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  • Getting rid of "static" references in C#

    - by DevEight
    Hello. I've recently begun learning C# but have encountered an annoying problem. Every variable I want available to all functions in my program I have to put a "static" in front of and also every function. What I'd like to know is how to avoid this, if possible? Also, small side question: creating public variables inside functions? This is what my program looks like right now, and I want to basically keep it like that, without having to add "static" everywhere: using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Net; using System.Threading; using System.Net.Sockets; namespace NetworkExercise { class Client { public IPAddress addr; public int port; public string name; public Thread thread; public TcpClient tcp; public NetworkStream stream; public Client(IPAddress addr, int port, string name, NetworkStream stream) { } } class Program { //NETWORK TcpListener tcpListener; Thread listenThread; ASCIIEncoding encoder = new ASCIIEncoding(); //DATA byte[] buffer = new byte[4096]; string servIp; int servPort; //CLIENT MANAGEMENT int clientNum; static void Main(string[] args) { beginConnect(); } public void beginConnect() { Console.Write("Server IP (leave blank if you're the host): "); servIp = Console.ReadLine(); Console.Write("Port: "); servPort = Console.Read(); tcpListener = new TcpListener(IPAddress.Any, servPort); listenThread = new Thread(new ThreadStart(listenForClients)); listenThread.Start(); } public void listenForClients() { tcpListener.Start(); Console.WriteLine("Listening for clients..."); while (true) { Client cl = new Client(null, servPort, null, null); cl.tcp = tcpListener.AcceptTcpClient(); ThreadStart pts = delegate { handleClientCom(cl); }; cl.thread = new Thread(pts); cl.thread.Start(); } } public void handleClientCom(Client cl) { cl.stream = cl.tcp.GetStream(); } } }

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  • How to cache queries in EJB and return result efficient (performance POV)

    - by Maxym
    I use JBoss EJB 3.0 implementation (JBoss 4.2.3 server) At the beginning I created native query all the time using construction like Query query = entityManager.createNativeQuery("select * from _table_"); Of couse it is not that efficient, I performed some tests and found out that it really takes a lot of time... Then I found a better way to deal with it, to use annotation to define native queries: @NamedNativeQuery( name = "fetchData", value = "select * from _table_", resultClass=Entity.class ) and then just use it Query query = entityManager.createNamedQuery("fetchData"); the performance of code line above is two times better than where I started from, but still not that good as I expected... then I found that I can switch to Hibernate annotation for NamedNativeQuery (anyway, JBoss's implementation of EJB is based on Hibernate), and add one more thing: @NamedNativeQuery( name = "fetchData2", value = "select * from _table_", resultClass=Entity.class, readOnly=true) readOnly - marks whether the results are fetched in read-only mode or not. It sounds good, because at least in this case of mine I don't need to update data, I wanna just fetch it for report. When I started server to measure performance I noticed that query without readOnly=true (by default it is false) returns result with each iteration better and better, and at the same time another one (fetchData2) works like "stable" and with time difference between them is shorter and shorter, and after 5 iterations speed of both was almost the same... The questions are: 1) is there any other way to speed query using up? Seems that named queries should be prepared once, but I can't say it... In fact if to create query once and then just use it it would be better from performance point of view, but it is problematic to cache this object, because after creating query I can set parameters (when I use ":variable" in query), and it changes query object (isn't it?). well, is here any way to cache them? Or named query is the best option I can use? 2) any other approaches how to make results retrieveng faster. I mean, for instance I don't need those Entities to be attached, I won't update them, all I need is just fetch collection of data. Maybe readOnly is the only available way, so I can't speed it up, but who knows :) P.S. I don't ask about DB performance, all I need now is how not to create query all the time, so use it efficient, and to "allow" EJB to do less job with the same result concerning data returning.

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  • Remove never-run call to templated function, get allocation error on run-time

    - by Narfanator
    First off, I'm a bit at a loss as to how to ask this question. So I'm going to try throwing lots of information at the problem. Ok, so, I went to completely redesign my test project for my experimental core library thingy. I use a lot of template shenanigans in the library. When I removed the "user" code, the tests gave me a memory allocation error. After quite a bit of experimenting, I narrowed it down to this bit of code (out of a couple hundred lines): void VOODOO(components::switchBoard &board){ board.addComponent<using_allegro::keyInputs<'w'> >(); } Fundementally, what's weirding me out is that it appears that the act of compiling this function (and the template function it then uses, and the template functions those then use...), makes this bug not appear. This code is not being run. Similar code (the same, but for different key vals) occurs elsewhere, but is within Boost TDD code. I realize I certainly haven't given enough information for you to solve it for me; I tried, but it more-or-less spirals into most of the code base. I think I'm most looking for "here's what the problem could be", "here's where to look", etc. There's something that's happening during compile because of this line, but I don't know enough about that step to begin looking. Sooo, how can a (presumably) compilied, but never actually run, bit of templated code, when removed, cause another part of code to fail? Error: Unhandled exceptionat 0x6fe731ea (msvcr90d.dll) in Switchboard.exe: 0xC0000005: Access violation reading location 0xcdcdcdc1. Callstack: operator delete(void * pUser Data) allocator< class name related to key inputs callbacks ::deallocate vector< same class ::_Insert_n(...) vector< " " ::insert(...) vector<" "::push_back(...) It looks like maybe the vector isn't valid, because _MyFirst and similar data members are showing values of 0xcdcdcdcd in the debugger. But the vector is a member variable...

