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• Dangling pointers and double free

  - by user151410

  After some painful experiences, I understand the problem of dangling pointers and double free. I am seeking proper solutions. aStruct has a number of fields including other arrays. aStruct *A=NULL, *B = NULL; A = (aStruct*) calloc(1, sizeof(sStruct)); B = A; free_aStruct(A); ... //bunch of other code in various places. ... free_aStruct(B); Is there any way to write free_aStruct(X) so that free_aStruct(B) exists gracefully?? void free_aStruct(aStruct *X){ if (X ! = NULL){ if (X->a != NULL){free(X->a); x->a = NULL;} free(X); X = NULL; } } Doing above only sets A = NULL when free_aStruct(A); is called. B is now dangling. How can this situation be avoided / remedied? Is reference counting the only viable solution? or, are there other "defensive" free approaches, to prevent free_aStruct(B); from exploding? Thanks, Russ

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• Working with extra fields in an Inline form - save_model, save_formset, can't make sense of the diff

  - by magicrebirth

  Suppose I am in the usual situation where there're extra fields in the many2many relationship: class Person(models.Model): name = models.CharField(max_length=128) class Group(models.Model): name = models.CharField(max_length=128) members = models.ManyToManyField(Person, through='Membership') class Membership(models.Model): person = models.ForeignKey(Person) group = models.ForeignKey(Group) date_joined = models.DateField() invite_reason = models.CharField(max_length=64) # other models which are unrelated to the ones above.. class Trip(models.Model): placeVisited = models.ForeignKey(Place) visitor = models.ForeignKey(Person) pleasuretrip = models.Boolean() class Place(models.Model): name = models.CharField(max_length=128) I want to add some extra fields in the Membership form that gets displayed through the Inline. These fields basically are a shortcut to the instantiation of another model (Trip). Trip can have its own admin views, but these shortcuts are needed because when my project partners are entering 'Membership' data in the system they happen to have also the 'Trip' information handy (and also because some of the info in Membership can just be copied over to Trip etc. etc.). So all I want to have is two extra fields in the Membership Inline - placeVisited and pleasuretrip - which together with the Person instance will let me instantiate the Trip model in the background... I found out I can easily add extra fields to the inline view by defining my own form. But once the data have been entered, how and when to reference to them in order to perform the save operations I need to do? class MyForm(forms.ModelForm): place = forms.ModelChoiceField(required=False, queryset=Place.objects.all(), label="place",) pleasuretrip = forms.BooleanField(required=False, label="...") class MembershipInline(admin.TabularInline): model = Membership form = MyForm def save_model(self, request, obj, form, change): place = form.place pleasuretrip = form.pleasuretrip person = form.person .... # now I can create Trip instances with those data .... obj.save() class GroupAdmin(admin.ModelAdmin): model = Group .... inlines = (MembershipInline,) This doesn't seem to work... I'm also a bit puzzled by the save_formset method... maybe is that the one I should be using? Many thanks in advance for the help!!!!

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• Why does Microsoft advise against readonly fields with mutable values?

  - by Weeble

  In the Design Guidelines for Developing Class Libraries, Microsoft say: Do not assign instances of mutable types to read-only fields. The objects created using a mutable type can be modified after they are created. For example, arrays and most collections are mutable types while Int32, Uri, and String are immutable types. For fields that hold a mutable reference type, the read-only modifier prevents the field value from being overwritten but does not protect the mutable type from modification. This simply restates the behaviour of readonly without explaining why it's bad to use readonly. The implication appears to be that many people do not understand what "readonly" does and will wrongly expect readonly fields to be deeply immutable. In effect it advises using "readonly" as code documentation indicating deep immutability - despite the fact that the compiler has no way to enforce this - and disallows its use for its normal function: to ensure that the value of the field doesn't change after the object has been constructed. I feel uneasy with this recommendation to use "readonly" to indicate something other than its normal meaning understood by the compiler. I feel that it encourages people to misunderstand the meaning of "readonly", and furthermore to expect it to mean something that the author of the code might not intend. I feel that it precludes using it in places it could be useful - e.g. to show that some relationship between two mutable objects remains unchanged for the lifetime of one of those objects. The notion of assuming that readers do not understand the meaning of "readonly" also appears to be in contradiction to other advice from Microsoft, such as FxCop's "Do not initialize unnecessarily" rule, which assumes readers of your code to be experts in the language and should know that (for example) bool fields are automatically initialised to false, and stops you from providing the redundancy that shows "yes, this has been consciously set to false; I didn't just forget to initialize it". So, first and foremost, why do Microsoft advise against use of readonly for references to mutable types? I'd also be interested to know: Do you follow this Design Guideline in all your code? What do you expect when you see "readonly" in a piece of code you didn't write?

