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• How would you TDD the functionality of getting the corresponding process of a running windows service?

  - by Matt Spinelli

  Purpose Over the last year or more I've been learning unit testing via books I've read recently like The Art of Unit Testing, Working Effectively with Legacy Code, and others. I've also been using unit tests, mocking frameworks, and the like, periodically at work and definitely see the value. However, I'm still having a hard time wrapping my mind around TDD (as opposed to TAD) when the situation calls for code that is gong to mostly use external API calls. Problem to solve Get the process associated with a windows service using the service name. example: Function GetProcess(ByVal serviceName As String) As Process Rules Show each major iteration in production & test code using TDD No need to see any other code or configuration that is required to get things to run. Just curious about the interfaces, concrete classes, and test methods. C# or VB.NET Must use the .Net framework regarding services/processes (i.e. System.Diagnostics.Process) Test Frameworks: Nunit or MSTest Isolation Frameworks: Moq, Rhino Mock, or Microsoft Moles Must write true unit tests (no integration tests) Additional notes As far as I can tell there are two approaches design wise. Use an Inversion of Control approach along with using the Adapter and/or Facade patterns to wrap the underlying .net framework objects dealing with processes and services. Keep the .net framework code in the class containing the Get Process method and use code detouring (interception) via Microsoft Moles to isolate the hard dependencies from the method under test.

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• Is creating a separate pool for each individual image created from a png appropriate?

  - by Panzercrisis

  I'm still possibly a little green about object-pooling, and I want to make sure something like this is a sound design pattern before really embarking upon it. Take the following code (which uses the Starling framework in ActionScript 3): [Embed(source = "/../assets/images/game/misc/red_door.png")] private const RED_DOOR:Class; private const RED_DOOR_TEXTURE:Texture = Texture.fromBitmap(new RED_DOOR()); private const m_vRedDoorPool:Vector.<Image> = new Vector.<Image>(50, true); . . . public function produceRedDoor():Image { // get a Red Door image } public function retireRedDoor(pImage:Image):void { // retire a Red Door Image } Except that there are four colors: red, green, blue, and yellow. So now we have a separate pool for each color, a separate produce function for each color, and a separate retire function for each color. Additionally there are several items in the game that follow this 4-color pattern, so for each of them, we have four pools, four produce functions, and four retire functions. There are more colors involved in the images themselves than just their predominant one, so trying to throw all the doors, for instance, in a single pool, and then changing their color properties around isn't going to work. Also the nonexistence of the static keyword is due to its slowness in AS3. Is this the right way to do things?

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• DB Schema for ACL involving 3 subdomains

