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  • Is there a Design Pattern for preventing dangling references?

    - by iFreilicht
    I was thinking about a design for custom handles. The thought is to prevent clients from copying around large objects. Now a regular handle class would probably suffice for that, but it doesn't solve the "dangling reference problem"; If a client has multiple handles of the same object and deletes the object via one of them, all the others would be invalid, but not know it, so the client could write or read parts of the memory he shouldn't have access to. Is there a design pattern to prevent this from happening? Two ideas: An observer-like pattern where the destructor of an object would notify all handles. "Handle handles" (does such a thing even exist?). All the handles don't really point to the object, but to another handle. When the object gets destroyed, this "master-handle" invalidates itself and therefore all that point to it.

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  • Programming Interview Question [duplicate]

    - by user136494
    This question already has an answer here: How to prepare yourself for programming interview questions? [duplicate] 6 answers I have an upcoming interview in a couple of days and had a question for you guys. I've heard that programming interviews have whiteboard problems where you solve a simple problem on a whiteboard. My question to you is? How many whiteboard problems do you have to solve? Is there more than 1? What are examples of whiteboard problems? Is FizzBuzz one of them? Where can I find practice problems for them? Anyone know of any good web sites?

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  • Is it a bad idea to list every function/method argument on a new line and why?

    - by dgnball
    I work with someone who, every time they call a function they put the arguments on a new line e.g. aFunction( byte1, short1, int1, int2, int3, int4, int5 ) ; I find this very annoying as it means the code isn't very compact, so I have to scan up and down more to actually make any sense of the logic. I'm interested to know whether this is actually bad practice and if so, how can I persuade them not to do it?

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  • What is the proper name for this design pattern in Python?

    - by James
    In Python, is the proper name for the PersonXXX class below PersonProxy, PersonInterface, etc? import rest class PersonXXX(object): def __init__(self,db_url): self.resource = rest.Resource(db_url) def create(self,person): self.resource.post(person.data()) def get(self): pass def update(self): pass def delete(self): pass class Person(object): def __init__(self,name, age): self.name = name self.age = age def data(self): return dict(name=self.name,age=self.age)

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  • Getting solutions off the internet. Bad or Good? [closed]

    - by Prometheus87
    I was looking on the internet for common interview questions. I came upon one that was about finding the occurrences of certain characters in an array. The solution written right below it was in my opinion very elegant. But then another thought came to my mind that, this solution is way better than what came to my mind. So even though I know the solution (that most probably someone with a better IQ had provided) my IQ was still the same. So that means that even though i may know the answer, it still wasn't mine. hence if that question was asked and i was hired upon my answer to that question i couldn't reproduce that same elegance in my other ventures within the organization My question is what do you guys think about such "borrowed intelligence"? Is it good? Do you feel that if solutions are found off the internet, it makes you think in that same more elegant way?

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  • Motivation and use of move constructors in C++

    - by Giorgio
    I recently have been reading about move constructors in C++ (see e.g. here) and I am trying to understand how they work and when I should use them. As far as I understand, a move constructor is used to alleviate the performance problems caused by copying large objects. The wikipedia page says: "A chronic performance problem with C++03 is the costly and unnecessary deep copies that can happen implicitly when objects are passed by value." I normally address such situations by passing the objects by reference, or by using smart pointers (e.g. boost::shared_ptr) to pass around the object (the smart pointers get copied instead of the object). What are the situations in which the above two techniques are not sufficient and using a move constructor is more convenient?

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  • My Last "Catch-Up" Post for 2010 Content

    - by KKline
    I did a lot of writing in 2010. Unfortunately, I didn't do a good job of keeping all of that writing equally distributed throughout all of the channels where I'm active. So here are a few more posts from my blog, put on-line during the months of November and December 2010, that I didn't get posted here on SQLBlog.com: 1. It's Time to Upgrade! So many of my customers and many of you, dear readers, are still on SQL Server 2005. Join Kevin Kline , SQL Server MVP and SQL Server Technology Strategist...(read more)

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  • Convenient practice for where to place images?