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• ASP.Net Gridview paging, pageindex always == 0.

  - by David Archer

  Hi all, Having a slight problem with my ASP.Net 3.5 app. I'm trying to get the program to pick up what page number has been clicked. I'm using ASP.Net's built in AllowPaging="True" function. It's never the same without code, so here it is: ASP.Net: <asp:GridView ID="GridView1" runat="server" CellPadding="4" ForeColor="#333333" GridLines="Vertical" Width="960px" AllowSorting="True" EnableSortingAndPagingCallbacks="True" AllowPaging="True" PageSize="25" > <RowStyle BackColor="#F7F6F3" ForeColor="#333333" /> <FooterStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White" /> <PagerStyle BackColor="#284775" ForeColor="White" HorizontalAlign="Center" /> <SelectedRowStyle BackColor="#E2DED6" Font-Bold="True" ForeColor="#333333" /> <HeaderStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White" /> <EditRowStyle BackColor="#999999" /> <AlternatingRowStyle BackColor="White" ForeColor="#284775" /> </asp:GridView> C#: var fillTable = from ft in db.IncidentDatas where ft.pUserID == Convert.ToInt32(ClientList.SelectedValue.ToString()) select new { Reference = ft.pRef.ToString(), Date = ft.pIncidentDateTime.Value.Date.ToShortDateString(), Time = ft.pIncidentDateTime.Value.TimeOfDay, Premesis = ft.pPremises.ToString(), Latitude = ft.pLat.ToString(), Longitude = ft.pLong.ToString() }; if (fillTable.Count() > 0) { GridView1.DataSource = fillTable; GridView1.DataBind(); var IncidentDetails = fillTable.ToList(); for (int i = 0; i < IncidentDetails.Count(); i++) { int pageno = GridView1.PageIndex; int pagenostart = pageno * 25; if (i >= pagenostart && i < (pagenostart + 25)) { //Processing } } } Any idea why GridView1.PageIndex is always = 0? The thing is, the processing works correctly for the grid view.... it will always go to the correct paging page, but it's always 0 when I try to get the number. Help!

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• Common NSNotification mistakes?

  - by Ben Packard

  A simplification... A building has an array of apartment objects. Each apartment has a single currentTenant. These tenants are of type Person. Note that currentTenant doesn't have a reference to the apartment, so can't send information back up the chain. When a tenant has a plumbing issue he raises an NSNotification: [nc postNotificationName:@"PlumbingIssue" object:self]; Each Apartment observes notifications ONLY FROM it's own current tenant (this is set up when the apartment is built, before there is a current tenant): [nc addObserver:self selector:@selector(alertBuildingManager:) name:@"PlumbingIssue" object:[self currentTenant]; When the apartment receives a notification from it's own currentTenant, it sends it's own notification, "PlumberRequired", along with the apartment number and the currentTenant in an NSDictionary. Apartment observes these notifications, which it will take from any apartment (or other object): [nc addObserver:self selector:@selector(callPlumber) name:@"PlumberRequired" object:nil]; Is there something I could be getting fundamentally wrong here? What's happening is that the apartment is receiving notifications from any and all currentTenants, rather than jus it's own. Sorry that the actual code is a bit too unwieldy to post. Was just wondering if there's a gap in my understanding about observing notifications from a particular sender?

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• No output got after execution.

  - by wilson88

  I am still stuck with getting output for a copied vector. Probably something am not doing right. I get no output. void Auctioneer::accept_bids(const BidList& bid){ BidList list; BidList list2; BidList::const_iterator iter; copy (list.begin(),list.end(), back_inserter(list2)); for(iter=list2.begin(); iter != list2.end(); iter++) { const Bid& bid = *iter; // Get a reference to the Bid object that the iterator points to cout << "Bid id : " << bid.bidId << endl; cout << "Trd id : " << bid.trdId << endl; cout << "Quantity: " << bid.qty << endl; cout << "Price : " << bid.price << endl; cout << "Type : " << bid.type << endl; } }

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• Loading enumerations from database

