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  • What makes a bad programming language bad?

    - by sub
    We have all seen things like the typing system of JavaScript (There is a funny post including a truth table somewhere around here). I consider this one of the main things that makes a programming language bad. Other things that spring to mind: Bad Error messages (Either obfuscated so you can't figure out whats wrong, not existing or simply too long and red) The language wasn't planned and just grew uncontrolled in all directions (PHP?) The language encourages bad programm(er/ing) habits such as: Global variables everywhere, bad variable names Inconsistent naming conventions inside the language I can't come up with any more at the moment and would be very happy to read what you think about this. What shouldn't be missing in a language created to be as bad (from the perspectives of the programmer, the company that hires to programmer, the team leader and the customer) as possible? (I ask this because I'm designing a bad, experimental language at the moment)

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  • GRAPH PROBLEM: find an algorithm to determine the shortest path from one point to another in a recta

    - by newba
    I'm getting such an headache trying to elaborate an appropriate algorithm to go from a START position to a EXIT position in a maze. For what is worth, the maze is rectangular, maxsize 500x500 and, in theory, is resolvable by DFS with some branch and bound techniques ... 10 3 4 7 6 3 3 1 2 2 1 0 2 2 2 4 2 2 5 2 2 1 3 0 2 2 2 2 1 3 3 4 2 3 4 4 3 1 1 3 1 2 2 4 2 2 1 Output: 5 1 4 2 Explanation: Our agent looses energy every time he gives a step and he can only move UP, DOWN, LEFT and RIGHT. Also, if the agent arrives with a remaining energy of zero or less, he dies, so we print something like "Impossible". So, in the input 10 is the initial agent's energy, 3 4 is the START position (i.e. column 3, line 4) and we have a maze 7x6. Think this as a kind of labyrinth, in which I want to find the exit that gives the agent a better remaining energy (shortest path). In case there are paths which lead to the same remaining energy, we choose the one which has the small number of steps, of course. I need to know if a DFS to a maze 500x500 in the worst case is feasible with these limitations and how to do it, storing the remaining energy in each step and the number of steps taken so far. The output means the agent arrived with remaining energy= 5 to the exit pos 1 4 in 2 steps. If we look carefully, in this maze it's also possible to exit at pos 3 1 (column 3, row 1) with the same energy but with 3 steps, so we choose the better one. With these in mind, can someone help me some code or pseudo-code? I have troubles working this around with a 2D array and how to store the remaining energy, the path (or number of steps taken)....

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  • UnitOfWork & StrcutureMap & Desktop Application

    - by Afshin Gh
    When developing Web App and using StrcutureMap i normally use HybridHttpOrThreadLocalScoped for my UnitOfWork Part. (unit of work starts up per web request and ...) What about a desktop app(windows service, console, ...)? There is no session and request in a desktop app. How should i manage UoW in this situation? any good reference or article? I don't want to make it singleton. What should I do?

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  • What open source database platform is most easily transferred from my personal machine into a window

    - by Tom
    I would like eventual interaction with MS Dynamics SL and/or MindTouch Core (running on WMware) for eventual intranet and/or internet display. I guess I am asking for front and back end recommendations for a database I am constructing, but since this is my first major project I would greatly appreciate any help and advice. I would also love an opportunity to learn a new language so the code base could be in any language. I do have a few more related questions for discussion; What is the viability of using Google hosting to provide the service to the public for free? Should I implement plone or another CMS if I have a large amount of output? Is there a structuring questionnaire or standards publication I could reference? Does UML diagramming provide additional options for portability? Thank you.

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  • Shortest Path algorithm of a different kind

    - by Ram Bhat
    Hey guys, Lets say you have a grid like this (made randomly) Now lets say you have a car starting randomly from one of the while boxes, what would be the shortest path to go through each one of the white boxes? you can visit each white box as many times as you want and cant Jump over the black boxes. The black boxes are like walls. In simple words you can move from white box to white box only.. You can move in any direction, even diagonally.