    - by Baumr
    A lot of developers place all image files inside a central directory, for example: /i/img/ /images/ /img/ Isn't it better (e.g. content architecture, on-page SEO, code maintainability, filename maintainability, etc.) to place them inside the relevant directories in which they are used? For example: example.com/logo.jpg example.com/about/photo-of-me.jpg example.com/contact/map.png example.com/products/category1-square.png example.com/products/category2-square.png example.com/products/category1/product1-thumb.jpg example.com/products/category1/product2-thumb.jpg example.com/products/category1/product1/product1-large.jpg example.com/products/category1/product1/product2-large.jpg example.com/products/category1/product1/product3-large.jpg What is the best practice here regarding all possible considerations (for static non-CMS websites)? N.B. The names product1-large and product1-thumb are just examples in this context to illustrate what kind of images they are. It is advised to use descriptive filenames for SEO benefit.

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  • Inspiring the method of teaching. Example- C++ :)

    - by Ashwin
    A year ago I graduated with a degree in Computer Science and Engineering. Considering C++ as the first choice of programming language I have been in the process of learning C++ in many ways. At first - five years back - I had many conceptions, most of which were so abstract to me. It started when I knew almost everything about Structs in C and nothing about Classes in C++. I went through a great time experimenting them all and learning a lot. I had a hard time evaluating Procedural programming vs Object-Oriented Programming. Deciding when to choose Procedural or Object-Oriented Programming took a great deal of patience for me. I knew that I cannot underestimate any of these Programming styles... Though Procedural programming is often a better choice than simple sequential unstructured programming, when solving problems with procedural programming, we usually divide one problem into several steps in order regarded as functions. Then we call these functions one by one to get the result of the problem. When solving problems with Object Oriented Priciples we divide one problem into several classes and form the interaction between them. Evaluating these two at the beginning (as a learner) required a lot of inspiration and thoughts. Instructing to think step by step. Relative concepts to understand deeply. Intensive interests to contrast both solving in both POP and OOP. If you were ever a mentor: What ideas/methods would you teach to students in which it will Inspire them to learn a programming language (in general, computer sciences)?

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  • Hosting several HTTP servers on single domain name

    - by Nakilon
    Several people have got a single domain name server.company.com server, where they are now supposed to host their infrastructure or temporal projects, written in different ways even in different programming languages. How do they divide the domain? Split into subdomains: john.server.company.com, kate.server.company.com, etc. This would need a lot of admins' assistance, time, etc. -- there would be no way for John and Kate to do it themselves. Split into url namespaces: server.company.com/john/, server.company.com/kate/, etc. Pro: They now can make a single welcome page at root with any additional info (if they need?) Con: Each server would need to know their namespace string constant, and hrefs like / whould need patching. Split into ports: server.company.com:8080, server.company.com:8081, etc. and make a single :80 welcome page. Pro: They still can make a single welcome page at :80 Con: ??? I would like to know more pros and cons for 2 and 3 solution.

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  • Refactor or Concentrate on Completing App

    - by Jiew Meng
    Would you refactor your app as you go or focus on completing app first? Refactoring will mean progress of app app will slow down. Completing app will mean you get a possibly very hard to maintain app later on? The app is a personal project. I don't really know how to answer "What drives the functionality and design", but I guess it's to solve inefficiencies in current software out there. I like minimal easy to use software too. So I am removing some features and add some that I feel will help.

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  • Who should control navigation in an MVVM application?

    - by SonOfPirate
    Example #1: I have a view displayed in my MVVM application (let's use Silverlight for the purposes of the discussion) and I click on a button that should take me to a new page. Example #2: That same view has another button that, when clicked, should open up a details view in a child window (dialog). We know that there will be Command objects exposed by our ViewModel bound to the buttons with methods that respond to the user's click. But, what then? How do we complete the action? Even if we use a so-called NavigationService, what are we telling it? To be more specific, in a traditional View-first model (like URL-based navigation schemes such as on the web or the SL built-in navigation framework) the Command objects would have to know what View to display next. That seems to cross the line when it comes to the separation of concerns promoted by the pattern. On the other hand, if the button wasn't wired to a Command object and behaved like a hyperlink, the navigation rules could be defined in the markup. But do we want the Views to control application flow and isn't navigation just another type of business logic? (I can say yes in some cases and no in others.) To me, the utopian implementation of the MVVM pattern (and I've heard others profess this) would be to have the ViewModel wired in such a way that the application can run headless (i.e. no Views). This provides the most surface area for code-based testing and makes the Views a true skin on the application. And my ViewModel shouldn't care if it displayed in the main window, a floating panel or a child window, should it? According to this apprach, it is up to some other mechanism at runtime to 'bind' what View should be displayed for each ViewModel. But what if we want to share a View with multiple ViewModels or vice versa? So given the need to manage the View-ViewModel relationship so we know what to display when along with the need to navigate between views, including displaying child windows / dialogs, how do we truly accomplish this in the MVVM pattern?