  - by Mosh

  Hello, I have a problem with mapping .NET enumerations to database tables. Imagine I have a table called Statuses with the following values: StatusID | Name 1 Draft 2 Ready ... ... In the application layer, I can either use a Repository to get all Statuses as an IList object. However, the problem with this approach is that I cannot reference a certain status in my business logic. For example, how can I implement something like this? if (myObject.Status is Ready) do this else if (myObject.Status is Draft) do that... Since the statuses are loaded dynamically, I cannot tell for sure what particular Status object in the List represents the Draft or Ready status. Alternatively, I could just use an enumeration like public enum Statuses { Draft, Ready }; Then I could easily use an enumeration in my business logic. if (myObject.Status == Statuses.Draft) // do something... However, the problem with this approach is that every time the user wants to modify the list of Statuses (adding a new status, or renaming an existing status) the application has to be re-compiled. We cannot load the statuses dynamically from the database. Has anyone else come across a similar situation? Any solutions/patterns? Cheers, Mosh

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• Unattended Install of SQL Server 2005 Express with LOCAL Server InstanceName

  - by Jeff

  I'm creating an install package using InnoSetup and installing SQL Server 2005 Express. Here's the code below that appears in my RUN section: Filename: "{app}\SQL Server 2005 Express\SQLEXPR.exe" ; Parameters: "-q /norebootchk /qn reboot=ReallySuppress addlocal=all INSTANCENAME=(LOCAL) SCCCHECKLEVEL=IncompatibleComponents:1;MDAC25Version:0 ERRORREPORTING=2 SQLAUTOSTART=1 SAPWD=passwordhere SECURITYMODE=SQL"; WorkingDir: {app}\SQL Server 2005 Express; StatusMsg: Installing Microsoft SQL Server 2005 Express... Please Wait...;Check:SQLVerifyInstall What I'm trying to accomplish is have the SQL Server package install but only have the instance name itself reference the name of the machine name and nothing more. What I'm receiving instead is a named instance instead of local such as MachineName\SQLEXPRESS which is not what I want to receive. I need a local instance instead of a named instance due to the way my code is written to be able to install and talk with the databases in question. I would change it, trust me, were it not the fact that this install package is a replacement to a previous package that used the MSDE installer. I have to be able to support both through code. Any suggestions are welcome but a clear and concise method to get the installer to quietly install using only the machine name is my main goal. Thanks for the help and support!

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• C++ Multiple inheritance with interfaces?

  - by umanga

  Greetings all, I come from Java background and I am having difficulty with multiple inheritance. I have an interface called IView which has init() method.I want to derive a new class called PlaneViewer implementing above interface and extend another class. (QWidget). My implementation is as: IViwer.h (only Header file , no CPP file) : #ifndef IVIEWER_H_ #define IVIEWER_H_ class IViewer { public: //IViewer(); ///virtual //~IViewer(); virtual void init()=0; }; #endif /* IVIEWER_H_ */ My derived class. PlaneViewer.h #ifndef PLANEVIEWER_H #define PLANEVIEWER_H #include <QtGui/QWidget> #include "ui_planeviewer.h" #include "IViewer.h" class PlaneViewer : public QWidget , public IViewer { Q_OBJECT public: PlaneViewer(QWidget *parent = 0); ~PlaneViewer(); void init(); //do I have to define here also ? private: Ui::PlaneViewerClass ui; }; #endif // PLANEVIEWER_H PlaneViewer.cpp #include "planeviewer.h" PlaneViewer::PlaneViewer(QWidget *parent) : QWidget(parent) { ui.setupUi(this); } PlaneViewer::~PlaneViewer() { } void PlaneViewer::init(){ } My questions are: Is it necessary to declare method init() in PlaneViewer interface also , because it is already defined in IView? 2.I cannot complie above code ,give error : PlaneViewer]+0x28): undefined reference to `typeinfo for IViewer' collect2: ld returned 1 exit status Do I have to have implementation for IView in CPP file?

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• Sitecore development. Sitecore.Web.UI.WebControl.GetCacheKey() throws NullReferenceException

  - by user344010

  I just click submit button and got an exception. Unable to debug, because this happens before the submit event handler work. I tried to clear sitecore caches, browser caches and cookies... nothing helps. here the stack trace. [NullReferenceException: Object reference not set to an instance of an object.] Sitecore.Web.UI.WebControl.GetCacheKey() +242 Sitecore.Web.UI.WebControl.Render(HtmlTextWriter output) +61 System.Web.UI.Control.RenderControlInternal(HtmlTextWriter writer, ControlAdapter adapter) +27 System.Web.UI.Control.RenderControl(HtmlTextWriter writer, ControlAdapter adapter) +99 System.Web.UI.Control.RenderControl(HtmlTextWriter writer) +25 System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children) +134 System.Web.UI.Control.RenderChildren(HtmlTextWriter writer) +19 System.Web.UI.HtmlControls.HtmlHead.RenderChildren(HtmlTextWriter writer) +17 System.Web.UI.HtmlControls.HtmlContainerControl.Render(HtmlTextWriter writer) +32 System.Web.UI.Control.RenderControlInternal(HtmlTextWriter writer, ControlAdapter adapter) +27 System.Web.UI.Control.RenderControl(HtmlTextWriter writer, ControlAdapter adapter) +99 System.Web.UI.Control.RenderControl(HtmlTextWriter writer) +25 System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children) +134 System.Web.UI.Control.RenderChildren(HtmlTextWriter writer) +19 System.Web.UI.Page.Render(HtmlTextWriter writer) +29 System.Web.UI.Control.RenderControlInternal(HtmlTextWriter writer, ControlAdapter adapter) +27 System.Web.UI.Control.RenderControl(HtmlTextWriter writer, ControlAdapter adapter) +99 System.Web.UI.Control.RenderControl(HtmlTextWriter writer) +25 System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1266

