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• How to retrieve indentity column vaule after insert using LINQ

  - by Hobey

  Could any of you please show me how to complete the following tasks? // Prepare object to be saved // Note that MasterTable has MasterTableId as a Primary Key and it is an indentity column MasterTable masterTable = new MasterTable(); masterTable.Column1 = "Column 1 Value"; masterTable.Column2 = 111; // Instantiate DataContext DataContext myDataContext = new DataContext("<<ConnectionStrin>>"); // Save the record myDataContext.MasterTables.InsertOnSubmit(masterTable); myDataContext.SubmitChanges(); // ?QUESTION? // Now I need to retrieve the value of MasterTableId for the record just inserted above. Kind Regards

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• Unmanaged C++ instantiation question

  - by Jim Jones

  Want to verify that my understanding of how this works. Have an unmanaged C++ Class with one public instance variable: char* character_encoding; and whose only constructor is defined as: TF_StringList(const char* encoding = "cp_1252"); when I use this class in either managed or unmanaged C++, the first thing I do is declare a pointer to an object of this class: const TF_StringList * categories; Then later I instantiate it: categories = new TF_StringList(); this gives me a pointer to an object of type TF_StringList whose variable character_encoding is set to "cp_1252"; So, is all that logic valid? Jim

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• Error Instantiating an Inner Class in Parent's Constructor...

  - by stormin986

  In my application's main class (subclass of Application), I have a public inner class that simply contains 3 public string objects. In the parent class I declare an object of that inner class. public class MainApplication extends Application { public class Data { public String x; public String y; public String z; } private Data data; MainApplication() { data = new Data() data.x = "String"; } } After I instantiate the object in the constructor, I get a runtime error when I try to assign any of the inner class object's variables. Any idea what's up here??

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• netbeans autocompletion when using singleton to retrieve object instead of new operator?

  - by fayer

  when i use the 'new' operator to instantiate a class, netbeans has no problem to autocomplete the members of the object. $instance = new Singleton(); $instance-> // shows test() method but when i use a singleton to retrieve an object it cannot autocomplete the members in the object retrieved. the getInstance code looks like this: public function test() { echo "hello"; } public static function getInstance() { if ( ! is_object(self::$_instance)) { self::$_instance = new self(); self::$_instance->initialize(); } return self::$_instance; } so i use: $instance = Singleton::getInstance(); $instance-> // no autocompletion! does anyone have the same problem? how do i work around it? thanks!

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• Using ActiveRecord::Base.transaction in a rake task?

  - by Brian Jordan

  I am writing a rake task which, at one point, uses a custom YAML file import method to seed the database. At one point in the import code, I have: ActiveRecord::Base.transaction do Trying to run the rake task throws: You have a nil object when you didn't expect it! You might have expected an instance of ActiveRecord::Base. The error occurred while evaluating nil.[] The stack trace points to the aforementioned line in the code. Is there a way to instantiate ActiveRecord::Base during a rake task? Thanks!

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• Plugin methods are missing in Firefox 3.6

  - by splintor

  Hi, We have a plugin that we use to enable printing and saving from our app. We instantiate it using tag with all needed attributes, and then call Save() or Print() method on the document.embeds[0] object. This used to work perfectly on Firefox 3.5 and earlier, but it no longer works in Firefox 3.6. In 3.6, document.embeds[0].Save is null, that is our custom methods are not defined on this object. Any idea why this happens, and what has changed in Firefox 3.6 that causes it? Any idea on how to debug it and find the cause? And most important, any idea of a workaround that will allow us to access this methods? Thanks, splintor

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• How to use the vtable to determine class type

  - by Alex Silverman

  I was recently on an interview for a position where C/C++ is the primary language and during one question I was told that it's possible to use the vtable to determine which class in a hierarchy a base pointer actually stores. So if, for example you have class A { public: A() {} virtual ~A() {} virtual void method1() {} }; class B : public A { public: B() {} virtual ~B() {} virtual void method1() {} }; and you instantiate A * pFoo = new B(), is it indeed possible to use the vtable to determine whether pFoo contains a pointer to an instance of A or B?