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  • Tinyxml Multi Task

    - by shaimagz
    I have a single xml file and every new thread of the program (BHO) is using the same Tinyxml file. every time a new window is open in the program, it runs this code: const char * xmlFileName = "C:\\browsarityXml.xml"; TiXmlDocument doc(xmlFileName); doc.LoadFile(); //some new lines in the xml.. and than save: doc.SaveFile(xmlFileName); The problem is that after the first window is adding new data to the xml and saves it, the next window can't add to it. although the next one can read the data in the xml, it can't write to it. I thought about two possibilities to make it work, but I don't know how to implement them: Destroy the doc object when I'm done with it. Some function in Tinyxml library to unload the file. Any help or better understanding of the problem will be great. Thanks.

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  • Should business objects be able to create their own DTOs?

    - by Sam
    Suppose I have the following class: class Camera { public Camera( double exposure, double brightness, double contrast, RegionOfInterest regionOfInterest) { this.exposure = exposure; this.brightness = brightness; this.contrast = contrast; this.regionOfInterest = regionOfInterest; } public void ConfigureAcquisitionFifo(IAcquisitionFifo acquisitionFifo) { // do stuff to the acquisition FIFO } readonly double exposure; readonly double brightness; readonly double contrast; readonly RegionOfInterest regionOfInterest; } ... and a DTO to transport the camera info across a service boundary (WCF), say, for viewing in a WinForms/WPF/Web app: using System.Runtime.Serialization; [DataContract] public class CameraData { [DataMember] public double Exposure { get; set; } [DataMember] public double Brightness { get; set; } [DataMember] public double Contrast { get; set; } [DataMember] public RegionOfInterestData RegionOfInterest { get; set; } } Now I can add a method to Camera to expose its data: class Camera { // blah blah public CameraData ToData() { var regionOfInterestData = regionOfInterest.ToData(); return new CameraData() { Exposure = exposure, Brightness = brightness, Contrast = contrast, RegionOfInterestData = regionOfInterestData }; } } or, I can create a method that requires a special IReporter to be passed in for the Camera to expose its data to. This removes the dependency on the Contracts layer (Camera no longer has to know about CameraData): class Camera { // beep beep I'm a jeep public void ExposeToReporter(IReporter reporter) { reporter.GetCameraInfo(exposure, brightness, contrast, regionOfInterest); } } So which should I do? I prefer the second, but it requires the IReporter to have a CameraData field (which gets changed by GetCameraInfo()), which feels weird. Also, if there is any even better solution, please share with me! I'm still an object-oriented newb.

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  • Tooltips with infinite timeout?

    - by romkyns
    I'm thinking of setting the timeout on all my tooltips in a WinForms application to infinity (or an extremely large value). The motivation is that it's annoying for the user if the tooltip disappears while I'm still reading it, without providing any extra value whatsoever as far as I can tell. Normally I wouldn't ask something like this on StackOverflow, but the overwhelming majority of all software sets timeouts on tooltips, so it makes me wonder whether perhaps there is some important consideration I'm missing? Or is this just an old convention that nobody gives further thought to? If you would hate infinite timeout as opposed to a short timeout, please explain why. (If you just think tooltips are a bad idea altogether then that's a separate consideration; this question is specifically about the infinite timeout.)

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  • Suggest Cassandra data model for an existing schema

    - by Andriy Bohdan
    Hello guys! I hope there's someone who can help me suggest a suitable data model to be implemented using nosql database Apache Cassandra. More of than I need it to work under high loads and large amounts of data. Simplified I have 3 types of objects: Product Tag ProductTag Product: key - string key name - string .... - some other fields Tag: key - string key name - unique tag words ProductTag: product_key - foreign key referring to product tag_key - foreign key referring to tag rating - this is rating of tag for this product Each product may have 0 or many tags. Tag may be assigned to 1 or many products. Means relation between products and tags is many-to-many in terms of relational databases. Value of "rating" is updated "very" often. I need to be run the following queries Select objects by keys Select tags for product ordered by rating Select products by tag order by rating Update rating by product_key and tag_key The most important is to make these queries really fast on large amounts of data, considering that rating is constantly updated.