  - by blacktie24

  Hi, I am trying to design a database schema for a web app which has 3 subdomains: a) internal employees b) clients c) contractors. The users will be able to communicate with each other to some degree, and there may be some resources that overlap between them. Any thoughts about this schema? Really appreciate your time and thoughts on this. Cheers! -- -- Table structure for table locations CREATE TABLE IF NOT EXISTS locations ( id bigint(20) NOT NULL, name varchar(250) NOT NULL ) ENGINE=InnoDB DEFAULT CHARSET=latin1; -- -- Table structure for table privileges CREATE TABLE IF NOT EXISTS privileges ( id int(11) NOT NULL AUTO_INCREMENT, name varchar(255) NOT NULL, resource_id int(11) NOT NULL, PRIMARY KEY (id) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=10 ; -- -- Table structure for table resources CREATE TABLE IF NOT EXISTS resources ( id int(11) NOT NULL AUTO_INCREMENT, name varchar(255) NOT NULL, user_type enum('internal','client','expert') NOT NULL, PRIMARY KEY (id) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=3 ; -- -- Table structure for table roles CREATE TABLE IF NOT EXISTS roles ( id int(11) NOT NULL AUTO_INCREMENT, name varchar(255) NOT NULL, type enum('position','department') NOT NULL, parent_id int(11) DEFAULT NULL, user_type enum('internal','client','expert') NOT NULL, PRIMARY KEY (id) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=3 ; -- -- Table structure for table role_perms CREATE TABLE IF NOT EXISTS role_perms ( id int(11) NOT NULL AUTO_INCREMENT, role_id int(11) NOT NULL, privilege_id int(11) NOT NULL, mode varchar(250) NOT NULL, PRIMARY KEY (id) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=2 ; -- -- Table structure for table users CREATE TABLE IF NOT EXISTS users ( id int(10) unsigned NOT NULL AUTO_INCREMENT, email varchar(255) NOT NULL, password varchar(255) NOT NULL, salt varchar(255) NOT NULL, type enum('internal','client','expert') NOT NULL, first_name varchar(255) NOT NULL, last_name varchar(255) NOT NULL, location_id int(11) NOT NULL, phone varchar(255) NOT NULL, status enum('active','inactive') NOT NULL DEFAULT 'active', PRIMARY KEY (id) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=4 ; -- -- Table structure for table user_perms CREATE TABLE IF NOT EXISTS user_perms ( id int(11) NOT NULL AUTO_INCREMENT, user_id int(11) NOT NULL, privilege_id int(11) NOT NULL, mode varchar(250) NOT NULL, PRIMARY KEY (id) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=2 ; -- -- Table structure for table user_roles CREATE TABLE IF NOT EXISTS user_roles ( id int(11) NOT NULL, user_id int(11) NOT NULL, role_id int(11) NOT NULL ) ENGINE=InnoDB DEFAULT CHARSET=latin1;

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• Using PDO with MVC

  - by mister martin

  I asked this question at stackoverflow and received no response (closed as duplicate with no answer). I'm experimenting with OOP and I have the following basic MVC layout: class Model { // do database stuff } class View { public function load($filename, $data = array()) { if(!empty($data)) { extract($data); } require_once('views/header.php'); require_once("views/$filename"); require_once('views/footer.php'); } } class Controller { public $model; public $view; function __construct() { $this->model = new Model(); $this->view = new View(); // determine what page we're on $page = isset($_GET['view']) ? $_GET['view'] : 'home'; $this->display($page); } public function display($page) { switch($page) { case 'home': $this->view->load('home.php'); break; } } } These classes are brought together in my setup file: // start session session_start(); require_once('Model.php'); require_once('View.php'); require_once('Controller.php'); new Controller(); Now where do I place my database connection code and how do I pass the connection onto the model? try { $db = new PDO('mysql:host='.DB_HOST.';dbname='.DB_DATABASE.'', DB_USERNAME, DB_PASSWORD); $db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION); } catch(PDOException $err) { die($err->getMessage()); } I've read about Dependency Injection, factories and miscellaneous other design patterns talking about keeping SQL out of the model, but it's all over my head using abstract examples. Can someone please just show me a straight-forward practical example?

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• Benefits of classic OOP over Go-like language

  - by tylerl

  I've been thinking a lot about language design and what elements would be necessary for an "ideal" programming language, and studying Google's Go has led me to question a lot of otherwise common knowledge. Specifically, Go seems to have all of the interesting benefits from object oriented programming without actually having any of the structure of an object oriented language. There are no classes, only structures; there is no class/structure inheritance -- only structure embedding. There aren't any hierarchies, no parent classes, no explicit interface implementations. Instead, type casting rules are based on a loose system similar to duck-typing, such that if a struct implements the necessary elements of a "Reader" or a "Request" or an "Encoding", then you can cast it and use it as one. Does such a system obsolete the concept of OOP? Or is there something about OOP as implemented in C++ and Java and C# that is inherently more capable, more maintainable, somehow more powerful that you have to give up when moving to a language like Go? What benefit do you have to give up to gain the simplicity that this new paradigm represents?