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• ViewModel Views relation/link/syncroniztion

  - by mehran

  Third try to describing problem: Try 1: Sunchronizing view model and view Try2: WPF ViewModel not active presenter Try3: I have some class for view models: public class Node : INotifyPropertyChanged { Guid NodeId { get; set; } public string Name { get; set; } } public class Connection: INotifyPropertyChanged { public Node StartNode { get; set; } public Node EndNode { get; set; } } public class SettingsPackModel { public List<Node> Nodes { get; private set; } public List<Connection> Connections { get; private set; } } I also have some templates to displays these models: <DataTemplate DataType="{x:Type vm:Node}">…</DataTemplate> <DataTemplate DataType="{x:Type vm:Connection}"> <my:ConnectionElment StartNodeElment="???" EndNodeElment="???"> </my:ConnectionElment> <DataTemplate> But the problem is that DataTemplate for Connection need reference ot two element of type UIElement , how can I pass these two, how can I fill ??? in above expression?

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• Rtti data manipulation and consistency in Delphi 2010

  - by Coco

  Has anyone an idea, how I can make TValue using a reference to the original data? In my serialization project, I use (as suggested in XML-Serialization) a generic serializer which stores TValues in an internal tree-structure (similar to the MemberMap in the example). This member-tree should also be used to create a dynamic setup form and manipulate the data. My idea was to define a property for the Data: TDataModel <T> = class {...} private FData : TValue; function GetData : T; procedure SetData (Value : T); public property Data : T read GetData write SetData; end; The implementation of the GetData, SetData Methods: procedure TDataModel <T>.SetData (Value : T); begin FData := TValue.From <T> (Value); end; procedure TDataModel <T>.GetData : T; begin Result := FData.AsType <T>; end; Unfortunately, the TValue.From method always makes a copy of the original data. So whenever the application makes changes to the data, the DataModel is not updated and vice versa if I change my DataModel in a dynamic form, the original data is not affected. Sure I could always use the Data property before and after changing anything, but as I use lot of Rtti inside my DataModel, I do not realy want to do this anytime. Perhaps someone has a better suggestion?

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• jQuery Grouping Similar Items w/ Multidimensional Array

  - by NessDan

  So I have this structure setup: <ul> <li>http://www.youtube.com/watch?v=dw1Vh9Yzryo</li> (Vid1) <li>http://www.youtube.com/watch?v=bOF3o8B292U</li> (Vid2) <li>http://www.youtube.com/watch?v=yAY4vNJd7A8</li> (Vid3) <li>http://www.youtube.com/watch?v=yAY4vNJd7A8</li> <li>http://www.youtube.com/watch?v=dw1Vh9Yzryo</li> <li>http://www.youtube.com/watch?v=bOF3o8B292U</li> <li>http://www.youtube.com/watch?v=yAY4vNJd7A8</li> <li>http://www.youtube.com/watch?v=dw1Vh9Yzryo</li> </ul> Vid1 is repeated 3 times, Vid2 is repeated 3 times, and Vid3 is repeated 2 times. I want to put them into a structure where I can reference them like this: youtube[0][repeated] = 3; youtube[0][download] = "http://www.youtube.com/get_video?video_id=dw1Vh9Yzryo&fmt=36" youtube[1][repeated] = 3; youtube[1][download] = "http://www.youtube.com/get_video?video_id=bOF3o8B292U&fmt=36" youtube[2][repeated] = 3; youtube[2][download] = "http://www.youtube.com/get_video?video_id=yAY4vNJd7A8&fmt=36" "This video was repeated " + youtube[0][repeated] + " times and you can download it here: " + youtube[0][download]; How can I set this multidimensional array up? Been Googling for hours and I don't know how to set it up. Can anyone help me out?

