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  • client-side data storage and retrieval with html and javascript

    - by pedalpete
    I'm building what I am hoping to be a fairly simple, quick and dirty demo app. So far, I've managed to build a bunch of components using only html and javascript. I know that eventually I'll hook-up a db, but at this point I'm just trying to show off some functionality. In the page, a user can select a bunch of other users (like friends). Then they go to a separate html page and there is some sorting info based on the selected users. So my first attempt was to put the selected users object into a cookie, and retrieve the cookie on the second page. Unfortunately, if the user changed their selection, the cookie wasn't getting updated, and my searches on StackOverflow seemed to say that deleting and updating cookies is unreliable. I tried function updateCookie(updatedUserList){ jQuery.cookie('userList',null); jQuery.cookie('userList',updatedUserList); } but though it set the cookie to null, it wouldn't update it on the second value. So I decided to put the selected users object into a form. Unfortunately, it looks like I can't retrieve the contents from the form on the client-side, only on the server-side. Is there another way to do this? I've worked in PHP and Rails, but I'm trying to do this quickly and simply before building it out into something larger and am trying to avoid any server-side processing for now, which I have managed to do up to this point.

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  • javascript read a text file

    - by Cyprus106
    I have looked everywhere and surprisingly can't find a good solution to this! I've got the following code that is supposed to read a text file and display it's contents. But it's not reading, for some reason. Am I doing something wrong? FTR, I can't use PHP for this. It's gotta be Javascript. var txtFile = new XMLHttpRequest(); txtFile.open("GET", "http://www.mysite.com/todaysTrivia.txt", true); txtFile.send(null); txtFile.onreadystatechange = function() { if (txtFile.readyState == 4) { // Makes sure the document is ready to parse. alert(txtFile.responseText+" - "+txtFile.status); //if (txtFile.status === 200) { // Makes sure it's found the file. var doc = document.getElementById("Trivia-Widget"); if (doc) { doc.innerHTML = txtFile.responseText ; } //} } txtFile.send(null); } Any good ideas what I'm doing wrong? It just keeps givimg me a zero status.

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  • In a Windows forms application, how can I setup can I set up the SelectedIndexChanged handle for 4 d

    - by Alex
    In a Windows forms application, within a DataGridView, I have 4 different DataGridCombobox controlshow can I set up the handler SelectedIndexChanged handler for the first combobox via the EditingControlShowing event. I added code for a second combobox but the SelectedIndexChanged didn't get wired up. Here's my code. Any advice would be appreciated. private ComboBox countryCombo; private EventHandler countryHandler; private ComboBox partCombo; private EventHandler partHandler; private void dataGridView2_EditingControlShowing(object sender, DataGridViewEditingControlShowingEventArgs e) { countryCombo = e.Control as ComboBox; if (countryCombo != null) { //remove any existing handler if there is one countryCombo.SelectedIndexChanged -= countryHandler; //add the new handler countryCombo.SelectedIndexChanged += new EventHandler(countryCombo_SelectedIndexChanged); } if (partCombo != null) { partCombo.SelectedIndexChanged -= partHandler; partCombo.SelectedIndexChanged += new EventHandler(partCombo_SelectedIndexChanged); } } private void countryCombo_SelectedIndexChanged(object sender, EventArgs e) { ComboBox box = (ComboBox) sender; //MessageBox.Show(box.Items.Count.ToString()); int rowNum = dataGridView2.CurrentCell.RowIndex; dataGridView2.BeginEdit(false); dataGridView2.Rows[0].Cells[2].Value = "abcdef"; dataGridView2.EndEdit(); } private void dataGridView2_CellContentClick(object sender, DataGridViewCellEventArgs e) { int cellColumn = e.ColumnIndex; //MessageBox.Show("Column is: " + cellColumn.ToString()); } private void partCombo_SelectedIndexChanged(object sender, EventArgs e) { ComboBox box = (ComboBox)sender; string partNumber = box.SelectedValue as string; // ToDo: now we need to get the HTSUS from the database so we can //populate the field int rowNum = dataGridView2.CurrentCell.RowIndex; dataGridView2.BeginEdit(false); dataGridView2.Rows[0].Cells[2].Value = "abcdef"; dataGridView2.EndEdit(); } } Al D.

