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  • C# DDD Populate Immutable Objects

    - by Russel
    Hi I have a immutable Customer class in my domain assembly. It contains the following GET properties : id, firstname and lastname. I have a CustomerRepository class in my persistence assembly. In turn, this CustomerRepository class should populate and return a Customer object using a remote web-serivce. My Customer class contains no setter properties and it contains a private constructor. The reason - I dont want the UI developer to get the wrong idea - He should not be able to create or change a Customer object. My question: How do I get my CustomerRepository to populate my Customer object. Reflection? Or should I sacrifice my design and enable a public constructor for constructing the customer object?

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  • Why does the use of interface-based programming appear to be limited to behaviour?

    - by Carnotaurus
    I have been doing a little thinking about inheritance vs. realization vs. composition. I am not about to post the whole detail here. So I was wondering, when are not talking about supporting unit testing: Why does interface-based programming seem to focus upon the grouping of common behaviour, e.g., IPettable (for an animal), IEditable (for a user control), ISubmitable (for a form), etc. Why does the use of interface-based programming appear to be limited to behaviour when we could pragmatically group not so much on behaviour but on commonsense physical similarities which could have nothing to do with behaviour? It is not that there is some limiting feature within OOP; so how come?

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  • Cakephp, an elegant solution to quantities?

    - by Smickie
    Hi, I have a shopping cart system in Cakephp, this table has all your usual maguffins: user_ids, product_ids, option_lists ect. It also has quantity. I currently have some awful nested loops to check if the record is the same as any in there, if so add one to the quantity. If not add a new cart item. This loop has to check associated list items and product options, so it goes quite deep. What I'm wondering is if there is a more elegant way of checking to see if two cart items in a database are similar (everything except for quantity). Cheers!

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  • Single-Page Web Apps: Client-side datastores & server persistence

    - by fig-gnuton
    How should client-side datastores & persistence be handled in a single-page web application? Global vars vs. DI/IoC: Should datastores be assigned to global variables so any part of the application can access them? Or should they be dependency injected where required? Server persistence: Assuming a datastore's data needn't always be persisted to the server immediately, should the datastore itself handle persistence? If not, then what class should handle persistence and how should the persistence class fit into the client-side architecture overall? Is the datastore considered the model in MVC, or is it something else since it just stores raw data?

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  • Stuck with the math in a Flash project, would parsing engine help?

    - by VideoDnd
    I've been stuck with the math in a Flash project? It's a loose design pattern my director formulated. My goal is to keep the project object oriented, and get 'non Flash obstacles' off my plate. Do you recommend using parsing engines for processing math? XML values going to AS3, updating a changing acceleration formula. I don't hate math, but it just doesn't seem OOP or good project planning to have the math stuck in Flash. Your comments are welcome.

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  • How do I implement a DataGrid with an MVVM approach.

    - by Fred
    Hi, I'd like to implement a sort of Addressbook/Contactbook using a Datagrid (or a List) and the MVVM pattern. Something like in Outlook/Thunderbird, where you've a list of your contacts displayed with a 2-3 main fields (name surname for example), and when you double-click a contact, then you get a new modal box that displays all the details of this specific contact. Since a couple of weeks/months, I'm reading a lot of stuff about MVVM pattern on the net, but somehow, I get confused. Until now, I could find any sample like this. (perhaps, I searched wrong?) How could I organize such an application? Thx in advance for your help.

