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  • Implementing the tree with reference to the root for each leaf

    - by AntonAL
    Hi, i implementing a products catalog, that looks, like this: group 1 subgroup 1 subgroup 2 item 1 item 2 ... item n ... subgroup n group 2 subgroup 1 ... subgroup n group 3 ... group n The Models: class CatalogGroup < ActiveRecord::Base has_many: catalog_items has_many :catalog_items_all, :class_name => "CatalogItem", :foreign_key => "catalog_root_group_id" end class CatalogItem < ActiveRecord::Base belongs_to :catalog_group belongs_to :catalog_root_group, :class_name => "CatalogGroup" end Migrations: class CreateCatalogItems < ActiveRecord::Migration def self.up create_table :catalog_items do |t| t.integer :catalog_group_id t.integer :catalog_root_group_id t.string :code t.timestamps end end For convenience, i referenced each CatalogItem to it's top-most CatalogGroup and named this association "catalog_root_group". This will give us the simple implementation of search request, like "show me all items in group 1". We will have a deal only with CatalogModel.catalog_root_group The problem is - this association does't work. I always get "catalog_root_group" equals to nil Also, i have tried to overcome the using of reference to root group ("catalog_root_group"), but i cannot construct appropriate search request in ruby ... Do you know, how to do it ?

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  • C# NullReferenceException when passing DataTable

    - by Timothy
    I've been struggling with a NullReferenceException and hope someone here will be able to point me in the right direction. I'm trying to create and populate a DataTable and then show the results in a DataGridView control. The basic code follows, and Execution stops with a NullReferenceException at the point where I invoke the new UpdateResults_Delegate. Oddly enough, I can trace entries.Rows.Count successfully before I return it from QueryEventEntries, so I can at least show 1) entries is not a null reference, and 2) the DataTable contains rows of data. I know I have to be doing something wrong, but I just don't know what. private delegate void UpdateResults_Delegate(DataTable entries); private void UpdateResults(DataTable entries) { dataGridView.DataSource = entries; } private void button_Click(object sender, EventArgs e) { Thread t = new Thread(new ThreadStart(PerformQuery)); t.Start(); } private void PerformQuery() { DateTime start = new DateTime(dateTimePicker1.Value.Year, dateTimePicker1.Value.Month, dateTimePicker1.Value.Day, 0, 0, 0); DateTime stop = new DateTime(dateTimePicker2.Value.Year, dateTimePicker2.Value.Month, dateTimePicker2.Value.Day, 0, 0, 0); DataTable entries = QueryEventEntries(start, stop); Invoke(new UpdateResults_Delegate(UpdateResults), entries); } private DataTable QueryEventEntries(DateTime start, DateTime stop) { DataTable entries = new DataTable(); entries.Columns.Add("colEventType", typeof(Int32)); entries.Columns.Add("colTimestamp", typeof(Int32)); entries.Columns.Add("colDetails", typeof(String)); ... conn.Open(); using (SqlDataReader r = cmd.ExecuteReader()) { while (r.Read()) { entries.Rows.Add(result.GetInt32(0), result.GetInt32(1), result.GetString(2)); } } return entries; }

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  • AS3 httpservice - pass arguments to event handlers by reference

    - by Shawn Simon
    I have this code: var service:HTTPService = new HTTPService(); if (search.Location && search.Location.length > 0 && chkLocalSearch.selected) { service.url = 'http://ajax.googleapis.com/ajax/services/search/local'; service.request.q = search.Keyword; service.request.near = search.Location; } else { service.url = 'http://ajax.googleapis.com/ajax/services/search/web'; service.request.q = search.Keyword + " " + search.Location; } service.request.v = '1.0'; service.resultFormat = 'text'; service.addEventListener(ResultEvent.RESULT, onServerResponse); service.send(); I want to pass the search object to the result method (onServerResponse) but if I do it in a closure it gets passed by value. Is there anyway to do it by reference without searching through my array of search objects for the value returned in the result? Sorry, this is simple but it's been a long day...