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  • How do you track bugs in your personal projects?

    - by bedwyr
    I'm trying to decide if I need to reassess my defect-tracking process for my home-grown projects. For the last several years, I really just track defects using TODO tags in the code, and keeping track of them in a specific view (I use Eclipse, which has a decent tagging system). Unfortunately, I'm starting to wonder if this system is unsustainable. The defects I find are typically associated with a snippet of code I'm working on; bugs which are not immediately understood tend to be forgotten, or ignored. I wrote an application for my wife which has had a severe defect for almost 9 months, and I keep forgetting to fix it. What mechanism do you use to track defects in your personal projects? Do you have a specific system, or a process for prioritizing and managing them?

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  • Why is nesting or piggybacking errors within errors bad in general?

    - by dietbuddha
    Why is nesting or piggybacking errors within errors bad in general? To me it seems bad intuitively, but I'm suspicious in that I cannot adequately articulate why it is bad. This may be because it is not in general bad and that it is only bad in specific instances. Why is it detrimental to design error/exception handling in such a way. The specific instance is that of a REST service. There is a desire by some to use http errors (specifically the 500 response) as a way to indicate any problem with specific instances of a resource. An example of an instance resource in this case would be: http://server/ticket/80 # instance http://server/ticket # not an instance So this is the behavior that is being proposed. If ticket 80 does not exist return a http response code of 500. Within the body of the error return the "real" error as an additional error code and description. If the ticket resource doesn't exist return a response code of 404.

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  • How to export 3D models that consist of several parts (eg. turret on a tank)?

    - by Will
    What are the standard alternatives for the mechanics of attaching turrets and such to 3D models for use in-game? I don't mean the logic, but rather the graphics aspects. My naive approach is to extend the MD2-like format that I'm using (blender-exported using a script) to include a new set of properties for a mesh that: is anchored in another 'parent' mesh. The anchor is a point and normal in the parent mesh and a point and normal in the child mesh; these will always be colinear, giving the child rotation but not translation relative to the parent point. has a normal that is aligned with a 'target'. Classically this target is the enemy that is being engaged, but it might be some other vector e.g. 'the wind' (for sails and flags (and smoke, which is a particle system but the same principle applies)) or 'upwards' (e.g. so bodies of riders bend properly when riding a horse up an incline etc). that the anchor and target alignments have maximum and minimum and a speed coeff. there is game logic for multiple turrets and on a model and deciding which engages which enemy. 'primary' and 'secondary' or 'target0' ... 'targetN' or some such annotation will be there. So to illustrate, a classic tank would be made from three meshes; a main body mesh, a turret mesh that is anchored to the top of the main body so it can spin only horizontally and a barrel mesh that is anchored to the front of the turret and can only move vertically within some bounds. And there might be a forth flag mesh on top of the turret that is aligned with 'wind' where wind is a function the engine solves that merges environment's wind angle with angle the vehicle is travelling in an velocity, or something fancy. This gives each mesh one degree of freedom relative to its parent. Things with multiple degrees of freedom can be modelled by zero-vertex connecting meshes perhaps? This is where I think the approach I outlined begins to feel inelegant, yet perhaps its still a workable system? This is why I want to know how it is done in professional games ;) Are there better approaches? Are there formats that already include this information? Is this routine?

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  • How to write efficient code in spite of heavy deadlines

    - by gladysbixly
    Hi all, I am working in an environment wherein we have many projects with strict deadlines on deliverables. We even talk directly to the clients so getting the jobs done and fast is a must. My issue is that i'd always write code for the first solution that comes to my mind, which of course I thought as best at that moment. It always ends up ugly though and i'd later realize that there are better ways to do it but can't afford to change due to time restrictions. Are there any tips by which I could make my code efficient yet deliver on time?

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  • Should I modify an entity with many parameters or with the entity itself?