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• Designing business objects, and gui actions

  - by fozz

  Developing a product ordering system using Java SE 6. The previous implementations used combo boxes, text fields, and check boxes. Preforming validation on action events from the GUI. The validation includes limiting existing combo boxes items, or even availability. The issue in the old system was that the action was received and all rules were applied to the entire business object. This resulted in a huge event change as options were changed multiple times. To be honest I have no idea how an infinite loop wasn't produced. Through the next iteration I stepped in and attempted to limit the chaos by controlling the order in which the selections could be made. Making configuration of BO's a top down approach. I implemented custom box models, action events, beans/binding, and an MVC pattern. However I still am unable to fully isolate action even chains. I'm thinking that I've approached the whole concept backwards in an attempt to stay closest to what was already in place. So the question becomes what do I design instead? I'm currently considering an implementation of Interfaces, Beans, Property Change Listeners to manage the back and forth. Other thoughts were validation exceptions, dynamic proxies.... I'm sure there are a ton of different ways. To say that one way is right is crazy, and I'm sure it will take a blending of multiple patterns. My knowledge of swing/awt validation is limited, previously I did backend logic only. Other considerations are were some sort of binding(jgoodies or otherwise) to directly bind GUI state to BO's.

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• Methodologies for Managing Users and Access?

  - by MadBurn

  This is something I'm having a hard time getting my head around. I think I might be making it more complicated than it is. What I'm trying to do is develop a method to store users in a database with varying levels of access, throughout different applications. I know this has been done before, but I don't know where to find how they did it. Here is an example of what I need to accomplish: UserA - Access to App1, App3, App4 & can add new users to App3, but not 4 or 1. UserB - Access to App2 only with ReadOnly access. UserC - Access to App1 & App4 and is able to access Admin settings of both apps. In the past I've just used user groups. However, I'm reaching a phase where I need a bit more control over each individual user's access to certain parts of the different applications. I wish this were as cut and dry as being able to give a user a role and let each role inherit from the last. Now, this is what I need to accomplish. But, I don't know any methods of doing this. I could easily just design something that works, but I know this has been done and I know this has been studied and I know this problem has been solved by much better minds than my own. This is for a web application and using sql server 2008. I don't need to store passwords (LDAP) and the information I need to store is actually very limited. Basically just username and access.

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• Is creating a separate pool for each individual png image in the same class appropriate?

  - by Panzercrisis

  I'm still possibly a little green about object-pooling, and I want to make sure something like this is a sound design pattern before really embarking upon it. Take the following code (which uses the Starling framework in ActionScript 3): [Embed(source = "/../assets/images/game/misc/red_door.png")] private const RED_DOOR:Class; private const RED_DOOR_TEXTURE:Texture = Texture.fromBitmap(new RED_DOOR()); private const m_vRedDoorPool:Vector.<Image> = new Vector.<Image>(50, true); . . . public function produceRedDoor():Image { // get a Red Door image } public function retireRedDoor(pImage:Image):void { // retire a Red Door Image } Except that there are four colors: red, green, blue, and yellow. So now we have a separate pool for each color, a separate produce function for each color, and a separate retire function for each color. Additionally there are several items in the game that follow this 4-color pattern, so for each of them, we have four pools, four produce functions, and four retire functions. There are more colors involved in the images themselves than just their predominant one, so trying to throw all the doors, for instance, in a single pool, and then changing their color properties around isn't going to work. Also the nonexistence of the static keyword is due to its slowness in AS3. Is this the right way to do things?

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• Are first-class functions a substitute for the Strategy pattern?

  - by Prog

  The Strategy design pattern is often regarded as a substitute for first-class functions in languages that lack them. So for example say you wanted to pass functionality into an object. In Java you'd have to pass in the object another object which encapsulates the desired behavior. In a language such as Ruby, you'd just pass the functionality itself in the form of an annonymous function. However I was thinking about it and decided that maybe Strategy offers more than a plain annonymous function does. This is because an object can hold state that exists independently of the period when it's method runs. However an annonymous function by itself can only hold state that ceases to exist the moment the function finishes execution. So my question is: when using a language that features first-class functions, would you ever use the Strategy pattern (i.e. encapsulate the functionality you want to pass around in an explicit object), or would you always use an annonymous function? When would you decide to use Strategy when you can use a first-class function?

