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  • jQuery async ajax query and returning value problem (scope, closure)

    - by glebovgin
    Hi. Code not working because of async query and variable scope problem. I can't understand how to solve this. Change to $.ajax method with async:false - not an option. I know about closures, but how I can implement it here - don't know. I've seen all topics here about closures in js and jQuery async problems - but still nothing. Help, please. Here is the code: var map = null; var marker; var cluster = null; function refreshMap() { var markers = []; var markerImage = new google.maps.MarkerImage('/images/image-1_32_t.png', new google.maps.Size(32, 32)); $.get('/get_users.php',{},function(data){ if(data.status == 'error') return false; var users = data.users; // here users.length = 1 - this is ok; for(var i in users) { //here I have every values from users - ok var latLng = new google.maps.LatLng(users[i].lat, users[i].lng); var mark = new google.maps.Marker({ position: latLng, icon: markerImage }); markers.push(mark); alert(markers.length); // length 1 } },'json'); alert(markers.length); // length 0 //if I have alert() above - I get result cluster = new MarkerClusterer(map, markers, { maxZoom: null, gridSize: null }); } Thanks.

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  • [SOLVED]Django - Passing variables to template based on db

    - by George 'Griffin
    I am trying to add a feature to my app that would allow me to enable/disable the "Call Me" button based on whether or not I am at [home|the office]. I created a model in the database called setting, it looks like this: class setting(models.Model): key = models.CharField(max_length=200) value = models.CharField(max_length=200) Pretty simple. There is currently one row, available, the value of it is the string True. I want to be able to transparently pass variables to the templates like this: {% if available %} <!-- Display button --> {% else %} <!-- Display grayed out button --> {% endif %} Now, I could add logic to every view that would check the database, and pass the variable to the template, but I am trying to stay DRY. What is the best way to do this? UPDATE I created a context processor, and added it's path to the TEMPLATE_CONTEXT_PROCESSORS, but it is not being passed to the template def available(request): available = Setting.objects.get(key="available") if open.value == "True": return {"available":True} else: return {} UPDATE TWO If you are using the shortcut render_to_response, you need to pass an instance of RequestContext to the function. from the django documentation: If you're using Django's render_to_response() shortcut to populate a template with the contents of a dictionary, your template will be passed a Context instance by default (not a RequestContext). To use a RequestContext in your template rendering, pass an optional third argument to render_to_response(): a RequestContext instance. Your code might look like this: def some_view(request): # ... return render_to_response('my_template.html', my_data_dictionary, context_instance=RequestContext(request)) Many thanks for all the help!

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  • Usage of CRTP in a call chain

    - by fhw72
    In my widget library I'd like to implement some kind of call chain to initialize a user supplied VIEW class which might(!) be derived from another class which adds some additional functionality like this: #include <iostream> template<typename VIEW> struct App { VIEW view; void init() {view.initialize(); } }; template<typename DERIVED> struct SpecializedView { void initialize() { std::cout << "SpecializedView" << std::endl; static_cast<DERIVED*>(this)->initialize(); } }; struct UserView : SpecializedView<UserView> { void initialize() {std::cout << "UserView" << std::endl; } }; int _tmain(int argc, _TCHAR* argv[]) { // Cannot be altered to: App<SpecializedView<UserView> > app; App<UserView> app; app.init(); return 0; } Is it possible to achieve some kind of call chain (if the user supplied VIEW class is derived from "SpecializedView") such that the output will be: console output: SpecializedView UserView Of course it would be easy to instantiate variable app with the type derived from but this code is hidden in the library and should not be alterable. In other words: The library code should only get the user derived type as parameter.