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  • C#/Java: Proper Implementation of CompareTo when Equals tests reference identity

    - by Paul A Jungwirth
    I believe this question applies equally well to C# as to Java, because both require that {c,C}ompareTo be consistent with {e,E}quals: Suppose I want my equals() method to be the same as a reference check, i.e.: public bool equals(Object o) { return this == o; } In that case, how do I implement compareTo(Object o) (or its generic equivalent)? Part of it is easy, but I'm not sure about the other part: public int compareTo(Object o) { if (! (o instanceof MyClass)) return false; MyClass other = (MyClass)o; if (this == other) { return 0; } else { int c = foo.CompareTo(other.foo) if (c == 0) { // what here? } else { return c; } } } I can't just blindly return 1 or -1, because the solution should adhere to the normal requirements of compareTo. I can check all the instance fields, but if they are all equal, I'd still like compareTo to return a value other than 0. It should be true that a.compareTo(b) == -(b.compareTo(a)), and the ordering should stay consistent as long as the objects' state doesn't change. I don't care about ordering across invocations of the virtual machine, however. This makes me think that I could use something like memory address, if I could get at it. Then again, maybe that won't work, because the Garbage Collector could decide to move my objects around. hashCode is another idea, but I'd like something that will be always unique, not just mostly unique. Any ideas?

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  • C++ Returning a Reference

    - by Devil Jin
    Consider the following code where I am returning double& and a string&. The thing works fine in the case of a double but not in the case of a string. Why is this difference in the behavior? In both the cases compiler does not even throws the Warning: returning address of local variable or temporary as I am returning a reference. #include <iostream> #include <string> using namespace std; double &getDouble(){ double h = 46.5; double &hours = h; return hours; } string &getString(){ string str = "Devil Jin"; string &refStr = str; return refStr; } int main(){ double d = getDouble(); cout << "Double = " << d << endl; string str = getString(); cout << "String = " << str.c_str() << endl; return 0; } Output: $ ./a.exe Double = 46.5 String =

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  • Null reference exception While Navigating to PlayListItem.

    - by Subhen
    Hi, I am trying to play the selected media from PlayList,if the selected index is not zero as below: if (playList.Items.Count == 0) { setPlayList(); if (selectedIndex!= 0) { if(custMediaElement.Playlist!=null) custMediaElement.GoToPlaylistItem(selectedIndex); } } The setPlayLIst method is as below: private void setPlayList() { IEnumerable eLevelData = pMainPage.GetDataFromDictonary(pMainPage.strChildFolderID); foreach (RMSMedia folderItems in eLevelData) { string strmediaURL = folderItems.strMediaFileName; string strmediaExtension = GetExtension(strmediaURL); if (strmediaExtension == "wmv" || strmediaExtension == "mp4" || strmediaExtension == "mp3" || strmediaExtension == "mpg") { PlaylistItem playListItem = new PlaylistItem(); string thumbSource = folderItems.strAlbumcoverImage; playListItem.MediaSource = new Uri(strmediaURL, UriKind.RelativeOrAbsolute); playListItem.Title = folderItems.strAlbumName; if (!string.IsNullOrEmpty(thumbSource)) playListItem.ThumbSource = new Uri(thumbSource, UriKind.RelativeOrAbsolute); playList.Items.Add(playListItem); } } custMediaElement.Playlist = playList; } But I am getting a Null reference Exception while trying to go to PlayList Item with the help of selected index , as explained in top. This works fine if I don't use custMediaElement.GoToPlaylistItem(selectedIndex); but in that case the Media Player Always plays the 1st Item , No matter , Which ever Song I select from the List Box. Below is few details from Stack Trace: ExpressionMediaPlayer.MediaPlayer.DoOpenPlaylistItem(PlaylistItem playlistItem) at ExpressionMediaPlayer.MediaPlayer.GoToPlaylistItem(Int32 playlistItemIndex) Thanks, Subhen

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  • Unable to find reference to std library math function inside library