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• What type of pattern would be used in this case

  - by Admiral Kunkka

  I want to know how to tackle this type of scenario. We are building a person's background, from scratch, and I want to know, conceptually, how to proceed with a secure object pattern in both design and execution... I've been reading on Factory patterns, Model-View-Controller types, Dependency injection, Singleton approaches... and I can't seem to grasp or 'fit' these types of designs decisions into what I'm trying to do.. First and foremost, I started with having a big jack-of-all-trades class, then I read some more, and some tips were to make sure your classes only have a single purpose.. which makes sense and I started breaking down certain things into other classes. Okay, cool. Now I'm looking at dependency injection and kind of didn't really know what's going on. Example/insight of what kind of heirarchy I need to accomplish... class Person needs to access and build from a multitude of different classes. class Culture needs to access a sub-class for culture benefits class Social needs to access class Culture, and other sub-classes class Birth needs to access Social, Culture, and other sub-classes class Childhood/Adolescence/Adulthood need to access everything. Also, depending on different rolls, this class heirarchy needs to create multiple people as well, such as Family, and their backgrounds using some, if not all, of these same classes. Think of it as a people generator, all random, with backgrounds and things that happen to them. Ageing, death of loved ones, military careers, e.t.c. Most of the generation is done randomly, making calls to a mt_rand function to pick from most of the selections inside the classes, guaranteeing the data to be absolutely random. I have most of the bulk-data down, and was looking for some insight from fellow programmers, what do you think?

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• Best way to go for simple online multi-player games?

  - by Mr_CryptoPrime

  I want to create a trivia game for my website. The graphic design does not have to be too fancy, probably no more advanced than a typical flash game. It needs to be secure because I want users to be able to play for real money. It also needs to run fast so users don't spend their time frustrated with game freezing. Compatibility, as with almost all online products, is key because of the large target market. I am most acquainted with Java programming, but I don't want to do it in Java if there is something much better. I am assuming I will have to utilize a variety of different languages in order for everything to come together. If someone could point out the main structure of everything so I could get a good start that would be great! 1) Language choice for simple secure online multiplayer games? 2) Perhaps use a database like MySQL, stored on a secure server for the trivia questions? 3) Free educational resources and even simpler projects to practice? Any ideas or suggestions would be helpful...Thanks!

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• Designs for outputting to a spreadsheet

  - by Austin Moore

  I'm working on a project where we are tasked to gather and output various data to a spreadsheet. We are having tons of problems with the file that holds the code to write the spreadsheet. The cell that the data belongs to is hardcoded, so anytime you need to add anything to the middle of the spreadsheet, you have to increment the location for all the fields after that in the code. There are random blank rows, to add padding between sections, and subsections within the sections, so there's no real pattern that we can replicate. Essentially, anytime we have to add or change anything to the spreadsheet it requires a many long and tedious hours. The code is all in this one large file, hacked together overtime in Perl. I've come up with a few OO solutions, but I'm not too familiar with OO programming in Perl and all my attempts at it haven't been great, so I've shied away from it so far. I've suggested we handle this section of the program with a more OO friendly language, but we can't apparently. I've also suggested that we scrap the entire spreadsheet idea, and just move to a webpage, but we can't do that either. We've been working on this project for a few months, and every time we have to change that file, we all dread it. I'm thinking it's time to start some refactoring. However, I don't even know what could make this file easier to work with. The way the output is formatted makes it so that it has to be somewhat hardcoded. I'm wondering if anyone has insight on any design patterns or techniques they have used to tackle a similar problem. I'm open to any ideas. Perl specific answers are welcome, but I am also interested in language-agnostic solutions.

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• Are DDD Aggregates really a good idea in a Web Application?