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  • Listening to PHP function calls to intercept the returned value

    - by Lansen Q
    I am working on making use of a Web Services API offered by the hosts of our internal system. I am accessing it via PHP with the built-in SOAP offering. The API session is initiated by a remote call to a function that returns some session tokens; every call to any function thereafter will return a new session token, which must accompany the next request. I have an API Client class that is doing the bulk of the work; what I would like to do is to set something up whereby any SOAP call that is made will make sure to update the API Client class' $session variable with the new session details, and then pass the data along. So far the only way I can think of doing this is creating a new class extending the SoapClient class, with a __call function wrapper to execute the function, update the new session token, and return the results nonetheless. I'm not sure that this will a) work b) be the best way to go about this. The wrapper class would be identical to making a SOAP call, and it would return an identical result, just it would update the session token before you get your result back. Thanks! Hope I explained myself properly.

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  • Using XSLT, how can I produce a table with elements at the position of the the node's attributes?

    - by Dr. Sbaitso
    Given the following XML: <items> <item> <name>A</name> <address>0</address> <start>0</start> <size>2</size> </item> <item> <name>B</name> <address>1</address> <start>2</start> <size>4</size> </item> <item> <name>C</name> <address>2</address> <start>5</start> <size>2</size> </item> </items> I want to generate the following output including colspan's +---------+------+------+------+------+------+------+------+------+ | Address | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | +---------+------+------+------+------+------+------+------+------+ | 0 | | | | | | | A | +---------+------+------+------+------+------+------+------+------+ | 1 | | | B | | | +---------+------+------+------+------+------+------+------+------+ | 2 | | C | | | | | | +---------+------+------+------+------+------+------+------+------+ | 3 | | | | | | | | | +---------+------+------+------+------+------+------+------+------+ I think I would be able to accomplish this with a mutable xslt variable, but alas, there's no such thing. Is it even possible? How?

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  • How can I work out if a date is on or before today?

    - by Yvonne
    My web application consists of library type system where books have due dates. I have the current date displayed on my page, simply by using this: date_default_timezone_set('Europe/London'); $date = date; print $date("d/m/Y"); I have set 'date' as a variable because I'm not sure if it makes a difference when I use it in the IF statement you're about see, on my library books page. On this page, I am simply outputting the due dates of the books, many have dates which have not yet reached todays date, and others which have dates greater than todays date. Basically, all I want is the due date to appear bold (or strong), if it has passed todays date (the system displayed date). This is what I have and thought would work: <? if ($duedate < $date) { echo '<td><strong>'; } else { echo '<td>'; } ?> <?php echo $date('d/m/Y', $timestamp);?></strong></td> I have declared $timestamp as a var which converts the date of default MySQL format to a UK version. Can anyone help me out? I thought this would've been very straight forward!

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  • What is the best way to add two strings together?

    - by Pim Jager
    I read somewehere (I thought on codinghorror) that it is bad practice to add strings together as if they are numbers, since like numbers, strings cannot be changed. Thus, adding them together creates a new string. So, I was wondering, what is the best way to add two strings together, when focusing on performance? Which of these four is better, or is there another way which is better? //Note that normally at least one of these two strings is variable $str1 = 'Hello '; $str2 = 'World!'; $output1 = $str1.$str2; //This is said to be bad $str1 = 'Hello '; $output2 = $str1.'World!'; //Also bad $str1 = 'Hello'; $str2 = 'World!'; $output3 = sprintf('%s %s', $str1, $str2); //Good? //This last one is probaply more common as: //$output = sprintf('%s %s', 'Hello', 'World!'); $str1 = 'Hello '; $str2 = '{a}World!'; $output4 = str_replace('{a}', $str1, $str2); Does it even matter?

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  • Adding an keyUp-event to form objects

    - by reporter
    Hello folks, I've got the issue to add a browser event to some input fields. The challenge I have to face is, that one parameter of my target function is the 'event'-variable and the second one an object. For a better understanding here some codes:The HTML object: <div id="1_dateFieldAdvanced" class="xp set"> <div id="1_dateFieldAdvanced_label" class="label">Birthday</div> <div id="1_dateFieldAdvanced_value" class="value date"> <input class="day" name="dayOfBirth" value="66" maxlength="2" type="text"> <input class="month" name="monthOfBirth" value="67" maxlength="2" type="text"> <input class="year" name="yearOfBirth" value="" maxlength="4" type="text"> </div> </div> The source code of target method is like below: function advancedDateFields(currentFieldAsObject, nextField, currentValueLength, ev){} Unfortunatly the HTML and the Javascript code is generated automatically, so I'm unable to refactore the code. My question is, how can I pass the key word 'event' and the other parameters? My tries did always fail. :-(