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• How to Create a Folder in the Current Document Library if it's not already present?

  - by Rosh Malai

  All I want to do is to create a folder "MetaFolder" inside a document library. User can be on any document library and I would like to create this folder after item is added (so on itemAdded event handler). I do NOT want workflow so please dont suggest workflow. This code works but I have to hardcode the url but need to get url from current url. also need to verify the folder uHippo does not exists in the current doc library... public override void ItemAdded(SPItemEventProperties properties) { base.ItemAdded(properties); using (SPSite currentSite = new SPSite(properties.WebUrl)) using (SPWeb currentWeb = currentSite.OpenWeb()) { // This code works and creates Folder in the "My TEST Doc library" //SPList docLib = currentWeb.Lists["My TEST Doc Library"]; //SPListItem folder = docLib.Folders.Add(docLib.RootFolder.ServerRelativeUrl, SPFileSystemObjectType.Folder, "My folder"); //folder.Update(); string doclibname = "Not a doclib"; //SPList doclibList = currentWeb.GetList(HttpContext.Current.Request.RawUrl); // NOT WORKING. Tried properties.weburl SPList doclibList = currentWeb.GetListFromUrl("https://mycompanyportal/sites/testsitecol/testwebsite/My%20TEST%20Doc%20Library/Forms/AllItems.aspx"); if (null != doclibList) { doclibname = doclibList.Title; } // this section also not working. // getting Object reference not set to an instance of an object or something like that. //if (currentWeb.GetFolder("uHippo").Exists == false) //{ SPListItem folder = doclibList.Folders.Add(doclibList.RootFolder.ServerRelativeUrl, SPFileSystemObjectType.Folder, "uHippo"); folder.Update(); //} } }

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• Multiple SessionFactories in Windows Service with NHibernate

  - by Rob Taylor

  Hi all, I have a Webapp which connects to 2 DBs (one core, the other is a logging DB). I must now create a Windows service which will use the same business logic/Data access DLLs. However when I try to reference 2 session factories in the Service App and call the factory.GetCurrentSession() method, I get the error message "No session bound to current context". Does anyone have a suggestion about how this can be done? public class StaticSessionManager { public static readonly ISessionFactory SessionFactory; public static readonly ISessionFactory LoggingSessionFactory; static StaticSessionManager() { string fileName = System.Configuration.ConfigurationSettings.AppSettings["DefaultNHihbernateConfigFile"]; string executingPath = System.IO.Path.GetDirectoryName(System.Reflection.Assembly.GetExecutingAssembly().GetName().CodeBase); fileName = executingPath + "\\" + fileName; SessionFactory = cfg.Configure(fileName).BuildSessionFactory(); cfg = new Configuration(); fileName = System.Configuration.ConfigurationSettings.AppSettings["LoggingNHihbernateConfigFile"]; fileName = executingPath + "\\" + fileName; LoggingSessionFactory = cfg.Configure(fileName).BuildSessionFactory(); } } The configuration file has the setting: <property name="current_session_context_class">call</property> The service sets up the factories: private ISession _session = null; private ISession _loggingSession = null; private ISessionFactory _sessionFactory = StaticSessionManager.SessionFactory; private ISessionFactory _loggingSessionFactory = StaticSessionManager.LoggingSessionFactory; ... _sessionFactory = StaticSessionManager.SessionFactory; _loggingSessionFactory = StaticSessionManager.LoggingSessionFactory; _session = _sessionFactory.OpenSession(); NHibernate.Context.CurrentSessionContext.Bind(_session); _loggingSession = _loggingSessionFactory.OpenSession(); NHibernate.Context.CurrentSessionContext.Bind(_loggingSession); So finally, I try to call the correct factory by: ISession session = StaticSessionManager.SessionFactory.GetCurrentSession(); Can anyone suggest a better way to handle this? Thanks in advance! Rob

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• Access report not showing data