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  • Various way to stop a thread - which is the correct way

    - by Yan Cheng CHEOK
    I had came across different suggestion of stopping a thread. May I know, which is the correct way? Or it depends? Using Thread Variable http://download.oracle.com/javase/1.4.2/docs/guide/misc/threadPrimitiveDeprecation.html private volatile Thread blinker; public void stop() { blinker = null; } public void run() { Thread thisThread = Thread.currentThread(); while (blinker == thisThread) { try { thisThread.sleep(interval); } catch (InterruptedException e){ } repaint(); } } Using boolean flag private volatile boolean flag; public void stop() { flag = false; } public void run() { while (flag) { try { thisThread.sleep(interval); } catch (InterruptedException e){ } repaint(); } } Using Thread Variable together with interrupt private volatile Thread blinker; public void stop() { blinker.interrupt(); blinker = null; } public void run() { Thread thisThread = Thread.currentThread(); while (!thisThread.isInterrupted() && blinker == thisThread) { try { thisThread.sleep(interval); } catch (InterruptedException e){ } repaint(); } }

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  • Copy constructor demo (crashing...)

    - by AKN
    Here is the program... class CopyCon { public: char *name; CopyCon() { name = new char; } CopyCon(const CopyCon &objCopyCon) { name = new char; _tcscpy(name,objCopyCon.name); } ~CopyCon() { if( name != NULL ) { delete name; name = NULL; } } }; int main() { CopyCon objCopyCon1; objCopyCon1.name = "Hai"; CopyCon objCopyCon2(objCopyCon1); objCopyCon1.name = "Hello"; cout<<objCopyCon2.name<<endl; return 0; } Once the code execution completes, when the destructor called, it crashes on 'delete' saying... Debug Error! Program: ... HEAP CORRUPTION DETECTED: after Normal block (#124) at 0x00366990. CRT detected that the application wrote to memory after end of heap buffer. (Press Retry to debug the application) Don't we have to clear the heap memory in destructor. What's wrong with this program? Pls someone help! Copy constructor works perfectly as intended. But still... !?

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  • Oracle User definied aggregate function for varray of varchar

    - by baju
    I am trying to write some aggregate function for the varray and I get this error code when I'm trying to use it with data from the DB: ORA-00600 internal error code, arguments: [kodpunp1], [], [], [], [], [], [], [], [], [], [], [] [koxsihread1], [0], [3989], [45778], [], [], [], [], [], [], [], [] Code of the function is really simple(in fact it does nothing ): create or replace TYPE "TEST_VECTOR" as varray(10) of varchar(20) ALTER TYPE "TEST_VECTOR" MODIFY LIMIT 4000 CASCADE create or replace type Test as object( lastVector TEST_VECTOR, STATIC FUNCTION ODCIAggregateInitialize(sctx in out Test) return number, MEMBER FUNCTION ODCIAggregateIterate(self in out Test, value in TEST_VECTOR) return number, MEMBER FUNCTION ODCIAggregateMerge(self IN OUT Test, ctx2 IN Test) return number, MEMBER FUNCTION ODCIAggregateTerminate(self IN Test, returnValue OUT TEST_VECTOR, flags IN number) return number ); create or replace type body Test is STATIC FUNCTION ODCIAggregateInitialize(sctx in out Test) return number is begin sctx := Test(TEST_VECTOR()); return ODCIConst.Success; end; MEMBER FUNCTION ODCIAggregateIterate(self in out Test, value in TEST_VECTOR) return number is begin self.lastVector := value; return ODCIConst.Success; end; MEMBER FUNCTION ODCIAggregateMerge(self IN OUT Test, ctx2 IN Test) return number is begin return ODCIConst.Success; end; MEMBER FUNCTION ODCIAggregateTerminate(self IN Test, returnValue OUT TEST_VECTOR, flags IN number) return number is begin returnValue := self.lastVector; return ODCIConst.Success; end; end; create or replace FUNCTION test_fn (input TEST_VECTOR) RETURN TEST_VECTOR PARALLEL_ENABLE AGGREGATE USING Test; Next I create some test data: create table t1_test_table( t1_id number not null, t1_value TEST_VECTOR not null, Constraint PRIMARY_KEY_1 PRIMARY KEY (t1_id) ) Next step is to put some data to the table insert into t1_test_table (t1_id,t1_value) values (1,TEST_VECTOR('x','y','z')) Now everything is prepared to perform queries: Select test_fn(TEST_VECTOR('y','x')) from dual Query above work well Select test_fn(t1_value) from t1_test_table where t1_id = 1 Version of Oracle DBMS I use: 11.2.0.3.0 Does anyone tried do such a thing? What can be the reason that it does not work? How to solve it? Thanks in advance for help.