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  • Having trouble understanding some code (Ruby on Rails)

    - by user284194
    I posted a question awhile ago asking how I could limit the rate at which a form could be submitted from a rails application. I was helped by a very patient user and their solution works great. The code was for my comments controller, and now I find myself wanting to add this functionality to another controller, my Messages controller. I immediately tried reusing the working code from the comments controller but I couldn't get it to work. Instead of asking for the working code, could someone please help me understand my working comment controller code? class CommentsController < ApplicationController #... before_filter :post_check def record_post_time cookies[:last_post_at] = Time.now.to_i end def last_post_time Time.at((cookies[:last_post_at].to_i rescue 0)) end MIN_POST_TIME = 2.minutes def post_check return true if (Time.now - last_post_time) > MIN_POST_TIME flash[:warning] = "You are trying to reply too fast." @message = Message.find(params[:message_id]) redirect_to(@message) return false end #... def create @message = Message.find(params[:message_id]) @comment = @message.comments.build(params[:comment]) if @comment.save record_post_time flash[:notice] = "Replied to \"#{@message.title}\"" redirect_to(@message) else render :action => "new" end end def update @message = Message.find(params[:message_id]) @comment = Comment.find(params[:id]) if @comment.update_attributes(params[:comment]) record_post_time redirect_to post_comment_url(@message, @comment) else render :action => "edit" end end #... end My Messages controller is pretty much a standard rails generated controller with a few before filters and associated private methods for DRYing up the code and a redirect for non existent pages. I'll explain how much of the code I understand. When a comment is created, a cookie is created with a last_post_time value. If they try to post another comment, the cookie is checked if the last one was made in the last two minutes. If it was a flash warning is displayed and no comment is recorded. What I don't really understand is how the post_check method works and how I can adapt it for my simpler posts controller. I thought I could reuse all the code in the message controller with the exception of the line: @message = Message.find(params[:message_id]) # (don't need the redirect code) in the post_check method. But it trips up on the "record_post_time" in the create action/method. I really want to understand this. Can someone explain why this doesn't work? I greatly appreciate you reading my lengthy question.

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  • Is foreign key reference from two different primary key from two different tables valid?

    - by arundex
    I have a foreign key that has to refer primary keys of two different tables. Table 1: animal animal_ id (primary key) Table 2: bird bird_ id (primary key) Table 3: Pet_info pet_id, type ENUM ('bird', 'animal') foreign key (pet_ id) references animal(animal_id), bird(bird_id) So, I need to check for pet_id either from animal or bird table depending on the need. Is this valid? Or should I go for some restructuring . . . NOTE: I referred this . . but I'm not sure whether I have to change my existing design

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  • What is the MVC version of this code?

