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• c# how to set up and use session state from preinit

  - by Praesagus

  OK so to set and read variables from the current session String Myvar =(string) System.Web.HttpContext.Current.Session[“MyVariable”] To set System.Web.HttpContext.Current.Session[“MyVariable”] = “NewValue” I can do neither, I get a System.NullReferenceException: Object reference not set to an instance of an object. from System.Web.HttpContext.Current.Session. In my web.config I have <sessionState mode="StateServer" stateConnectionString="tcpip=127.0.0.1:42424" cookieless="false" timeout="20"> </sessionState> I have read a dozen articles on the the necessity of IHttpHandler and an IRequiresSessionState interface. I think the issue may be caused because I am requesting this information in Page_PreInit. I found a solution in a stack overflow article but I don't seem be using it properly to actually make this go. I am not sure what I am missing. Thanks in advance.

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• template pass by const reference

  - by 7vies

  Hi, I've looked over a few similar questions, but I'm still confused. I'm trying to figure out how to explicitly (not by compiler optimization etc) and C++03-compatible avoid copying of an object when passing it to a template function. Here is my test code: #include <iostream> using namespace std; struct C { C() { cout << "C()" << endl; } C(const C&) { cout << "C(C)" << endl; } ~C() { cout << "~C()" << endl; } }; template<class T> void f(T) { cout << "f<T>" << endl; } template<> void f(C c) { cout << "f<C>" << endl; } // (1) template<> void f(const C& c) { cout << "f<C&>" << endl; } // (2) int main() { C c; f(c); return 0; } (1) accepts the object of type C, and makes a copy. Here is the output: C() C(C) f<C> ~C() ~C() So I've tried to specialize with a const C& parameter (2) to avoid this, but this simply doesn't work (apparently the reason is explained in this question). Well, I could "pass by pointer", but that's kind of ugly. So is there some trick that would allow to do that somehow nicely? EDIT: Oh, probably I wasn't clear. I already have a templated function template<class T> void f(T) {...} But now I want to specialize this function to accept a const& to another object: template<> void f(const SpecificObject&) {...} But it only gets called if I define it as template<> void f(SpecificObject) {...}

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• How to get title from a website by xpath?

  - by qxxx

  I am playing around with xpath, but have no Idea how to for example get a title from a website using xpath, here is my code but I don't know what to do next... $dom = new DOMDocument(); $dom->loadHTMLFile("http://www.cool.de"); $x=new DOMXPath($dom); $result = $x->query("//TITLE"); //...??? and print_r($result) shows me only "Object", is there a function like print_r to see what is inside an object so I don't have to guess?

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• Why people do not like OOP? [closed]

  - by Gabriel Šcerbák

  I do not understand why people choose C++ over Smalltalk in past and why Java over Python or Ruby. What is it that ties people so much to the procedural programming and makes it so difficult to go "all the way" to object oriented programming? What makes OOP hard? Should not objects be an abstraction which is easier to grasp for people, i.e. a more natural one than procedures? Is education the problem (because people tend to learn procedural programming before object oriented)?

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• Help me understand Dispose() implementation code from MSDN

  - by Benny

  the following code is from MSDN: Idisposable pattern protected virtual void Dispose(bool disposing) { // If you need thread safety, use a lock around these // operations, as well as in your methods that use the resource. if (!_disposed) { if (disposing) { if (_resource != null) _resource.Dispose(); Console.WriteLine("Object disposed."); } // Indicate that the instance has been disposed. _resource = null; _disposed = true; } } why the following statement: _resource = null; _disposed = true; are not enclosed by if (disposing) statement block? for me i would probably write like this: if (disposing) { if (_resource != null) { _resource.Dispose(); _resource = null; _disposed = true; } Console.WriteLine("Object disposed."); } anything wrong with my version?

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• Why can't I read session variables

  - by Marty Goetz

  I have a c# .net web application. I create session variables but when I try to read them after I leave the page that they were created from I can't. Created on page 1 Session["UserName"] = "WhatEver"; Then I do Response.Redirect("~/whatever.aspx"); and try to read to read the session variable in the Page_Load method of the new page string userName = Session["UserName"].ToString(); I receive "Object reference not set to an instance of an object." Why am I receiving this error and what can I do to fix the problem? I would greatly appreciate any help anyone can give me.