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  • Python + Expat: Error on &#0; entities

    - by clacke
    I have written a small function, which uses ElementTree and xpath to extract the text contents of certain elements in an xml file: #!/usr/bin/env python2.5 import doctest from xml.etree import ElementTree from StringIO import StringIO def parse_xml_etree(sin, xpath): """ Takes as input a stream containing XML and an XPath expression. Applies the XPath expression to the XML and returns a generator yielding the text contents of each element returned. >>> parse_xml_etree( ... StringIO('<test><elem1>one</elem1><elem2>two</elem2></test>'), ... '//elem1').next() 'one' >>> parse_xml_etree( ... StringIO('<test><elem1>one</elem1><elem2>two</elem2></test>'), ... '//elem2').next() 'two' >>> parse_xml_etree( ... StringIO('<test><null>&#0;</null><elem3>three</elem3></test>'), ... '//elem2').next() 'three' """ tree = ElementTree.parse(sin) for element in tree.findall(xpath): yield element.text if __name__ == '__main__': doctest.testmod(verbose=True) The third test fails with the following exception: ExpatError: reference to invalid character number: line 1, column 13 Is the � entity illegal XML? Regardless whether it is or not, the files I want to parse contain it, and I need some way to parse them. Any suggestions for another parser than Expat, or settings for Expat, that would allow me to do that?

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  • cant open device

    - by yoavstr
    I have a little problem. I install this module into my kernel and its written under /proc When I try to open() it from user mode I get the following message: "Can't open device file: my_dev" static int module_permission(struct inode *inode, int op, struct nameidata *foo) { //if its write if ((op == 2)&&(writer == DOESNT_EXIST)){ writer = EXIST ; return 0; } //if its read if (op == 4 ){ numOfReaders++; return 0; } return -EACCES; } int procfs_open(struct inode *inode, struct file *file) { try_module_get(THIS_MODULE); return 0; } static struct file_operations File_Ops_4_Our_Proc_File = { .read = procfs_read, .write = procfs_write, .open = procfs_open, .release = procfs_close, }; static struct inode_operations Inode_Ops_4_Our_Proc_File = { .permission = module_permission, /* check for permissions */ }; int init_module() { /* create the /proc file */ Our_Proc_File = create_proc_entry(PROC_ENTRY_FILENAME, 0644, NULL); /* check if the /proc file was created successfuly */ if (Our_Proc_File == NULL){ printk(KERN_ALERT "Error: Could not initialize /proc/%s\n", PROC_ENTRY_FILENAME); return -ENOMEM; } Our_Proc_File->owner = THIS_MODULE; Our_Proc_File->proc_iops = &Inode_Ops_4_Our_Proc_File; Our_Proc_File->proc_fops = &File_Ops_4_Our_Proc_File; Our_Proc_File->mode = S_IFREG | S_IRUGO | S_IWUSR; Our_Proc_File->uid = 0; Our_Proc_File->gid = 0; Our_Proc_File->size = 80; //i added init the writewr status writer = DOESNT_EXIST; numOfReaders = 0 ; printk(KERN_INFO "/proc/%s created\n", PROC_ENTRY_FILENAME); return 0; }