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• PHP Object Oriented Web Application

  - by Sev

  I have a class called "Layout" for the layout of the page, another class called "User" for the user. Every page I create, I instantiate a new Layout. When a user logs in, there is a new User instantiated. How do I get an instance of the layout class to know about the instantiated user? I could also save the entire instance of the User in a session variable. I assume that's a bad idea though. What are the best practices for this?

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• Why does C++ mandate that complex only be instantiated for float, double, or long double?

  - by templatetypedef

  According to the C++ ISO spec, §26.2/2: The effect of instantiating the template complex for any type other than float, double or long double is unspecified. Why would the standard authors explicitly add this restriction? This makes it unspecified, for example, what happens if you make complex<int> or a complex<MyCustomFixedPointType> and seems like an artificial restriction. Is there a reason for this limitation? Is there a workaround if you want to instantiate complex with your own custom type? I'm primarily asking this question because of this earlier question, in which the OP was confused as to why abs was giving bizarre outputs for complex<int>. That said, this still doesn't quite make sense given that we also might want to make complex numbers out of fixed-points types, higher-precision real numbers, etc. Thanks!

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• Is it okay if my ViewModel 'creates' bindable user controls for my View?

  - by j0rd4n

  I have an entry-point View with a tab control. Each tab is going to have a user control embedded within it. Each embedded view inherits from the same base class and will need to be updated as a key field on the entry-point view is updated. I'm thinking the easiest way to design this page is to have the entry-point ViewModel create and expose a collection of the tabbed views so the entry-point View can just bind to the user control elements using a DataTemplate on the tab control. Is it okay for a ViewModel to instantiate and provide UI elements for its View?

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• [iPhone app] Inserting special char un NSString for URL use

  - by Dough

  Hi, I'm using HTTP connection to share data with my JSON server. I use URLs like "MyServlet?param1=value1" and so on... I'm now facing a problem with one of my servlet (I can't change it because some other views are using it) : The servlet is working with a syntax including those symbols "{" and "}". The exact syntax is {(value1_value2)(value3_value4)(value5_value6)}{(value7_value8)(value9_value10)(value11_value12)}{(value13_value14)(value15_value16)(value17_value18)} Values are integers, the problem is only when I use "{" and "}" my UrlConnection returns an error for bad URL. I use this to instantiate my NSString : NSString *myURL = [NSString stringWithFormat:@"http://somesite.com/Servlet?PARAM={(%@)}"]; How can I code those char in my NSString ? Thanks in advance !

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• Use of private constructor to prevent instantiation of class?

  - by cringe

  Hi guys! Right now I'm thinking about adding a private constructor to a class that only holds some String constants. public class MyStrings { // I want to add this: private MyString() {} public static final String ONE = "something"; public static final String TWO = "another"; ... } Is there any performance or memory overhead if I add a private constructor to this class to prevent someone to instantiate it? Do you think it's necessary at all or that private constructors for this purpose are a waste of time and code clutter?

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• Java Swing architecture for flipping through JPane based views

  - by imhotep

  Hi all, I have done a couple of simple swing based apps with static layout, but now I've run into a problem while trying to create an app containing multiple views which are changed by pressing appropriate navigational button. You could compare the idea to a website so that every view has buttons to access certain other views but this would work inside a single JFrame. I've found that maybe CardLayout (Cardlayout example) might be appropriate solution for this kind of structure, but I'm unable to figure out a way to switch the views from the buttons which are inside of the JPanes that I've implemented in their separate classes, Of course one way would be to instantiate everything in the parent class like in the small java tutorial example, but this isn't quite clean nor modular for multiple views, isn't it. How can this be implemented so that I can access the view switching method?

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• Is the .Net HashSet uniqueness calculation completely based on Hash Codes?

