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  • Javascript object encapsulation that tracks changes

    - by Raynos
    Is it possible to create an object container where changes can be tracked Said object is a complex nested object of data. (compliant with JSON). The wrapper allows you to get the object, and save changes, without specifically stating what the changes are Does there exist a design pattern for this kind of encapsulation Deep cloning is not an option since I'm trying to write a wrapper like this to avoid doing just that. The solution of serialization should only be considered if there are no other solutions. An example of use would be var foo = state.get(); // change state state.update(); // or state.save(); client.tell(state.recentChange()); A jsfiddle snippet might help : http://jsfiddle.net/Raynos/kzKEp/ It seems like implementing an internal hash to keep track of changes is the best option. [Edit] To clarify this is actaully done on node.js on the server. The only thing that changes is that the solution can be specific to the V8 implementation.

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  • Class architecture, no friends allowed

    - by Captain Comic
    The question of why there are no friends in C# has been extensively discussed. I have the following design problems. I have a class that has only one public function AddOrder(Order ord). Clients are allowed to call only this function. All other logic must be hidden. Order class is listening to market events and must call other other function of TradingSystem ExecuteOrder, so I have to make it public as well. Doing that I will allow clients of Trading system to call this function and I don't want that. class TradingSystem { // Trading system stores list of orders List<Order> _orders; // this function is made public so that Order can call ir public ExecuteOrder(Order ord) { } // this function is made public for external clients public AddOrder(OrderRequest ordreq) { // create order and pass it this order.OnOrderAdded(this); } } class Order { TradingSystem _ts; public void OnOrderAdded(TradingSystem ts) { _ts = ts; } void OnMarketEvent() { _ts.ExecuteOrder() } }

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  • MVC4 not binding a list of basic types

    - by admanb
    I cannot, for the life of me, get this data to bind. Here's my JavaScript: var params = { 'InvItemIDs': ["188475", "188490"]}; $.post("api/Orders/OrderFromInventory?" + $.param(params)) and the Controller action: public HttpResponseMessage OrderFromInventory(IList<int> InvItemIDs) { return new HttpResponseMessage(); } I've built the query string so that it's sending: ?InvItemIDs=188475&InvItemIDs=188490 as well as ?InvItemIDs[]=188475&InvItemIDs[]=188490 and even ?InvItemIDs[0]=188475&InvItemIDs[1]=188490 and none of them are binding. InvItemIDs is always null. What am I doing wrong? EDIT: So it turns out all this is a bug (or something) in the new Web API controller code in MVC4. As soon as I moved the exact same code over to a standard controller it started working. I'm still interested if anyone has any insight as to why the Web API would break this binding.

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  • mvc - how to avoid log out when refresh a page

    - by user235973457
    I have built the MVC application with WCF service. The major problem I have experienced with refreshing page. I have created a login page with session (username and password). But when you refresh the home page by pressing F5, it would automatically log out. That is my problem. I need to stay the home page after refresh. I have been googling around to find a solution but it seems not helpful. Any idea? Your advise or code example much appreciated.

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  • Refactoring thick client legacy application

    - by Paul
    I am working on a fat client legacy C++ application which has a lot of business logic mixed in with the presentation side of things. I want to clean things out and refactor the code out completely, so there is a clear seperation of concerns. I am looking at MVC or some other suitable design pattern in order to achieve this. I would like to get recommendations from people who have walked this road before - Do I use MVP or MVC (or another pattern)? What is/are the best practices for undertaking something like this (i.e. useful steps/checks) ?

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  • Separating data from the UI code with Linq to SQL entities

    - by Sir Psycho
    If it's important to keep data access 'away' from business and presentation layers, what alternatives or approaches can I take so that my LINQ to SQL entities can stay in the data access layer? So far I seem to be simply duplicating the classes produced by sqlmetal, and passing those object around instead simply to keep the two layers appart. For example, I have a table in my DB called Books. If a user is creating a new book via the UI, the Book class generated by sqlmetal seems like a perfect fit although I'm tightly coupling my design by doing so.