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  • BufferedWriter overwriting itself

    - by Danson
    I want to read in a file and create a duplicate of the file but my code only write the last line in the file. How do I make so that whenever I call write(), it writes to a new line. I want to create a new file for the duplicate so I can't add true to FileWriter constructor. This is my code: //Create file reader BufferedReader iReader = new BufferedReader(new FileReader(args[1])); //Create file writer BufferedWriter oWriter = new BufferedWriter(new FileWriter(args[2], true)); String strLine; //reading file int iterate = 0; while((strLine = iReader.readLine()) != null) { instructions[iterate] = strLine; } //creating duplicate for(int i = 0; i < instructions.length; i++) { if(instructions[i] != null) { oWriter.write(instructions[i]); oWriter.newLine(); } else { break; } } try { iReader.close(); oWriter.close(); } catch (IOException e) { e.printStackTrace(); }

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  • Dynamic table memory usage

    - by Dan
    I use a dynamic table: <html> <body> <button id="button">Build table</button> <div id="container"> <script type="text/javascript"> window.onload=function(){ var table = null; var row = "<tr><td>111111111111111111111111111111111111111111111111111111</td>" + "<td>222222222222222222222222222222222222222222222222222222</td>" + "<td>333333333333333333333333333333333333333333333333333333</td></tr>"; var data = null; for (var i = 0; i < 2000; i++){ data += row; } var obj = document.getElementById("button"); obj.onclick=function buildTable(){ document.getElementById("container").innerHTML = "<div><table><tbody>" + data + "</tbody></table></div>"; }; }; </script> </body> </html> Using chromes task manager, each time new data is loaded the memory usage increases considerably and doesn't go down, so after some time the app consumes a lot of memory and requires the browser to be closed. Is there any change in the code I can use to solve this or is it a browser side problem?

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  • LicenseChecker checkAccess leaks ServiceConnection

    - by Bill The Ape
    I am receiving this exception in LogCat every time I press the Back button in my app: Activity has leaked ServiceConnection com.android.vending.licensing.LicenseChecker@471cc039 that was originally bound here The code responsible for this leak in onCreate() is: mLicenseCheckerCallback = new MyLicenseCheckerCallback(); mChecker.checkAccess(mLicenseCheckerCallback); How do I get rid of this leak? I tried not assigning MyLicenseCheckerCallback to a member, thinking perhaps when the activity goes onPause() the reference to the callback is responsible for the leak: mChecker.checkAccess(new MyLicenseCheckerCallback()); But that didn't get rid of the leak. Update: Thanks to @zapl's comment below, I looked at Google's LicenseChecker.java: /** Unbinds service if necessary and removes reference to it. */ private void cleanupService() { if (mService != null) { try { mContext.unbindService(this); } catch (IllegalArgumentException e) { // Somehow we've already been unbound. This is a non-fatal error. Log.e(TAG, "Unable to unbind from licensing service (already unbound)"); } mService = null; } } At first I thought that I may be neglecting to call it, but I double-checked and I am calling mChecker.onDestroy(); in my activity's onDestroy(). I also checked onDestroy() in LicenseChecker.java and it is calling unbindService: /** * Inform the library that the context is about to be destroyed, so that * any open connections can be cleaned up. * <p> * Failure to call this method can result in a crash under certain * circumstances, such as during screen rotation if an Activity requests * the license check or when the user exits the application. */ public synchronized void onDestroy() { cleanupService(); mHandler.getLooper().quit(); } So, what is really going on? Is this a bug in LVL?

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  • ASP.NET how can access public properties of MasterPage from external Class ?