  - by Brian Smith

  I have two queries that I am using to generate a report from, the problem is when I run the report, three fields do not show any data at all for some reason. Query 1: SELECT ClientSummary.Field3 AS PM, ClientSummary.[Client Nickname 2] AS [Project #], ClientSummary.[Client Nickname 1] AS Customer, ClientSummary.[In Reference To] AS [Job Name], ClientSummary.Field10 AS Contract, (select sum([Billable Slip Value]) from Util_bydate as U1 where U1.[Client Nickname 2] = ClientSummary.[Client Nickname 2]) AS [This Week], (select sum([Billable Slip Value]) from Util as U2 where U2.[Client Nickname 2] = ClientSummary.[Client Nickname 2] ) AS [To Date], [To Date]/[Contract] AS [% Spent], 0 AS Backlog, ClientSummary.[Total Slip Fees & Costs] AS Billed, ClientSummary.Payments AS Paid, ClientSummary.[Total A/R] AS Receivable, [Forms]![ReportMenu]![StartDate] AS [Start Date], [Forms]![ReportMenu]![EndDate] AS [End Date] FROM ClientSummary; Query 2: SELECT JobManagement_Summary.pm, JobManagement_Summary.[project #], JobManagement_Summary.Customer, JobManagement_Summary.[Job Name], JobManagement_Summary.Contract, IIf(IsNull([This Week]),0,[This Week]) AS [N_This Week], IIf(IsNull([To Date]),0,[To Date]) AS [N_To Date], [% Spent], JobManagement_Summary.Backlog, JobManagement_Summary.Billed, JobManagement_Summary.Paid, JobManagement_Summary.Receivable, JobManagement_Summary.[Start Date], JobManagement_Summary.[End Date] FROM JobManagement_Summary; When I run the report from query 2 these 3 fields don't appear. N_This Week, N_To Date and % Spent. All have no data. It isn't the IIF functions, as it doesn't matter if I have those in there or remove them. Any thoughts? If I connect directly to the first recordset it works fine, but then SQL throws the error message: Multi-level GROUP BY cause not allowed in subquery. Is there any way to get around that message to link to it directly or does anyone have ANY clue why these fields are coming back blank? I am at wits end here!

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• ASP.NET/C#: How to use a Subclassed Control on a Page?

  - by Bob Kaufman

  I've subclassed DropDownList to add functionality specific to my application: public class MyDropDownList : DropDownList { ... } ... then referenced it in Web.Config, which is where I figure things start to go wrong: <pages theme="Main"> <controls> <add tagPrefix="bob" tagName="MyDropDownList" src="~/Components/MyDropDownList.cs" /> </controls> </pages> my reference to it does not work: <tr><td>Category</td> <td><bob:MyDropDownList runat="server" ID="Category"... /> and my best clue is the complier error message: "The file 'src' is not a valid [sic] here because it doesn't expose a type." I figure I'm misapplying knowledge of how to create a Web User Control here. What I want to be able to do is refer to this control on an ASP.NET page just like I would the parent DropDownList. Refactoring back into a Web User Control that contains a DropDownList is not desirable, because I want to apply a RequiredFieldValidator to it.

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• Dynamic Method Creation

  - by TJMonk15

  So, I have been trying to research this all morning, and have had no luck. I am trying to find a way to dynamically create a method/delegate/lambda that returns a new instance of a certain class (not known until runtime) that inherits from a certain base class. I can guarantee the following about the unknown/dynamic class It will always inherit from one known Class (Row) It will have atleast 2 constructors (one accepting a long, and one accepting an IDataRecord) I plan on doign the following: Finding all classes that have a certain attribute on them Creating a delegate/method/lambda/whatever that creates a new instance of the class Storing the delegate/whatever along with some properties in a struct/class Insert the struct into a hashtable When needed, pull the info out of the hashtable and calling the delegate/whatever to get a new instance of the class and returning it/adding it to a list/etc. I need help only with #2 above!!! I have no idea where to start. I really just need some reference material to get me started, or some keywords to throw into google. This is for a compact/simple to use ORM for our office here. I understand the above is not simple, but once working, should make maintaining the code incredibly simple. Please let me know if you need any more info! And thanks in advance! :)

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• Why is a NullReferenceException thrown when a ToolStrip button is clicked twice with code in the `Click` event handler?

