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  • Embedded programming books

    - by Velho Kerho
    What embedded programming/design books would you suggest? With embedded I mean near to hardware programming in ASM and C/C++. I'm looking something related to best practices in embedded programming/design. Operation system could be Linux, Real Time Linux or any other RTOS.

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  • client-server application design

    - by nelly
    Hi, i want to create a client-server application using sockets on .net platform and being new to networking programming and i have a dilemma. The client will send data to server often and also the server will notify clients often. What is the best way to design it? should the server keep a thread to communicate with each client until it quits or just the clients send data to the server and it update the clients regularly(few seconds) or none of those? Some help would be great. Thanks guys.

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  • design function: underlying structure to store list of results for print to file

    - by forest.peterson
    is this a good approach to print a list of items to csv file with a sublist attached to each item. The gist of the function is when an item is found that does not exactly macth then a list of close matches is generated - this works now writing out one list at a time to a command window. For export to a csv file I think all the lists must be generated, stored and then written at once. Right now I use a struct to store the attributes printed, each struct is an item on the list - these structs are then added to a sorted stack and when printed they pop off into write out. Is a stack of stacks of structs a good design?

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  • Data access layer using Linq to SQL

    - by Andrei Tanasescu
    I am building a c# - linq - sql server winforms/asp.net application, accessing a database. I would like my business logic layer to be easily testable, and that means not littering it with Linq database queries everywhere. What design patterns/ best practices are available for the following use cases - inserting/updating a new object - searching for an object - loading a bunch of related data into a sort of "presentation" object that could be displayed by various views ?

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  • A better name for INeedSomething... ?

    - by Daniel Severin
    I was trying pick a name for an interface through which I can pass something into an object like: If the object is INeedX then SetX(some x) method will be called; If the object is INeedY then SetY(some y) method will be called; and so on. (funny as hell, I know :) ) I try to find a different name for this kind of interfaces but I can't figure this out. Does anybody have an idea how to name the INeedSomething interface ?

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  • Is directly executing SQL bad app design?

    - by Michael Lowman
    I'm developing an iOS application that's a manager/viewer for another project. The idea is the app will be able to process the data stored in a database into a number of visualizations-- the overall effect being similar to cacti. I'm making the visualizations fully user-configurable: the user defines what she wants to see and adds restrictions. She might specify, for instance, to graph a metric over the last three weeks with user accounts that are currently active and aren't based in the United States. My problem is that the only design I can think of is more or less passing direct SQL from the iOS app to the backend server to be executed against the database. I know it's bad practice and everything should be written in terms of stored procedures. But how else do I maintain enough flexiblity to keep fully user-defined queries? While the application does compose the SQL, direct SQL is never visible or injectable by the user. That's all abstracted away in UIDateTimeChoosers, UIPickerViews, and the like.

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  • Orverride Problem for Custom Design on Product - Magneto

    - by Chris
    I am running several sites in several different languages off of single instance of magneto. There are two main styles Site 1 Site 2 Each site has some cusomtimizations based on language So each shop view has an some templates defined Site 2 - DE Site 2 - UK Now the problem is that when I apply a product level design, it forget's about the language level definition and skips back to the main definition. I want it to work like this Site 2 Site 2 DE Product Style But Instead it seems to work like this Site 2 Site 2 DE Product Style Where Site 2 DE is not ignored because a custom product style has been defined. How can I get the first hierarchy to work? So that my product styles do not override the language styles completely.

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  • Formal name of Magento’s Class Override Design Pattern?

    - by Alan Storm
    Magento is a newish (past 5 years) PHP based Ecommerce system with an architecture that's similar to the Java Spring framework (or so I've been told) One of the features of the Framework is certain classes are not directly instantiated. Rather than do something like $model = new Mage_Foo_Model_Name(); you pass an identifier into a static method on a global application object $model = Mage::getModel('foo/name'); and this instantiates the class for you. One of the wins with this approach is getModel checks a global configuration system for the foo/name identifier, and instantiates the class name it finds in the configuration system. This allows you to change the behavior of a Model system wide with a single configuration change. Is there a formal, Gang of Four or otherwise, name that describes this system/design pattern? The instantiation itself looks like a classic Factory pattern, but I'm specifically interested in the whole "override a class in the system via configuration" aspect. Is there a name/concept that covers this, or is it contained within the worldview of a Factory?