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  • MouseWheel Event Fire

    - by Rahat
    I have a problem on calling my private method on MouseWheel event. In fact my mouse wheel event gets fired properly when i only increment a variable or display something in Title bar etc. But when i want to call a private method, that method gets called only one time which is not the requirement i want to call that method depending on the speed of scroll i.e. when scroll is done one time slowly call the private method one time but when the scroll is done in high speed call the private method more than one time depending on the scroll speed. For further explanation i am placing the sample code which displays the value of i in Title bar and add it in the Listbox control properly depending on the scroll speed but when i want to call the private method more than one time depending upon the scroll speed, that method gets called only one time. public partial class Form1 : Form { ListBox listBox1 = new ListBox(); int i = 0; public Form1() { InitializeComponent(); // Settnig ListBox control properties this.listBox1.Anchor = ((System.Windows.Forms.AnchorStyles)((((System.Windows.Forms.AnchorStyles.Top | System.Windows.Forms.AnchorStyles.Bottom) | System.Windows.Forms.AnchorStyles.Left) | System.Windows.Forms.AnchorStyles.Right))); this.listBox1.FormattingEnabled = true; this.listBox1.Location = new System.Drawing.Point(13, 13); this.listBox1.Name = "listBox1"; this.listBox1.Size = new System.Drawing.Size(259, 264); this.listBox1.TabIndex = 0; // Attaching Mouse Wheel Event this.listBox1.MouseWheel += new MouseEventHandler(Form1_MouseWheel); // Adding Control this.Controls.Add(this.listBox1); } void Form1_MouseWheel(object sender, MouseEventArgs e) { i++; this.Text = i.ToString(); this.listBox1.Items.Add(i.ToString()); // Uncomment the following line to call the private method // this method gets called only one time irrelevant of the // mouse wheel scroll speed. // this.LaunchThisEvent(); } private void Form1_Load(object sender, EventArgs e) { this.listBox1.Select(); } private void LaunchThisEvent() { // Display message each time // this method gets called. MessageBox.Show(i.ToString()); } } How to call the private method more than one time depending upon the speed of the mouse wheel scroll?

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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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  • Ruby/Rails - Add records to an object with each loop iteration / Object vs Arrays

    - by ChrisWesAllen
    I'm trying to figure out how to add records to an existing object for each iteration of a loop. I'm having a hard time discovering the difference between an object and an array. I have this @events = Event.find(1) @loops = Choices.find(:all, :limit => 5) #so loop for 5 instances of choice model for loop in @loops @events = Event.find(:all,:conditions => ["event.id = ?", loop.event_id ]) end I'm trying to add a new events to the existing @events object based on the id of whatever the loop variable is. But the ( = ) operator just creates a new instance of the @events object. I tried ( += ) and ( << ) as operators but got the error "You have a nil object when you didn't expect it! You might have expected an instance of Array. The error occurred while evaluating nil" I tried created an array events = [] events << Event.find(1) @loops = Choices.find(:all, :limit => 5) #so loop for 5 instances of choice model for loop in @loops events << Event.find(:all,:conditions => ["event.id = ?", loop.event_id ]) end But I dont know how to call that arrays attributes within the view With objects I was able do create a loop within the view and call all the attributes of that object as well... <table> <% for event in @events %> <tr> <td><%= link_to event.title, event %></td> <td><%= event.start_date %></td> <td><%= event.price %></td> </tr> <% end %> </table> How could i do this with an array set? So the questions are 1) Whats the difference between arrays and objects? 2) Is there a way to add into the existing object for each iteration? 3) If I use an array, is there a way to call the attributes for each array record within the view?

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  • jQuery i++ and i-- problems ... what on earth???

    - by michael
    Could someone please tell me what I am doing wrong? I'm not a newbie at programming but I feel like it tonight! Every time I increment the incrementing variable it throws a fit! When add one to it, it behaves fine, but if I try to add one more to it it wants to add 2 more. And then if I try to de-increment it wants to subtract from the original number that it was assigned to. I've tried: i++; i = i+1; i = i++; Nothing seems to work. It's got to be a stupid mistake. Press the buttons to increment and de-increment. http://michaelreynolds.net/iphone/ here's the code: var dayNum = 30; //---------------------------------------------------------------------- $.jQTouch({ icon: 'dailyqoteicon.png', statusBar: false, initializeTouch: 'a.touch' }); //---------------------------------------------------------------------- $(document).ready(function(){ //$(function(){}); $(function(){ $('a.touch').swipe( function(event, info){ //alert("jQTouch swipe event"); //alert(info.direction); }); }); $(function updateVerse(){ //alert("updateVerse called"); $.ajax({ type: "GET", dataType: 'JSON', data: 'day='+ dayNum, url: 'forward.php', success: function(data){ var obj = $.parseJSON(data); $("h2.quote").html(""); $("h3.reference").html(""); $("h2.quote").append(obj.quote); $("h3.reference").append(obj.reference, " ", obj.version); //$("span.version").append(obj.version); //----------------------------------- // JSON string {"id":"1","quote":"For to me, to live is Christ, and to die is gain","reference":"Philippians 1:21","version":"NKJV"} }, error: function(request, error){ alert("problem retrieving json data string"); } }); function addDayNum(){ dayNum = dayNum + 1; //dayNum = dayNum++; } function subDayNum(){ dayNum = dayNum - 1; //dayNum = dayNum--; } $("div#header a.next").tap( function(){ addDayNum(); //dayNum++;// doesn't work at all //dayNum = dayNum + 1;//doesn't work at all updateVerse(); //alert(dayNum); //alert("next clicked"); }); $("div#header a.prev").live('click', function(){ subDayNum(); //dayNum--;//doesn't work at all //dayNum = dayNum - 1;// doesn't work at all updateVerse(); //alert(dayNum); //alert("previous clicked"); }); }); });

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  • Lift session valid ajax callback from a static javascript