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  • Codechef practice question help needed - find trailing zeros in a factorial

    - by manugupt1
    I have been working on this for 24 hours now, trying to optimize it. The question is how to find the number of trailing zeroes in factorial of a number in range of 10000000 and 10 million test cases in about 8 secs. The code is as follows: #include<iostream> using namespace std; int count5(int a){ int b=0; for(int i=a;i>0;i=i/5){ if(i%15625==0){ b=b+6; i=i/15625; } if(i%3125==0){ b=b+5; i=i/3125; } if(i%625==0){ b=b+4; i=i/625; } if(i%125==0){ b=b+3; i=i/125; } if(i%25==0){ b=b+2; i=i/25; } if(i%5==0){ b++; } else break; } return b; } int main(){ int l; int n=0; cin>>l; //no of test cases taken as input int *T = new int[l]; for(int i=0;i<l;i++) cin>>T[i]; //nos taken as input for the same no of test cases for(int i=0;i<l;i++){ n=0; for(int j=5;j<=T[i];j=j+5){ n+=count5(j); //no of trailing zeroes calculted } cout<<n<<endl; //no for each trialing zero printed } delete []T; } Please help me by suggesting a new approach, or suggesting some modifications to this one.

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  • Memcache key generation strategy

    - by Maxim Veksler
    Given function f1 which receives n String arguments, would be considered better random key generation strategy for memcache for the scenario described below ? Our Memcache client does internal md5sum hashing on the keys it gets public class MemcacheClient { public Object get(String key) { String md5 = Md5sum.md5(key) // Talk to memcached to get the Serialization... return memcached(md5); } } First option public static String f1(String s1, String s2, String s3, String s4) { String key = s1 + s2 + s3 + s4; return get(key); } Second option /** * Calculate hash from Strings * * @param objects vararg list of String's * * @return calculated md5sum hash */ public static String stringHash(Object... strings) { if(strings == null) throw new NullPointerException("D'oh! Can't calculate hash for null"); MD5 md5sum = new MD5(); // if(prevHash != null) // md5sum.Update(prevHash); for(int i = 0; i < strings.length; i++) { if(strings[i] != null) { md5sum.Update("_" + strings[i] + "_"); // Convert to String... } else { // If object is null, allow minimum entropy by hashing it's position md5sum.Update("_" + i + "_"); } } return md5sum.asHex(); } public static String f1(String s1, String s2, String s3, String s4) { String key = stringHash(s1, s2, s3, s4); return get(key); } Note that the possible problem with the second option is that we are doing second md5sum (in the memcache client) on an already md5sum'ed digest result. Thanks for reading, Maxim.

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  • I cannot grok MVC, what it is, and what it is not?

    - by Hao
    I cannot grok what MVC is, what mindset or programming model should I acquire so MVC stuff can instantly "lightbulb" on my head? If not instantly, what simple programs/projects should I try to do first so I can apply the neat things MVC brings to programming. OOP is intuitive and easier, object is all around us, and the benefits of code reuse using OOP-paradigm instantly click to anyone. You can probably talk to anybody about OOP in a few minutes and lecture some examples and they would get it. While OOP somehow raise the intuitiveness aspect of programming, MVC seems to do the opposite. I'm getting negative thoughts that some future employers(or even clients) would look down upon me for not using MVC technology. Though I probably get the skinnable aspect of MVC, but when I try to apply it to my own project, I don't know where to start. And also some programmers even have diverging views on how to accomplish MVC properly. Take this for instance from Jeff's post about MVC: The view is simply how you lay the data out, how it is displayed. If you want a subset of some data, for example, my opinion is that is a responsibility of the model. So maybe some programmers use MVC, but they somehow inadvertently use the View or the Controller to extract a subset of data. Why we can't have a definitive definition of what and how to accomplish MVC properly? And also, when I search for MVC .NET programs, most of it applies to web programs, not desktop apps, this intrigue me further. My guess is, this is most advantageous to web apps, there's not much problem about intermixed view(html) and controller(program code) in desktop apps.