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  • Downsides to immutable objects in Java?

    - by parkr
    The advantages of immutable objects in Java seem clear: consistent state automatic thread safety simplicity You can favour immutability by using private final fields and constructor injection. But, what are the downsides to favouring immutable objects in Java? i.e. incompatibility with ORM or web presentation tools? Inflexible design? Implementation complexities? Is it possible to design a large-scale system (deep object graph) that predominately uses immutable objects?

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  • Adding a Design time Panel to a TabPage at run time

    - by BDotA
    Hi, I wish to have a Panel with the controls on it at design time but I want to add this panel to a desired tabPage of my TabControl at run time. I wrote something like this, did not work : the panel does not show up in the tab page. please help me. panel2.Parent = tabGuy.TabPages[0]; tabGuy.SuspendLayout(); tabGuy.TabPages[0].Controls.Add(panel2); tabGuy.ResumeLayout(); panel2.Show();

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  • mysql database design: threads and replies

    - by ajsie
    in my forum i have threads and replies. one thread has multiple replies. but then, a reply can be a reply of an reply (like google wave). because of that a reply has to have a column "reply_id" so it can point to the parent reply. but then, the "top-level" replies (the replies directly under the thread) will have no parent reply. so how can i fix this? how should the columns be in the reply table (and thread table). at the moment it looks like this: threads: id title body replies: id thread_id (all replies will belong to a thread) reply_id (here lies the problem. the top-level replies wont have a parent reply) body what could a smart design look like to enable reply a reply?

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  • MySql database design for a quiz

    - by Mark
    I'm making an online quiz with php and mysql and need a bit of help deciding how to design the database for optimal insert of questions/answers and to select questions for the quiz. The table will hold 80 questions each with 4 possible options plus the correct answer. When retrieving the questions and options from the database I will randomly select 25 questions and their options. Is it better to make a single column for all questions, options, and correct answers? For example: ID | Q | OPT1 | OPT2 | OPT3 | OPT4 | ANS Or would it be better to make a column for each individual question, option, and correct answer? For example: Q1 | Q1_OPT1 | Q1_OPT2 | Q1_OPT3 | Q1_OPT5 | Q1_ANS | Q2 | Q2_OPT1 | Q2_OPT2...

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  • Singleton design potential leak

    - by iBrad Apps
    I have downloaded a library off of github and have noticed that in the main singleton of the library there is a possible leak in this bit of code: +(DDGameKitHelper*) sharedGameKitHelper { @synchronized(self) { if (instanceOfGameKitHelper == nil) { [[DDGameKitHelper alloc] init]; } return instanceOfGameKitHelper; } return nil; } Now obviously there is no release or autorelease anywhere so I must do it but how and in what way properly? I have looked at various Singleton design patterns on the Internet and they just assign, in this case, instanceOfGameKitHelper to the alloc and init line. Anyway how would I properly fix this? Thanks!

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  • C# design question (Connections)

    - by David
    Hello, I would like to hear your suggestions on kind of design problem which I have in c#. So, I am making a program where people can meet and draw in the same window over the internet or LAN. I am drawing into a bitmap and than I set it to a pictureBox component. I have a hard time to decide how to send updates to each user, what is the best way to do it. Should I send coordinates of mouse and than do the drawing on each users screen or stream the image to each. Maybe you know better solution to keep it synchronized and efficient. Thank you.