  - by Mystere Man

  I'm diving in to Domain Driven Design and some of the concepts i'm coming across make a lot of sense on the surface, but when I think about them more I have to wonder if that's really a good idea. The concept of Aggregates, for instance makes sense. You create small domains of ownership so that you don't have to deal with the entire domain model. However, when I think about this in the context of a web app, we're frequently hitting the database to pull back small subsets of data. For instance, a page may only list the number of orders, with links to click on to open the order and see its order id's. If i'm understanding Aggregates right, I would typically use the repository pattern to return an OrderAggregate that would contain the members GetAll, GetByID, Delete, and Save. Ok, that sounds good. But... If I call GetAll to list all my order's, it would seem to me that this pattern would require the entire list of aggregate information to be returned, complete orders, order lines, etc... When I only need a small subset of that information (just header information). Am I missing something? Or is there some level of optimization you would use here? I can't imagine that anyone would advocate returning entire aggregates of information when you don't need it. Certainly, one could create methods on your repository like GetOrderHeaders, but that seems to defeat the purpose of using a pattern like repository in the first place. Can anyone clarify this for me?

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• How to handle fine grained field-based ACL permissions in a RESTful service?

  - by Jason McClellan

  I've been trying to design a RESTful API and have had most of my questions answered, but there is one aspect of permissions that I'm struggling with. Different roles may have different permissions and different representations of a resource. For example, an Admin or the user himself may see more fields in his own User representation vs another less-privileged user. This is achieved simply by changing the representation on the backend, ie: deciding whether or not to include those fields. Additionally, some actions may be taken on a resource by some users and not by others. This is achieved by deciding whether or not to include those action items as links, eg: edit and delete links. A user who does not have edit permissions will not have an edit link. That covers nearly all of my permission use cases, but there is one that I've not quite figured out. There are some scenarios whereby for a given representation of an object, all fields are visible for two or more roles, but only a subset of those roles my edit certain fields. An example: { "person": { "id": 1, "name": "Bob", "age": 25, "occupation": "software developer", "phone": "555-555-5555", "description": "Could use some sunlight.." } } Given 3 users: an Admin, a regular User, and Bob himself (also a regular User), I need to be able to convey to the front end that: Admins may edit all fields, Bob himself may edit all fields, but a regular User, while they can view all fields, can only edit the description field. I certainly don't want the client to have to make the determination (or even, for that matter, to have any notion of the roles involved) but I do need a way for the backend to convey to the client which fields are editable. I can't simply use a combination of representation (the fields returned for viewing) and links (whether or not an edit link is availble) in this scenario since it's more finely grained. Has anyone solved this elegantly without adding the logic directly to the client?

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• How to Effectively Create Bullet Patterns

  - by SoulBeaver

  I'm currently creating a top-down shooter like Touhou. The most important factor of the game is that there are many diverse patterns and ways at which bullets are generated and shot at the player, see this video: http://www.youtube.com/watch?v=4Nb5Ohbt1Sg#start=0:60;end=9:53; At the moment, I'm using a class "Pattern" which has a series of steps on moving and shooting. However, I feel this method is quite laborous as I have to create a new Pattern for each attack and perhaps new Bullet classes that will implement a certain behavior. This question received a comment suggesting I should look into BulletML for easy creation and storage of bullets with a specific pattern. It looks decent, but it led me to wonder, what other solutions do you have that I should take into consideration? Update My current design is as follows: An example of an implemented pattern: My GigasPattern first executes a teleport which moves Alice to a certain point (X, Y) on the screen. After this is completed, the pattern starts using the Mover to move the sprite around (whereas teleporting has separate effects and animation). These are of no concern, really, as they are quite simple. The Shooter also creates various Attacks, which are classes again that the Shooter can use to create various patterns of bullets, much like the one in the question I posted. Once the Mover has reached it's destination, both it and the shooter stop and return to an inactive state. The pattern completes, is removed by the AI and a new one gets chosen.

