribute sugar, created with Moose::Exporter): # adds an accessor to a sibling module sub foreignTable { my ($meta, $table, %args) = @_; my $class = 'MyApp::Dir1::Dir2::' . $table; my $dbAccessor = lcfirst $table; eval "require $class" or do { die "Can't load $class: $@" }; $meta->add_attribute( $table, is => 'ro', isa => $class, init_arg => undef, # don't allow in constructor lazy => 1, predicate => 'has_' . $table, default => sub { my $this = shift; $this->debug("in builder for $class"); ### here's the line that uses a hash value as the method name my @args = ($args{primaryKey} => $this->${\$args{primaryKey}}); push @args, ( _dbObject => $this->_dbObject->$dbAccessor ) if $args{fkRelationshipExists}; $this->debug("passing these values to $class -> new: @args"); $class->new(@args); }, ); } I've replaced the marked line above with this: my $pk_accessor = $this->meta->find_attribute_by_name($args{primaryKey})->get_read_method_ref; my @args = ($args{primaryKey} => $this->$pk_accessor); PS. I've just noticed that this same technique (using the Moose meta class to look up the coderef rather than assuming its naming convention) cannot also be used for predicates, as Class::MOP::Attribute does not have a similar get_predicate_method_ref accessor. :(

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• go programming POST FormValue can't be printed

  - by poor_programmer

  Before I being a bit of background, I am very new to go programming language. I am running go on Win 7, latest go package installer for windows. I'm not good at coding but I do like some challenge of learning a new language. I wanted to start learn Erlang but found go very interesting based on the GO I/O videos in youtube. I'm having problem with capturing POST form values in GO. I spend three hours yesterday to get go to print a POST form value in the browser and failed miserably. I don't know what I'm doing wrong, can anyone point me to the right direction? I can easily do this in another language like C#, PHP, VB, ASP, Rails etc. I have search the entire interweb and haven't found a working sample. Below is my sample code. Here is Index.html page {{ define "title" }}Homepage{{ end }} {{ define "content" }} <h1>My Homepage</h1> <p>Hello, and welcome to my homepage!</p> <form method="POST" action="/"> <p> Enter your name : <input type="text" name="username"> </P> <p> <button>Go</button> </form> <br /><br /> {{ end }} Here is the base page <!DOCTYPE html> <html lang="en"> <head> <title>{{ template "title" . }}</title> </head> <body> <section id="contents"> {{ template "content" . }} </section> <footer id="footer"> My homepage 2012 copy </footer> </body> </html> now some go code package main import ( "fmt" "http" "strings" "html/template" ) var index = template.Must(template.ParseFiles( "templates/_base.html", "templates/index.html", )) func GeneralHandler(w http.ResponseWriter, r *http.Request) { index.Execute(w, nil) if r.Method == "POST" { a := r.FormValue("username") fmt.Fprintf(w, "hi %s!",a); //<-- this variable does not rendered in the browser!!! } } func helloHandler(w http.ResponseWriter, r *http.Request) { remPartOfURL := r.URL.Path[len("/hello/"):] fmt.Fprintf(w, "Hello %s!", remPartOfURL) } func main() { http.HandleFunc("/", GeneralHandler) http.HandleFunc("/hello/", helloHandler) http.ListenAndServe("localhost:81", nil) } Thanks! PS: Very tedious to add four space before every line of code in stackoverflow especially when you are copy pasting. Didn't find it very user friendly or is there an easier way?

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• Effective Data Validation

  - by John Conde

  What's an effective way to handle data validation, say, from a form submission? Originally I had a bunch of if statements that checked each value and collected invalid values in an array for later retrieval (and listing). // Store errors here $errors = array(); // Hypothetical check if a string is alphanumeric if (!preg_match('/^[a-z\d]+$/i', $fieldvalue)) { $errors[$fieldname] = 'Please only use letters and numbers for your street address'; } // etc... What I did next was create a class that handles various data validation scenarios and store the results in an internal array. After data validation was complete I would check to see if any errors occurred and handle accordingly: class Validation { private $errorList = array(); public function isAlphaNumeric($string, $field, $msg = '') { if (!preg_match('/^[a-z\d]+$/i', $string)) { $this->errorList[$field] = $msg; } } // more methods here public function creditCard($cardNumber, $field, $msg = '') { // Validate credit card number } // more methods here public function hasErrors() { return count($this->errorList); } } /* Client code */ $validate = new Validation(); $validate->isAlphaNumeric($fieldvalue1, $fieldname1, 'Please only use letters and numbers for your street address'); $validate->creditCard($fieldvalue2, $fieldname2, 'Please enter a valid credit card number'); if ($validate->hasErrors()) { // Handle as appropriate } Naturally it didn't take long before this class became bloated with the virtually unlimited types of data to be validated. What I'm doing now is using decorators to separate the different types of data into their own classes and call them only when needed leaving generic validations (i.e. isAlphaNumeric()) in the base class: class Validation { private $errorList = array(); public function isAlphaNumeric($string, $field, $msg = '') { if (!preg_match('/^[a-z\d]+$/i', $string)) { $this->errorList[$field] = $msg; } } // more generic methods here public function setError($field, $msg = '') { $this->errorList[$field] = $msg; } public function hasErrors() { return count($this->errorList); } } class ValidationCreditCard { protected $validate; public function __construct(Validation $validate) { $this->validate = $validate; } public function creditCard($cardNumber, $field, $msg = '') { // Do validation // ... // if there is an error $this->validate->setError($field, $msg); } // more methods here } /* Client code */ $validate = new Validation(); $validate->isAlphaNumeric($fieldvalue, $fieldname, 'Please only use letters and numbers for your street address'); $validateCC = new ValidationCreditCard($validate); $validateCC->creditCard($fieldvalue2, $fieldname2, 'Please enter a valid credit card number'); if ($validate->hasErrors()) { // Handle as appropriate } Am I on the right track? Or did I just complicate data validation more then I needed to?