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  • Improve SQL strategy - denormalize in object-children-images case

    - by fesja
    Hi, I have a Tour object which has many Place objects. For the list of tours, I want to show some info of the tour, the number of places of the tour, and three Place's images. Right one my SQL queries are (i'm using Doctrine with Symfony on MySQL) get Tour get Tour 1 places get Tour 2 places get Tour 3 places ... get Tour n places If I have a three Tour list, it's not so bad; but I'm sure it can get bad if I do a 10-20 tour-list. So, thinking on how to improve the queries I've thought of several measures: Having a place count cache Storing the urls of three images on a new tour field. The problem with 2. is that if I change the image, I have to check all the tours to update that image for another one. What solution do you think is best to scale the system in a near future? Any other suggestion. thanks!

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  • What's wrong with the architecture of a game object drawing and updating itself?

    - by Ricket
    What are the reasons for and against a game object drawing and updating itself? For example, if you have a game where the player has a position on screen, why not have an all-encompassing class: public class Player { private int x, y, xVelocity, yVelocity; private Sprite s; //... public Player() { // load the sprite here, somehow? } public void draw(CustomGraphicsClass g) { g.draw(s, x, y); } public void update(long timeElapsed) { x += (xVelocity * timeElapsed); y += (yVelocity * timeElapsed); } } What is wrong with this design? What are the downfalls or concerns? How would you better write something like this, or better architect this type of thing in a game? Also, somewhat connected, how would you implement loading that Sprite image? And furthermore, how would you then implement collision between two Players? (I should probably separate these extra two questions into new questions, huh?)

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  • Creating objects and referencing before saving object to db

    - by Flexo
    Sorry about the vague title, but i didnt know how to ask the question in one line :) I have an order with nested itemgroups that again have nested items. the user specify the amount of item that he would like to have in each itemgroup. I would like to create these items in the create method of the orders controller when the order itself is being created. I kinda have 2 problems here. First, how do i set the reference of the items, or better yet, put the items into the @order object so they are saved when the @order is saved? the items are being stored in the db as the code is now, but the reference is not set because the order is not stored in the db yet so it doesnt have an id yet. Second, im not sure im using the correct way to get the id from my itemgroup. @order = Order.new(params[:order]) @order.itemgroups.each do |f| f.amount.times do @item = Item.new() @item.itemgroup_id = f.id @item.save end end

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  • Tool to maintain a Data Mapping between two systems

    - by ktaylorjohn
    We have XML interfaces between multiple systems. An Enterprise Domain Model is missing in the overall architecture, hence the terms Product/Customer/User means different things to different systems. We currently use excel sheets to map the elements in incoming XML to what the actual Field means within our system. Additionally, it contains the values of Mandatory/Optional and length of each field. We call this the Data Dictionary. Any changes to the XML go through rounds of deliberation and updates to Word and Excel documents. Is there a better way to do this? Any tool/GUI based approach which all systems and owners can view?

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  • benefit os having a factory for object creation?

    - by ajsie
    im trying to understand the factory design pattern. i dont understand why it's good to have a middleman between the client and the product (object that the client wants). example with no factory: $mac = new Mac(); example with a factory: $appleStore = new AppleStore(); $mac = $appleStore->getProduct('mac'); how does the factory pattern decouple the client from the product? could someone give an example of a future code change that will impact on example 1 negative, but positive in example 2 so i understand the importance of decoupling? thanks

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  • Interpreters: Handling includes/imports

    - by sub
    I've built an interpreter in C++ and everything works fine so far, but now I'm getting stuck with the design of the import/include/however you want to call it function. I thought about the following: Handling includes in the tokenizing process: When there is an include found in the code, the tokenizing function is recursively called with the filename specified. The tokenized code of the included file is then added to the prior position of the include. Disadvantages: No conditional includes(!) Handling includes during the interpreting process: I don't know how. All I know is that PHP must do it this way as conditional includes are possible. Now my questions: What should I do about includes? How do modern interpreters (Python/Ruby) handle this? Do they allow conditional includes?