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• Advice on designing web application with a 40+ year lifetime

  - by user2708395

  Scenario Currently, I am apart of a health care project whose main requirement is to capture data with unknown attributes using user generated forms by health care providers. The second requirement is that data integrity is key and that the application will be used for 40+ years. We are currently migrating the client's data from the past 40 years from various sources (Paper, Excel, Access, etc...) to the database. Future requirements are: Workflow management of forms Schedule management of forms Security/Role based management Reporting engine Mobile/Tablet support Situation Only 6 months in, the current (contracted) architect/senior programmer has taken the "fast" approach and has designed a poor system. The database is not normalized, the code is coupled, the tiers have no dedicated purpose and data is starting to go missing since he has designed some beans to perform "deletes" on the database. The code base is extremely bloated and there are jobs just to synchronize data since the database is not normalized. His approach has been to rely on backup jobs to restore missing data and doesn't seem to believe in re-factoring. Having presented my findings to the PM, the architect will be removed when his contract ends. I have been given the task to re-architect this application. My team consists of me and one junior programmer. We have no other resources. We have been granted a 6-month requirement freeze in which we can focus on re-building this system. I suggested using a CMS system like Drupal, but for policy reasons at the client's organization, the system must be built from scratch. This is the first time that I will be designing a system with a 40+ lifespan. I have only worked on projects with 3-5 year lifespans, so this situation is very new, yet exciting. Questions What design considerations will make the system more "future proof"? What experiences have you had in designing such systems - both failures and successes? What questions should be asked to the client/PM to make the system more "future proof"?

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• Keeping a domain model consistent with actual data

  - by fstuijt

  Recently domain driven design got my attention, and while thinking about how this approach could help us I came across the following problem. In DDD the common approach is to retrieve entities (or better, aggregate roots) from a repository which acts as a in-memory collection of these entities. After these entities have been retrieved, they can be updated or deleted by the user, however after retrieval they are essentially disconnected from the data source and one must actively inform the repository to update the data source and make is consistent again with our in-memory representation. What is the DDD approach to retrieving entities that should remain connected to the data source? For example, in our situation we retrieve a series of sensors that have a specific measurement during retrieval. Over time, these measurement values may change and our business logic in the domain model should respond to these changes properly. E.g., domain events may be raised if a sensor value exceeds a predefined threshold. However, using the repository approach, these sensor values are just snapshots, and are disconnected from the data source. Does any of you have an idea on how to solve this following the DDD approach?

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• How can we best petition to bring Adobe creative software to Ubuntu?

  - by Sixthlaw

  Now I know its not as simple as asking for Adobe to support their design software on Ubuntu, but is there a way for the community and Canonical to make known to Adobe the rapidly growing amount of Linux users, and their desire for this great set of tools OFFICIALLY? I know that many of the answers I receive might be of the fashion "Its not going to happen", "use the free tools provided" or "Who knows it might happen in the near future", but this IS not what I am looking for. I have noticed, on sites like www.OmgUbuntu.com, there are links to pages where people can "like" the idea. Is there a way to try and get the whole community on board with this one, even Canonical, and as stated above, put forward this proposal to Adobe. The current requests for an Adobe CS, for Linux, are in dribs and drabs scattered all of the internet. Now is the best time to come up with productive solutions on how we can best gather statistics on the amount of people willing to buy the Adobe CS. These are the words of an Adobe employee: "I have forwarded this feedback on to the appropriate team who will consider it for future releases of Adobe software." The larger amount of people we have unified in the ONE community proposal, the greater chance we have of getting the software. How can we make this happen?