    - by Alex Marshall
    Hello, I've got several programs that use shared libraries. Those shared libraries in turn use various standard C libraries. ie Program A and Program B both use Shared Library S. Shared Library S uses std C math. I want to be able to statically link Shared Library S against the standard library, and then statically link Programs A and B against S so that I don't have to be dragging around the library files, because these programs are going to be running on an embedded system running BusyBox 0.61. However, when I try to statically link the programs against Shared Library S, I get an error message from GCC stating : ../lib/libgainscalecalc.a(gainscalecalc.): In function 'float2gs': [path to my C file].c:73: undefined reference to 'log' Can somebody please help me out ? The make commands I'm using are below : CFLAGS += -Wall -g -W INCFLAGS = -I$(CROSS_INCLUDE)/usr/include LIBFLAGS += -L$(CROSS_LIB)/usr/lib -lm gainscalecalc_static.o: gainscalecalc.c $(CC) $(CFLAGS) -c $< -I. $(INCFLAGS) -o $@ gainscalecalc_dynamic.o: gainscalecalc.c $(CC) $(CFLAGS) -fPIC -c $< -o $@ all: staticlib dynamiclib static_driver dynamic_driver clean: $(RM) *.o *.a *.so *~ driver core $(OBJDIR) static_driver: driver.c staticlib $(CC) $(CFLAGS) -static driver.c $(INCFLAGS) $(LIBFLAGS) -I. -L. -lgainscalecalc -o $@ dynamic_driver: driver.c dynamiclib $(CC) $(CFLAGS) driver.c -o $@ -L. -lgainscalecalc staticlib: gainscalecalc_static.o $(AR) $(ARFLAGS) libgainscalecalc.a gainscalecalc_static.o $(RANLIB) libgainscalecalc.a chmod 777 libgainscalecalc.a dynamiclib: gainscalecalc_dynamic.o $(CC) -shared -o libgainscalecalc.so gainscalecalc_dynamic.o chmod 777 libgainscalecalc.so Edit: Linking against the shared libraries compiles fine, I just haven't tested them out yet

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  • CrystalDecisions.Web reference version changes suddenly when run the webapp

    - by Somebody
    I'm breaking my head with this issue, I have a webapp that has a report using crystal report, in the development pc it works fine, but when copy the same project to another pc, when I load the project (VS 2003) the following msg appears: One or more projects in solution need to be updated to use Crystal Reports XI Release 2. If you choose "Yes", the update will be applied permanently... I choose "Yes" and after that I can see that CrystalDecisions.Web reference has the correct version, and location according to the develpment machine, in this case: 11.5.3300.0. But when run the webapp, I can see when the version and path suddenly changes to: 11.0.3300.0. And when trying to see the report the following error appears: Parser Error Message: The base class includes the field 'CrystalReportViewer1', but its type (CrystalDecisions.Web.CrystalReportViewer) is not compatible with the type of control (CrystalDecisions.Web.CrystalReportViewer). the asp.net has the following: <%@ Register TagPrefix="cr" Namespace="CrystalDecisions.Web" Assembly="CrystalDecisions.Web, Version=11.5.3300.0, Culture=neutral, PublicKeyToken=692fbea5521e1304" %> How is this possible? what's happening here? EDIT This is what I did: the wrong version (11.0.3300.0) was located at: C:\Program Files\Common Files\Business Objects\3.0\managed and the right version (11.5.3300.0) is located at: C:\Program Files\Business Objects\Common\3.5\managed So I just deleted the files of the wrong solution, and I made it work in my new computer, no more errors when running the webapp, the report shows fine. But when try to do the same thing in production server, a different error came out, now an exception: This report could not be loaded due to the following issue: The type initializer for 'CrystalDecisions.CristalReports.Engine.ReportDocument' threw an exception. Any idea what could be causing this error now? Here is the code: Try Dim cr As New ReportDocument cr.Load(strpath) cr.SetDatabaseLogon("usring", "pwding") Select Case rt Case 1 cr.SummaryInfo.ReportTitle = "RMA Ticket" Case 2 cr.SummaryInfo.ReportTitle = "Service Ticket" End Select 'cr.SummaryInfo.ReportTitle = tt cr.SetParameterValue("TicketNo", tn) 'cr.SummaryInfo.ReportComments = comment CrystalReportViewer1.PrintMode = CrystalDecisions.Web.PrintMode.ActiveX CrystalReportViewer1.ReportSource = cr CrystalReportViewer1.ShowFirstPage() 'cr.Close() 'cr.Dispose() Catch ex As Exception MsgBox1.alert("This report could not be loaded due to the following issue: " & ex.Message) End Try