    - by Saeed Neamati
    We have a SOA-based system. The service methods are like: UpdateEntity(Entity entity) For small entities, it's all fine. However, when entities get bigger and bigger, to update one property we should follow this pattern in UI: Get parameters from UI (user) Create an instance of the Entity, using those parameters Get the entity from service Write code to fill the unchanged properties Give the result entity to the service Another option that I've experienced in previous experiences is to create semantic update methods for each update scenario. In other words instead of having one global all-encompasing update method, we had many ad-hoc parametric methods. For example, for the User entity, instead of having UpdateUser (User user) method, we had these methods: ChangeUserPassword(int userId, string newPassword) AddEmailToUserAccount(int userId, string email) ChangeProfilePicture(int userId, Image image) ... Now, I don't know which method is truly better, and for each approach, we encounter problems. I mean, I'm going to design the infrastructure for a new system, and I don't have enough reasons to pick any of these approaches. I couldn't find good resources on the Internet, because of the lack of keywords I could provide. What approach is better? What pitfalls each has? What benefits can we get from each one?

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  • Refactoring and Open / Closed principle

    - by Giorgio
    I have recently being reading a web site about clean code development (I do not put a link here because it is not in English). One of the principles advertised by this site is the Open Closed Principle: each software component should be open for extension and closed for modification. E.g., when we have implemented and tested a class, we should only modify it to fix bugs or to add new functionality (e.g. new methods that do not influence the existing ones). The existing functionality and implementation should not be changed. I normally apply this principle by defining an interface I and a corresponding implementation class A. When class A has become stable (implemented and tested), I normally do not modify it too much (possibly, not at all), i.e. If new requirements arrive (e.g. performance, or a totally new implementation of the interface) that require big changes to the code, I write a new implementation B, and keep using A as long as B is not mature. When B is mature, all that is needed is to change how I is instantiated. If the new requirements suggest a change to the interface as well, I define a new interface I' and a new implementation A'. So I, A are frozen and remain the implementation for the production system as long as I' and A' are not stable enough to replace them. So, in view of these observation, I was a bit surprised that the web page then suggested the use of complex refactorings, "... because it is not possible to write code directly in its final form." Isn't there a contradiction / conflict between enforcing the Open / Closed Principle and suggesting the use of complex refactorings as a best practice? Or the idea here is that one can use complex refactorings during the development of a class A, but when that class has been tested successfully it should be frozen?

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  • Notifications for Expiring DBSNMP Passwords