    - by ChrisJamesC
    I am currently implementing a graph visualisation tool using lift on the server side and d3 ( a javascript visualisation framework) for all the visualisation. The problem I have is that in the script I want to get session dependent data from the server. So basically, my objective is to write lift-valid ajax callbacks in a static js script. Here is what I tried so far: What I have tried so far If you feel that the best solution is one that I already tried feel free to post a detailed answer telling me how to use it exactly and how it completely solves my problem. REST interface Usually what one would do to get data from a javascript function in lift is to create a REST interface. However this interface will not be linked to any session. This is the solution I got from my previous question: Get json data in d3 from lift snippet Give function as argument of script Another solution would be to give the ajaxcallback as an argument of the main script called to generate my graph. However I expect to have a lot of callbacks and I don't want to have to mess with the arguments of my script. Write the ajax callback in another script using lift and call it from the main script This solution, which is similar to a hidden text input is probably the more likely to work. However it is not elegant and it would mean that I would have to load a lot of scripts on load, which is not really conveniant. Write the whole script in lift and then serve it to the client This solution can be elegant, however my script is very long and I would really prefer that it remainss static. What I want On client side While reviewing the source code of my webpage I found that the callback for an ajaxSelect is: <select onchange="liftAjax.lift_ajaxHandler('F966066257023LYKF4=' + encodeURIComponent(this.value), null, null, null)" name="F96606625703QXTSWU" id="node_delete" class="input"> Moreover, there is a variable containing the state of the page in the end of the webpage: var lift_page = "F96606625700QRXLDO"; So, I am wondering if it is possible to simulate that my ajaxcall is valid using this liftAjax.lift_ajaxHandler function. However I don't know the exact synthax to use. On server side Since I "forged" a request on client side, I would now like to get the request on client side and to dispatch it to the correct function. This is where the LiftRules.dispatch object seems the best solution: when it is called, all the session management has been made (the request is authentified and linked to a session), however I don't know how to write the correct piece of code in the append function. Remark In lift all names of variables are changed to a random string in order to increase the security, I would like to have the same behavior in my application even if that will probably mean that I will have to "give" the javascript these values. However an array of 15 string values is still a better tradeoff than 15 functions as argument of a javascript function.

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  • Having problems creating an array from XML data in Acrobat Javascript, please help if you can

    - by Kevin Minke
    I have a manually created array that already works example below: var PartsData = { 179: { ref:"", partNum: "201-2007-C00-00", descript: "System Monitor Card (Tracewell Only)", cage: "39764", qty: "1", SMR: "XBOZZ", UOC: "A" }}; Now this array above is is just one value in the array and it works fine. Here is the XML that I am trying to use to dynamically change the values. <?xml version="1.0" encoding="utf-8"?> <partsTables> <partsList> <part sheetNum="ta1"> <breakDownIndexNo>-1 </breakDownIndexNo> <referenceDesg/> <indent>20534220P01 </indent> <description/> <cage>TAC RI, GRADE-A SHOCK (TEC RACK), ALT P/N 72304-1</cage> <qtyPerAssy>23991 </qtyPerAssy> <smr>1 </smr> <uoc>ADODD </uoc> <blank/> </part> </partsList> </partsTables> I have this parsing just fine in Acrobat. Now I want to make the array work for me in using these values. if I have the following below it will work. Where part.item(i).indent.value equals the value of the indent node, etc. newArr = { 179: { ref: part.item(i).referenceDesg.value, partNum: part.item(i).indent.value, descript: part.item(i).cage.value, cage: part.item(i).qtyPerAssy.value, qty: part.item(i).smr.value, SMR: part.item(i).uoc.value, UOC: part.item(i).blank.value}}; As soon as I try to make the 179 value, which is in the breakDownIndexNo node, dynamic by using the direct part.item(i).breakDownIndexNo.value it will not compile. Acrobat is using javascript so I'm not sure why I can not get this to parse. I have tried to create a variable out of the breakDownIndexNo node and typed it to both a String and an Integer. this will let it create the array but it will not let me output from the array. newArr[indexNum].partNum gives me "no properties" where newArr[179].partNum if I were to manually set the index number to 179 will print out the value of part.item(i).indent.value. If any of you have an idea or an answer please let me know.

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  • C++ function not found during compilation