    - by eugeneK
    Why i can't access MasterPage's public property (MessagePlaceholder) from other Class (Errors) ? my master page code behind using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.UI; using System.Web.UI.WebControls; public partial class MyMasterPage : System.Web.UI.MasterPage { public string MessagePlaceholder { get { return messagePlaceholder.InnerHtml; } set { messagePlaceholder.InnerHtml = value; } } protected void Page_Load(object sender, EventArgs e) { if (!IsPostBack) { messagePlaceholder.InnerHtml = Errors.getMessage(); } } } my Errors Class public static string getMessage() { HttpContext c = HttpContext.Current; string messageType = ""; if (c.Session["errorMessage"] != null) { messageType = "errorMessage"; } else if (c.Session["successMessage"] != null) { messageType = "successMessage"; } if (!string.IsNullOrEmpty(messageType)) { StringBuilder userMessageSb = new StringBuilder(); userMessageSb.Append(string.Format("<div id=\"{0}\" title=\"{1}\">{2}</div>", messageType, messageType.Replace("Message",string.Empty), c.Session[messageType])); // fix so message will not re-appear c.Session.Remove(messageType); messageType = userMessageSb.ToString(); } return messageType; } public static void setSuccess(string successMessage, bool isRedirect) { HttpContext.Current.Session["successMessage"] = successMessage; } public static void setError(string errorMessage, bool isRedirect) { HttpContext.Current.Session["errorMessage"] = errorMessage; if (!isRedirect) { ((HttpContext.Current.CurrentHandler as System.Web.UI.Page).Master as MyMasterPage).MessagePlaceholder = getMessage(); } } this is how i set error if (true) { Errors.setError("this is an error demo", false); return; } or with redirect after error if (true) { Errors.setError("yet another error", true); Response.Redirect("~/error.aspx"); }

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  • MySQL to PostreSQL and Named Scope

    - by Lowgain
    I've got a named scope for one of my models that works fine. The code is: named_scope :inbox_threads, lambda { |user| { :include => [:deletion_flags, :recipiences], :conditions => ["recipiences.user_id = ? AND deletion_flags.user_id IS NULL", user.id], :group => "msg_threads.id" }} This works fine on my local copy of the app with a MySQL database, but when I push my app to Heroku (which only uses PostgreSQL), I get the following error: ActiveRecord::StatementInvalid (PGError: ERROR: column "msg_threads.subject" must appear in the GROUP BY clause or be used in an aggregate function: SELECT "msg_threads"."id" AS t0_r0, "msg_threads"."subject" AS t0_r1, "msg_threads"."originator_id" AS t0_r2, "msg_thr eads"."created_at" AS t0_r3, "msg_threads"."updated_at" AS t0_r4, "msg_threads"."url_key" AS t0_r5, "deletion_flags"."id" AS t1_r0, "deletion_flags"."user_id" AS t1_r1, "deletion_flags"."msg_thread_id" AS t1_r2, "deletion_flags"."confirmed" AS t1_r3, "deletion_flags"."created_at" AS t1_r4, "deletion_flags"."updated_at" AS t1_r5, "recipiences"."id" AS t2_r0, "recipiences"."user_id" AS t2_r1, "recipiences"."msg_thread_id" AS t2_r2, "recipiences"."created_at" AS t2_r3, "recipien ces"."updated_at" AS t2_r4 FROM "msg_threads" LEFT OUTER JOIN "deletion_flags" ON deletion_flags.msg_thread_id = msg_threads.id LEFT OUTER JOIN "recipiences" ON recipiences.msg_thread_id = msg_threads.id WHERE (recipiences.user_id = 1 AND deletion_flags.user_id IS NULL) GROUP BY msg_threads.id) I'm not as familiar with the working of Postgres, so what would I need to add here to get this working? Thanks!