    - by Courtney Llamas
    Most user accounts these days have a password profile on them that automatically expires the password after a set number of days.   Depending on your company’s security requirements, this may be as little as 30 days or as long as 365 days, although typically it falls between 60-90 days. For a normal user, this can cause a small interruption in your day as you have to go get your password reset by an admin. When this happens to privileged accounts, such as the DBSNMP account that is responsible for monitoring database availability, it can cause bigger problems. In Oracle Enterprise Manager 12c you may notice the error message “ORA-28002: the password will expire within 5 days” when you connect to a target, or worse you may get “ORA-28001: the password has expired". If you wait too long, your monitoring will fail because the password is locked out. Wouldn’t it be nice if we could get an alert 10 days before our DBSNMP password expired? Thanks to Oracle Enterprise Manager 12c Metric Extensions (ME), you can! See the Oracle Enterprise Manager Cloud Control Administrator’s Guide for more information on Metric Extensions. To create a metric extension, select Enterprise / Monitoring / Metric Extensions, and then click on Create. On the General Properties screen select either Cluster Database or Database Instance, depending on which target you need to monitor.  If you have both RAC and Single instance you may need to create one for each. In this example we will create a Cluster Database metric.  Enter a Name for the ME and a Display Name. Then select SQL for the Adapter.  Adjust the Collection Schedule as desired, for this example we will collect this metric every 1 day. Notice for metric collected every day, we can determine the exact time we want to collect. On the Adapter page, enter the query that you wish to execute.  In this example we will use the query below that specifically checks for the DBSNMP user that is expiring within 10 days. Of course, you can adjust this query to alert for any user that can cause an outage such as an application account or service account such as RMAN. select username, account_status, trunc(expiry_date-sysdate) days_to_expirefrom dba_userswhere username = 'DBSNMP'and expiry_date is not null; The next step is to create the columns to store the data returned from the query.  Click Add and add a column for each of the fields in the same order that data is returned.  The table below will help you complete the column additions. Name Display Name Column Type Value Type Metric Category Unit Username User Name Key String Security AccountStatus Account Status Data String Security DaysToExpire Days Until Expiration Data Number Security Days When creating the DaysToExpire column, you can add a default threshold here for Warning and Critical (say < 10 and 5).  When all columns have been added, click Next. On the Credentials page, you can choose to use the default monitoring credentials or specify new credentials.  We will use the default credentials established for our target (dbsnmp). The next step is to test your Metric Extension.  Click on Add to select a target for testing, then click Select. Now click the button Run Test to execute the test against the selected target(s). We can see in the example below that the Metric Extension has executed and returned a value of 68 days to expire. Click Next to proceed. Review the metric extension in the final screen and click Finish. The metric will be created in Editable status.  Select the metric, click Actions and select Deployable Draft. You can do this once more to move to Published. Finally, we want to apply this metric to a target. When managing many targets, it’s best to add your metric to a template, for details on adding a Metric Extension to a template see the Administrator’s Guide. For this example, we will deploy this to a target directly. Select Actions / Deploy to Targets. Click Add and select the target you wish to deploy to and click Submit.  Once deployment is complete, we can go to the target and view the Metric & Collection Settings to see the new metric and its thresholds.   After some time, you will find the metric has collected and the days to expiration for DBSNMP user can be seen in the All Metrics view.   For metrics collected once per day, you may have to wait up to 24 hours to see the metric and current severity. In the example below, the current severity is Clear (green check) as it is not scheduled to expire within 10 days. To test the notification, we can edit the thresholds for the new metric so they trigger an alert.  Our password expires in 139 days, so we’ll change our Warning to 140 and leave Critical at 5, in our example we also changed the collection time to every 5 minutes.  At the next collection, you’ll find that the current severity changes to a Warning and any related Incident Rules would be triggered to create an Incident or Notification as desired. Now that you get a notification that your DBSNMP passwords is about to expire, you can use OEM Command Line Interface (EM CLI) verb update_db_password to change it at both the database target and the OEM target in one step.  The caveat is you must know the existing password to use the update_db_password command.  To learn more about EM CLI, see the Oracle Enterprise Manager Command Line Interface Guide.  Below is an example of changing the password with the update_db_password verb.  $ ./emcli update_db_password -target_name=emrep -target_type=oracle_database -user_name=dbsnmp -change_at_target=yes -change_all_references=yes Enter value for old_password :Enter value for new_password :Enter value for retype_new_password :Successfully submitted a job to change the password in Enterprise Manager and on the target database: "emrep"Execute "emcli get_jobs -job_id=FA66C1C4D663297FE0437656F20ACC84" to check the status of the job.Search for job name "CHANGE_PWD_JOB_FA66C1C4D662297FE0437656F20ACC84" on the Jobs home page to check job execution details. The subsequent job created will typically run quickly enough that a blackout is not needed, however if you submit a script with many targets to change, your job may run slower so adding a blackout to the script is recommended. $ ./emcli get_jobs -job_id=FA66C1C4D663297FE0437656F20ACC84 Name Type Job ID Execution ID Scheduled Completed TZ Offset Status Status ID Owner Target Type Target Name CHANGE_PWD_JOB_FA66C1C4D662297FE0437656F20ACC84 ChangePassword FA66C1C4D663297FE0437656F20ACC84 FA66C1C4D665297FE0437656F20ACC84 2014-05-28 09:39:12 2014-05-28 09:39:18 GMT-07:00 Succeeded 5 SYSMAN oracle_database emrep After implementing the above Metric Extension and using the EM CLI update_db_password verb, you will be able to stay on top of your DBSNMP password changes without experiencing an unplanned monitoring outage.  

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  • What are other ideologies to establish relationships between distinct users besides followers/following and friends?

    - by user784637
    Websites like myspace and facebook establish relationships between distinct users using the "friending" ideology, where one user sends a request to be accepted by another user in order for them to have the mutual permission to do stuff like post messages on each others walls. Less restrictive than the "friending" ideology, Twitter and instagram use the followers/following ideology where you can subscribe to the tweets or posts of another user without their permission. Less restrictive than the "followers/following" ideology, email and calling someone on the phone allows you to directly contact anyone. Are there other ideologies that have been successfully implemented either in social networking sites or other real world constructs to establish relations between users?