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  • Need help, stuck on "How to send text message using java script to avoid post back"

    - by user287745
    this is what i have implemented, for further code, how to send this text of the text box to the server to store in variable or database without post back. it can be done by using ajax and update plane but i wold like to implement it using javascript script. <div id="CommentID" style=" width:30%; height:30%"> <asp:Button ID="Button1" runat="server" Text="Comment" OnClientClick="visibleDiv('id1'); return false;" /> <div id="id1" runat="server" style="visibility: hidden; background-color:Green; width:100%; height:100%"> <asp:TextBox ID="TextBox1" runat="server" AutoCompleteType="Disabled" Rows="3" TextMode="MultiLine" Width="98%"></asp:TextBox> <asp:Button ID="Button2" runat="server" Text="Post" onclick="Button2_Click" /> <asp:Button ID="Button3" runat="server" Text="Cancel" OnClientClick="visibleDiv('id1'); return false;" /> </div> </div>

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  • find a duplicate series in SQL

    - by SomeMiscGuy
    I have a table with 3 columns containing a variable number of records based off of the first column which is a foreign key. I am trying to determine if I can detect when there is a duplicate across multiple rows for an entire series declare @finddupseries table ( portid int, asset_id int, allocation float ) ; INSERT INTO @finddupseries SELECT 250, 6, 0.05 UNION ALL SELECT 250, 66, 0.8 UNION ALL SELECT 250, 2, 0.105 UNION ALL SELECT 250, 4, 0.0225 UNION ALL SELECT 250, 5, 0.0225 UNION ALL SELECT 251, 13, 0.6 UNION ALL SELECT 251, 2, 0.3 UNION ALL SELECT 251, 5, 0.1 UNION ALL SELECT 252, 13, 0.8 UNION ALL SELECT 252, 2, 0.15 UNION ALL SELECT 252, 5, 0.05 UNION ALL SELECT 253, 13, 0.4 UNION ALL SELECT 253, 2, 0.45 UNION ALL SELECT 253, 5, 0.15 UNION ALL SELECT 254, 6, 0.05 UNION ALL SELECT 254, 66, 0.8 UNION ALL SELECT 254, 2, 0.105 UNION ALL SELECT 254, 4, 0.0225 UNION ALL SELECT 254, 5, 0.0225 select * from @finddupseries The records for portid 250 and 254 match. Is there any way I can write a query to detect this? edit: yes, the entire series must match. Also, if there was a way to determine which one it DID match would be helpful as the actual table has around 10k records. thanks!

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  • PHP while loop, table row

    - by Elliott
    Hi, I'm trying to loop through a database and output data into a div, if there are 3 divs horizontally accross it will the start a new tr until it reaches another 3 etc. It is currently outputted like : [] [] [] [] [] [] Currently I have it working when it reaches 3 it starts a new row, but I don't know how I can only echo a new tr once? As it creates a new table row each time. echo '<table><tr>'; while ($result) { $i ++; if ($i&3) { echo '<td> <div>Row Data</div> </td>'; } else { echo '<tr> <td> <div>Row Data</div> </td></tr>'; } } echo '</tr></table>'; The $result variable is the recordset from my sql query, everything works fine I just don't know how to only create a new table row once? Thanks

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  • Why is post() not updating the DOM after it returns? Wierd timing problem observed.