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  • Running processes at different times stops events from working - C

    - by Jamie Keeling
    Hello, This is a question which follows on from my previously answered question here At first I assumed I had a problem with the way I was creating my events due to the handles for OpenEvent returning NULL, I have managed to find the real cause however I am not sure how to go about it. Basically I use Visual Studio to launch both Process A and B at the same time, in the past my OpenEvent handle wouldn't work due to Process A looking for the address of the event a fraction of a second before Process B had time to make it. My solution was to simply allow Process B to run before Process A, fixing the error. The problem I have now is that Process B now reads events from Process A and as you expect it too returns a null handle when trying to open the events from Process A. I am creating the events in WM_CREATE message of both processes, furthermore I also create a thread at the same time to open/read/act upon the events. It seems if I run them at the same time they don't get chance to see each other, alternatively if I run one before the other one of them misses out and can't open a Handle. Can anyone suggest a solution? Thanks.

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  • GWT + Seam, cannot fetch scoped beans from gwt servlet in seam resource servlet.

    - by David Göransson
    Hello all I am trying to get session and conversation scoped beans to a gwt servlet in the seam resource servlet. I have a conversation scoped bean: @Name ("viewFormCopyAction") @Scope (ScopeType.CONVERSATION) public class ViewFormCopyAction {} and a session scoped bean: @Name ("authenticator") @Scope (ScopeType.SESSION) public class AuthenticatorAction {} There is a RemoteService interface: @RemoteServiceRelativePath ("strokesService") public interface StrokesService extends RemoteService { public Position getPosition (int conversationId); } with corresponding async interface: public interface StrokesServiceAsync extends RemoteService { public void getPosition (int conversationId, AsyncCallback callback); } and implementation: @Name ("com.web.actions.forms.gwt.client.StrokesService") @Scope (ScopeType.EVENT) public class StrokesServiceImpl implements StrokesService { @In Manager manager; @Override @WebRemote public Position getPosition (int conversationId) { manager.switchConversation( "" + conversationId ); ViewFormCopyAction vfca = (ViewFormCopyAction) Component.getInstance( "viewFormCopyAction" ); AuthenticatorAction aa = (AuthenticatorAction) Component.getInstance( "authenticator" ); return null; } } The gwt page is within an IFrame in a regular seam page and the conversationId is propagted with the src attribute of the IFrame. Both bean objects end up with only null values. Can anyone see anything wrong with the code? I know that I could use strings instead of the int, but never mind that at this point.

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  • Use a jquery UI slider to control the resizing of a youtube video.

    - by HV
    Hi, I have a resizable div with the video width and height 100% of the div. I can resize it using the corners but I want to control this with a ui slider and maintain the "aspectRatio: 16/9" that .resizable() provides. This is what I have so far <script> $(function(){ var slide_int = null; function update_slider(){ var offset = $('.ui-slider-handle').offset(); var value = $('#slider-range-max').slider('option', 'value'); $('#Youtube').width(+value); } $('#slider-range-max').slider({ step: 5, min: 200, max: 950, start: function(event, ui){ $('#amount').empty(); slide_int = setInterval(update_slider, 5); }, slide: function(event, ui){ setTimeout(update_slider, 5); }, stop: function(event, ui){ clearInterval(slide_int); slide_int = null; } $('#Youtube') .resizable({aspectRatio: 16/9});}); The Slider <div id="slider-range-max"></div> Div <div id="Youtube"> <object width="100%" height="100%"> <param name="movie" value="http://www.youtube.com/v/JC7aWY5chyI&hl=en_US&fs=1&"> </param> <param name="allowFullScreen" value="true"> </param> <param name="allowscriptaccess" value="always"> </param> <embed src="http://www.youtube.com/v/JC7aWY5chyI&hl=en_US&fs=1&" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="100%" height="100%"></embed> </object> </div> Thanks

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  • SQLAlchemy, one to many vs many to one