    - by Ian Boyd
    i'm trying to wrap my head around how to enterprise up my code: taking a simple routine and splitting it up into 5 or 6 methods in 3 or 4 classes. i quickly came up three simple examples of code how i currently write it. Could someone please convert these into an MVC/MVP obfuscated version? Example 1: The last name is mandatory. Color the text box red if nothing is entered. Color it green if stuff is entered: private void txtLastname_TextChanged(object sender, EventArgs e) { //Lastname mandatory. //Color pinkish if nothing entered. Greenish if entered. if (txtLastname.Text.Trim() == "") { //Lastname is required, color pinkish txtLastname.BackColor = ControlBad; } else { //Lastname entered, remove the coloring txtLastname.BackColor = ControlGood; } } Example 2: The first name is optional, but try to get it. We'll add a bluish tint to this "try to get" field: private void txtFirstname_TextChanged(object sender, EventArgs e) { //Firstname can be blank. //Hint them that they should *try* to get it with a bluish color. //If they do enter stuff: it better be not all spaces. if (txtFirstname.Text == "") { //Nothing there, hint it blue txtFirstname.BackColor = ControlRequired; } else if (txtFirstname.Text.Trim() == "") { //They entered spaces - bad user! txtFirstname.BackColor = ControlBad; } else { //Entered stuff, remove coloring txtFirstname.BackColor = SystemColors.Window; } } Example 3 The age is totally optional. If an age is entered, it better be valid: private void txtAge_TextChanged(object sender, EventArgs e) { //Age is optional, but if entered it better be valid int nAge = 0; if (Int32.TryParse(txtAge.Text, out nAge)) { //Valid integer entered if (nAge < 0) { //Negative age? i don't think so txtAge.BackColor = ControlBad; } else { //Valid age entered, remove coloring txtAge.BackColor = SystemColors.Window; } } else { //Whatever is in there: it's *not* a valid integer, if (txtAge.Text == "") { //Blank is okay txtAge.BackColor = SystemColors.Window; } else { //Not a valid age, bad user txtAge.BackColor = ControlBad; } } } Every time i see MVC code, it looks almost like random splitting of code into different methods, classes, and files. i've not been able to determine a reason or pattern to their madness. Without any understanding of they why it's being one some way, it makes no sense. And using the words model, view, controller and presenter, like i'm supposed to know what that means, doesn't help. The model is your data. The view shows data on screen. The controller is used to carry out the users actions And oranges taste orangy. Here's my attempt at splitting things up in order to make the code more difficult to follow. Is this anywhere close to MVC? private void txtFirstname_TextChanged(object sender, EventArgs e) { FirstnameTextChangedHandler(sender, e); } private void FirstnameTextChangedHandler(sender, e) { string firstname = GetFirstname(); Color firstnameTextBoxColor = GetFirstnameTextBoxColor(firstname); SetFirstNameTextBoxColor(firstnameTextBoxColor); } private string GetFirstname() { return txtFirstname.Text; } private Color GetFirstnameTextBoxColor(string firstname) { //Firstname can be blank. //Hint them that they should *try* to get it with a bluish color. //If they do enter stuff: it better be not all spaces. if (firstname == "") { //Nothing there, hint it blue return GetControlRequiredColor(); } else if (firstname.Trim() == "") { //They entered spaces - bad user! return GetControlBadColor(); } else { //Entered stuff, remove coloring return GetControlDefaultColor(); } } private Color GetControlRequiredColor() { return ControlRequired; } private Color GetControlBadColor() { return ControlBad; } private Color GetControlGoodColor() { return ControlGood; } //am i doin it rite i've obfuscated the code, but it's still altogether. The next step in the MVC obfuscation, i gather, is to hide the code in 3 or 4 different files. It's that next step that i don't understand. What is the logical separation of which functions are moved into what other classes? Can someone translate my 3 simple examples above into full fledged MVC obfuscation? Edit: Not ASP/ASP.NET/Online. Pretend it's on a desktop, handheld, surface, kiosk. And pretend it's language agnostic.

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  • How the swing's BoxModel works ?

    - by sasquatch90
    Let's say I would like to create a simple calculator. It consists of 3 fields. Text field to show result, field with checkboxes to select system and field with numbers. What kind of component should I use for each element ? How can I position elements in my window ? How can I position elements inside component (ie checkboxes) ? This is what I'm trying to achieve. http://img28.imageshack.us/img28/7691/lab8c.jpg

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  • Stored Procedure or calculations via IQueryable?

    - by Shawn Mclean
    This is a question that is based on choosing performance over design practices. If I have a method that will be executed many times a second; public static IQueryable<IPerson> InRadius(this IQueryable<IPerson> query, Coordinate center, double radius) { return (from u in query where CallHeavyMathFormula(u, center, radius) select u); } This extension method for IQueryable generates a SQL that does some heavy maths calculation (Cosine, Sine, etc). This would mean the application sends 1-2KB of sql to the server per call. I've heard of placing all application logic, in your application. I also would like to change to a database such as azure or one of those scalable databases in the future. How do I handle something like this? Should I leave it as it is now or write stored procedures? How do applications like twitter or facebook do it?

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  • Should I dive into ASP.NET MVC or start with ASP.NET Webforms?

    - by Sahat
    I plan to pick up Silverlight in the future. Possibility of going into Microsoft WPF. Currently learning Objective-C 2.0 w/ Cocoa. I already know Pros and Cons of ASP.NET MVC vs ASP.NET Webforms. What I want to know is what would be more "efficient" for me to learn given the circumstances above? By efficient I mean learning one design pattern once and then re-using it. Objective-C I believe uses MVC approach? What about Silverlight? WPF? So what do you think? Also as a side question is it true that ASP.NET Webforms is often used by freelancers/small companies and ASP.NET MVC in large enterprises?