  - by Patrick

  I created a clean WindowsFormsApplication solution, added a ToolStrip to the main form, and placed one button on it. I've added also an OpenFileDialog, so that the Click event of the ToolStripButton looks like the following: private void toolStripButton1_Click(object sender, EventArgs e) { openFileDialog1.ShowDialog(); } I didn't change any other properties or events. The funny thing is that when I double-click the ToolStripButton (the second click must be quite fast, before the dialog opens), then cancel both dialogs (or choose a file, it doesn't really matter) and then click in the client area of main form, a NullReferenceException crashes the application (error details attached at the end of the post). Please note that the Click event is implemented while DoubleClick is not. What's even more strange that when the OpenFileDialog is replaced by any user-implemented form, the ToolStripButton blocks from being clicked twice. I'm using VS2008 with .NET3.5. I didn't change many options in VS (only fontsize, workspace folder and line numbering). Does anyone know how to solve this? It is 100% replicable on my machine, is it on others too? One solution that I can think of is disabling the button before calling OpenFileDialog.ShowDialog() and then enabling the button back (but it's not nice). Any other ideas? And now the promised error details: System.NullReferenceException was unhandled Message="Object reference not set to an instance of an object." Source="System.Windows.Forms" StackTrace: at System.Windows.Forms.NativeWindow.WindowClass.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam) at System.Windows.Forms.UnsafeNativeMethods.PeekMessage(MSG& msg, HandleRef hwnd, Int32 msgMin, Int32 msgMax, Int32 remove) at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(Int32 dwComponentID, Int32 reason, Int32 pvLoopData) at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context) at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context) at System.Windows.Forms.Application.Run(Form mainForm) at WindowsFormsApplication1.Program.Main() w C:\Users\Marchewek\Desktop\Workspaces\VisualStudio\WindowsFormsApplication1\Program.cs:line 20 at System.AppDomain._nExecuteAssembly(Assembly assembly, String[] args) at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args) at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly() at System.Threading.ThreadHelper.ThreadStart_Context(Object state) at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Threading.ThreadHelper.ThreadStart() InnerException:

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• Lazarus Pascal - DB Connection - clarification

  - by itsols

  The following code is from the docs here: Program ConnectDB var AConnection : TSQLConnection; Procedure CreateConnection; begin AConnection := TIBConnection.Create(nil); AConnection.Hostname := 'localhost'; AConnection.DatabaseName := '/opt/firebird/examples/employee.fdb'; AConnection.UserName := 'sysdba'; AConnection.Password := 'masterkey'; end; begin CreateConnection; AConnection.Open; if Aconnection.Connected then writeln('Succesful connect!') else writeln('This is not possible, because if the connection failed, ' + 'an exception should be raised, so this code would not ' + 'be executed'); AConnection.Close; AConnection.Free; end. The main body of the code makes sense to me BUT I don't get where TSQLConnection came from. I cannot use CTRL + Space to autocomplete it either, which means my program has no reference to it. I'm trying to connect to Postgres by the way. Can someone please state what TSQLConnection is? Thanks!

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• Wicket: How to implement an IDataProvider/LoadableDetachableModel for indexed lists

  - by cretzel

  What's the best way to implement an IDataProvider and a LoadableDetachable in Wicket for an indexed list? Suppose I have a Customer who has a list of Adresses. class Customer { List adresses; } Now I want to implement a data provider/ldm for the adresses of a customer. I suppose the usual way is an IDataProvider as an inner class which refers to the customer model of the component, like: class AdressDataProvider implements IDataProvider { public Iterator iterator() { Customer c = (Customer)Component.this.getModel(); // somehow get the customer model return c.getAdresses().iterator(); } public IModel model(Object o) { Adress a = (Adress) o; // Return an LDM which loads the adress by id. return new AdressLoadableDetachableModel(a.getId()); } } Question: How would I implement this, when the adress does not have an ID (e.g. it's a Hibernate Embeddable/CollectionOfElements) but can only be identified by its index in the customer.adresses list? How do I keep reference to the owning entity and the index? In fact, I know a solution, but I wonder if there's a common pattern to do this.

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• KeyStore, HttpClient, and HTTPS: Can someone explain this code to me?

  - by stormin986

  I'm trying to understand what's going on in this code. KeyStore trustStore = KeyStore.getInstance(KeyStore.getDefaultType()); FileInputStream instream = new FileInputStream(new File("my.keystore")); try { trustStore.load(instream, "nopassword".toCharArray()); } finally { instream.close(); } SSLSocketFactory socketFactory = new SSLSocketFactory(trustStore); Scheme sch = new Scheme("https", socketFactory, 443); httpclient.getConnectionManager().getSchemeRegistry().register(sch); My Questions: trustStore.load(instream, "nopassword".toCharArray()); is doing what exactly? From reading the documentation load() will load KeyStore data from an input stream (which is just an empty file we just created), using some arbitrary "nopassword". Why not just load it with null as the InputStream parameter and an empty string as the password field? And then what is happening when this empty KeyStore is being passed to the SSLSocketFactory constructor? What's the result of such an operation? Or -- is this simply an example where in a real application you would have to actually put a reference to an existing keystore file / password?