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  • actionscript-3: refactor interface inheritance to get rid of ambiguous reference error

    - by maxmc
    hi! imagine there are two interfaces arranged via composite pattern, one of them has a dispose method among other methods: interface IComponent extends ILeaf { ... function dispose() : void; } interface ILeaf { ... } some implementations have some more things in common (say an id) so there are two more interfaces: interface ICommonLeaf extends ILeaf { function get id() : String; } interface ICommonComponent extends ICommonLeaf, IComponent { } so far so good. but there is another interface which also has a dispose method: interface ISomething { ... function dispose() : void; } and ISomething is inherited by ICommonLeaf: interface ICommonLeaf extends ILeaf, ISomething { function get id() : String; } As soon as the dispose method is invoked on an instance which implements the ICommonComponent interface, the compiler fails with an ambiguous reference error because ISomething has a method called dispose and ILeaf also has a dispose method, both living in different interfaces (IComponent, ISomething) within the inheritace tree of ICommonComponent. I wonder how to deal with the situation if the IComponent, the ILeaf and the ISomething can't change. the composite structure must also work for for the ICommonLeaf & ICommonComponent implementations and the ICommonLeaf & ICommonComponent must conform to the ISomething type. this might be an actionscript-3 specific issue. i haven't tested how other languages (for instance java) handle stuff like this.

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  • Replace low level web-service reference call transport with custom one

    - by hoodoos
    I'm not sure if title sounds right actually, so I will give more explanation here. I will begin from very beginning :) I'm using c# and .net for my development. I have an application that makes requests to some soap web-service and for each user request it produces 3 to 10 requests for web-service, they should all run async to finish in one time, so I use Async method of the web-service generated reference and then wait for result on callback. But it seems like it starts a thread (or takes it from pool) for every async call I make, so if I have 10 clients I got to spawn 30 to 100 threads and it sounds terrible even for my 16 cores server :) So i wanted to replace low level transport implementation with my own which uses non-blocking sockets and can handle at least 50 sockets run parallel in one thread with not much overhead. But I actually dunno where to put my override best. I analyzed System.Web.Services.Protocols.SoapHttpClientProtocol class and see that it has some GetWebRequest method which I actually could use. If only I could somehow interupt the object it creates and get a http request with all headers and body from there and then send it with my own sockets.. Any ideas what approach to use? Or maybe there's something built in the framework I can use?

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  • Passing data structures to different threads

    - by Robb
    I have an application that will be spawning multiple threads. However, I feel there might be an issue with threads accessing data that they shouldn't be. I'm relatively new to threading so bare with me. Here is the structure of the threaded application (sorry for the crudeness): MainThread / \ / \ / \ Thread A Thread B / \ / \ / \ / \ / \ / \ Thread A_1 Thread A_2 Thread B_1 Thread B_2 Under each lettered thread (which could be many), there will only be two threads and they are fired of sequentially. The issue i'm having is I'm not entirely sure how to pass in a datastructure into these threads. So, the datastructure is created in MainThread, will be modified in the lettered thread (Thread A, etc) specific to that thread and then a member variable from that datastructure is sent to Letter_Numbered threads. Currently, the lettered thread class has a member variable and when the class is constructed, the datastructure from mainthread is passed in by reference, invoking the copy constructor so the lettered thread has it's own copy to play with. The lettered_numbered thread simply takes in a string variable from the data structure within the lettered thread. My question is, is this accceptable? Is there a much better way to ensure each lettered thread gets its own data structure to play with? Sorry for the somewhat poor explanation, please leave comments and i'll try to clarify.