    - by sadvaw
    Dear Everyone, I have the following data: CREATE TABLE `groups` ( `bookID` INT NOT NULL, `groupID` INT NOT NULL, PRIMARY KEY(`bookID`), KEY( `groupID`) ); and a book table which basically has books( bookID, name, ... ), but WITHOUT groupID. There is no way for me to determine what the groupID is at the time of the insert for books. I want to do this in sqlalchemy. Hence I tried mapping Book to the books joined with groups on book.bookID=groups.bookID. I made the following: tb_groups = Table( 'groups', metadata, Column('bookID', Integer, ForeignKey('books.bookID'), primary_key=True ), Column('groupID', Integer), ) tb_books = Table( 'books', metadata, Column('bookID', Integer, primary_key=True), tb_joinedBookGroup = sql.join( tb_books, tb_groups, \ tb_books.c.bookID == tb_groups.c.bookID) and defined the following mapper: mapper( Group, tb_groups, properties={ 'books': relation(Book, backref='group') }) mapper( Book, tb_joinedBookGroup ) ... However, when I execute this piece of code, I realized that each book object has a field groups, which is a list, and each group object has books field which is a singular assigment. I think my definition here must have been causing sqlalchemy to be confused about the many-to-one vs one-to-many relationship. Can someone help me sort this out? My desired goal is g.books = [b, b, b, .. ] book.group = g, where g is an instance of group, and b is an instance of book

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  • Is the C++ compiler optimizer allowed to break my destructor ability to be called multiple times?

    - by sharptooth
    We once had an interview with a very experienced C++ developer who couldn't answer the following question: is it necessary to call the base class destructor from the derived class destructor in C++? Obviously the answer is no, C++ will call the base class destructor automagically anyway. But what if we attempt to do the call? As I see it the result will depend on whether the base class destructor can be called twice without invoking erroneous behavior. For example in this case: class BaseSafe { public: ~BaseSafe() { } private: int data; }; class DerivedSafe { public: ~DerivedSafe() { BaseSafe::~BaseSafe(); } }; everything will be fine - the BaseSafe destructor can be called twice safely and the program will run allright. But in this case: class BaseUnsafe { public: BaseUnsafe() { buffer = new char[100]; } ~BaseUnsafe () { delete[] buffer; } private: char* buffer; }; class DerivedUnsafe { public: ~DerivedUnsafe () { BaseUnsafe::~BaseUnsafe(); } }; the explicic call will run fine, but then the implicit (automagic) call to the destructor will trigger double-delete and undefined behavior. Looks like it is easy to avoid the UB in the second case. Just set buffer to null pointer after delete[]. But will this help? I mean the destructor is expected to only be run once on a fully constructed object, so the optimizer could decide that setting buffer to null pointer makes no sense and eliminate that code exposing the program to double-delete. Is the compiler allowed to do that?

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  • Forcing a templated object to construct from a pointer

    - by SalamiArmi
    I have a fictional class: template<typename T> class demonstration { public: demonstration(){} ... T *m_data; } At some point in the program's execution, I want to set m_data to a big block of allocated memory and construct an object T there. At the moment, I've been using this code: void construct() { *m_data = T(); } Which I've now realised is probably not the best idea... wont work under certain cirumstances, if T has a private assignment operator for example. Is there a normal/better way to do what I'm attempting here?

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  • What is Ruby's double-colon (::) all about?

    - by Meltemi
    I'd probably be able to answer this for myself if "::" wasn't so hard to Google. Didn't see anything on SO so thought I'd try my luck. What is this double-colon :: all about? I see it everywhere in Rails: class User < ActiveRecord::Base or… ActionController::Routing::Routes.draw do |map| I found a definition from this guy: The :: is a unary operator that allows: constants, instance methods and class methods defined within a class or module, to be accessed from anywhere outside the class or module. but that just leads to more questions. What good is scope (private, protected) if you can just use :: to expose anything?