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  • Very basic database theory.

    - by John R
    I have a set of tables to show the relationship between organziations and supporters below. Although I have done some basic mySQL querries, I know very little about database 'design'. I plan to querry the database for: -a list of contributors to a specific organization... or, -a list of organizations that a specific suporter supports. The database tables for organiations and contributors may have other columns in the future and recieve a lesser amount of querries based on that information. A | X A | Y A | Z B | X B | Y C | X C | Z How should the tables be set up? I assume that there should be a third table, but there is still redundent information in the third table. Is there a better way of setting up the tables? +----+-------+ +-------------+----------+ +----+-------+ | id | org | | org | contr | | id | contr.| +----+-------+ +-------------+----------+ +----+-------+ | 1 | A | | 1 | 1 | | 1 | X | | 2 | B | | 1 | 2 | | 2 | Y | | 3 | C | | 1 | 3 | | 3 | Z | +----+-------+ | 2 | 1 | +----+-------+ | 2 | 2 | | 3 | 1 | | 3 | 3 | +-------------+----------+

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  • Magento, 1 db field not saved

    - by david parloir
    Hi there, I have a problem with 1 field of the db. With this code: $expireMonth = Mage::getStoreConfig('points_options/config_points/expiration_period', Mage::app()->getStore()->getId()); if (!is_null($expireMonth) && ($expireMonth > 0)) { $expireDate = date("Y-m-d H:i:s", strtotime("+" . $expireMonth . " month")); } else { $expireDate = NULL; } //die($expireDate); //store in points history table $this->_pointsModel->setCustomerId($this->_customer->getId()) ->setOrdersId('welcome') ->setPointsPending($pointsForNewCustomer) ->setPointsComment(Mage::helper('points')->__('welcome points')) ->setDateAdded(date('Y-m-d H:i:s')) ->setPointsStatus(2)//confirmed ->setPointsType('WE') ->setStoreId(Mage::app()->getStore()->getId()) ->setExpireDate($expireDate) ->save(); every field is saved in the table, except for expire_date. If I uncoment the die($expireData), I see the correct value, something like 2012-01-13 13:21:12. The filed is defined as: `expire_date` datetime NULL Any thaughts? edit: the solution is: $expireDate = date("Y-m-d H:i:s", strtotime("+" . $expireMonth . " months")); check out the "s" in my strtotime expression

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  • How do you plan for starting a new web system?

    - by Kerry
    I've been creating more and more systems recently and I find more and more planning and preparation I do before starting the project. I determine what libraries or frameworks I will be using, what languages, the basic architecture of how the site will flow, etc. I've also heard of other design processes such as hanging styrofoam balls to show where classes are and how they relate, which is a process I've never heard of nor do I know how it works. Is there any software that helps with this process? Are there any guidelines or steps or do you have a recommended set of steps or guidelines that you follow when designing a new project?

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  • How to handle request/response propagation up and down a widget hierarchy in a GUI app?

    - by fig-gnuton
    Given a GUI application where widgets can be composed of other widgets: If the user triggers an event resulting in a lower level widget needing data from a model, what's the cleanest way to be able to send that request to a controller (or the datastore itself)? And subsequently get the response back to that widget? Presumably one wouldn't want the controller or datastore to be a singleton directly available to all levels of widgets, or is this an acceptable use of singleton? Or should a top level controller be injected as a dependency through a widget hierarchy, as far down as the lowest level widget that might need that controller? Or a different approach entirely?

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  • Why and How to avoid Event Handler memory leaks ?