    - by Sephrial
    Hi all, I have the following code that is really bugging me, I'm thinking perhaps the post() function needs to be blocking. I am new to jQuery(latest version) and AJAX, but I'm using ColdFusion which returns some HTML in the data variable. var dataResult; var statusResult; $.post('fh_result.cfm',$('#myform').serialize(),function(data,status){ dataResult = data; statusResult = status; }); //alert(statusResult); if ('success' == statusResult) { alert(statusResult); $('#result').html(dataResult); } When I uncomment out the first alert, it returns 'undefined' but then it goes into the if block and the next alert box it says 'success'. If I comment out that line it doesn't make it into the if statement at all. My guess is that I want to make this a blocking call or something because I want to insert the data on the page after the post. I also have a problem when I re-write the top code as follows: var dataResult; var statusResult; $.post('fh_result.cfm',$('#myform').serialize(),function(data,status){ dataResult = data; statusResult = status; alert(statusResult); $('#result').html(dataResult); }); //alert(statusResult); Now in this case, the alert says 'success' when I comment out the second alert box. When I uncomment it out, I get one alert that says success and the other that says undefined, but this time it updates the DOM with the result of the postback as desired. How can I do this without the alert box?

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  • Problem displaying the Message box in MFC

    - by kiddo
    I have a simple MFC program which displays the progressbar..I used the below code to display the progress bar.. HWND dialogHandle = CreateWindowEx(0,WC_DIALOG,L"Proccessing...",WS_OVERLAPPEDWINDOW|WS_VISIBLE, 600,300,280,120,NULL,NULL,NULL,NULL); HWND progressBarHandle = CreateWindowEx(NULL,PROGRESS_CLASS,NULL,WS_CHILD|WS_VISIBLE|PBS_MARQUEE,40,20,200,20, dialogHandle,(HMENU)IDD_PROGRESS,NULL,NULL); while(FALSE == testResult) { MSG msg; SendMessage(progressBarHandle, PBM_SETRANGE, 0, MAKELPARAM( 0, 100 ) ); SendMessage(progressBarHandle,PBM_SETPOS,0,0); ShowWindow(progressBarHandle,SW_SHOW); Sleep(50); if(TRUE == myCondition)//myCondition is a bool variable which is decalred globally { DestroyWindow(dialogHandle); AfxMessageBox(L"Test Success"); } } when I execute the above code..the message box displays only after a mouseover event.like if I move the mouse the message box will display if not it will not display until i move the mouse. And also while the progressbar is running if I try to move the progress bar window..it displays a windows background at the place of displacement and also in the new region or sometimes its getting stuck.Please help me with this!

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  • How to use strtok in C properly so there is no memory leak?

    - by user246392
    I am somewhat confused by what happens when you call strtok on a char pointer in C. I know that it modifies the contents of the string, so if I call strtok on a variable named 'line', its content will change. Assume I follow the bellow approach: void function myFunc(char* line) { // get a pointer to the original memory block char* garbageLine = line; // Do some work // Call strtok on 'line' multiple times until it returns NULL // Do more work free(garbageLine); } Further assume that 'line' is malloced before it is passed to myFunc. Am I supposed to free the original string after using strtok or does it do the job for us? Also, what happens if 'line' is not malloced and I attempt to use the function above? Is it safer to do the following instead? (Assume the programmer won't call free if he knows the line is not malloced) Invocation char* garbageLine = line; myFunc(line); free(garbageLine); Function definition void function myFunc(char* line) { // Do some work // Call strtok on 'line' multiple times until it returns NULL // Do more work }

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  • login script in php using session variables

    - by kracekumar
    ? username: '; } else { $user=$_POST['user']; $query="select name from login where name='$user'"; $result=mysql_query($query) or die(mysql_error()); $rows=mysql_num_rows($result)or die(mysql_error()); session_start(); //echo "results"; $username=mysql_fetch_array($result) or die(mysql_error()); $fields=mysql_num_fields($result) or die(mysql_error()); echo "username:$username[0]"; $_SESSION['username']=$username[0]; $sesion_username=$_SESSION['username']; //echo "rows:$rows"." "."fields:$fields"; echo""."username:$sesion_username"; } ? i wanted to create a site where user can login and upload their details depending on their user name have stored their details in a database,the problem i am facing is two people 'a' and 'b' login one after other session_variable $_SESSION['username'] will have 'b's' username ,so i can't display 'a's' details now. . . . what i want to achieve is when a user logins in i want to store his name and other details in session variable and navigate him according and display his details