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• MediaFileUpload of HTML in UTF-8 encoding using Python and Google-Drive-SDK

  - by Victoria

  Looking for example using MediaFileUpload has a reference to the basic documentation for creating/uploading a file to Google Drive. However, while I have code that creates files, converting from HTML to Google Doc format. It works perfectly when they contain only ASCII characters, but when I add a non-ASCII character, it fails, with the following traceback: Traceback (most recent call last): File "d:\my\py\ckwort.py", line 949, in <module> rids, worker_documents = analyze( meta, gd ) File "d:\my\py\ckwort.py", line 812, in analyze gd.mkdir( **iy ) File "d:\my\py\ckwort.py", line 205, in mkdir self.create( **( kw['subop'])) File "d:\my\py\ckwort.py", line 282, in create media_body=kw['media_body'], File "D:\my\py\gdrive2\oauth2client\util.py", line 120, in positional_wrapper return wrapped(*args, **kwargs) File "D:\my\py\gdrive2\apiclient\http.py", line 676, in execute headers=self.headers) File "D:\my\py\gdrive2\oauth2client\util.py", line 120, in positional_wrapper return wrapped(*args, **kwargs) File "D:\my\py\gdrive2\oauth2client\client.py", line 420, in new_request redirections, connection_type) File "D:\my\py\gdrive2\httplib2\__init__.py", line 1597, in request (response, content) = self._request(conn, authority, uri, request_uri, method, body, headers, redirections, cachekey) File "D:\my\py\gdrive2\httplib2\__init__.py", line 1345, in _request (response, content) = self._conn_request(conn, request_uri, method, body, headers) File "D:\my\py\gdrive2\httplib2\__init__.py", line 1282, in _conn_request conn.request(method, request_uri, body, headers) File "C:\Python27\lib\httplib.py", line 958, in request self._send_request(method, url, body, headers) File "C:\Python27\lib\httplib.py", line 992, in _send_request self.endheaders(body) File "C:\Python27\lib\httplib.py", line 954, in endheaders self._send_output(message_body) File "C:\Python27\lib\httplib.py", line 812, in _send_output msg += message_body UnicodeDecodeError: 'ascii' codec can't decode byte 0xc3 in position 370: ordinal not in range(128) I don't find any parameter to use to specify what file encoding should be used by MediaFileUpload (My files are using UTF-8). Am I missing something?

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• Django: How to dynamically add tag field to third party apps without touching app's source code

  - by Chris Lawlor

  Scenario: large project with many third party apps. Want to add tagging to those apps without having to modify the apps' source. My first thought was to first specify a list of models in settings.py (like ['appname.modelname',], and call django-tagging's register function on each of them. The register function adds a TagField and a custom manager to the specified model. The problem with that approach is that the function needs to run BEFORE the DB schema is generated. I tried running the register function directly in settings.py, but I need django.db.models.get_model to get the actual model reference from only a string, and I can't seem to import that from settings.py - no matter what I try I get an ImportError. The tagging.register function imports OK however. So I changed tactics and wrote a custom management command in an otherwise empty app. The problem there is that the only signal which hooks into syncdb is post_syncdb which is useless to me since it fires after the DB schema has been generated. The only other approach I can think of at the moment is to generate and run a 'south' like database schema migration. This seems more like a hack than a solution. This seems like it should be a pretty common need, but I haven't been able to find a clean solution. So my question is: Is it possible to dynamically add fields to a model BEFORE the schema is generated, but more specifically, is it possible to add tagging to a third party model without editing it's source. To clarify, I know it is possible to create and store Tags without having a TagField on the model, but there is a major flaw in that approach in that it is difficult to simultaneously create and tag a new model.

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• Is a call to the following method considered late binding?

  - by AspOnMyNet

  1) Assume: • B1 defines methods virtualM() and nonvirtualM(), where former method is virtual while the latter is non-virtual • B2 derives from B1 • B2 overrides virtualM() • B2 is defined inside assembly A • Application app doesn’t have a reference to assembly A In the following code application app dynamically loads an assembly A, creates an instance of a type B2 and calls methods virtualM() and nonvirtualM(): Assembly a=Assembly.Load(“A”); Type t= a.GetType(“B2”); B1 a = ( B1 ) Activator.CreateInstance ( “t” ); a.virtualM(); a.nonvirtualM(); a) Is call to a.virtualM() considered early binding or late binding? b) I assume a call to a.nonvirtualM() is resolved during compilation time? 2) Does the term late binding refer only to looking up the target method at run time or does it also refer to creating an instance of given type at runtime? thanx EDIT: 1) A a=new A(); a.M(); As far as I know, it is not known at compile time where on the heap (thus at which memory address ) will instance a be created during runtime. Now, with early binding the function calls are replaced with memory addresses during compilation process. But how can compiler replace function call with memory address, if it doesn’t know where on the heap will object a be created during runtime ( here I’m assuming the address of method a.M will also be at same memory location as a )? 2) The method slot is determined at compile time I assume that by method slot you’re referring to the entry point in V-table?

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