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  • CSSRules is empty

    - by Stephanie
    I have this very simple HTML page, and I'm trying to get the CSSRules of #poulet, but when I'm accessing the documents.styleSheets[0].cssRules I get this error in Chrome v5.0.375.55: Uncaught TypeError: Cannot read property 'length' of null Here is what my code looks like: //HTML FILE window.onload = function(){ var test = findKeyframesRule('poulet'); alert(test); } <div id="poulet"> allo </div> //JS FILE function findKeyframesRule(rule) { var ss = document.styleSheets; for (var i = 0; i < ss.length; ++i) { for (var j = 0; j < ss[i].cssRules.length; ++j) { if (ss[i].cssRules[j].type == window.CSSRule.WEBKIT_KEYFRAMES_RULE && ss[i].cssRules[j].name == rule) return ss[i].cssRules[j]; } } return null; } //CSS FILE html, body{ background: #cccccc; } #poulet{ border: 10px solid pink; } The files can be found here. I really need help on this one, please!!! D:

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  • What happens when a computer program runs?

    - by gaijinco
    I know the general theory but I can't fit in the details. I know that a program resides in the secondary memory of a computer. Once the program begins execution it is entirely copied to the RAM. Then the processor retrive a few instructions (it depends on the size of the bus) at a time, puts them in registers and executes them. I also know that a computer program uses two kinds of memory: stack and heap, which are also part of the primary memory of the computer. The stack is used for non-dynamic memory, and the heap for dynamic memory (for example, everything related to the new operator in C++) What I can't understand is how those two things connect. At what point is the stack used for the execution of the instructions? Instructions go from the RAM, to the stack, to the registers?

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  • Unreachable code detected in case statement

    - by alex
    I have a code: protected override bool ProcessCmdKey(ref Message msg, Keys keyData) { switch (keyData) { case Keys.Alt|Keys.D1: if (this._condition1) { return true; } else { return base.ProcessCmdKey(ref msg, keyData); } break; case Keys.Control |Keys.U: if (this._condition2) { return true; } else { return base.ProcessCmdKey(ref msg, keyData); } break; default: return base.ProcessCmdKey(ref msg, keyData); } return true; It gives me "unreachable code detected" warning on breaks. Is it good practice not to use break operator here ? I don't want to turn off "unreachable code detected" warning. PS: There are many case in my ProcessCmdKey method.

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  • How can I use a compound condition in a join in Linq?

    - by Gary McGill
    Let's say I have a Customer table which has a PrimaryContactId field and a SecondaryContactId field. Both of these are foreign keys that reference the Contact table. For any given customer, either one or two contacts may be stored. In other words, PrimaryContactId can never be NULL, but SecondaryContactId can be NULL. If I drop my Customer and Contact tables onto the "Linq to SQL Classes" design surface, the class builder will spot the two FK relationships from the Customer table to the Contact table, and so the generated Customer class will have a Contact field and a Contact1 field (which I can rename to PrimaryContact and SecondaryContact to avoid confusion). Now suppose that I want to get details of all the contacts for a given set of customers. If there was always exactly one contact then I could write something like: from customer in customers join contact in contacts on customer.PrimaryContactId equals contact.id select ... ...which would be translated into something like: SELECT ... FROM Customer INNER JOIN Contact ON Customer.FirstSalesPersonId = Contact.id But, because I want to join on both the contact fields, I want the SQL to look something like: SELECT ... FROM Customer INNER JOIN Contact ON Customer.FirstSalesPersonId = Contact.id OR Customer.SecondSalesPersonId = Contact.id How can I write a Linq expression to do that?

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  • How to Detect Trusted Connection in Crystal Reports using VB.NET?

    - by Michael
    I have some Crystal Reports connecting to a Sql Server db that I would like to detect whether the connection is trusted or whether I need to supply the log on info (reports are not supplied by me so I can't control the connect method). If I just blindly supply login credentials, it won't connect if it is a trusted connection. The following does not work: oRpt = oCR.OpenReport("C:\MyReport.rpt") if oRpt.Database.Tables(1).ConnectionProperties.Item("Integrated Security") = True then 'trusted connection else 'supply login credentials end if It gives the following error: Operator '=' is not defined for type 'IConnectionProperty' and type 'Boolean'. I cannot find how create a construct in vb.net for IConnectionProperty. I can't find any documents from Crystal that explain it. I am using Crystal Reports XI - Developer

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