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  • Looks like COM object is created, but JScript fails to get a reference

    - by damix911
    I'm using the following code to create a COM component that I have developed and registered. var mycom = new ActiveXObject("Mirabilis.ComponentServices.1"); mycom.SetFirstNumber(5); mycom.SetSecondNumber(3); The first line runs fine, while if I alter the ProgID (that is, the string passed to ActiveXObject) I get the message Automation server can't create object. This suggests that at least the basics of the registration mechanism are working properly. I integrated some logging calls into the DLL. When I run the script I get the proof into the log file that both this call to QueryInterface: STDAPI DllGetClassObject( const CLSID &clsid, const IID &iid, void **ppv) { ... CAddFactory *pAddFact = new CAddFactory; ... HRESULT hr = pAddFact->QueryInterface(iid, ppv); if (hr == S_OK) writeToLogFile("Class QueryInterface returned S_OK"); else writeToLogFile("Class QueryInterface failed"); return hr; ... } and this one: HRESULT __stdcall CAddFactory::CreateInstance( IUnknown *pUnknownOuter, const IID &iid, void **ppv) { ... CAddObj *pObject = new CAddObj; ... HRESULT hr = pObject->QueryInterface(iid, ppv); if (hr == S_OK) writeToLogFile("Object QueryInterface returned S_OK"); else writeToLogFile("Object QueryInterface failed"); return hr; ... } return S_OK. However, when JScript gets to line 3 of the script, I get the following error message: 'mycom' is null or not an object Why is this happening? It looks like JScript should be able to obtain a reference. Some attempts I made I tried to return S_FALSE from DllCanUnloadNow to be sure that the DLL will not be unloaded, just in case, but with no luck.

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  • Cyclic Reference - protocols and subclasses

    - by blindJesse
    I'm getting some cyclic reference (I think) problems between a few classes that require imported headers due to either subclassing or protocol definitions. I can explain why things are set up this way but I'm not sure it's essential. Basically these classes are managing reciprocal to-many data relationships. The layout is this: Class A imports Class B because it's a delegate of Class B and needs its protocol definition. Class B imports Class C because it's a subclass of Class C. Class C imports Class A because it's a delegate of Class A and needs its protocol definition. Here's some sample code that illustrates the problem. The errors I'm getting are as follows: In Class A - "Can't find protocol definition for Class_B_Delegate". In Class B - "Can't find interface declaration for Class C - superclass of Class B." In Class C - "Can't find protocol definition for Class_A_Delegate". Class A header: #import <Foundation/Foundation.h> #import "Class_B.h" @protocol Class_A_Delegate @end @interface Class_A : NSObject <Class_B_Delegate> { } @end Class B header: #import <Foundation/Foundation.h> #import "Class_C.h" @protocol Class_B_Delegate <NSObject> @end @interface Class_B : Class_C { } @end Class C Header: #import <Foundation/Foundation.h> #import "Class_A.h" @interface Class_C : NSObject <Class_A_Delegate> { } @end

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  • Passing Derived Class Instances as void* to Generic Callbacks in C++

    - by Matthew Iselin
    This is a bit of an involved problem, so I'll do the best I can to explain what's going on. If I miss something, please tell me so I can clarify. We have a callback system where on one side a module or application provides a "Service" and clients can perform actions with this Service (A very rudimentary IPC, basically). For future reference let's say we have some definitions like so: typedef int (*callback)(void*); // This is NOT in our code, but makes explaining easier. installCallback(string serviceName, callback cb); // Really handled by a proper management system sendMessage(string serviceName, void* arg); // arg = value to pass to callback This works fine for basic types such as structs or builtins. We have an MI structure a bit like this: Device <- Disk <- MyDiskProvider class Disk : public virtual Device class MyDiskProvider : public Disk The provider may be anything from a hardware driver to a bit of glue that handles disk images. The point is that classes inherit Disk. We have a "service" which is to be notified of all new Disks in the system, and this is where things unravel: void diskHandler(void *p) { Disk *pDisk = reinterpret_cast<Disk*>(p); // Uh oh! // Remainder is not important } SomeDiskProvider::initialise() { // Probe hardware, whatever... // Tell the disk system we're here! sendMessage("disk-handler", reinterpret_cast<void*>(this)); // Uh oh! } The problem is, SomeDiskProvider inherits Disk, but the callback handler can't receive that type (as the callback function pointer must be generic). Could RTTI and templates help here? Any suggestions would be greatly appreciated.