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  • AS3: Array of objects parsed from XML remains with zero length

    - by Joel Alejandro
    I'm trying to parse an XML file and create an object array from its data. The data is converted to MediaAlbum classes (class of my own). The XML is parsed correctly and the object is loaded, but when I instantiate it, the Albums array is of zero length, even when the data is loaded correctly. I don't really know what the problem could be... any hints? import Nem.Media.*; var mg:MediaGallery = new MediaGallery("test.xml"); trace(mg.Albums.length); MediaGallery class: package Nem.Media { import flash.net.URLRequest; import flash.net.URLLoader; import flash.events.*; public class MediaGallery { private var jsonGalleryData:Object; public var Albums:Array = new Array(); public function MediaGallery(xmlSource:String) { var loader:URLLoader = new URLLoader(); loader.load(new URLRequest(xmlSource)); loader.addEventListener(Event.COMPLETE, loadGalleries); } public function loadGalleries(e:Event):void { var xmlData:XML = new XML(e.target.data); var album; for each (album in xmlData.albums) { Albums.push(new MediaAlbum(album.attribute("name"), album.photos)); } } } } XML test source: <gallery <albums <album name="Fútbol 9" <photos <photo width="600" height="400" filename="foto1.jpg" / <photo width="600" height="400" filename="foto2.jpg" / <photo width="600" height="400" filename="foto3.jpg" / </photos </album <album name="Fútbol 8" <photos <photo width="600" height="400" filename="foto4.jpg" / <photo width="600" height="400" filename="foto5.jpg" / <photo width="600" height="400" filename="foto6.jpg" / </photos </album </albums </gallery

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  • Initializing objects on the fly

    - by pocoa
    I have a vector called players and a class called Player. And what I'm trying to do is to write: players.push_back(Player(name, Weapon(bullets))); So I want to be able to create players in a loop. But I see an error message says "no matching function for call Player::Player..." Then I've changed that to: Weapon w(bullets); Player p(name, w); players.push_back(p); Here is my Player definition: class Player { public: Player(string &name, Weapon &weapon); private string name; Weapon weapon; } I'm just trying to learn what is the difference between these definitions. And is this the right way to pass an object to an object constructor. Note: These are not my actual class definitions. I'm just trying to learn something about object oriented programming in C++ with coding it. I mean I know that Weapon should be initialized in Player :)

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  • How to merge objects in php ?

    - by The Devil
    Hey everybody, I'm currently re-writing a class which handles xml files. Depending on the xml file and it's structure I sometimes need to merge objects. Lets say once I have this: <page name="a title"/> And another time I have this: <page name="a title"> <permission>administrator</permission> </page> Before, I needed only the attributes from the "page" element. That's why a lot of my code expects an object containing only the attributes ($loadedXml-attributes()). Now there are xml files in which the <permission> element is required. I did manage to merge the objects (though not as I wanted) but I can't get to access one of them (most probably it's something I'm missing). To merge my objects I used this code: (object) array_merge( (array) $loadedXml->attributes(), (array) $loadedXml->children() ); This is what I get from print_r(): stdClass Object ( [@attributes] => Array ( [name] => a title ) [permission] => Array ( [0] => administrator ) ) So now my question is how to access the @attributes method ? Thanks in advance, The Devil

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  • c# creating a database query METHOD

    - by Sinaesthetic
    I'm not sure if im delluded but what I would like to do is create a method that will return the results of a query, so that i can reuse the connection code. As i understand it, a query returns an object but how do i pass that object back? I want to send the query into the method as a string argument, and have it return the results so that I can use them. Here's what i have which was a stab in the dark, it obviously doesn't work. This example is me trying to populate a listbox with the results of a query; the sheet name is Employees and the field/column is name. The error i get is "Complex DataBinding accepts as a data source either an IList or an IListSource.". any ideas? public Form1() { InitializeComponent(); openFileDialog1.ShowDialog(); openedFile = openFileDialog1.FileName; lbxEmployeeNames.DataSource = Query("Select [name] FROM [Employees$]"); } public object Query(string sql) { System.Data.OleDb.OleDbConnection MyConnection; System.Data.OleDb.OleDbCommand myCommand = new System.Data.OleDb.OleDbCommand(); string connectionPath; //build connection string connectionPath = "provider=Microsoft.Jet.OLEDB.4.0;Data Source='" + openedFile + "';Extended Properties=Excel 8.0;"; MyConnection = new System.Data.OleDb.OleDbConnection(connectionPath); MyConnection.Open(); myCommand.Connection = MyConnection; myCommand.CommandText = sql; return myCommand.ExecuteNonQuery(); }