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  • Resources for Programmatic Rendering of Topology Maps

    - by bn
    Servus, Do you know of any frameworks, APIS, languages, or other resources that are well suited for drawing topology maps that allow a user to interact with objects on the map? I am not constrained by language choice and the program can be web-based, or stand-alone. I thought I would check before rolling my own. My goal is not to draw cartographic maps, but more like this picture: http://www.fineconnection.com/files/images/GraphicalNM.PNG, or if you are familiar with Edward Tufte's books, the data-visualization mechanisms he describes such as a map of a metro or subway. Also, if you have had any experience rendering these types of user interfaces or usage of underlying datastructures, I would be grateful to hear any thoughts you have on the subject, advice, any "gotchas." Thank you very for your time, -bn

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  • SDL side-scroller scrolls inconsistantly

    - by SDLFunTimes
    So I'm working on an upgrade from my previous project (that I posted here for code review) this time implementing a repeating background (like what is used on cartoons) so that SDL doesn't have to load really big images for a level. There's a strange inconsistency in the program, however: the first time the user scrolls all the way to the right 2 less panels are shown than is specified. Going backwards (left) the correct number of panels is shown (that is the panels repeat the number of times specified in the code). After that it appears that going right again (once all the way at the left) the correct number of panels is shown and same going backwards. Here's some selected code and here's a .zip of all my code constructor: Game::Game(SDL_Event* event, SDL_Surface* scr, int level_w, int w, int h, int bpp) { this->event = event; this->bpp = bpp; level_width = level_w; screen = scr; w_width = w; w_height = h; //load images and set rects background = format_surface("background.jpg"); person = format_surface("person.png"); background_rect_left = background->clip_rect; background_rect_right = background->clip_rect; current_background_piece = 1; //we are displaying the first clip rect_in_view = &background_rect_right; other_rect = &background_rect_left; person_rect = person->clip_rect; background_rect_left.x = 0; background_rect_left.y = 0; background_rect_right.x = background->w; background_rect_right.y = 0; person_rect.y = background_rect_left.h - person_rect.h; person_rect.x = 0; } and here's the move method which is probably causing all the trouble: void Game::move(SDLKey direction) { if(direction == SDLK_RIGHT) { if(move_screen(direction)) { if(!background_reached_right()) { //move background right background_rect_left.x += movement_increment; background_rect_right.x += movement_increment; if(rect_in_view->x >= 0) { //move the other rect in to fill the empty space SDL_Rect* temp; other_rect->x = -w_width + rect_in_view->x; temp = rect_in_view; rect_in_view = other_rect; other_rect = temp; current_background_piece++; std::cout << current_background_piece << std::endl; } if(background_overshoots_right()) { //sees if this next blit is past the surface //this is used only for re-aligning the rects when //the end of the screen is reached background_rect_left.x = 0; background_rect_right.x = w_width; } } } else { //move the person instead person_rect.x += movement_increment; if(get_person_right_side() > w_width) { //person went too far right person_rect.x = w_width - person_rect.w; } } } else if(direction == SDLK_LEFT) { if(move_screen(direction)) { if(!background_reached_left()) { //moves background left background_rect_left.x -= movement_increment; background_rect_right.x -= movement_increment; if(rect_in_view->x <= -w_width) { //swap the rect in view SDL_Rect* temp; rect_in_view->x = w_width; temp = rect_in_view; rect_in_view = other_rect; other_rect = temp; current_background_piece--; std::cout << current_background_piece << std::endl; } if(background_overshoots_left()) { background_rect_left.x = 0; background_rect_right.x = w_width; } } } else { //move the person instead person_rect.x -= movement_increment; if(person_rect.x < 0) { //person went too far left person_rect.x = 0; } } } } without the rest of the code this doesn't make too much sense. Since there is too much of it I'll upload it here for testing. Anyway does anyone know how I could fix this inconsistency?

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  • How do we greatly optimize our MySQL database (or replace it) when using joins?