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  • Several domains using 302 redirect to our domain

    - by Yamaha32088
    I am wondering what implications we can run into if one of our dealers is redirecting several of their domains using a 302 to our domain. The reason they are doing this is because they want to have time to build on their current sites but still want some content on the domains they own. Currently our domain is under a Manual Penalty for back links that we are working on removing. I do not like the idea of them linking back to our site but I need logical reasons other than "because I don't want you to".

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  • Snake Game Help

    - by MuhammadA
    I am making a snake game and learning XNA at the same time. I have 3 classes : Game.cs, Snake.cs and Apple.cs My problem is more of a conceptual problem, I want to know which class is really responsible for ... detecting collision of snake head on apple/itself/wall? which class should increase the snakes speed, size? It seems to me that however much I try and put the snake stuff into snake.cs that game.cs has to know a lot about the snake, like : -- I want to increase the score depending on size of snake, the score variable is inside game.cs, which means now I have to ask the snake its size on every hit of the apple... seems a bit unclean all this highly coupled code. or -- I DO NOT want to place the apple under the snake... now the apple suddenly has to know about all the snake parts, my head hurts when I think of that. Maybe there should be some sort of AppleLayer.cs class that should know about the snake... Whats the best approach in such a simple scenario? Any tips welcome. Game.cs : using System; using System.Collections.Generic; using System.Linq; using Microsoft.Xna.Framework; using Microsoft.Xna.Framework.Audio; using Microsoft.Xna.Framework.Content; using Microsoft.Xna.Framework.GamerServices; using Microsoft.Xna.Framework.Graphics; using Microsoft.Xna.Framework.Input; using Microsoft.Xna.Framework.Media; using Microsoft.Xna.Framework.Design; namespace Snakez { public enum CurrentGameState { Playing, Paused, NotPlaying } public class Game1 : Microsoft.Xna.Framework.Game { private GraphicsDeviceManager _graphics; private SpriteBatch _spriteBatch; private readonly Color _niceGreenColour = new Color(167, 255, 124); private KeyboardState _oldKeyboardState; private SpriteFont _scoreFont; private SoundEffect _biteSound, _crashSound; private Vector2 _scoreLocation = new Vector2(10, 10); private Apple _apple; private Snake _snake; private int _score = 0; private int _speed = 1; public Game1() { _graphics = new GraphicsDeviceManager(this); Content.RootDirectory = "Content"; } /// <summary> /// Allows the game to perform any initialization it needs to before starting to run. /// This is where it can query for any required services and load any non-graphic /// related content. Calling base.Initialize will enumerate through any components /// and initialize them as well. /// </summary> protected override void Initialize() { base.Initialize(); } /// <summary> /// LoadContent will be called once per game and is the place to load /// all of your content. /// </summary> protected override void LoadContent() { _spriteBatch = new SpriteBatch(GraphicsDevice); _scoreFont = Content.Load<SpriteFont>("Score"); _apple = new Apple(800, 480, Content.Load<Texture2D>("Apple")); _snake = new Snake(Content.Load<Texture2D>("BodyBlock")); _biteSound = Content.Load<SoundEffect>("Bite"); _crashSound = Content.Load<SoundEffect>("Crash"); } /// <summary> /// UnloadContent will be called once per game and is the place to unload /// all content. /// </summary> protected override void UnloadContent() { Content.Unload(); } /// <summary> /// Allows the game to run logic such as updating the world, /// checking for collisions, gathering input, and playing audio. /// </summary> /// <param name="gameTime">Provides a snapshot of timing values.</param> protected override void Update(GameTime gameTime) { KeyboardState newKeyboardState = Keyboard.GetState(); if (newKeyboardState.IsKeyDown(Keys.Escape)) { this.Exit(); // Allows the game to exit } else if (newKeyboardState.IsKeyDown(Keys.Up) && !_oldKeyboardState.IsKeyDown(Keys.Up)) { _snake.SetDirection(Direction.Up); } else if (newKeyboardState.IsKeyDown(Keys.Down) && !_oldKeyboardState.IsKeyDown(Keys.Down)) { _snake.SetDirection(Direction.Down); } else if (newKeyboardState.IsKeyDown(Keys.Left) && !