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  • I cant put a string in a switch nor an array in a class

    - by TimothyTech
    Okay, im making a pretty big file in my opinion, so i wanted to separate it into several files for cleaner code. so i have my main .cpp file and two header files holding my classes. well the header files dont hold strings, it aboslutely wont budge. i call the library in both my .cpp file and even tried it in my header file. another issue i ran into is using strings to make switches function, reason being if i use integers in a switch if the user inputs a alphabetical character the program goes into an endless loop. string choice; switch (choice) { case "1" : //... break; case "2" : //... break; } and my last issue is when i create an object in a case it gives an error. says cross initialization of object. string choice; switch (choice) { case "1" : Class object; break; case "2" : //... break; }

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  • How To Delete objet whit mouse click ?

    - by Meko
    Hi all. I made a simple FlowChat Editor that creates rectangles and triangles and connect them each other and shows the way from up to down. I can move this elements on screen to .But I am tying to create button to delete element which I clicked. There is problem that I can delete mytriangle object but but I cant delete myRectangle objects.It deletes but not object which i clicked.I delete from first object to last ..Here my code ... if (deleteObj) { if (rectsList.size() != 0) { for (int i = 0; i < rectsList.size(); i++) { MyRect rect = (MyRect) rectsList.get(i); if (e.getX() <= rect.c.x + 50 && e.getX() >= rect.c.x - 50 && e.getY() <= rect.c.y + 15 && e.getY() >= rect.c.y - 15) { rectsList.remove(rect); System.out.println("This is REctangle DELETED\n"); } } } if (triangleList.size() != 0) { for (int j = 0; j < triangleList.size(); j++) { MyTriangle trian = (MyTriangle) triangleList.get(j); if (e.getX() <= trian.c.x + 20 && e.getX() >= trian.c.x - 20 && e.getY() <= trian.c.y + 20 && e.getY() >= trian.c.y - 20) { triangleList.remove(trian); System.out.println("This is Triangle Deleted\n"); } } }

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  • Sockets server design advice

    - by Rob
    We are writing a socket server in c# and need some advice on the design. Background: Clients (from mobile devices) connect to our server app and we leave their socket open so we can send data back down to them whenever we need to. The amount of data varies but we generally send/receive data from each client every few seconds, so it's quite intensive. The amount of simultaneous connections can range from 50-500 (and more in the future). We have already written a server app using async sockets and it works, however we've come across some stumbling blocks and we need to make sure that what we're doing is correct. We have a collection which holds our client states (we have no socket/connection pool at the moment, should we?). Each time a client connects we create a socket and then wait for them to send us some data and in receiveCallBack we add their clientstate object to our connections dictionary (once we have verified who they are). When a client object then signs off we shutdown their socket and then close it as well as remove them from our collection of clients dictionary. Presumably everything happens in the right order, everything works as expected. However, almost everyday it stops accepting connections, or so we think, either that or it connects but doesn't actually do anything past that and we can't work out why it's just stopping. There are few things that we'r'e unsure about 1) Should we be creating some kind of connection pool as opposed to just a dictionary of client sockets 2) What happens to the sockets that connect but then don't get added to our dictionary, they just linger around in memory doing nothing, should we create ANOTHER dictionary that holds the sockets as soon as they are created? 3) What's the best way of finding if clients are no longer connected? We've read some many methods but we're not sure of the best one to use, send data or read data, if so how? 4) If we loop through the connections dictonary to check for disposed clients, should we be locking the dictionary, if so how does this affect other clients objects trying to use it at the same time, will it throw an error or just wait? 5) We often get disposedSocketException within ReceiveCallBack method at random times, does this mean we are safe to remove that socket from the collection? We can't seem to find any production type examples which show any of this working. Any advice would be greatly received