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  • Session State Anti-Pattern

    - by Curiosity
    I know the SOLID principles and other design patterns fairly well and have been programming for some time now - seeing many a bit of code throughout the years. Having said that, I'm having trouble coming up with a name to give the pattern, or lack thereof, to bits of code I've been dealing with at a current engagement. The application is an ASP.NET C# WebForms application, backed by a SQL Server/Mainframe backend (more mainframe than backend) and it's riddled with Session State properties being accessed/mutated from multiple pages/classes. Accessing/mutating global variables/application state was usually shunned upon while I was in school. Apparently the creators of this magnificent application didn't think it was such a bad idea. Question: Is there a name for such a pattern/anti-pattern that relies so heavily on Session State? I'd like to call the pig by its name ...

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  • Full stack framework for Java

    - by Jonathan Barbero
    Hello everyone, I'm looking for a full stack framework (from persistency to view generation (CRUD)) for Java. I don't have experience with Rails style frameworks, like Grails, but I worked a lot with Hibernate, Struts, Spring ... I prefer a framework that let you naturally modify the business domain design with the less effort ( i.e. writing the sql querys to modify the tables and constrains, change the view pages, etc ... ). I was looking a bit about this topic, I saw Naked Objects for example but its development has stopped. So, I want to hear about your experience. Thanks in advance.

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  • How can CopyOnWriteArrayList be thread-safe?

    - by Shooshpanchick
    I've taken a look into OpenJDK's sources of CopyOnWriteArrayList and it seems that all write operations are protected by the same lock and read operations are not protected at all. As I understand, under JMM all accesses to a variable (both read and write) should be protected by lock or reordering effects may occur. For example, set(int, E) method contains these lines (under lock): /* 1 */ int len = elements.length; /* 2 */ Object[] newElements = Arrays.copyOf(elements, len); /* 3 */ newElements[index] = element; /* 4 */ setArray(newElements); The get(int) method, on the other hand, only does return get(getArray(), index);. In my understanding of JMM, this means that get may observe the array in an inconsistent state if statements 1-4 are reordered like 1-2(new)-4-2(copyOf)-3. Do I understand JMM incorrectly or is there any other explanations on why CopyOnWriteArrayList is thread-safe?

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  • ado.net data entity problem

    - by ognjenb
    I have this error Cannot implicitly convert type 'System.Linq.IQueryable' to 'Mvc.Models.engineer'. An explicit conversion exists (are you missing a cast?) after write this code engineer Ing = new engineer(); Ing = from j in testPersons.ibekoengineer select j.Name; What is wrong?

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  • Books on data-intensive enterprise integration patterns

    - by Tristan
    I'm trying to understand design patterns used by data-intensive enterprise applications. A classic example is the financial industry, where system must consume, analyze, and execute on real-time financial data while providing information and configuration options to a broad set of traders and analysts. One can imagine similar system in airlines, major supply chain operations, and utility providers. Are there good books that provide and inside view of how these systems work? Enterprise Integration Patterns is one example, but I'm looking for something with more real-world applications, particularly in finance.

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  • Is there anything like Zope Page Templates for Ruby on Rails?

    - by dan
    I have a Ruby on Rails app that I built myself, but which needs a redesign by a professional designer. I know most designers just give you Photoshop mockups and slices, but I would like to hire someone to implement the design as well, which means rewriting the css style sheets and the erb and haml templates. The problem is that I want someone else to implement the redesign without exposing my business logic code to the redesign implementer. Also, I wish there was a way to allow a designer to implement a redesign on a Ruby on Rails site without having to know anything about Ruby on Rails. Are either of these scenarios possible using any combination of software tools? I guess I'm looking for something like Zope Page Templates, but for Ruby on Rails. http://quintagroup.com/cms/zpthttp://quintagroup.com/cms/zpt

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  • I have to generate PL/SQL using Java. Most of the procedures are common. Only a few keeps changing.