    - by jkaz
    Hi there, This is the first time I'm approaching an extremely high-volume situation. This is an ad server based on MySQL. However, the query that is used incorporates a lot of JOINs and is generally just slow. (This is Rails ActiveRecord, btw) sel = Ads.find(:all, :select = '*', :joins = "JOIN campaigns ON ads.campaign_id = campaigns.id JOIN users ON campaigns.user_id = users.id LEFT JOIN countries ON countries.campaign_id = campaigns.id LEFT JOIN keywords ON keywords.campaign_id = campaigns.id", :conditions = [flashstr + "keywords.word = ? AND ads.format = ? AND campaigns.cenabled = 1 AND (countries.country IS NULL OR countries.country = ?) AND ads.enabled = 1 AND campaigns.dailyenabled = 1 AND users.uenabled = 1", kw, format, viewer['country'][0]], :order = order, :limit = limit) My questions: Is there an alternative database like MySQL that has JOIN support, but is much faster? (I know there's Postgre, still evaluating it.) Otherwise, would firing up a MySQL instance, loading a local database into memory and re-loading that every 5 minutes help? Otherwise, is there any way I could switch this entire operation to Redis or Cassandra, and somehow change the JOIN behavior to match the (non-JOIN-able) nature of NoSQL? Thank you!

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  • O(log n) algorithm for computing rank of union of two sorted lists?

    - by Eternal Learner
    Given two sorted lists, each containing n real numbers, is there a O(log?n) time algorithm to compute the element of rank i (where i coresponds to index in increasing order) in the union of the two lists, assuming the elements of the two lists are distinct? I can think of using a Merge procedure to merge the 2 lists and then find the A[i] element in constant time. But the Merge would take O(n) time. How do we solve it in O(log n) time?

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  • How to Manage project in this scenario

    - by vijay.shad
    Hi All, I am working on a web application which has got good amount of static or pre-login pages. These pages can have some simple forms as well where we would like to capture the visitor's details. Post login, I have got my main application. I am confused about the development and deployment architecture of my application. Post login part of my application has a release cycle of 1-2 months while pre-login pages are to be updated on a weekly basis. It is difficult to make a release of pre-login pages as the overall war also contains post-login application & which sometimes is not release ready. Currently, I have got both these parts bundled in the single war project. Please help me by letting me know the best practices whereby I can achieve following: Manage the releases of these two parts independently. I am using Maven. So is there a way I can share the resources, such as CSS, images etc between these two parts. Header and footer of my application is going to be same on pre-login & post-login pages. I was thinking of deploying these apps as two war files in my tomcat container. But then how will I manage the common resources like Css, images etc. Rgds Vijay

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  • CQRS - The query side

    - by mattcodes
    A lot of the blogsphere articles related to CQRS (command query repsonsibility) seperation seem to imply that all screens/viewmodels are flat. e.g. Name, Age, Location Of Birth etc.. and thus the suggestion that implementation wise we stick them into fast read source etc.. single table per view mySQL etc.. and pull them out with something like primitive SqlDataReader, kick that nasty nhibernate ORM etc.. However, whilst I agree that domain models dont mapped well to most screens, many of the screens that I work with are more dimensional, and Im sure this is pretty common in LOB apps. So my question is how are people handling screen where by for example it displays a summary of customer details and then a list of their orders with a [more detail] link etc.... I thought about keeping with the straight forward SQL query to the Query Database breaking off the outer join so can build a suitable ViewModel to View but it seems like overkill? Alternatively (this is starting to feel yuck) in CustomerSummaryView table have a text/big (whatever the type is in your DB) column called Orders, and the columns for the Order summary screen grid are seperated by , and rows by |. Even with XML datatype it still feeel dirty. Any thoughts on an optimal practice?

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  • CSS repeat pattern with linear gradient

    - by luca
    I'm on my first approach with photoshop patterns.I'm buildin a webpage where I want to use my pattern to give a nice effect to my webpage background. The pattern I found is 120x120 px If I was done here I should use this css: background-imag:url(mypattern.jpg); background-repeat:repeat; But Im not done.Id like to *add to my page's background a linear gradient(dir=top/down col=light-blue/green) with the pattern fill layer on top of it, with blending mode=darken *. This is the final effect: I come to the point. QUESTION: Combining linear vertical-gradient effect and my 120x120 pattern is it possible to find a pattern that I could use to repeat itself endlessly both vertical and horizontal??which is a common solution in this case? Hope It's clear thanks Luca