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  • How to make += operator keep the object reference?

    - by orloffm
    Say, I have a class: class M { public int val; And also a + operator inside it: public static M operator +(M a, M b) { M c = new M(); c.val = a.val + b.val; return c; } } And I've got a List of the objects of the class: List<M> ms = new List(); M obj = new M(); obj.val = 5; ms.Add(obj); Some other object: M addie = new M(); addie.val = 3; I can do this: ms[0] += addie; and it surely works as I expect - the value in the list is changed. But if I want to do M fromList = ms[0]; fromList += addie; it doesn't change the value in ms for obvious reasons. But intuitively I expect ms[0] to also change after that. Really, I pick the object from the list and then I increase it's value with some other object. So, since I held a reference to ms[0] in fromList before addition, I want still to hold it in fromList after performing it. Are there any ways to achieve that?

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  • Object reference not set to an instance of an object

    - by MBTHQ
    Can anyone help with the following code? I'm trying to get data from the database colum to the datagridview... I'm getting error over here "Dim sql_1 As String = "SELECT * FROM item where item_id = '" + DataGridView_stockout.CurrentCell.Value.ToString() + "'"" Private Sub DataGridView_stockout_CellMouseClick(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewCellMouseEventArgs) Handles DataGridView_stockout.CellMouseClick Dim i As Integer = Stock_checkDataSet1.Tables(0).Rows.Count > 0 Dim thiscur_stok As New System.Data.SqlClient.SqlConnection("Data Source=MBTHQ\SQLEXPRESS;Initial Catalog=stock_check;Integrated Security=True") ' Sql Query Dim sql_1 As String = "SELECT * FROM item where item_id = '" + DataGridView_stockout.CurrentCell.Value.ToString() + "'" ' Create Data Adapter Dim da_1 As New SqlDataAdapter(sql_1, thiscur_stok) ' Fill Dataset and Get Data Table da_1.Fill(Stock_checkDataSet1, "item") Dim dt_1 As DataTable = Stock_checkDataSet1.Tables("item") If i >= DataGridView_stockout.Rows.Count Then 'MessageBox.Show("Sorry, DataGridView_stockout doesn't any row at index " & i.ToString()) Exit Sub End If If 1 >= Stock_checkDataSet1.Tables.Count Then 'MessageBox.Show("Sorry, Stock_checkDataSet1 doesn't any table at index 1") Exit Sub End If If i >= Stock_checkDataSet1.Tables(1).Rows.Count Then 'MessageBox.Show("Sorry, Stock_checkDataSet1.Tables(1) doesn't any row at index " & i.ToString()) Exit Sub End If If Not Stock_checkDataSet1.Tables(1).Columns.Contains("os") Then 'MessageBox.Show("Sorry, Stock_checkDataSet1.Tables(1) doesn't any column named 'os'") Exit Sub End If 'DataGridView_stockout.Item("cs_stockout", i).Value = Stock_checkDataSet1.Tables(0).Rows(i).Item("os") Dim ab As String = Stock_checkDataSet1.Tables(0).Rows(i)(0).ToString() End Sub I keep on getting the error saying "Object reference not set to an instance of an object" I dont know where I'm going wrong. Help really appreciated!!