    - by forthewinwin
    For a homework assignment: I'm supposed to create randomized alphabetial keys, print them to a file, and then hash each of them into a hash table using the function "goodHash", found in my below code. When I try to run the below code, it says my "goodHash" "identifier isn't found". What's wrong with my code? #include <iostream> #include <vector> #include <cstdlib> #include "math.h" #include <fstream> #include <time.h> using namespace std; // "makeKey" function to create an alphabetical key // based on 8 randomized numbers 0 - 25. string makeKey() { int k; string key = ""; for (k = 0; k < 8; k++) { int keyNumber = (rand() % 25); if (keyNumber == 0) key.append("A"); if (keyNumber == 1) key.append("B"); if (keyNumber == 2) key.append("C"); if (keyNumber == 3) key.append("D"); if (keyNumber == 4) key.append("E"); if (keyNumber == 5) key.append("F"); if (keyNumber == 6) key.append("G"); if (keyNumber == 7) key.append("H"); if (keyNumber == 8) key.append("I"); if (keyNumber == 9) key.append("J"); if (keyNumber == 10) key.append("K"); if (keyNumber == 11) key.append("L"); if (keyNumber == 12) key.append("M"); if (keyNumber == 13) key.append("N"); if (keyNumber == 14) key.append("O"); if (keyNumber == 15) key.append("P"); if (keyNumber == 16) key.append("Q"); if (keyNumber == 17) key.append("R"); if (keyNumber == 18) key.append("S"); if (keyNumber == 19) key.append("T"); if (keyNumber == 20) key.append("U"); if (keyNumber == 21) key.append("V"); if (keyNumber == 22) key.append("W"); if (keyNumber == 23) key.append("X"); if (keyNumber == 24) key.append("Y"); if (keyNumber == 25) key.append("Z"); } return key; } // "makeFile" function to produce the desired text file. // Note this only works as intended if you include the ".txt" extension, // and that a file of the same name doesn't already exist. void makeFile(string fileName, int n) { ofstream ourFile; ourFile.open(fileName); int k; // For use in below loop to compare with n. int l; // For use in the loop inside the below loop. string keyToPassTogoodHash = ""; for (k = 1; k <= n; k++) { for (l = 0; l < 8; l++) { // For-loop to write to the file ONE key ourFile << makeKey()[l]; keyToPassTogoodHash += (makeKey()[l]); } ourFile << " " << k << "\n";// Writes two spaces and the data value goodHash(keyToPassTogoodHash); // I think this has to do with the problem makeKey(); // Call again to make a new key. } } // Primary function to create our desired file! void mainFunction(string fileName, int n) { makeKey(); makeFile(fileName, n); } // Hash Table for Part 2 struct Node { int key; string value; Node* next; }; const int hashTableSize = 10; Node* hashTable[hashTableSize]; // "goodHash" function for Part 2 void goodHash(string key) { int x = 0; int y; int keyConvertedToNumber = 0; // For-loop to produce a numeric value based on the alphabetic key, // which is then hashed into hashTable using the hash function // declared below the loop (hashFunction). for (y = 0; y < 8; y++) { if (key[y] == 'A' || 'B' || 'C') x = 0; if (key[y] == 'D' || 'E' || 'F') x = 1; if (key[y] == 'G' || 'H' || 'I') x = 2; if (key[y] == 'J' || 'K' || 'L') x = 3; if (key[y] == 'M' || 'N' || 'O') x = 4; if (key[y] == 'P' || 'Q' || 'R') x = 5; if (key[y] == 'S' || 'T') x = 6; if (key[y] == 'U' || 'V') x = 7; if (key[y] == 'W' || 'X') x = 8; if (key[y] == 'Y' || 'Z') x = 9; keyConvertedToNumber = x + keyConvertedToNumber; } int hashFunction = keyConvertedToNumber % hashTableSize; Node *temp; temp = new Node; temp->value = key; temp->next = hashTable[hashFunction]; hashTable[hashFunction] = temp; } // First two lines are for Part 1, to call the functions key to Part 1. int main() { srand ( time(NULL) ); // To make sure our randomization works. mainFunction("sandwich.txt", 5); // To test program cin.get(); return 0; } I realize my code is cumbersome in some sections, but I'm a noob at C++ and don't know much to do it better. I'm guessing another way I could do it is to AFTER writing the alphabetical keys to the file, read them from the file and hash each key as I do that, but I wouldn't know how to go about coding that.

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  • MooTools event listener disappears after element.innerHTML is changed

    - by acoder
    Hi everyone, I am trying to achieve this task using MooTools. Description: I attached an event listener to "myButton" link. A click on this link initiates an AJAX request and updates "myDiv" content based on the response text. During this request a POST variable is being sent to "button.php", but it's not used at the moment.. (i wish to use it later) OK, as a result, "myDiv" gets exactly the same link with the same ID (myButton) + a random number, so that we could see that each click generates a new number. The problem: After the first click on "myButton", "myDiv" updates correctly, showing a random number. When I click "myButton" for the second time (this time in newly updated div), the div does not refresh anymore. Please note that I need "myButton" to be inside "myDiv", and "myDiv" must be updated (refreshed) after each click without having to refresh the entire page. Can somebody show me how to achieve this task based on this simplified code example? index.html <html> <head> <script type="text/javascript" src="mootools-1.2.4-core-nc.js"></script> <script> window.addEvent('domready', function() { $('myButton').addEvent('click', function(e) { e.stop(); var myRequest = new Request({ method: 'post', url: 'button.php', data: { action : 'test' }, onRequest: function() { $('myDiv').innerHTML = '<img src="images/loading.gif" />'; }, onComplete: function(response) { $('myDiv').innerHTML = response; } }); myRequest.send(); $('myButton').removeEvent('click'); }); }); </script> </head> <body> <div id="myDiv"> <a id="myButton" href="#">Button</a> </div> </body> </html> button.php <a id="myButton" href="#">Button</a> clicked <?php echo rand(1,100); ?>

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  • Custom cell in list in Flash AS3

    - by Stian Flatby
    I am no expert in Flash, and I need some quick help here, without needing to learn everything from scratch. Short story, I have to make a list where each cell contains an image, two labels, and a button. List/Cell example: img - label - label - button img - label - label - button As a Java-programmer, I have tried to quicly learn the syntax and visualness of Flash and AS3, but with no luck so far. I have fairly understood the basics of movie clips etc. I saw a tutorial on how to add a list, and add some text to it. So I dragged in a list, and in the code went list.addItem({label:"hello"}); , and that worked ofc. So i thought if I double-clicked the MC of the list, i would get to tweak some things. In there I have been wandering around different halls of cell-renderers etc. I have now come to the point that I entered the CellRenderer_skinUp or something, and customized it to my liking. When this was done, I expected i could use list.addItem(); and get an empty "version" of my cell, with the img, labels and the button. But AS3 expects an input in addItem. From my object-oriented view, I am thinking that i have to create an object of the cell i have made, but i have no luck reaching it.. I tried to go var test:CellRenderer = list.listItem; list.addItem(test); ..But with no luck. This is just for funsies, but I really want to make this work, however not so much that I am willing to read up on ALOT of Flash and AS3. I felt that I was closing in on the prize, but the compiler expected a semicolon after the variable (list.addItem({test:something});). Note: If possible, I do NOT want this: list.addItem({image:"src",label:"text",label"text",button:"text"}); Well.. It actually is what I want, but I would really like to custom-draw everything. Does anyone get what I am trying to do, and has any answers for me? Am I approaching this the wrong way? I have searched the interwebs for custom list-cells, but with no luck. Please, any guiding here is appreciated! Sti