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  • Create a Python User() class that both creates new users and modifies existing users

    - by ensnare
    I'm trying to figure out the best way to create a class that can modify and create new users all in one. This is what I'm thinking: class User(object): def __init__(self,user_id): if user_id == -1 self.new_user = True else: self.new_user = False #fetch all records from db about user_id self._populateUser() def commit(self): if self.new_user: #Do INSERTs else: #Do UPDATEs def delete(self): if self.new_user == False: return False #Delete user code here def _populate(self): #Query self.user_id from database and #set all instance variables, e.g. #self.name = row['name'] def getFullName(self): return self.name #Create a new user >>u = User() >>u.name = 'Jason Martinez' >>u.password = 'linebreak' >>u.commit() >>print u.getFullName() >>Jason Martinez #Update existing user >>u = User(43) >>u.name = 'New Name Here' >>u.commit() >>print u.getFullName() >>New Name Here Is this a logical and clean way to do this? Is there a better way? Thanks.

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  • How to restrict access to a class's data based on state?

    - by Marcus Swope
    In an ETL application I am working on, we have three basic processes: Validate and parse an XML file of customer information from a third party Match values received in the file to values in our system Load customer data in our system The issue here is that we may need to display the customer information from any or all of the above states to an internal user and there is data in our customer class that will never be populated before the values have been matched in our system (step 2). For this reason, I would like to have the values not even be available to be accessed when the customer is in this state, and I would like to have to avoid some repeated logic everywhere like: if (customer.IsMatched) DisplayTextOnWeb(customer.SomeMatchedValue); My first thought for this was to add a couple interfaces on top of Customer that would only expose the properties and behaviors of the current state, and then only deal with those interfaces. The problem with this approach is that there seems to be no good way to move from an ICustomerWithNoMatchedValues to an ICustomerWithMatchedValues without doing direct casts, etc... (or at least I can't find one). I can't be the first to have come across this, how do you normally approach this? As a last caveat, I would like for this solution to play nice with FluentNHibernate :) Thanks in advance...

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  • Synonym for "Many-to-Many" relationship (relational databases)

    - by Byron
    What's a synonym for a "many-to-many" relationship? I've finished writing an object-relational mapper but I'm still stumped as to what to name the function that adds that relation. addParent() and addChild() seemed quite logical for the many-to-one/one-to-many and addSuperclass() for one-to-one inheritance, but addManyToMany() would sound quite unintuitive to an object-oriented programmer. addSibling() or addCousin() doesn't really make sense either. Any suggestions? And before you dismiss this as a non-programming question, please remember that consistent naming schemes and encapsulation are pretty integral to programming :)

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  • DDD and MVC: Difference between 'Model' and 'Entity'

    - by Nathan Loding
    I'm seriously confused about the concept of the 'Model' in MVC. Most frameworks that exist today put the Model between the Controller and the database, and the Model almost acts like a database abstraction layer. The concept of 'Fat Model Skinny Controller' is lost as the Controller starts doing more and more logic. In DDD, there is also the concept of a Domain Entity, which has a unique identity to it. As I understand it, a user is a good example of an Entity (unique userid, for instance). The Entity has a life-cycle -- it's values can change throughout the course of the action -- and then it's saved or discarded. The Entity I describe above is what I thought Model was supposed to be in MVC? How off-base am I? To clutter things more, you throw in other patterns, such as the Repository pattern (maybe putting a Service in there). It's pretty clear how the Repository would interact with an Entity -- how does it with a Model? Controllers can have multiple Models, which makes it seem like a Model is less a "database table" than it is a unique Entity. So, in very rough terms, which is better? No "Model" really ... class MyController { public function index() { $repo = new PostRepository(); $posts = $repo->findAllByDateRange('within 30 days'); foreach($posts as $post) { echo $post->Author; } } } Or this, which has a Model as the DAO? class MyController { public function index() { $model = new PostModel(); // maybe this returns a PostRepository? $posts = $model->findAllByDateRange('within 30 days'); while($posts->getNext()) { echo $posts->Post->Author; } } } Both those examples didn't even do what I was describing above. I'm clearly lost. Any input?

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