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  • Android SDK and Java

    - by Soonts
    Android SDK Manager complains "WARNING: Java not found in your path". Instead of using the information from Windows registry, the software tries to search Java in the default installation folders, and fails (I don't install software in program files because I don't like space characters in my paths). Of course I know how to modify the %PATH% environment variable. The question is — which Java does it need? After installing the latest JDK, I’ve got 4 distinct versions of java.exe file, in the following 4 folders: system32, jre6\bin, jdk1.6.0_26\bin, and jdk1.6.0_26\jre\bin. Size ranges from 145184 to 171808. All of them print version “1.6.0_26” when launched with the “-version” argument. The one in system32 has .exe version “6.0.250.6”, the rest of them is “6.0.260.3”. All 4 files are different (I’ve calculated the MD5 checksums). Q1. Which folder should I add to %PATH% to make the Android SDK happy? Q2. Why does Oracle build that many variants of java.exe of the same version for the same platform? Thanks in advance! P.S. I'm using Windows 7 SP1 x64 home premium, and downloaded the 64-bit version of JDK, jdk-6u26-windows-x64.exe.

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  • In C# should I reuse a function / property parameter to compute cleaner temporary value or create a

    - by Hamish Grubijan
    The example below may not be problematic as is, but it should be enough to illustrate a point. Imagine that there is a lot more work than trimming going on. public string Thingy { set { // I guess we can throw a null reference exception here on null. value = value.Trim(); // Well, imagine that there is so much processing to do this.thingy = value; // That this.thingy = value.Trim() would not fit on one line ... So, if the assignment has to take two lines, then I either have to abusereuse the parameter, or create a temporary variable. I am not a big fan of temporary variables. On the other hand, I am not a fan of convoluted code. I did not include an example where a function is involved, but I am sure you can imagine it. One concern I have is if a function accepted a string and the parameter was "abused", and then someone changed the signature to ref in both places - this ought to mess things up, but ... who would knowingly make such a change if it already worked without a ref? Seems like it is their responsibility in this case. If I mess with the value of value, am I doing something non-trivial under the hood? If you think that both approaches are acceptable, then which do you prefer and why? Thanks.

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  • PHP array minor problem

    - by Sennheiser
    I'm really not sure how to explain this. It's so simple I can't fathom why it's not working. I have a loop. It puts a bunch of strings into an array. If I fill a single variable with any given string, it will output it perfectly. But filling an array with the strings will make it give me the dreaded: Array Array Array Array Array Array Array Array Note: my strings are not all 'Array'. The way I loop is: while(...) { $arr[] = $resultFromLoop; } Here is my var_dump. array(1) { ["tagName"]=> string(5) "magic" } array(1) { ["tagName"]=> string(4) "nunu" } array(1) { ["tagName"]=> string(5) "books" } array(1) { ["tagName"]=> string(0) "" } array(1) { ["tagName"]=> string(3) "zzz" } array(1) { ["tagName"]=> string(4) "grey" } array(1) { ["tagName"]=> string(3) "new" } array(1) { ["tagName"]=> string(6) "flight" }

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  • Should convert String to Int in java @ 1.5 or use other method?