    - by gillyb
    Hey There, I just came to realize, by reading some questions and answers on StackOverflow, that adding event handlers using += in C# (or i guess, other .net languages) can cause common memory leaks... I have used event handlers like this in the past many times, and never realized that they can cause, or have caused, memory leaks in my applications. How does this work (meaning, why does this actually cause a memory leak) ? How can I fix this problem ? Is using -= to the same event handler enough ? Are there common design patterns or best practices for handling situations like this ? Example : How am I supposed to handle an application that has many different threads, using many different event handlers to raise several events on the UI ? Are there any good and simple ways to monitor this efficiently in an already built big application ? Thanks in advance!

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  • Sequencing ajax requests

    - by Scott Evernden
    I find I sometimes need to iterate some collection and make an ajax call for each element. I want each call to return before moving to the next element so that I don't blast the server with requests - which often leads to other issues. And I don't want to set async to false and freeze the browser. Usually this involves setting up some kind of iterator context that i step thru upon each success callback. I think there must be a cleaner simpler way? Does anyone have a clever design pattern for how to neatly work thru a collection making ajax calls for each item?

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  • How can I get a property as an Entity in Action of Asp.Net Mvc ?

    - by Felipe
    Hi all, i'd like to know how can I get a property like an entity, for example: My Model: public class Product { public int Id { get; set; } public string Name { get; set; } public Category Category { get; set; } } View: Name: <%=Html.TextBoxFor(x => x.Name) %> Category: <%= Html.DropDownList("Category", IEnumerable<SelectListItem>)ViewData["Categories"]) %> Controller: public ActionResult Save(Product product) { /// produtct.Category ??? } and how is the category property ? It's fill by the view ? ASP.Net MVC know how to fill this object by ID ? Thanks!

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  • Designing Relational Survey Questionnaires Database

    - by user1213055
    I'm trying to build a simple sql database for following access database. Currently there is no relationship and I just have two tables male and female with 6 sections in each form. How can I design it a better way so end user can connect to the database and analyze using STATA or SPSS ? I'm really confused whether I should create one table with all fields or break down into different tables. The database is specific to this study only so I'm not looking for a generic survey database where user can create surveys and capture them. Any feedback or suggestion is much appreciated.

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  • How do I manipulate a tree of immutable objects?

    - by Frederik
    I'm building an entire application out of immutable objects so that multi-threading and undo become easier to implement. I'm using the Google Collections Library which provides immutable versions of Map, List, and Set. My application model looks like a tree: Scene is a top-level object that contains a reference to a root Node. Each Node can contain child Nodes and Ports. An object graph might look like this: Scene | +-- Node | +-- Node | +- Port +-- Node | +- Port +- Port If all of these objects are immutable, controlled by a top-level SceneController object: What is the best way to construct this hierarchy? How would I replace an object that is arbitrarily deep in the object tree? Is there a way to support back-links, e.g. a Node having a "parent" attribute?

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  • SQL Server concurrency and generated sequence

    - by Goyuix
    I need a sequence of numbers for an application, and I am hoping to leverage the abilities of SQL Server to do it. I have created the following table and procedure (in SQL Server 2005): CREATE TABLE sequences ( seq_name varchar(50) NOT NULL, seq_value int NOT NULL ) CREATE PROCEDURE nextval @seq_name varchar(50) AS BEGIN DECLARE @seq_value INT SET @seq_value = -1 UPDATE sequences SET @seq_value = seq_value = seq_value + 1 WHERE seq_name = @seq_name RETURN @seq_value END I am a little concerned that without locking the table/row another request could happen concurrently and end up returning the same number to another thread or client. This would be very bad obviously. Is this design safe in this regard? Is there something I can add that would add the necessary locking to make it safe? Note: I am aware of IDENTITY inserts in SQL Server - and that is not what I am looking for this in particular case. Specifically, I don't want to be inserting/deleting rows. This is basically to have a central table that manages the sequential number generator for a bunch of sequences.

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