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• Depending on fixed version of a library and ignore its updates

  - by Moataz Elmasry

  I was talking to a technical boss yesterday. Its about a project in C++ that depends on opencv and he wanted to include a specific opencv version into the svn and keep using this version ignoring any updates which I disagreed with.We had a heated discussion about that. His arguments: Everything has to be delivered into one package and we can't ask the client to install external libraries. We depend on a fixed version so that new updates of opencv won't screw our code. We can't guarantee that within a version update, ex from 3.2.buildx to 3.2.buildy. Buildy the function signatures won't change. My arguments: True everything has to be delivered to the client as one package,but that's what build scripts are for. They download the external libraries and create a bundle. Within updates of the same version 3.2.buildx to 3.2.buildy its impossible that a signature change, unless it is a really crappy framework, which isn't the case with opencv. We deprive ourselves from new updates and features of that library. If there's a bug in the version we took, and even if there's a bug fix later, we won't be able to get that fix. Its simply ineffiecient and anti design to depend on a certain version/build of an external library as it makes our project difficult in the future to adopt to new changes. So I'd like to know what you guys think. Does it really make sense to include a specific version of external library in our svn and keep using it ignoring all updates?

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• Is there a common programming term for the problems of adding features to an already-featureful program?

  - by Jeremy Friesner

  I'm looking for a commonly used programming term to describe a software-engineering phenomenon, which (for lack of a better way to describe it) I'll illustrate first with a couple of examples-by-analogy: Scenario 1: We want to build/extend a subway system on the outskirts of a small town in Wyoming. There are the usual subway-problems to solve, of course (hiring the right construction company, choosing the best route, buying the subway cars), but other than that it's pretty straightforward to implement the system because there aren't a huge number of constraints to satisfy. Scenario 2: Same as above, except now we need to build/extend the subway system in downtown Los Angeles. Here we face all of the problems we did in case (1), but also additional problems -- most of the applicable space is already in use, and has a vocal constituency which will protest loudly if we inconvenience them by repurposing, redesigning, or otherwise modifying the infrastructure that they rely on. Because of this, extensions to the system happen either very slowly and expensively, or they don't happen at all. I sometimes see a similar pattern with software development -- adding a new feature to a small/simple program is straightforward, but as the program grows, adding further new features becomes more and more difficult, if only because it is difficult to integrate the new feature without adversely affecting any of the large number of existing use-cases or user-constituencies. (even with a robust, adaptable program design, you run into the problem of the user interface becoming so elaborate that the program becomes difficult to learn or use) Is there a term for this phenomenon?

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• Is wrapping a third party code the only solution to unit test its consumers? [closed]

  - by Songo

  I'm doing unit testing and in one of my classes I need to send a mail from one of the methods, so using constructor injection I inject an instance of Zend_Mail class which is in Zend framework. Now some people argue that if a library is stable enough and won't change often then there is no need to wrap it. So assuming that Zend_Mail is stable and won't change and it fits my needs entirely, then I won't need a wrapper for it. Now take a look at my class Logger that depends on Zend_Mail: class Logger{ private $mailer; function __construct(Zend_Mail $mail){ $this->mail=$mail; } function toBeTestedFunction(){ //Some code $this->mail->setTo('some value'); $this->mail->setSubject('some value'); $this->mail->setBody('some value'); $this->mail->send(); //Some } } However, Unit testing demands that I test one component at a time, so I need to mock the Zend_Mail class. In addition I'm violating the Dependency Inversion principle as my Logger class now depends on concretion not abstraction. Now is wrapping Zend_Mail the only solution or is there a better approach to this problem? The code is in PHP, but answers doesn't have to be. This is more of a design issue than a language specific feature

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• Static / Shared Helper Functions vs Built-In Methods

  - by Nathan

  This is a simple question but a design consideration that I often run across in my day to day development work. Lets say that you have a class that represents some kinds of collection. Public Class ModifiedCustomerOrders Public Property Orders as List(Of ModifiedOrders) End Class Within this class you do all kinds of important work, such as combining many different information sources and, eventually, build the Modified Customer Orders. Now, you have different processes that consume this class, each of which needs a slightly different slice of the ModifiedCustomerOrders items. To enable this, you want to add filtering functionality. How do you go about this? Do you: Add Filtering calls to the ModifiedCustomerOrders class so that you can say: MyOrdersClass.RemoveCanceledOrders() Create a Static / Shared "tooling" class that allows you to call: OrdersFilters.RemoveCanceledOrders(MyOrders) Create an extension method to accomplish the same feat as #2 but with less typing: MyOrders.RemoveCanceledOrders() Create a "Service" method that handles the getting of Orders as appropriate to the calling function, while using one of the previous approaches "under the hood". OrdersService.GetOrdersForProcessA() Others? I tend to prefer the tooling / extension method approaches as they make testing a little bit simpler. Although I dependency inject all my sourcing data into the ModifiedCustomerOrders, having it as part of the class makes it a little bit more complicated to test. Typically, I choose to use extension methods where I am doing parameterless transformations / filters. As they get more complex, I will move it into a static class instead. Thoughts on this approach? How would you approach it?