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  • C++ vector and segmentation faults

    - by Headspin
    I am working on a simple mathematical parser. Something that just reads number = 1 + 2; I have a vector containing these tokens. They store a type and string value of the character. I am trying to step through the vector to build an AST of these tokens, and I keep getting segmentation faults, even when I am under the impression my code should prevent this from happening. Here is the bit of code that builds the AST: struct ASTGen { const vector<Token> &Tokens; unsigned int size, pointer; ASTGen(const vector<Token> &t) : Tokens(t), pointer(0) { size = Tokens.size() - 1; } unsigned int next() { return pointer + 1; } Node* Statement() { if(next() <= size) { switch(Tokens[next()].type) { case EQUALS : Node* n = Assignment_Expr(); return n; } } advance(); } void advance() { if(next() <= size) ++pointer; } Node* Assignment_Expr() { Node* lnode = new Node(Tokens[pointer], NULL, NULL); advance(); Node* n = new Node(Tokens[pointer], lnode, Expression()); return n; } Node* Expression() { if(next() <= size) { advance(); if(Tokens[next()].type == SEMICOLON) { Node* n = new Node(Tokens[pointer], NULL, NULL); return n; } if(Tokens[next()].type == PLUS) { Node* lnode = new Node(Tokens[pointer], NULL, NULL); advance(); Node* n = new Node(Tokens[pointer], lnode, Expression()); return n; } } } }; ... ASTGen AST(Tokens); Node* Tree = AST.Statement(); cout << Tree->Right->Data.svalue << endl; I can access Tree->Data.svalue and get the = Node's token info, so I know that node is getting spawned, and I can also get Tree->Left->Data.svalue and get the variable to the left of the = I have re-written it many times trying out different methods for stepping through the vector, but I always get a segmentation fault when I try to access the = right node (which should be the + node) Any help would be greatly appreciated.

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  • Why does every thread in my application use a different hibernate session?

    - by Ittai
    Hi, I have a web-application which uses hibernate and for some reason every thread (httprequest or other threads related to queueing) uses a different session. I've implemented a HibernateSessionFactory class which looks like this: public class HibernateSessionFactory { private static final ThreadLocal<Session> threadLocal = new ThreadLocal<Session>(); private static Configuration configuration = new AnnotationConfiguration(); private static org.hibernate.SessionFactory sessionFactory; static { try { configuration.configure(configFile); sessionFactory = configuration.buildSessionFactory(); } catch (Exception e) {} } private HibernateSessionFactory() {} public static Session getSession() throws HibernateException { Session session = (Session) threadLocal.get(); if (session == null || !session.isOpen()) { if (sessionFactory == null) { rebuildSessionFactory();//This method basically does what the static init block does } session = (sessionFactory != null) ? sessionFactory.openSession(): null; threadLocal.set(session); } return session; } //More non relevant methods here. Now from my testing it seems that the threadLocal member is indeed initialized only once when the class is first loaded by the JVM but for some reason when different threads access the getSession() method they use different sessions. When a thread first accesses this class (Session) threadLocal.get(); will return null but as expected all other access requests will yeild the same session. I'm not sure how this can be happening as the threadLocal variable is final and the method threadLocal.set(session) is only used in the above context (which I'm 99.9% sure has to yeild a non null session as I would have encountered a NullPointerException at a different part of my app). I'm not sure this is relevant but these are the main parts of my hibernate.cfg.xml file: <hibernate-configuration> <session-factory> <property name="connection.url">someURL</property> <property name="connection.driver_class"> com.microsoft.sqlserver.jdbc.SQLServerDriver</property> <property name="dialect">org.hibernate.dialect.SQLServerDialect</property> <property name="hibernate.connection.isolation">1</property> <property name="hibernate.connection.username">User</property> <property name="hibernate.connection.password">Password</property> <property name="hibernate.connection.pool_size">10</property> <property name="show_sql">false</property> <property name="current_session_context_class">thread</property> <property name="hibernate.hbm2ddl.auto">update</property> <property name="hibernate.cache.use_second_level_cache">false</property> <property name="hibernate.cache.provider_class">org.hibernate.cache.NoCacheProvider</property> <!-- Mapping files --> I'd appreciate any help granted and of course if anyone has any questions I'd be happy to clarify. Ittai

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  • Python: (sampling with replacement): efficient algorithm to extract the set of UNIQUE N-tuples from a set