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• Calculating the Angle Between Two vectors Using Dot Product

  - by P. Avery

  I'm trying to calculate the angle between two vectors so that I can rotate a character in the direction of an object in 3D space. I have two vectors( character & object), loc_look, and modelPos respectively. For simplicity's sake I am only trying to rotate along the up axis...yaw. loc_look = D3DXVECTOR3 (0, 0, 1), modelPos = D3DXVECTOR3 (0, 0, 15); I have written this code which seems to be the correct calculations. My problem arises, seemingly, because the rotation I apply to the character's look vector(loc_look) exceeds the value of the object's position (modelPos). Here is my code: BOOL CEntity::TARGET() { if(graphics.m_model->m_enemy) { D3DXVECTOR3 modelPos = graphics.m_model->position; D3DXVec3Normalize(&modelPos, &modelPos); //D3DXVec3Normalize(&loc_look, &loc_look); float dot = D3DXVec3Dot(&loc_look, &modelPos); float yaw = acos(dot); BOOL neg = (loc_look.x > modelPos.x) ? true : false; switch ( neg ) { case false: Yaw(yaw); return true; case true: Yaw(-yaw); return true; } } else return false; } I rotate the character's orientation matrix with the following code: void CEntity::CalculateOrientationMatrix(D3DXMATRIX *orientationMatrix) { D3DXMatrixRotationAxis(&rotY, &loc_up, loc_yaw); D3DXVec3TransformCoord(&loc_look, &loc_look, &rotY); D3DXVec3TransformCoord(&loc_right, &loc_right, &rotY); D3DXMatrixRotationAxis(&rotX, &loc_right, loc_pitch); D3DXVec3TransformCoord(&loc_look, &loc_look, &rotX); D3DXVec3TransformCoord(&loc_up, &loc_up, &rotX); D3DXMatrixRotationAxis(&rotZ, &loc_look, loc_roll); D3DXVec3TransformCoord(&loc_up, &loc_up, &rotZ); D3DXVec3TransformCoord(&loc_right, &loc_right, &rotZ); *orientationMatrix *= rotX * rotY * rotZ; orientationMatrix->_41 = loc_position.x; orientationMatrix->_42 = loc_position.y; orientationMatrix->_43 = loc_position.z; //D3DXVec3Normalize(&loc_look, &loc_look); SetYawPitchRoll(0,0,0); // Reset Yaw, Pitch, & Roll Amounts } Also to note, the modelPos.x increases by 0.1 each iteration so the character will face the object as it moves along the x-axis... Now, when I run program, in the first iteration everything is fine(I haven't rotated the character yet). On the second iteration, the loc_look.x value is greater than the modelPos.x value(I rotated the character too much using the angle specified with the dot product calculations in the TARGET function). Therefore on the second iteration my code will rotate the character left to adjust for the difference in the vectors' x values... How can I tighten up the measurements so that I do not rotate my character's look vector by too great a value?