    - by blog
    I have to generate PL-SQL code, with some common code(invariable) and a variable code. I don't want to use any external tools. Some ways that I can think: Can I go and maintain the common code in a template and with markers, where my java code will generate code in the markers and generate a new file. Maintain the common code in static constant String and then generate the whole code in StringBuffer and at last write to file. But, I am not at all satisfied with both the ideas. Can you please suggest any better ways of doing this or the use of any design patterns or anything? Thanks in Advance.

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  • Using Remote Web Page to Initialize iPhone App

    - by Chris_K
    My iPhone app relies on a vendor's XML feed to provide data. But that feed is not locked down. The vendor could change the format of the XML at any time, although so far they've promised not to. Since I might want to tell my app to use a different URL for its data source, I'd like to set up a single "Command Central" Web page, on my own server, to direct the app to the correct data source. In other words, each time my app starts, in the background and unseen by the user, it would visit "http://www.myserver.com/iphoneapp_data_sources.xml" to retrieve the URL for retrieving data from my vendor. That way, if my vendor suddenly changes the exact URL or the XML feed that the app needs, I can update that Web page and ensure that all installations of the app are using the correct XML feed. Does anyone have any advice or examples showing this kind of approach? It seems as if this must be a common problem, but so far I haven't found a well-established design pattern that fits it.

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  • the News Feed technique

    - by Rawhi
    I have been read a lot of articles to make a good design for my database so I can get the most recent updates for every single user by executing a - kind of - complex query then I send the data using ajax as a JSON to JS file that makes an appropriate edits for the records. It seems fast but I don't know if it will be as much as fast if the site has a large number of users . so iv'e started looking for an alternatives . and I found something called NodeJS , I really didn't understand what it is stand for and hope that you can help me with that. from another hand if the facebook doesn't use a normal db to do whatever he does , then I think there is no way to do it . helpful link : What's the best manner of implementing a social activity stream? waiting for your comments. best regards

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  • Securing input of private / protected methods?

    - by ts
    Hello, normally, all sane developers are trying to secure input of all public methods (casting to proper types, validating, sanitizing etc.) My question is: are you in your code validating also parameters passed to protected / private methods? In my opinion it is not necessary, if you securize properly parameters of public methods and return values from outside (other classes, db, user input etc...). But I am constantly facing frameworks and apps (ie. prestashop to name one) where validation is often repeated in method call, in method body and once again for securize returned value - which, I think, is creating performace overhead and is also a sign of bad design.

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  • How do I insert data into a object relational table with multiple ref in the schema.

    - by Yiling
    I have a table with a schema of Table(number, ref, ref, varchar2, varchar2,...). How would I insert a row of data into this table? When I do: "insert into table values (1, select ref(p), ref(d), '239 F.3d 1343', '35 USC § 283', ... from plaintiff p, defendant d where p.name='name1' and d.name='name2');" I get a "missing expression" error. If I do: "insert into table 1, select ref(p), ref(d), ... from plaintiff p, defendant where p.name=...;" I get a "missing keyword VALUES" error.

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  • Windows Phone: Updating backend datastore (via web service) while keeping UI very responsive

    - by will
    I am developing a Windows Phone app where users can update a list. Each update, delete, add etc need to be stored in a database that sits behind a web service. As well as ensuring all the operations made on the phone end up in the cloud, I need to make sure the app is really responsive and the user doesn’t feel any lag time whatsoever. What’s the best design to use here? Each check box change, each text box edit fires a new thread to contact the web service? Locally store a list of things that need to be updated then send to the server in batch every so often (what about the back button)? Am I missing another even easier implementation? Thanks in advance,

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