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• JSObject-like stuff in ActionScript 3?

  - by johncch

  I would like to ask if there is a liveconnect equivalent for ActionScript 3. I understand that there is the ExternalInterface class inside AS3 but it only supports calling a method by name. The really cool thing about Java and LiveConnect is that you can do something like function jsFunc(name) = { this.name = name; this.talk = function(){ alert('hello world my name is ' + this.name); } } javaapplet.function(new jsFunc("bob")); The above approaches pseudo code since I never tested it but I've seen it in action. In AS3, while I am able to pass in an instance of JavaScript "object" into AS, it is often converted into an ActionScript Object instance which does away with all the functions as far as I'm aware. I saw an implementation of JSInterface but I don't think it does specifically that. Is there any way to make OO like javascript work with ActionScript 3?

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• How can I plot a time series graph with Perl?

  - by Jazz

  I have some data from a database (SQLite), mapping a value (an integer) to a date. A date is a string with this format: YYYY-MM-DD hh:mm. The dates are not uniformly distributed. I want do draw a line graph with the dates on X and the values on Y. What is the easiest way to do this with Perl? I tried DBIx::Chart but I could not make it recognize my dates. I also tried GD::Graph, but as the documentation says: GD::Graph does not support numerical x axis the way it should. Data for X axes should be equally spaced

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• Connecting data to a GUI - OOP

  - by tau

  I have an application with several graphs and tables on it. I worked fast and just made classes like Graph and Table that each contained a request object (pseudo-code): class Graph { private request; public function setDateRange(dateRange) { request.setDateRange(dateRange); } public function refresh() { request.getData(function() { //refresh the display }); } } Upon a GUI event (say, someone changes the date range dropdown), I'd just call the setters on the Graph instance and then refresh it. Well, when I added other GUI elements like tables and whatnot, they all basically had similar methods (setDateRange and other things common to the request). What are some more elegant OOP ways of doing this? The application is very simple and I don't want to over-architect it, but I also don't want to have a bunch of classes with basically the same methods that are just routing to a request object. I also don't want to set up each GUI class as inheriting from the request class, but I'm open to any ideas really.

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• Casting objects in C# (ASP.Net MVC)

  - by Mortanis

  I'm coming from a background in ColdFusion, and finally moving onto something modern, so please bear with me. I'm running into a problem casting objects. I have two database tables that I'm using as Models - Residential and Commercial. Both of them share the majority of their fields, though each has a few unique fields. I've created another class as a container that contains the sum of all property fields. Query the Residential and Commercial, stuff it into my container, cunningly called Property. This works fine. However, I'm having problems aliasing the fields from Residential/Commercial onto Property. It's quite easy to create a method for each property: fillPropertyByResidential(Residential source) and fillPropertyByCommercial(Commercial source), and alias the variables. That also works fine, but quite obviously will copy a bunch of code - all those fields that are shared between the two main Models. So, I'd like a generic fillPropertyBySource() that takes the object, and detects if it's Residential or Commercial, fills the particular fields of each respective type, then do all the fields in common. Except, I gather in C# that variables created inside an If are only in the scope of the if, so I'm not sure how to do this. public property fillPropertyBySource(object source) { property prop = new property(); if (source is Residential) { Residential o = (Residential)source; //Fill Residential only fields } else if (source is Commercial) { Commercial o = (Commercial)source; //Fill Commercial only fields } //Fill fields shared by both prop.price = (int)o.price; prop.bathrooms = (float)o.bathrooms; return prop; } "o" being a Commercial or Residential only exists within the scope of the if. How do I detect the original type of the source object and take action? Bear with me - the shift from ColdFusion into a modern language is pretty..... difficult. More so since I'm used to procedural code and MVC is a massive paradigm shift. Edit: I should include the error: The name 'o' does not exist in the current context For the aliases of price and bathrooms in the shared area.