  - by RobV

  I was wondering whether the .Net HashSet<T> is based completely on hash codes or whether it uses equality as well? I have a particular class that I may potentially instantiate millions of instances of and there is a reasonable chance that some hash codes will collide at that point. I'm considering using HashSet's to store some instances of this class and am wondering if it's actually worth doing - if the uniqueness of an element is only determined on its hash code then that's of no use to me for real applications MSDN documentation seems to be rather vague on this topic - any enlightenment would be appreciated

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• Showing an image after loading it from sql database

  - by user330075

  I have a problem showing the image form database in a view Details and a ImageController. Inside the view I have: img src=Url.Action("GetFile","Image", new {id= Model.id}) and in controller: public FileContentResult GetFile(int idl) { //int idl = 32; SqlDataReader rdr; byte[] fileContent = null; ........... return File(,,); } When the view is called, function GetFile it just won't work. But if I cut out the parameter int id1 and I instantiate it as a variable it does work. public FileContentResult GetFile() { int idl = 32; SqlDataReader rdr; byte[] fileContent = null; ........... return File(,,); } Why?

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• how to generate large image in compact framework

  - by Buthrakaur

  I need to generate large images (A4 image at 200 DPI, PNG format would be fine) in my compact framework application. This is impossible to do in standard way due to memory limitations (such big image will throw OOMException). Is there any library which offers file-backed stream image generation? Or I could generate many smaller stripes of images (each stripe representing a row of the large image) using standard Bitmap approach, but I need to merge them together afterwards - is there any method how to merge many smaller images into one large without having to instantiate large Bitmap instance (which would again cause OOM)?

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• How do I dynamically update an instance array to hold a list of dynamic methods on instantiation?

  - by Will

  I am trying to dynamically define methods based on xml mappings. This works really well. However I want to create an instance variable that is a array of the dynamically defined methods. My code looks something like this def xml_attr_reader(*args) xml_list = "" args.each do |arg| string_val = "def #{arg}; " + " xml_mapping.#{arg}; " + "end; " self.class_eval string_val xml_hash = xml_list + "'#{arg}'," end self.class_eval "@xml_attributes = [] if @xml_attributes.nil?;" + "@xml_attributes = @xml_attributes + [#{xml_list}];" + "puts 'xml_attrs = ' + @xml_attributes.to_s;" + "def xml_attributes;" + " puts 'xml_attrs = ' + @xml_attributes.to_s;" + " @xml_attributes;" + "end" end So everything works except when I call xml_attributes on an instance it return null (and prints out 'xml_attrs = '). While the puts before the definition actually prints out the correct array. (when I instantiate the instance)

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• C++: Can a macro expand "abc" into 'a', 'b', 'c'?

  - by Peter Alexander

  I've written a variadic template that accepts a variable number of char parameters, i.e. template <char... Chars> struct Foo; I was just wondering if there were any macro tricks that would allow me to instantiate this with syntax similar to the following: Foo<"abc"> or Foo<SOME_MACRO("abc")> or Foo<SOME_MACRO(abc)> etc. Basically, anything that stops you from having to write the characters individually, like so Foo<'a', 'b', 'c'> This isn't a big issue for me as it's just for a toy program, but I thought I'd ask anyway.

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• Manage bad_alloc exception in C++ construtor

  - by Jimmy zhang

  I have Java experience and recently am doing some C++ coding. My question is that if I have class A, in which I have to instantiate class B and class C as two of the member variables of A. If in the constructor of A, should I assume that allocations of class B and C never fail, and handle the bad allocation exception in the destructor of A? If I don't make that assumption, meaning that I add some try catch block to catch bad_alloc of class B and class C, then if the allocation exception occurs, should I do clean up in the constructor of A? What are the recommended practices? If "new" generates a bad allocation, what value does the pointer carry?