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  • operator+ overload returning object causing memory leaks, C++

    - by lampshade
    The problem i think is with returing an object when i overload the + operator. I tried returning a reference to the object, but doing so does not fix the memory leak. I can comment out the two statements: dObj = dObj + dObj2; and cObj = cObj + cObj2; to free the program of memory leaks. Somehow, the problem is with returning an object after overloading the + operator. #include <iostream> #include <vld.h> using namespace std; class Animal { public : Animal() {}; virtual void eat() = 0 {}; virtual void walk() = 0 {}; }; class Dog : public Animal { public : Dog(const char * name, const char * gender, int age); Dog() : name(NULL), gender(NULL), age(0) {}; virtual ~Dog(); Dog operator+(const Dog &dObj); private : char * name; char * gender; int age; }; class MyClass { public : MyClass() : action(NULL) {}; void setInstance(Animal &newInstance); void doSomething(); private : Animal * action; }; Dog::Dog(const char * name, const char * gender, int age) : // allocating here, for data passed in ctor name(new char[strlen(name)+1]), gender(new char[strlen(gender)+1]), age(age) { if (name) { size_t length = strlen(name) +1; strcpy_s(this->name, length, name); } else name = NULL; if (gender) { size_t length = strlen(gender) +1; strcpy_s(this->gender, length, gender); } else gender = NULL; if (age) { this->age = age; } } Dog::~Dog() { delete name; delete gender; age = 0; } Dog Dog::operator+(const Dog &dObj) { Dog d; d.age = age + dObj.age; return d; } void MyClass::setInstance(Animal &newInstance) { action = &newInstance; } void MyClass::doSomething() { action->walk(); action->eat(); } int main() { MyClass mObj; Dog dObj("Scruffy", "Male", 4); // passing data into ctor Dog dObj2("Scooby", "Male", 6); mObj.setInstance(dObj); // set the instance specific to the object. mObj.doSomething(); // something happens based on which object is passed in dObj = dObj + dObj2; // invoke the operator+ return 0; }

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  • jQuery.extend() not giving deep copy of object formed by constructor

    - by two7s_clash
    I'm trying to use this to clone a complicated Object. The object in question has a property that is an array of other Objects, and each of these have properties of different types, mostly primitives, but a couple further Objects and Arrays. For example, an ellipsed version of what I am trying to clone: var asset = new Assets(); function Assets() { this.values = []; this.sectionObj = Section; this.names = getNames; this.titles = getTitles; this.properties = getProperties; ... this.add = addAsset; function AssetObj(assetValues) { this.name = ""; this.title = ""; this.interface = ""; ... this.protected = false; this.standaloneProtected = true; ... this.chaptersFree = []; this.chaptersUnavailable = []; ... this.mediaOptions = { videoWidth: "", videoHeight: "", downloadMedia: true, downloadMediaExt: "zip" ... } this.chaptersAvailable = []; if (typeof assetValues == "undefined") { return; } for (var name in assetValues) { if (typeof assetValues[name] == "undefined") { this[name] = ""; } else { this[name] = assetValues[name]; } } ... function Asset() { return new AssetObj(); } ... function getProperties() { var propertiesArray = new Array(); for (var property in this.values[0]) { propertiesArray.push(property); } return propertiesArray; } ... function addAsset(assetValues) { var newValues; newValues = new AssetObj(assetValues); this.values.push(newValues); } } When I do var copiedAssets = $.extend(true, {}, assets); copiedAssets.values == [], while assets.values == [Object { name="section_intro", more...}, Object { name="select_textbook", more...}, Object { name="quiz", more...}, 11 more...] When I do var copiedAssets = $.extend( {}, assets); all copiedAssets.values.[X].properties are just pointers to the value in assets. What I want is a true deep copy all the way down. What am I missing? Do I need to write a custom extend function? If so, any recommended patterns?