    - by Homunculus Reticulli
    I have a set of items, from which I want to select DISSIMILAR tuples (more on the definition of dissimilar touples later). The set could contain potentially several thousand items, although typically, it would contain only a few hundreds. I am trying to write a generic algorithm that will allow me to select N items to form an N-tuple, from the original set. The new set of selected N-tuples should be DISSIMILAR. A N-tuple A is said to be DISSIMILAR to another N-tuple B if and only if: Every pair (2-tuple) that occurs in A DOES NOT appear in B Note: For this algorithm, A 2-tuple (pair) is considered SIMILAR/IDENTICAL if it contains the same elements, i.e. (x,y) is considered the same as (y,x). This is a (possible variation on the) classic Urn Problem. A trivial (pseudocode) implementation of this algorithm would be something along the lines of def fetch_unique_tuples(original_set, tuple_size): while True: # randomly select [tuple_size] items from the set to create first set # create a key or hash from the N elements and store in a set # store selected N-tuple in a container if end_condition_met: break I don't think this is the most efficient way of doing this - and though I am no algorithm theorist, I suspect that the time for this algorithm to run is NOT O(n) - in fact, its probably more likely to be O(n!). I am wondering if there is a more efficient way of implementing such an algo, and preferably, reducing the time to O(n). Actually, as Mark Byers pointed out there is a second variable m, which is the size of the number of elements being selected. This (i.e. m) will typically be between 2 and 5. Regarding examples, here would be a typical (albeit shortened) example: original_list = ['CAGG', 'CTTC', 'ACCT', 'TGCA', 'CCTG', 'CAAA', 'TGCC', 'ACTT', 'TAAT', 'CTTG', 'CGGC', 'GGCC', 'TCCT', 'ATCC', 'ACAG', 'TGAA', 'TTTG', 'ACAA', 'TGTC', 'TGGA', 'CTGC', 'GCTC', 'AGGA', 'TGCT', 'GCGC', 'GCGG', 'AAAG', 'GCTG', 'GCCG', 'ACCA', 'CTCC', 'CACG', 'CATA', 'GGGA', 'CGAG', 'CCCC', 'GGTG', 'AAGT', 'CCAC', 'AACA', 'AATA', 'CGAC', 'GGAA', 'TACC', 'AGTT', 'GTGG', 'CGCA', 'GGGG', 'GAGA', 'AGCC', 'ACCG', 'CCAT', 'AGAC', 'GGGT', 'CAGC', 'GATG', 'TTCG'] Select 3-tuples from the original list should produce a list (or set) similar to: [('CAGG', 'CTTC', 'ACCT') ('CAGG', 'TGCA', 'CCTG') ('CAGG', 'CAAA', 'TGCC') ('CAGG', 'ACTT', 'ACCT') ('CAGG', 'CTTG', 'CGGC') .... ('CTTC', 'TGCA', 'CAAA') ] [[Edit]] Actually, in constructing the example output, I have realized that the earlier definition I gave for UNIQUENESS was incorrect. I have updated my definition and have introduced a new metric of DISSIMILARITY instead, as a result of this finding.

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  • Android Progress Dialog not showing

    - by ilomambo
    This is the handler, in the main Thread, which shows and dismisses a progress dialog. public static final int SHOW = 0; public static final int DISMISS = 1; public Handler pdHandler = new Handler() { @Override public void handleMessage(Message msg) { Log.i(TAG, "+ handleMessage(msg:" + msg + ")"); switch(msg.what) { case SHOW: pd = ProgressDialog.show(LogViewer.this, "", getText(R.string.loading_msg), true); break; case DISMISS: if(pd != null) { pd.dismiss(); pd = null; } break; } } }; The message to show the progress is: pdHandler.sendMessage(pdHandler.obtainMessage(SHOW)); The message to dismiss it is: pdHandler.sendMessage(pdHandler.obtainMessage(DISMISS)); It works well when I call it before I start an AsyncTask, the AsyncTask onPostExecute() dismisses it. But when it runs within a runnable (runOnUiThread), the dialog does not show. Examining the pd variable on the debugger, it shows that is is created, it is running and it is visible, but in practice it is not visible. Any suggestion? UPDATE: I did the obvious test I should have done in the first place. I commented the DISMISS message. And the progress dialog did show up. It appeared too late, after the runnable was finished. I undestand now that the DISMISS message did dismiss the not-yet-visible ProgressDialog, that's why I did not see it. The question becomes now: I need the ProgressDialog to show BEFORE the runnable code is executed. And it is not so straight forward. My call hierarchy is like this: onScrollEventChanged --> runOnUiThread ( --> checkScrollLimits --> if need to scroll show ProgressDialog "Loading" get new data into table dismiss ProgressDIalog ) I tried something like this: onScrollEventChanged --> checkScrollLimits --> if need to scroll show ProgressDialog "Loading" --> runOnUiThread ( get new data into table dismiss ProgressDIalog ) But still the dismiss message got there before the ProgressDialog could show. According to Logcat there is a five second interval between the arrival of the SHOW message and the arrival of the DISMISS message. UPDATE II: I though I will use the isShowing() method of ProgressDIalog pd = ProgressDialog.show(...) while(!pd.isShowing()); But it does not help at all, it returns true even if the dialog is not showing yet.

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  • posting php code using jquery .html()

    - by Emmanuel Imwene
    simple query,but it's giving me a headache, i need a division to be updated with a changed session variable each time a user clicks on a name,i figured i'd use .html() using jquery to update the division, i don't know if you can do this, but here goes: $("#inner").html('<?php session_start(); if(file_exists($_SESSION['full'])||file_exists($_SESSION['str'])){ if(file_exists($_SESSION['full'])) { $full=$_SESSION['full']; $handlle = fopen($full, "r"); $contents = fread($handlle, filesize($full)); fclose($handlle); echo $contents; echo '<script type="text/javascript" src="jquery-1.8.0.min (1).js">'; echo '</script>'; echo '<script type="text/javascript">'; echo 'function loadLog(){ var oldscrollHeight = $("#inner").attr("scrollHeight") - 20; $.ajax({ url: \''.$_SESSION['full'].'\', cache: false, success: function(html){ $("#inner").html(html); //Insert chat log into the #chatbox div var newscrollHeight = $("#inner").attr("scrollHeight") - 20; if(newscrollHeight > oldscrollHeight){ $("#inner").animate({ scrollTop: newscrollHeight }, \'normal\'); //Autoscroll to bottom of div } }, }); } setInterval (loadLog, 2500);'; echo '</script>'; } else { $str=$_SESSION['str']; if(file_exists($str)) { $handle = fopen($str, 'r'); $contents = fread($handle, filesize($str)); fclose($handle); echo $contents; $full=$_SESSION['full']; $handlle = fopen($full, "r"); $contents = fread($handlle, filesize($full)); fclose($handlle); echo $contents; echo '<script type="text/javascript" src="jquery-1.8.0.min (1).js">'; echo '</script>'; echo '<script type="text/javascript">'; echo 'function loadLog(){ var oldscrollHeight = $("#inner").attr("scrollHeight") - 20; $.ajax({ url: \''.$_SESSION['str'].'\', cache: false, success: function(html){ $("#inner").html(html); //Insert chat log into the #chatbox div var newscrollHeight = $("#inner").attr("scrollHeight") - 20; if(newscrollHeight > oldscrollHeight){ $("#inner").animate({ scrollTop: newscrollHeight }, \'normal\'); //Autoscroll to bottom of div } }, }); } setInterval (loadLog, 2500);'; echo '</script>'; } } } ?>'); is that legal, if not, how would i accomplish this?