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• multi-thread access MySQL error

  - by user188916

  I have written a simple multi-threaded C program to access MySQL,it works fine except when i add usleep() or sleep() function in each thread function. i created two pthreads in the main method, int main(){ mysql_library_init(0,NULL,NULL); printf("Hello world!\n"); init_pool(&p,100); pthread_t producer; pthread_t consumer_1; pthread_t consumer_2; pthread_create(&producer,NULL,produce_fun,NULL); pthread_create(&consumer_1,NULL,consume_fun,NULL); pthread_create(&consumer_2,NULL,consume_fun,NULL); mysql_library_end(); } void * produce_fun(void *arg){ pthread_detach(pthread_self()); //procedure while(1){ usleep(500000); printf("producer...\n"); produce(&p,cnt++); } pthread_exit(NULL); } void * consume_fun(void *arg){ pthread_detach(pthread_self()); MYSQL db; MYSQL *ptr_db=mysql_init(&db); mysql_real_connect(); //procedure while(1){ usleep(1000000); printf("consumer..."); int item=consume(&p); addRecord_d(ptr_db,"test",item); } mysql_thread_end(); pthread_exit(NULL); } void addRecord_d(MYSQL *ptr_db,const char *t_name,int item){ char query_buffer[100]; sprintf(query_buffer,"insert into %s values(0,%d)",t_name,item); //pthread_mutex_lock(&db_t_lock); int ret=mysql_query(ptr_db,query_buffer); if(ret){ fprintf(stderr,"%s%s\n","cannot add record to ",t_name); return; } unsigned long long update_id=mysql_insert_id(ptr_db); // pthread_mutex_unlock(&db_t_lock); printf("add record (%llu,%d) ok.",update_id,item); } the program output errors like: [Thread debugging using libthread_db enabled] [New Thread 0xb7ae3b70 (LWP 7712)] Hello world! [New Thread 0xb72d6b70 (LWP 7713)] [New Thread 0xb6ad5b70 (LWP 7714)] [New Thread 0xb62d4b70 (LWP 7715)] [Thread 0xb7ae3b70 (LWP 7712) exited] producer... producer... consumer...consumer...add record (31441,0) ok.add record (31442,1) ok.producer... producer... consumer...consumer...add record (31443,2) ok.add record (31444,3) ok.producer... producer... consumer...consumer...add record (31445,4) ok.add record (31446,5) ok.producer... producer... consumer...consumer...add record (31447,6) ok.add record (31448,7) ok.producer... Error in my_thread_global_end(): 2 threads didn't exit [Thread 0xb72d6b70 (LWP 7713) exited] [Thread 0xb6ad5b70 (LWP 7714) exited] [Thread 0xb62d4b70 (LWP 7715) exited] Program exited normally. and when i add pthread_mutex_lock in function addRecord_d,the error still exists. So what exactly the problem is?

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• Copy constructor bug

  - by user168715

  I'm writing a simple nD-vector class, but am encountering a strange bug. I've stripped out the class to the bare minimum that still reproduces the bug: #include <iostream> using namespace std; template<unsigned int size> class nvector { public: nvector() {data_ = new double[size];} ~nvector() {delete[] data_;} template<unsigned int size2> nvector(const nvector<size2> &other) { data_ = new double[size]; int i=0; for(; i<size && i < size2; i++) data_[i] = other[i]; for(; i<size; i++) data_[i] = 0; } double &operator[](int i) {return data_[i];} const double&operator[](int i) const {return data_[i];} private: const nvector<size> &operator=(const nvector<size> &other); //Intentionally unimplemented for now double *data_; }; int main() { nvector<2> vector2d; vector2d[0] = 1; vector2d[1] = 2; nvector<3> vector3d(vector2d); for(int i=0; i<3; i++) cout << vector3d[i] << " "; cout << endl; //Prints 1 2 0 nvector<3> other3d(vector3d); for(int i=0; i<3; i++) cout << other3d[i] << " "; cout << endl; //Prints 1 2 0 } //Segfault??? On the surface this seems to work fine, and both tests print out the correct values. However, at the end of main the program crashes with a segfault, which I've traced to nvector's destructor. At first I thought the (incorrect) default assignment operator was somehow being called, which is why I added the (currently) unimplemented explicit assignment operator to rule this possibility out. So my copy constructor must be buggy, but I'm having one of those days where I'm staring at extremely simple code and just can't see it. Do you guys have any ideas?

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• Loosely coupled implicit conversion