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• Persisting sensitve data in asp.net, odd implementation

  - by rawsonstreet

  For reasons not in scope of this question I have implemented a .net project in an iframe which runs from a classic asp page. The classic asp site persisted a few sensitive values by hitting the db on each page. I have passed there variables as xml to the aspx page, now I need to make these values available on any page of this .net site. I've looked into the cache object but we are on a web farm so I am not sure it would work. Is there a way I can can instantiate an object in a base page class and have other pages inherit from the base page to access these values? What is the best way to persist these values? A few more points to consider the site runs in https mode and I cannot use session variables, and I would like to avoid cookies if possible..

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• castle windsor container not wiring properties correctly

  - by Damian

  I have a class that i want to instantiate thru castle in configuration. public class MyMappings : IMappings { Mapping FirstMapping { get; set; } Mapping SecondMapping { get; set; } OtherType ThirdMapping { get; set; } OtherType FourthMapping { get; set; } Mapping FifthMapping { get; set; } OtherType SixMapping { get; set; } } In my configuration i have the following: ${anothercomponentIDForCompomentOftypeMapping} The problem i am facing is that is assigning the same value to all properties of the same type, completly ignoring the name of the parameter. This properties are optional, i just want to initialize the value for one of them. Thanks,

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• How to track dealloc of an abstract object class (NSMutable...)

  - by Thomas Tempelmann

  I have a bug in my code caused by a premature freeing of a ObjC object. I seem not to be able to find it by just looking at my code. There's usually a simple trick to track the dealloc to any class: Implement dealloc, and set a breakpoint. This even usually works with standard objects, by subclassing them and making sure I instantiate the subclass instead of the standard class. However, this does not seem to work with NSMutableArray, and probably neither with similar NSMutable... classes. Some explanations for this can be found here: link text Any other ideas how to track the dealloc invocation of a particular class or object so that I can see the call stack? It's probably possible with DTrace. Any pointers without having to read the entire dtrace docs first?

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• Realtime processing and callbacks with Python and C++

  - by Doughy

  I need to write code to do some realtime processing that is fairly computationally complex. I would like to create some Python classes to manage all my scripting, and leave the intensive parts of the algorithm coded in C++ so that they can run as fast as possible. I would like to instantiate the objects in Python, and have the C++ algorithms chime back into the script with callbacks in python. Something like: myObject = MyObject() myObject.setCallback(myCallback) myObject.run() def myCallback(val): """Do something with the value passed back to the python script.""" pass Will this be possible? How can I run a callback in python from a loop that is running in a C++ module? Anyone have a link or a tutorial to help me do this correctly?

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• Figuring out what makes a C++ class abstract in VS2008

  - by suszterpatt

  I'm using VS2008 to build a plain old C++ program (not C++/CLI). I have an abstract base class and a non-abstract derived class, and building this: Base* obj; obj = new Derived(); fails with the error "'Derived': cannot instantiate abstract class". (It may be worth noting, however, that if I hover over Base with the cursor, VS will pop up a tooltip saying "class Base abstract", but hovering over Derived will only say "class Derived" (no "abstract")). The definitions of these classes are fairly large and I'd like to avoid manually checking if each method has been overridden. Can VS do this for me somehow? Any general tips on pinpointing the exact parts of the class' definition that make it abstract?

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• Unable to access static var from Document Class in AS3

  - by omidomid

  I have a Document class called "CityModule", and an asset with class "City". Below is the coe for each. For some reason, I am unable to access the static variables of the City class from CityModule: CityModule.as: package { public class CityModule extends MovieClip { public function CityModule() { var buildings:Array = City.getBuildings(); } } } } City.as: package { import flash.display.MovieClip; public class City extends MovieClip { private static var _buildings:Array = [ {className:'City.Generic1', type:'generic'}, {className:'City.Generic2', type:'generic'}, {className:'City.Generic3', type:'generic'} ]; public function City(){ //empty } public static function getBuildings():Array{ return _buildings; } } } Doing this gives me a "Call to a possibly undefined method getBuildings" error. If I instantiate an instance of City, I can see any public/ getters/ setters perfectly fine. But static isn't working...

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