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• How can I create a generic constructor? (ie. BaseClass.FromXml(<param>)

  - by SofaKng

  I'm not sure how to describe this but I'm trying to create a base class that contains a shared (factory) function called FromXml. I want this function to instantiate an object of the proper type and then fill it via an XmlDocument. For example, let's say I have something like this: Public Class XmlObject Public Shared Function FromXml(ByVal source as XmlDocument) As XmlObject // <need code to create SPECIFIC TYPE of object and return it End Function End Class Public Class CustomObject Inherits XmlObject End Class I'd like to be able to do something like this: Dim myObject As CustomObject = CustomObject.FromXml(source) Is this possible?

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• Using Assert to compare two objects

  - by baron

  Hi everyone, Writing test cases for my project, one test I need is to test deletion. This may not exactly be the right way to go about it, but I've stumbled upon something which isn't making sense to me. Code is like this: [Test] private void DeleteFruit() { BuildTestData(); var f1 = new Fruit("Banana",1,1.5); var f2 = new Fruit("Apple",1,1.5); fm.DeleteFruit(f1,listOfFruit); Assert.That(listOfFruit[1] == f2); } Now the fruit object I create line 5 is the object that I know should be in that position (with this specific dataset) after f1 is deleted. Also if I sit and debug, and manually compare objects listOfFruit[1] and f2 they are the same. But that Assert line fails. What gives?

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• store data in asp.net pages (Not Sessions)

  - by ARB

  I am creating 4 asp.net pages. first three pages have 'CONTINUE' button and last page has 'SUBMIT' button. I am not allowed to use Sessions to store first three pages data. and i need to use 'BACK' button on last three pages. when i click 'BACK' button i need to maintain the previous page data entered by user. As my pages do some postbacks, i cannot use javascript.history function. My restrictions are: As the application is served from a web farm, a session object cannot be used. However, for the purpose of this excersise, consider session object as database-like persistent space where you can store your data. your code should show an easy way to switch to a different persistent space. What is databse like persistent space and how to write a code to switch to different persistent space?... Please give me some idea on how to proceed.... Thank you

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• How can I "override" deepcopy in Python?

  - by Az

  Hi there, I'd like to override __deepcopy__ for a given SQLAlchemy-mapped class such that it ignores any SQLA attributes but deepcopies everything else that's part of the class. I'm not particularly familiar with overriding any of Python's built-in objects in particular but I've got some idea as to what I want. Let's just make a very simple class User that's mapped using SQLA. class User(object): def __init__(self, user_id, name): self.user_id = user_id self.name = name I've used dir() to see, before and after mapping, what SQLAlchemy-specific attributes there are and I've found _sa_class_manager and _sa_instance_state. Provided those are the only ones how would I ignore that when defining __deepcopy__? Also, are there any attributes the SQLA injects into the mapped object? (I asked this in a previous question (as an edit a few days after I selected an answer to the main question, though) but I think I missed the train there. Apologies for that.)

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• How can I create an http handler to redirect all traffic to HTML pages?

  - by Eitan

  Our company would like to redirect all calls to html files on our server to a separate page. The html pages are NOT in an asp.net application. In order to do this, I've been writing and IIS Handler in asp.net. 1) Is this possible to add an IIS handler to redirect static content that isn't served by any asp.net engine, i.e. stand alone files on the server? 2) If it is possible, how do I do this? I created an http handler in a class library. In the app.config I added the handler to the and sections. I added the DLL to the GAC, I changed the html mapping to my custom IIS dll and nothing works. Is there a tutorial or explanation from A to B on how to do this? Thanks. E p.s. I'm using IIS 7.5

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• relating data stored in NoSQL DB to data stored in SQL DB

  - by seanbrant

  Whats the best way to use a SQL DB along side a NoSQL DB? I want to keep my users and other data in postgres but have some data that would be better suited for a NoSQL DB like redis. I see a lot of talk about switching to NoSQL but little talk on integrating it with existing systems. I think it would be foolish to throw the baby out with the bath water and ditch SQL all together, unless it makes things easier to maintain and develop. I'm wondering what the best approach is for relating data stored in SQL to my data in redis. I was thinking of something along the line of this. User object stored in SQL Book object in redis, key sh1 hash of value, value is a JSON string Relations stored in redis, key User.pk:books, value redis set of sha1's Anyone have experience, tips, better ways?