    - by NiksBestJPro
    I'm writing a program in which I want to terminate program by pressing any key(whether character or numbers), so I did a conversion from string to int using Integer.parseInt(variable) method and compare choices if it is not desired choice it should terminate the program but it show an error Exception in thread "main" java.lang.NumberFormatException: for input string: "d". program code is as follows:- public class mainClass { public static void main(String[]ar) { double res=0; Scanner in = new Scanner(System.in); Tdata td1 = new Tdata(); //another class object System.out.println("*Temperature Conversion*"); System.out.println("------------------------------"); System.out.println("Press 1- C2F"); System.out.println("Press 2- F2C"); System.out.println("<- Press aNY kEY TO Exit -"); String choice = in.nextLine(); //==================================================================== int ch = Integer.parseInt(choice); System.out.println("String has converted: " +ch); //verifying if converted into int if(ch == 1 || ch == 2) { if(ch == 1) { td1.getVal(37.4); res = td1.C2F(); System.out.println("Resulted Temperature: "+res); } else if(ch == 2) { td1.getVal(104.2); res = td1.F2C(); System.out.println("Resulted Temperature: "+res); } else { System.out.println("mind your input plz"); } } else { System.out.println("<- You select to exit ->"); System.exit(0); } //========================================================================================= }//end of main }//end of public class Now I think that I should convert undesired input to its previous state ie. String state.. is it right way or should Try another predefined method available in api. -Thanks! Niks

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  • Generic Singleton Fasade design pattern

    - by Paul
    Hi I try write singleton fasede pattern with generics. I have one problem, how can I call method from generic variable. Something like this: T1 t1 = new T1(); //call method from t1 t1.Method(); In method SingletonFasadeMethod I have compile error: Error 1 'T1' does not contain a definition for 'Method' and no extension method 'Method' accepting a first argument of type 'T1' could be found (are you missing a using directive or an assembly reference?) Any advace? Thank, I am beginner in C#. All code is here: namespace GenericSingletonFasade { public interface IMyInterface { string Method(); } internal class ClassA : IMyInterface { public string Method() { return " Calling MethodA "; } } internal class ClassB : IMyInterface { public string Method() { return " Calling MethodB "; } } internal class ClassC : IMyInterface { public string Method() { return "Calling MethodC"; } } internal class ClassD : IMyInterface { public string Method() { return "Calling MethodD"; } } public class SingletonFasade<T1,T2,T3> where T1 : class,new() where T2 : class,new() where T3 : class,new() { private static T1 t1; private static T2 t2; private static T3 t3; private SingletonFasade() { t1 = new T1(); t2 = new T2(); t3 = new T3(); } class SingletonCreator { static SingletonCreator() { } internal static readonly SingletonFasade<T1,T2,T3> uniqueInstace = new SingletonFasade<T1,T2,T3>(); } public static SingletonFasade<T1,T2,T3> UniqueInstace { get { return SingletonCreator.uniqueInstace; } } public string SingletonFasadeMethod() { //Problem is here return t1.Method() + t2.Method() + t3.Method(); } } }

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  • How to implement the "System.out.println(ClassName::MethodName <then my message>)" of Eclipse in Netbeans?

    - by Sen
    I would like to know if there is the same feature as in eclipse to automatically generate and print the System.out.println(ClassName::MethodName <then my message>) functionality (which will print the class name and method name for debugging in the console) in Netbeans also. For example, in Eclipse Editor, Typing syst + Ctrl+ Space will auto generate a System.out.println(ClassName::MethodName ) type output in the console. Is such a method available in Netbeans? As of now, I have only two methods here in Netbeans: sout + Tab (System.out.println()) and soutv + Tab (System.out.println(prints the variable used just above the line)) automatically. Let me rephrase, instead of myMethod1, I want to get the enclosing method name. Eg. : public class X { public void myMethod1(int a) { System.out.println(X::myMethod1()); // This should be produced when I type the Code-Template abbreviation (example: syst) and press tab (or corresponding key). } } public class Y { public void myMethod2(int b) { System.out.println(Y::myMethod2()); // This should be produced when I type the Code-Template abbreviation (example: syst) and press tab (or corresponding key). } } Update: With the following code template: syst = System.out.println("${classVar editable="false" currClassName default="getClass()"}"); I am able to print the classname, but still no clue for the Method name.

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  • XSLT; parse escaped text to a node-set and extract subelements

    - by Tom W
    Hello SO; I've been fighting with this problem all day and am just about at my wit's end. I have an XML file in which certain portions of data are stored as escaped text but are themselves well-formed XML. I want to convert the whole hierarchy in this text node to a node-set and extract the data therein. No combination of variables and functions I can think of works. The way I'd expect it to work would be: <xsl:variable name="a" select="InnerXML"> <xsl:for-each select="exsl:node-set($a)/*"> 'do something </xsl:for-each> The input element InnerXML contains text of the form <root><element a>text</element a><element b><element c/><element d>text</element d></element b></root> but that doesn't really matter. I just want to navigate the xml like a normal node-set. Where am I going wrong?