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  • Basic data alignment question

    - by Broken Logic
    I've been playing around to see how my computer works under the hood. What I'm interested in is seeing is what happens on the stack inside a function. To do this I've written the following toy program: #include <stdio.h> void __cdecl Test1(char a, unsigned long long b, char c) { char c1; unsigned long long b1; char a1; c1 = 'b'; b1 = 4; a1 = 'r'; printf("%d %d - %d - %d %d Total: %d\n", (long)&b1 - (long)&a1, (long)&c1 - (long)&b1, (long)&a - (long)&c1, (long)&b - (long)&a, (long)&c - (long)&b, (long)&c - (long)&a1 ); }; struct TestStruct { char a; unsigned long long b; char c; }; void __cdecl Test2(char a, unsigned long long b, char c) { TestStruct locals; locals.a = 'b'; locals.b = 4; locals.c = 'r'; printf("%d %d - %d - %d %d Total: %d\n", (long)&locals.b - (long)&locals.a, (long)&locals.c - (long)&locals.b, (long)&a - (long)&locals.c, (long)&b - (long)&a, (long)&c - (long)&b, (long)&c - (long)&locals.a ); }; int main() { Test1('f', 0, 'o'); Test2('f', 0, 'o'); return 0; } And this spits out the following: 9 19 - 13 - 4 8 Total: 53 8 8 - 24 - 4 8 Total: 52 The function args are well behaved but as the calling convention is specified, I'd expect this. But the local variables are a bit wonky. My question is, why wouldn't these be the same? The second call seems to produce a more compact and better aligned stack. Looking at the ASM is unenlightening (at least to me), as the variable addresses are still aliased there. So I guess this is really a question about the assembler itself allocates the stack to local variables. I realise that any specific answer is likely to be platform specific. I'm more interested in a general explanation unless this quirk really is platform specific. For the record though, I'm compiling with VS2010 on a 64bit Intel machine.

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  • My code gets an argument error, expecting 1 but got 0 - AS3

    - by Louis Cottier
    I've got this code with a variable of platform, which I'm trying to link with the actual object of Platform in my .fla file but I get this error when I run it; ArgumentError: Error #1063: Argument count mismatch on Code(). Expected 1, got 0. In my output window. package { import flash.display.MovieClip; import flash.events.MouseEvent; import flash.events.KeyboardEvent; import flash.events.Event; import flash.ui.Keyboard; public class Code extends MovieClip { var charSpeed:int = 0; var velocity:int = 0; var gravity:Number = 1; var Jump:Boolean = false; public function startGame(){ stage.addEventListener(KeyboardEvent.KEY_DOWN, checkKeyDown); stage.addEventListener(KeyboardEvent.KEY_UP, checkKeyUp); stage.addEventListener(Event.ENTER_FRAME, loop); } private var platform:Platform; public function Code(value:Platform) { platform = value; } function checkKeyDown(evt:KeyboardEvent){ if (evt.keyCode == Keyboard.LEFT){ charSpeed -= 10; } if (evt.keyCode == Keyboard.RIGHT){ charSpeed += 10; } if (evt.keyCode == Keyboard.DOWN){ if(!Jump){ velocity -= 14; Jump = true; } } } function checkKeyUp(evt:KeyboardEvent){ if (evt.keyCode == Keyboard.LEFT){ charSpeed = 0; } if (evt.keyCode == Keyboard.RIGHT){ charSpeed = 0; } } function loop(evt:Event){ player.x = velocity; if (player.x < 0){ player.x = 0; } if (player.x > 550){ player.x = 550; } velocity += gravity; var Platform:Array = new Array(platform) if (!Platform.hitTestPoint(player.x, player.y, true)){ player.y += velocity; } for (var i = 0; i < 10; i++){ if (Platform.hitTestPoint(player.x, player.y, true)){ player.y--; velocity = 0; Jump = false; } } } } } The as3 file name is Code, and the fla file name is Game. My objective is to get my player to move around on the platform using the arrow keys. The linkage of my platform is "Platform". If anyone could help that would be great

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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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  • Calculation of average and Timestamping

    - by user554230
    pls do sumone help me to solve this for me and the number should be variable and not constant. the output should be: Timestamping In 6 Digit 8 5 6 3 0 1 Average In 6 Digit 9 8 7 6 5 2 class Timestamp1 extends Average1 { public static void main (String args[]) { int i = 103658; int j = 10; int k = i % j; System.out.println(" Timestamping In 6 Digit " ); System.out.println(" " + k); int o = 10365; int p = 10; int q = o % p; System.out.println(" " + q); int l = 1036; int m = 10; int n = l % m; System.out.println(" " + n); int r = 103; int s = 10; int t = r % s; System.out.println(" " + t); int u = 10; int v = 10; int w = u % v; System.out.println(" " + w); int x = 1; int y = 10; int z = x % y; System.out.println(" " + z); class Average1 extends Timestamp1 { public void main() { int i = 256789; int j = 10; int k = i % j; System.out.println(" Average In 6 Digit "); System.out.println(" " + k); int o = 25678; int p = 10; int q = o % p; System.out.println(" " + q); int l = 2567; int m = 10; int n = l % m; System.out.println(" " + n); int r = 256; int s = 10; int t = r % s; System.out.println(" " + t); int u = 25; int v = 10; int w = u % v; System.out.println(" " + w); int x = 2; int y = 10; int z = x % y; System.out.println(" " + z); } } } }