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• Treating a fat webservice in .net 3.5 c#

  - by Chris M

  I'm dealing with an obese 3rd party webservice that returns about 3mb of data for a simple search results, about 50% of the data in that response is junk. Would it make sense then to remap this data to my own result object and ditch the response so I'm storing 1-2 mb in memory for filtering and sorting rather than using the web-responses own object and using 2-4 or am I missing a point? So far I've been accessing the webservice from a separate project and using a new class to provide the interaction and to handle the persistence so my project looks like this |- Web (mvc2 proj) |- DAL (database/storage fluent-nhibernate) |- SVCGateway (interaction layer + webservice related models) |- Services -------------- |- Tests |- Specs I'm trying to make the application behave fast and I also need to store the result set temporarily in case a customer goes to view the product and wants to go back to the results. (Service returns only 500 of possible 14K results). So basically I'm looking for confirmation that I'm doing the right thing in pushing the results into my own objects or if I'm breaking some rule or even if there's a better way of handling it. Thanks

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• Working with Multiple Layers - KineticJS

  - by Bruno Sampaio

  I'm using KineticJS 4.0.5 and I'm currently trying to draw the contents of several layers but only the last one added to stage is drawn... If I understood the documentation correctly this should be possible, otherwise why would we need a layer? I have three different layers: a background layer with just a Kinectic.Rect object; a elements layer with several types of shapes; and a top layer with elements I want to be always on top of everything. I populate those layers inside a draw function I have inside a object I created, this object also has a shape attribute which refers to the background and a contents attribute with the elements to add to the elements layer. My code for the draw function is the following: this.draw = function() { var stage = E.game.stage, layers = E.game.layers; stage.clear(); // Add Background this.shape.setSize(stage.getWidth(), stage.getHeight()); layers.background.add(this.shape); // Iterate over contents for(var i = 0; i < this.contents.length; i++) { layers.elements.add(this.contents[i].shape); } // Draw Everything stage.add(layers.background); stage.add(layers.elements); stage.add(layers.top); // This one is currently empty stage.draw(); } After running this function, only layers.top is drawn in the canvas, and if I comment the line where it is added only layers.elements is drawn. However the stage has 3 childrens (I checked it with inspect element on chrome) and in the documentation it says the draw function draws all layers... Am I doing something wrong here? Or it isn't possible? And if it's not possible why would I need a layer and a stage? Wouldn't one be enough? Thank you in advance. Edit: I was able to solve the problem, I was applying a white background color with css to the canvas element and since each layer creates a new canvas element above the others I could only see the contents for the top most layer (in this case just white). However, I still have a problem related with multiple layers that I didn't have before with just one layer. When I use the clear function on the stage it should clear the layers right? But instead the layers remain exactly the same, even if I try to call clear on each individual layer they won't change... I'm also using the stage draw function after clearing them but still no changes at all... The only solution I found until now was by removing the layer from the stage and adding it again :s Is there a better way to reset the layers contents? Thank you again and sorry for the confusion with the first question.

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• How do I get the NextVal from an oracle Sequence thru NHibernate

  - by trainer

  I am working on c# .net 4.0 and using NHibernate to talk with an Oracle DB. You would think something as simple as this is already addressed somewhere but sadly its not. I need the NextVal from an Oracle sequence. I do not need to insert it a database as part of an Id or Primary key. I just need to use the next val on the c# side. Can somebody help me out with xml mapping and C# file(or a link) to achieve this. Thanks. Something like int NextValueOfSequence = GetNextValueofSequence(); public int GetNextValueOfSequence() { // Access NHibernate to return the next value of the sequence. }

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• Empty dict-like collection problem in SQLAlchemy