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• What are solutions and tradeoffs to maintain search result consistency in a web application

  - by iammichael

  Consider a web application with a custom search function that must display the results in a paged manner (twenty per page with up to hundreds of thousands of total results) and the ability to drill down to individual results that maintain next/previous links to navigate through the results. Re-executing the search on each page request to get the appropriate results for that page of data can be too expensive (up to 15s per search). Also, since the underlying data can change frequently (e.g. addition of new results), re-executing could cause the next/previous functionality to result in inconsistent behavior (e.g. the same results reappearing on a later page after having been viewed on an earlier page). What options exist to ensure the search results can be viewed across multiple pages in a consistent manner, and what tradeoffs does each option have in terms of network, CPU, memory, and storage requirements? EDIT: I thought caching the query search results was an obvious necessity. The question is really asking about where to cache the result set and what tradeoffs might exist to each. For example, storing the ids of the entities in the result set on the client, or storing the IDs of the entities themselves in the users session on the web server, or in a temporary table in the database. I'm not looking specifically for a single solution as different scenarios may result in different approaches (and such a question would be more suited for stackoverflow.com rather than here), but more of a design comparison between the possible approaches.

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• Should I think about switching to another platform as a .Net developer? [closed]

  - by A. Karimi

  I’ve been a developer for about 10 years and I’ve almost worked on Microsoft stack. At the last several years I’ve been introduced to some good practices such as IoC and other primary design patterns. Now I feel so much comfortable using these patterns and concepts and I’m very angry why we didn’t do that earlier! They exist and used by many developers since more than 5 years ago but why I and many of my colleagues began using them a little later. As you may know Java developers are more ahead in these fields (concepts, patterns and …) than .Net developers. Am I right? Now the question is, “Why we (as .NET developers) weren’t ahead so much? Isn’t it because we are using Microsoft stack?”. I know ALT.NET but why we are trying make a closed ecosystem open and finding alternatives for Microsoft Echo Chamber, while there are natively open ecosystems like Java!? I've always liked most of the Microsoft works very much but I’m worried about this issue. I am even ask myself should I move to another platform?

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• How to implement isValid correctly?

  - by Songo

  I'm trying to provide a mechanism for validating my object like this: class SomeObject { private $_inputString; private $_errors=array(); public function __construct($inputString) { $this->_inputString = $inputString; } public function getErrors() { return $this->_errors; } public function isValid() { $isValid = preg_match("/Some regular expression here/", $this->_inputString); if($isValid==0){ $this->_errors[]= 'Error was found in the input'; } return $isValid==1; } } Then when I'm testing my code I'm doing it like this: $obj = new SomeObject('an INVALID input string'); $isValid = $obj->isValid(); $errors=$obj->getErrors(); $this->assertFalse($isValid); $this->assertNotEmpty($errors); Now the test passes correctly, but I noticed a design problem here. What if the user called $obj->getErrors() before calling $obj->isValid()? The test will fail because the user has to validate the object first before checking the error resulting from validation. I think this way the user depends on a sequence of action to work properly which I think is a bad thing because it exposes the internal behaviour of the class. How do I solve this problem? Should I tell the user explicitly to validate first? Where do I mention that? Should I change the way I validate? Is there a better solution for this? UPDATE: I'm still developing the class so changes are easy and renaming functions and refactoring them is possible.

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