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  • How to reference an embedded JCA resource adapater

    - by cg
    For our current J2EE project based on JBoss, we need to interface with a remote system using message driven beans and a JCA resource adapter provided as a RAR file by a third party. I would like to package and deploy the entire project as an EAR file to our JBoss server. Most notably, the RAR file should be embedded within the EAR file and not be deployed globally. All of this is working fine so far, but I'm not particularly happy with the way the RAR file is referenced. The jboss.xml packaged with the MDB for example, currently looks like this: <jboss> <enterprise-beans> <message-driven> <ejb-name>testBean1</ejb-name> <resource-adapter-name>test1.ear#thirdparty-1.0.rar</resource-adapter-name> </message-driven> </enterprise-beans> </jboss> While this is generally working fine, it will break when the EAR file is renamed to "test2.ear". Is there a way to reference the embedded RAR file without hard-coding the containing archive's name?

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  • Basic question on retain/release semantics from Apple's reference library

    - by davetron5000
    I have done Objective-C way back when, and have recently (i.e. just now) read the documentation on Apple's site regarding the use of retain and release. However, there is a bit of code in their Creating an iPhone Application page that has me a bit confused: - (void)setUpPlacardView { // Create the placard view -- it calculates its own frame based on its image. PlacardView *aPlacardView = [[PlacardView alloc] init]; self.placardView = aPlacardView; [aPlacardView release]; // What effect does this have on self.placardView?! placardView.center = self.center; [self addSubview:placardView]; } Not seeing the entire class, it seems that self.placardView is also a PlacardView * and the assignment of it to aPlacardView doesn't seem to indicate it will retain a reference to it. So, it appears to me that the line I've commented ([aPlacardView release];) could result in aPlacardView having a retain count of 0 and thus being deallocated. Since self.placardView points to it, wouldn't that now point at deallocated memory and cause a problem?

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  • Entity Framework: Auto-updating foreign key when setting a new object reference

    - by Adrian Grigore
    Hi, I am porting an existing application from Linq to SQL to Entity Framework 4 (default code generation). One difference I noticed between the two is that a foreign key property are not updated when resetting the object reference. Now I need to decide how to deal with this. For example supposing you have two entity types, Company and Employee. One Company has many Employees. In Linq To SQL, setting the company also sets the company id: var company=new Company(ID=1); var employee=new Employee(); Debug.Assert(employee.CompanyID==0); employee.Company=company; Debug.Assert(employee.CompanyID==1); //Works fine! In Entity Framework (and without using any code template customization) this does not work: var company=new Company(ID=1); var employee=new Employee(); Debug.Assert(employee.CompanyID==0); employee.Company=company; Debug.Assert(employee.CompanyID==1); //Throws, since CompanyID was not updated! How can I make EF behave the same way as LinqToSQL? I had a look at the default code generation T4 template, but I could not figure out how to make the necessary changes.

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  • Delete only reference to child object

    - by Al
    I'm running in to a bit of a problem where any attempt to delete just the reference to a child also deletes the child record. My schema looks like this Person Organisation OrganisationContacts : Person OrgId PersonId Role When removing an Organisation i want to only delete the record in OrgnaisationContacts, but not touch the Person record. My Mapping looks like this Code: public OrganisationMap() { Table("Organsations"); .... HasMany<OrganisationContact>(x => x.Contacts) .Table("OrganisationContacts ") .KeyColumn("OrgId") .Not.Inverse() .Cascade.AllDeleteOrphan(); } public class OrganisationContactMap : SubclassMap<OrganisationContact> { public OrganisationContactMap() { Table("OrganisationContacts"); Map(x => x.Role, "PersonRole"); Map(x => x.IsPrimary); } } At the moment just removing a contact from the IList either doesn't reflect in the database at all, or it issues two delete statements DELETE FROM OrganisationContact & DELETE FROM Person, or tries to set PersonId to null in the OrganisationContacts table. All of which are not desirable. Any help would be great appreciated.