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  • How do I make this Java code operate properly? [Multi-threaded, race condition]

    - by Fixee
    I got this code from a student, and it does not work properly because of a race condition involving x++ and x--. He added synchronized to the run() method trying to get rid of this bug, but obviously this only excludes threads from entering run() on the same object (which was never a problem in the first place) but doesn't prevent independent objects from updating the same static variable x at the same time. public class DataRace implements Runnable { static volatile int x; public synchronized void run() { for (int i = 0; i < 10000; i++) { x++; x--; } } public static void main(String[] args) throws Exception { Thread [] threads = new Thread[100]; for (int i = 0; i < threads.length; i++) threads[i] = new Thread(new DataRace()); for (int i = 0; i < threads.length; i++) threads[i].start(); for (int i = 0; i < threads.length; i++) threads[i].join(); System.out.println(x); // x not always 0! } } Since we cannot synchronize on x (because it is primitive), the best solution I can think of is to create a new static object like static String lock = ""; and enclose the x++ and x-- within a synchronized block, locking on lock. But this seems really awkward. Is there a better way?

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  • optimization math computation (multiplication and summing)

    - by wiso
    Suppose you want to compute the sum of the square of the differences of items: $\sum_{i=1}^{N-1} (x_i - x_{i+1})^2$, the simplest code (the input is std::vector<double> xs, the ouput sum2) is: double sum2 = 0.; double prev = xs[0]; for (vector::const_iterator i = xs.begin() + 1; i != xs.end(); ++i) { sum2 += (prev - (*i)) * (prev - (*i)); // only 1 - with compiler optimization prev = (*i); } I hope that the compiler do the optimization in the comment above. If N is the length of xs you have N-1 multiplications and 2N-3 sums (sums means + or -). Now suppose you know this variable: sum = $x_1^2 + x_N^2 + 2 sum_{i=2}^{N-1} x_i^2$ Expanding the binomial square: $sum_i^{N-1} (x_i-x_{i+1})^2 = sum - 2\sum_{i=1}^{N-1} x_i x_{i+1}$ so the code becomes: double sum2 = 0.; double prev = xs[0]; for (vector::const_iterator i = xs.begin() + 1; i != xs.end(); ++i) { sum2 += (*i) * prev; prev = (*i); } sum2 = -sum2 * 2. + sum; Here I have N multiplications and N-1 additions. In my case N is about 100. Well, compiling with g++ -O2 I got no speed up (I try calling the inlined function 2M times), why?

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  • Replace an embed or iframe youtube video by an tumbnail + link to vídeo.

    - by Evel
    I need an javascript that can be placed on header that recognizes an youtube embed or iframe player and replaces it by a tumbnail linked to the vídeo on youtube. The script should identifies an code like this ones: <object width="560" height="340"><param name="movie" value="http://www.youtube.com/v/J4oJWUJpbLY?fs=1&amp;hl=pt_BR&amp;hd=1&amp;color1=0x5d1719&amp;color2=0xcd311b"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/J4oJWUJpbLY?fs=1&amp;hl=pt_BR&amp;hd=1&amp;color1=0x5d1719&amp;color2=0xcd311b" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="560" height="340"></embed></object> <iframe title="YouTube video player" class="youtube-player" type="text/html" width="560" height="345" src="http://www.youtube.com/embed/J4oJWUJpbLY?hd=1" frameborder="0"></iframe> And replace by it: <a href="http://www.youtube.com/watch?v=n1VCUF2xqKk" target="_blank"><img src="http://img.youtube.com/vi/n1VCUF2xqKk/default.jpg" alt="" /></a> Look that the variable is the video ID. It is possible?

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