_oldKeyboardState.IsKeyDown(Keys.Left)) { _snake.SetDirection(Direction.Left); } else if (newKeyboardState.IsKeyDown(Keys.Right) && !_oldKeyboardState.IsKeyDown(Keys.Right)) { _snake.SetDirection(Direction.Right); } _oldKeyboardState = newKeyboardState; _snake.Update(); if (_snake.IsEating(_apple)) { _biteSound.Play(); _score += 10; _apple.Place(); } base.Update(gameTime); } /// <summary> /// This is called when the game should draw itself. /// </summary> /// <param name="gameTime">Provides a snapshot of timing values.</param> protected override void Draw(GameTime gameTime) { GraphicsDevice.Clear(_niceGreenColour); float frameRate = 1 / (float)gameTime.ElapsedGameTime.TotalSeconds; _spriteBatch.Begin(); _spriteBatch.DrawString(_scoreFont, "Score : " + _score, _scoreLocation, Color.Red); _apple.Draw(_spriteBatch); _snake.Draw(_spriteBatch); _spriteBatch.End(); base.Draw(gameTime); } } } Snake.cs : using System; using System.Collections.Generic; using System.Linq; using System.Text; using Microsoft.Xna.Framework.Graphics; using Microsoft.Xna.Framework; namespace Snakez { public enum Direction { Up, Down, Left, Right } public class Snake { private List<Rectangle> _parts; private readonly Texture2D _bodyBlock; private readonly int _startX = 160; private readonly int _startY = 120; private int _moveDelay = 100; private DateTime _lastUpdatedAt; private Direction _direction; private Rectangle _lastTail; public Snake(Texture2D bodyBlock) { _bodyBlock = bodyBlock; _parts = new List<Rectangle>(); _parts.Add(new Rectangle(_startX, _startY, _bodyBlock.Width, _bodyBlock.Height)); _parts.Add(new Rectangle(_startX + bodyBlock.Width, _startY, _bodyBlock.Width, _bodyBlock.Height)); _parts.Add(new Rectangle(_startX + (bodyBlock.Width) * 2, _startY, _bodyBlock.Width, _bodyBlock.Height)); _parts.Add(new Rectangle(_startX + (bodyBlock.Width) * 3, _startY, _bodyBlock.Width, _bodyBlock.Height)); _direction = Direction.Right; _lastUpdatedAt = DateTime.Now; } public void Draw(SpriteBatch spriteBatch) { foreach (var p in _parts) { spriteBatch.Draw(_bodyBlock, new Vector2(p.X, p.Y), Color.White); } } public void Update() { if (DateTime.Now.Subtract(_lastUpdatedAt).TotalMilliseconds > _moveDelay) { //DateTime.Now.Ticks _lastTail = _parts.First(); _parts.Remove(_lastTail); /* add new head in right direction */ var lastHead = _parts.Last(); var newHead = new Rectangle(0, 0, _bodyBlock.Width, _bodyBlock.Height); switch (_direction) { case Direction.Up: newHead.X = lastHead.X; newHead.Y = lastHead.Y - _bodyBlock.Width; break; case Direction.Down: newHead.X = lastHead.X; newHead.Y = lastHead.Y + _bodyBlock.Width; break; case Direction.Left: newHead.X = lastHead.X - _bodyBlock.Width; newHead.Y = lastHead.Y; break; case Direction.Right: newHead.X = lastHead.X + _bodyBlock.Width; newHead.Y = lastHead.Y; break; } _parts.Add(newHead); _lastUpdatedAt = DateTime.Now; } } public void SetDirection(Direction newDirection) { if (_direction == Direction.Up && newDirection == Direction.Down) { return; } else if (_direction == Direction.Down && newDirection == Direction.Up) { return; } else if (_direction == Direction.Left && newDirection == Direction.Right) { return; } else if (_direction == Direction.Right && newDirection == Direction.Left) { return; } _direction = newDirection; } public bool IsEating(Apple apple) { if (_parts.Last().Intersects(apple.Location)) { GrowBiggerAndFaster(); return true; } return false; } private void GrowBiggerAndFaster() { _parts.Insert(0, _lastTail); _moveDelay -= (_moveDelay / 100)*2; } } } Apple.cs : using System; using System.Collections.Generic; using System.Linq; using System.Text; using Microsoft.Xna.Framework.Graphics; using Microsoft.Xna.Framework; namespace Snakez { public class Apple { private readonly int _maxWidth, _maxHeight; private readonly Texture2D _texture; private readonly Random random = new Random(); public Rectangle Location { get; private set; } public Apple(int screenWidth, int screenHeight, Texture2D texture) { _maxWidth = (screenWidth + 1) - texture.Width; _maxHeight = (screenHeight + 1) - texture.Height; _texture = texture; Place(); } public void Place() { Location = GetRandomLocation(_maxWidth, _maxHeight); } private Rectangle GetRandomLocation(int maxWidth, int maxHeight) { // x and y -- multiple of 20 int x = random.Next(1, maxWidth); var leftOver = x % 20; x = x - leftOver; int y = random.Next(1, maxHeight); leftOver = y % 20; y = y - leftOver; return new Rectangle(x, y, _texture.Width, _texture.Height); } public void Draw(SpriteBatch spriteBatch) { spriteBatch.Draw(_texture, Location, Color.White); } } }