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  • Memory leaks getting sub-images from video (cvGetSubRect)

    - by dnul
    Hi, i'm trying to do video windowing that is: show all frames from a video and also some sub-image from each frame. This sub-image can change size and be taken from a different position of the original frame. So , the code i've written does basically this: cvQueryFrame to get a new image from the video Create a new IplImage (img) with sub-image dimensions ( window.height,window.width) Create a new Cvmat (mat) with sub-image dimensions ( window.height,window.width) CvGetSubRect(originalImage,mat,window) seizes the sub-image transform Mat (cvMat) to img (IplImage) using cvGetImage my problem is that for each frame i create new IplImage and cvMat which take a lot of memory and when i try to free the allocated memory I get a segmentation fault or in the case of the CvMat the allocated space does not get free (valgrind keeps telling me its definetly lost space). the following code does it: int main(void){ CvCapture* capture; CvRect window; CvMat * tmp; //window size window.x=0;window.y=0;window.height=100;window.width=100; IplImage * src=NULL,*bk=NULL,* sub=NULL; capture=cvCreateFileCapture( "somevideo.wmv"); while((src=cvQueryFrame(capture))!=NULL){ cvShowImage("common",src); //get sub-image sub=cvCreateImage(cvSize(window.height,window.width),8,3); tmp =cvCreateMat(window.height, window.width,CV_8UC1); cvGetSubRect(src, tmp , window); sub=cvGetImage(tmp, sub); cvShowImage("Window",sub); //free space if(bk!=NULL) cvReleaseImage(&bk); bk=sub; cvReleaseMat(&tmp); cvWaitKey(20); //window dimensions changes window.width++; window.height++; } } cvReleaseMat(&tmp); does not seem to have any effect on the total amount of lost memory, valgrind reports the same amount of "definetly lost" memory if i comment or uncomment this line. cvReleaseImage(&bk); produces a segmentation fault. notice i'm trying to free the previous sub-frame which i'm backing up in the bk variable. If i comment this line the program runs smoothly but with lots of memory leaks I really need to get rid of memory leaks, can anyone explain me how to correct this or even better how to correctly perform image windowing? Thank you

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  • RoR custom routing/Method/View problem all methods come back as undefined

    - by Jeff
    I am playing with custom view and routes. I think that I have everything right but obviously not. Essentially I tried to copy the show method and show.html.erb but for some reason it will not work. My controller class fatherController < ApplicationController def show @father = Father.find(params[:id]) respond_to do |format| format.html # show.html.erb format.xml { render :xml => @father } end end def ofmine @father = Father.find(params[:id]) respond_to do |format| format.html # show.html.erb format.xml { render :xml => @father } end end end My routes.rb Parent::Application.routes.draw do resources :fathers do resources :kids end match 'hospitals/:id/ofmine' => 'father#show2' end when I go to 127.0.0.1:/father/1 it works fine but when I try to go to 127.0.0.1:/father/1/ofmine it gives the following error. It doesn't matter what the variable/method that is called; it occurs at the first one to be displayed. Both show.html.erb and show2.html.erb are the exact same files My Error from webserver commandline > Processing by fathersController#show2 > as HTML Parameters: {"id"=>"1"} > Rendered fathers/show2.html.erb within > layouts/application (31.6ms) Completed > in 37ms > > ActionView::Template::Error (undefined > method `name' for nil:NilClass): > 4: <td>Name</td><td></td> > 5: </tr> > 6: <tr> > 7: <td><%= @father.name %></td><td></td> > 8: </tr> > 9: <tr> > 10: <td>City</td><td>State</td> app/views/fathers/show2.html.erb:7:in > `_app_views_fatherss_show__html_erb___709193087__616989688_0' Error as displayed on actual page NoMethodError in Fathers#show2 Showing /var/ruby/chs/app/views/fathers/show2.html.erb where line #7 raised: undefined method `name' for nil:NilClass Extracted source (around line #7): 4: Name 5: 6: 7: <%= @father.name % 8: 9: 10: CityState If anyone could tell me what in the world I am doing wrong I would appreciate it greatly.

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  • c# Lambda Expression built with LinqKit does not compile

    - by Frank Michael Kraft
    This lambda does not compile, but I do not understand why. using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Linq.Expressions; using LinqKit; namespace ConsoleApplication2 { class Program { static void Main(string[] args) { var barModel = new BarModel(); string id = "some"; Console.WriteLine(barModel.subFor(id).ToString()); // output: m => (True AndAlso (m.key == value(ConsoleApplication2.Bar`1+<>c__DisplayClass0[ConsoleApplication2.Model]).id)) Console.ReadKey(); var subworkitems = barModel.list.Where(barModel.subFor(id).Compile()); // Exception {"variable 'm' of type 'ConsoleApplication2.Model' referenced from scope '', but it is not defined"} Console.WriteLine(subworkitems.ToString()); Console.ReadKey(); } } class Bar<TModel> { public Bar(Expression<Func<TModel, string>> foreignKeyExpression) { _foreignKeyExpression = foreignKeyExpression; } private Expression<Func<TModel, string>> _foreignKeyExpression { get; set; } public Expression<Func<TModel, bool>> subFor(string id) { var ex = forTargetId(id); return ex; } public Expression<Func<TModel, bool>> forTargetId(String id) { var fc = _foreignKeyExpression; Expression<Func<TModel, bool>> predicate = m => true; var result = predicate.And(m => fc.Invoke(m) == id).Expand(); return result; } } class Model { public string key; public string value; } class BarModel : Bar<Model> { public List<Model> list; public BarModel() : base(m => m.key) { list = new List<Model>(); } } }

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