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

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

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  • targeting sprites from a method in the document class - null object reference

    - by Freddyk
    Hi I am trying to code a flash app entirely in the document class. I am using GestureWorks with a touch screen. When a user essentially presses a button it calls a method that should hide a specific graphic but not the graphic they touched. Essentially I need a way to refer to a graphic on the screen using a method besides 'e.target'. //This code works because it can access 'e.target'. private function photo1SpriteFlickHandler(e:GestureEvent):void { var openTween:Tween = new Tween(e.target, "x", Strong.easeOut, 232, 970, 5, true); } //this code gives me a null object reference because I am using 'photo1Sprite' rather than 'e.target' private function photo1SpriteFlickHandler(e:GestureEvent):void { var openTween:Tween = new Tween(photo1Sprite, "x", Strong.easeOut, 232, 970, 5, true); } //photo1Sprite has already been programatically added to the screen as so: var photo1Sprite = new TouchSprite(); var photo1Loader=new Loader(); photo1Loader.load(new URLRequest("media/photos1/photo1.jpg")); photo1Loader.contentLoaderInfo.addEventListener(Event.COMPLETE,loaderComplete); photo1Sprite.x = 232; photo1Sprite.y = 538; photo1Sprite.scaleX = .3; photo1Sprite.scaleY = .3; photo1Sprite.blobContainerEnabled = true; photo1Sprite.addEventListener(TouchEvent.TOUCH_DOWN, startDrag_Press); photo1Sprite.addEventListener(TouchEvent.TOUCH_UP, stopDrag_Release); photo1Sprite.addChild(photo1Loader); addChild(photo1Sprite); So I can make photo1Sprite react if my method is attached to it directly using 'e.target' but not if I am trying to call it from a method that was called from another element on the screen.

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  • NoClassDefFoundError when trying to reference external jar files

    - by opike
    I have some 3rd party jar files that I want to reference in my tomcat web application. I added this line to catalina.properties: shared.loader=/home/ollie/dev/java/googleapi_samples/gdata/java/lib/*.jar but I'm still getting this error: org.apache.jasper.JasperException: javax.servlet.ServletException: java.lang.NoClassDefFoundError: com/google/gdata/util/ServiceException org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:491) org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:401) org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313) org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260) javax.servlet.http.HttpServlet.service(HttpServlet.java:717) I verified that the com.google.gdata.util.ServiceException is in the gdata-core-1.0.jar file which is in the directory: /home/ollie/dev/java/googleapi_samples/gdata/java/lib I did bounce tomcat after I modified catalina.properties. Update 1: I tried copying the gdata-core-1.0.jar file into /var/lib/tomcat6/webapp/examples/WEB-INF/lib as a test but that didn't fix the problem either. Update 2: It actually does work when I copy the jar file directly into the WEB-INF/lib directory. There was a permissions issue that I had to resolve. But it's still not working when I use the shared.loader setting. I reconfirmed that the path is correct.

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  • Retruning reference to object not changing the address in c++

    - by ashish-sangwan
    I am trying to understand function returning reference. For that i have written a simple program :- include using namespace std; class test { int i; friend test& func(); public: test(int j){i=j;} void show(){cout< }; test& func() { test temp(10); return temp; //// Address of temp=0xbfcb2874 } int main() { test obj1(50); // Address of obj1=0xbfcb28a0 func()=obj1; <= Problem:The address of obj1 is not changing obj1.show(); // // Address of obj1=0xbfcb28a0 return 0; } I run the program using gdb and observed that the address of obj1 still remains same but i expect it to get changed to 0xbfcb2874. I am not clear with the concept. Please help. Thanks in advance

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  • Returning reference to object is not changing the address in c++

    - by ashish-sangwan
    I am trying to understand functions returning a reference. For that I have written a simple program: #include<iostream> using namespace std; class test { int i; friend test& func(); public: test(int j){i=j;} void show(){cout<<i<<endl;} }; test& func() { test temp(10); return temp; //// Address of temp=0xbfcb2874 } int main() { test obj1(50); // Address of obj1=0xbfcb28a0 func()=obj1; <= Problem:The address of obj1 is not changing obj1.show(); // // Address of obj1=0xbfcb28a0 return 0; } I ran the program using gdb and observed that the address of obj1 still remains same, but I expect it to get changed to 0xbfcb2874. I am not clear with the concept. Please help.

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