  - by maksymko

  I have a mapping in SQLAlchemy that looks like this: t_property_value = sa.Table('property_value', MetaData, autoload = True, autoload_with = engine) orm.mapper(PropertyValue, t_property_value) t_estate = sa.Table('estate', MetaData, autoload = True, autoload_with = engine) orm.mapper(Estate, t_estate, properties = dict( property_hash = orm.relation(PropertyValue, collection_class = column_mapped_collection(t_property_value.c.property_id)) )) Now, everything seems to be fine, when I load the Estate object and it has some relations to PropertyValue objects. However, when it does not, then property_hash attribute is None, instead of being something dict-like, so I can not add new relations like this: estate.property_hash[prop_id] = PropertyValue(...) because I get the "'NoneType' object does not support item assignment" error. So, is there any way to force SQLAlchemy to create proper empty collection?

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• Error while coping datacolumn with data from one table to another .

  - by Harikrishna

  I have one Datatable like DataTable addressAndPhones; And there are four columns name,address,phoneno,and other details and I only want two columns Name and address from that so I do for that is DataTable addressAndPhones2; addressAndPhones2.Columns.Add(new DataColumn(addressAndPhones.Columns["name"].ColumnName)); addressAndPhones2.Columns.Add(new DataColumn(addressAndPhones.Columns["address"].ColumnName)); But it gives me error so how can I copy fix no of columns data from one table to another table ? ERROR :Object reference not set to an instance of an object.

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• error string list handle in C#

  - by Chelsea_cole

  Same namespace: 2 forms. public class Account //frm1 { public string Username; public string Password; } public class ListAcc { public static List<Account> UserList; } private void button1_Click(object sender, EventArgs e) { List<Account> UserList = new List<Account>(); Account acc = new Account(); acc.Username = textBox1.Text; acc.Password = textBox2.Text; UserList.Add(acc); } private void button2_Click(object sender, EventArgs e) //frm2 { string p = frmDangky.ListAcc.UserList[0].Username; // null ->error string p = frmDangky.ListAcc.UserList[0].Password; // null ->error } Someone help me? :( why my string is NULL???????? The textBox is not empty... Thanks!

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• How do you add objects to a javascript namespace?

  - by Fletcher Moore

  var Test = (function() { return { useSub: function () { this.Sub.sayHi(); }, init: function () { $(document).ready(this.useSub); } }; })(); Test.Sub = (function () { return { sayHi: function () { alert('hi'); } }; })(); Test.useSub(); // works Test.init(); // explodes Above I am trying to create a Test namespace and add an object Sub to it. I was doing fine until I tried using the object in jQuery. The error is "Uncaught TypeError: Cannot call method 'sayHi' of undefined". If there is a better way to do this, I am open to it.

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• Delegation, is this just opinionated or is there a common pattern?

  - by user1446714

  If I have a java class containing substantial code and I wish to add extra features, am I right in thinking the delegate class would have the additional features added as methods. Then my original class would create the delegate object and just call the extra functionality via the delegate instance? I am being told by somebody else that my original class should become the delegate and that the class containing the new functionality should contain an instance of the original class, to use as a delegate? This seemed a little backward to me, because there would be far more delegate calls because most of the code is now in the delegate.... I was always under the impression the delegate object would contain the additional new behaviour and an instance of it would be in the original class to inboke the new behaviour from?

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• Unnecessary 'else' statement

  - by Vitalii Fedorenko

  As you know, in Eclipse you can turn on "Unnecessary 'else' statement" check that will trigger on if-then-else with premature return. And, from my experience, there are two most possible situations when use such statement: 1) Pre-check: if (validate(arg1)) { return false; } doLotOfStuff(); 2) Post-check: doLotOfStuff(); if (condition) { return foo; } else { return bar; } In the second case, if the trigger is on, Eclipse will suggest you to change the code to: doLotOfStuff(); if (condition) { return foo; } return bar; However, I think that the return with else statement is more readable as it is like direct mapping of business logic. So I am curios if this "Unnecessary 'else' statement" code convention is widespread or else statement is more preferable?

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