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  • Unsure how to design JavaScript / jQuery functionality which uses XML to create HTML objects

    - by Jack Roscoe
    Hi, I'm using JavScript and jQuery to read an XML document and subsequently use the information from the XML to create HTML objects. The main 'C' nodes in the XML document all have a type attribute, and depending on the type I want to run a function which will create a new html object using the other attributes assigned to that particular 'C' node node. Currently, I have a for loop which extracts each 'C' node from the XML and also it's attributes (e.g. width, height, x, y). Also inside the for loop, I have an if statement which checks the 'type' attribute of the current 'C' node being processed, and depending on the type it will run a different function which will then create a new HTML object with the attributes which have been drawn from the XML. The problem is that there may be more than one 'C' node of the same type, so for example when I'm creating the function that will run when a 'C' node of 'type=1' is detected, I cannot use the 'var p = document.createElement('p')' because if a 'C' node of the same type comes up later in the loop it will clash and override that element with that variable that has just been created. I'm not really sure how to approach this? Here is my entire script. If you need me to elaborate on any parts please ask, I'm sure it's not written in the nicest possible way: var arrayIds = new Array(); $(document).ready(function(){ $.ajax({ type: "GET", url: "question.xml", dataType: "xml", success: function(xml) { $(xml).find("C").each(function(){ arrayIds.push($(this).attr('ID')); }); var svgTag = document.createElement('SVG'); // Create question type objects function ctyp3(x,y,width,height,baC) { alert('test'); var r = document.createElement('rect'); r.x = x; r.y = y; r.width = width; r.height = height; r.fillcolor = baC; svgTag.appendChild(r); } // Extract question data from XML var questions = []; for (j=0; j<arrayIds.length; j++) { $(xml).find("C[ID='" + arrayIds[j] + "']").each(function(){ // pass values questions[j] = { typ: $(this).attr('typ'), width: $(this).find("I").attr('wid'), height: $(this).find("I").attr('hei'), x: $(this).find("I").attr('x'), y: $(this).find("I").attr('x'), baC: $(this).find("I").attr('baC'), boC: $(this).find("I").attr('boC'), boW: $(this).find("I").attr('boW') } alert($(this).attr('typ')); if ($(this).attr('typ') == '3') { ctyp3(x,y,width,height,baC); // alert('pass'); } else { // Add here // alert('fail'); } }); } } }); });

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  • Object relationships

    - by Hammerstein
    This stems from a recent couple of posts I've made on events and memory management in general. I'm making a new question as I don't think the software I'm using has anything to do with the overall problem and I'm trying to understand a little more about how to properly manage things. This is ASP.NET. I've been trying to understand the needs for Dispose/Finalize over the past few days and believe that I've got to a stage where I'm pretty happy with when I should/shouldn't implement the Dispose/Finalize. 'If I have members that implement IDisposable, put explicit calls to their dispose in my dispose method' seems to be my understanding. So, now I'm thinking maybe my understanding of object lifetimes and what holds on to what is just wrong! Rather than come up with some sample code that I think will illustrate my point, I'm going to describe as best I can actual code and see if someone can talk me through it. So, I have a repository class, in it I have a DataContext that I create when the repository is created. I implement IDisposable, and when my calling object is done, I call Dispose on my repository and explicitly call DataContext.Dispose( ). Now, one of the methods of this class creates and returns a list of objects that's handed back to my front end. Front End - Controller - Repository - Controller - Front End. (Using Redgate Memory Profiler, I take a snapshot of my software when the page is first loaded). My front end creates a controller object on page load and then makes a request to the repository sending back a list of items. When the page is finished loading, I call Dispose on the controller which in turn calls dispose on the context. In my mind, that should mean that my connection is closed and that I have no instances of my controller class. If I then refresh the page, it jumps to two 'Live' instances of the controller class. If I look at the object retention graph, the objects I created in my call to the list are being held onto ultimately by what looks like Linq. The controller/repository aside, if I create a list of objects somewhere, or I create an object and return it somewhere, am I safe to just assume that .NET will eventually come and clean things up for me or is there a best practice? The 'Live' instances suggest to me that these are still in memory and active objects, the fact that RMP apparently forces GC doesn't mean anything?

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