  - by ltjax

  Implicit conversion can be really useful when types are semantically equivalent. For example, imagine two libraries that implement a type identically, but in different namespaces. Or just a type that is mostly identical, except for some semantic-sugar here and there. Now you cannot pass one type into a function (in one of those libraries) that was designed to use the other, unless that function is a template. If it's not, you have to somehow convert one type into the other. This should be trivial (or otherwise the types are not so identical after-all!) but calling the conversion explicitly bloats your code with mostly meaningless function-calls. While such conversion functions might actually copy some values around, they essentially do nothing from a high-level "programmers" point-of-view. Implicit conversion constructors and operators could obviously help, but they introduce coupling, so that one of those types has to know about the other. Usually, at least when dealing with libraries, that is not the case, because the presence of one of those types makes the other one redundant. Also, you cannot always change libraries. Now I see two options on how to make implicit conversion work in user-code: The first would be to provide a proxy-type, that implements conversion-operators and conversion-constructors (and assignments) for all the involved types, and always use that. The second requires a minimal change to the libraries, but allows great flexibility: Add a conversion-constructor for each involved type that can be externally optionally enabled. For example, for a type A add a constructor: template <class T> A( const T& src, typename boost::enable_if<conversion_enabled<T,A>>::type* ignore=0 ) { *this = convert(src); } and a template template <class X, class Y> struct conversion_enabled : public boost::mpl::false_ {}; that disables the implicit conversion by default. Then to enable conversion between two types, specialize the template: template <> struct conversion_enabled<OtherA, A> : public boost::mpl::true_ {}; and implement a convert function that can be found through ADL. I would personally prefer to use the second variant, unless there are strong arguments against it. Now to the actual question(s): What's the preferred way to associate types for implicit conversion? Are my suggestions good ideas? Are there any downsides to either approach? Is allowing conversions like that dangerous? Should library implementers in-general supply the second method when it's likely that their type will be replicated in software they are most likely beeing used with (I'm thinking of 3d-rendering middle-ware here, where most of those packages implement a 3D vector).

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• Should I create a unique clustered index, or non-unique clustered index on this SQL 2005 table?

  - by Bremer

  I have a table storing millions of rows. It looks something like this: Table_Docs ID, Bigint (Identity col) OutputFileID, int Sequence, int …(many other fields) We find ourselves in a situation where the developer who designed it made the OutputFileID the clustered index. It is not unique. There can be thousands of records with this ID. It has no benefit to any processes using this table, so we plan to remove it. The question, is what to change it to… I have two candidates, the ID identity column is a natural choice. However, we have a process which does a lot of update commands on this table, and it uses the Sequence to do so. The Sequence is non-unique. Most records only contain one, but about 20% can have two or more records with the same Sequence. The INSERT app is a VB6 piece of crud throwing thousands insert commands at the table. The Inserted values are never in any particular order. So the Sequence of one insert may be 12345, and the next could be 12245. I know that this could cause SQL to move a lot of data to keep the clustered index in order. However, the Sequence of the inserts are generally close to being in order. All inserts would take place at the end of the clustered table. Eg: I have 5 million records with Sequence spanning 1 to 5 million. The INSERT app will be inserting sequence’s at the end of that range at any given time. Reordering of the data should be minimal (tens of thousands of records at most). Now, the UPDATE app is our .NET star. It does all UPDATES on the Sequence column. “Update Table_Docs Set Feild1=This, Field2=That…WHERE Sequence =12345” – hundreds of thousands of these a day. The UPDATES are completely and totally, random, touching all points of the table. All other processes are simply doing SELECT’s on this (Web pages). Regular indexes cover those. So my question is, what’s better….a unique clustered index on the ID column, benefiting the INSERT app, or a non-unique clustered index on the Sequence, benefiting the UPDATE app?

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• VBScript Can not Select XML nodes

  - by urbanMethod

  I am trying to Select nodes from some webservice response XML to no avail. For some reason I am able to select the root node ("xmldata") however, when I try to drill deeper("xmldata/customers") everything is returned empty! Below is the a sample of the XML that is returned by the webservice. <xmldata> <customers> <customerid>22506</customerid> <firstname>Jim</firstname> <issuperadmin>N</issuperadmin> <lastname>Jones</lastname> </customers> </xmldata> and here is the code I am trying to select customerid, firstname, and lastname; ' Send the Xml oXMLHttp.send Xml_to_Send ' Validate the Xml dim xmlDoc set xmlDoc = Server.CreateObject("Msxml2.DOMDocument") xmlDoc.load (oXMLHttp.ResponseXML.text) if(len(xmlDoc.text) = 0) then Xml_Returned = "<B>ERROR in Response xml:<BR>ERROR DETAILS:</B><BR><HR><BR>" end if dim nodeList Set nodeList = xmlDoc.SelectNodes("xmldata/customers") For Each itemAttrib In nodeList dim custID, custLname, custFname custID =itemAttrib.selectSingleNode("customerid").text custLname =itemAttrib.selectSingleNode("lastname").text custFname =itemAttrib.selectSingleNode("firstname").text response.write("News Subject: " & custID) response.write("<br />News Subject: " & custLname) response.write("<br />News Date: " & custFname) Next The result of the code above is zilch! nothing is written to the page. One strange thing is if I select the root element and get its length as follows; Set nodeList = xmlDoc.SelectNodes("xmldata") Response.Write(nodeList.length) '1 is written to page It correctly determines the length of 1. However when I try the same with the next node down as follows; Set nodeList2 = xmlDoc.SelectNodes("xmldata/customers") Response.Write(nodeList.length) '0 is written to page It returns a length of 0. WHY! Please note that this isn't the only way I have attempted to access the values of these nodes. I just can not work out what I am doing wrong. Could someone please help me out. Cheers.

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