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  • Could someone break this nasty habit of mine please?

    - by MimiEAM
    I recently graduated in cs and was mostly unsatisfied since I realized that I received only a basic theoretical approach in a wide range of subjects (which is what college is supposed to do but still...) . Anyway I took the habit of spending a lot of time looking for implementations of concepts and upon finding those I will used them as guides to writing my own implementation of those concepts just for fun. But now I feel like the only way I can fully understand a new concept is by trying to implement from scratch no matter how unoptimized the result may be. Anyway this behavior lead me to choose by default the hard way, that is time consuming instead of using a nicely written library until I hit my head again a huge wall and then try to find a library that works for my purpose.... Does anyone else do that and why? It seems so weird why would anyone (including me) do that ? Is it a bad practice ? and if so how can i stop doing that ?

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  • Should we consider code language upon design?

    - by Codex73
    Summary This question aims to conclude if an applications usage will be a consideration when deciding upon development language. What factors if any could be considered upon language writing could be taken into context. Application Type: Web Question Of the following popular languages, when should we use one or the other? What factors if any could be considered upon language writing could be taken into context. Languages PHP Ruby Python My initial thought is that language shouldn't be considered as much as framework. Things to consider on framework are scalability, usage, load, portability, modularity and many more. Things to consider on Code Writing maybe cost, framework stability, community, etc.

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  • Heterogeneous Datacenter Management with Enterprise Manager 12c

    - by Joe Diemer
    The following is a Guest Blog, contributed by Bryce Kaiser, Product Manager at Blue MedoraWhen I envision a perfect datacenter, it would consist of technologies acquired from a single vendor across the entire server, middleware, application, network, and storage stack - Apps to Disk - that meets your organization’s every IT requirement with absolute best-of-breed solutions in every category.   To quote a familiar motto, your datacenter would consist of "Hardware and Software, Engineered to Work Together".  In almost all cases, practical realities dictate something far less than the IT Utopia mentioned above.   You may wish to leverage multiple vendors to keep licensing costs down, a single vendor may not have an offering in the IT category you need, or your preferred vendor may quite simply not have the solution that meets your needs.    In other words, your IT needs dictate a heterogeneous IT environment.  Heterogeneity, however, comes with additional complexity. The following are two pretty typical challenges:1) No End-to-End Visibility into the Enterprise Wide Application Deployment. Each vendor solution which is added to an infrastructure may bring its own tooling creating different consoles for different vendor applications and platforms.2) No Visibility into Performance Bottlenecks. When multiple management tools operate independently, you lose diagnostic capabilities including identifying cross-tier issues with database, hung-requests, slowness, memory leaks and hardware errors/failures causing DB/MW issues. As adoption of Oracle Enterprise Manager (EM) has increased, especially since the release of Enterprise Manager 12c, Oracle has seen an increase in the number of customers who want to leverage their investments in EM to manage non-Oracle workloads.  Enterprise Manager provides a single pane of glass view into their entire datacenter.  By creating a highly extensible framework via the Oracle EM Extensibility Development Kit (EDK), Oracle has provided the tooling for business partners such as my company Blue Medora as well as customers to easily fill gaps in the ecosystem and enhance existing solutions.  As mentioned in the previous post on the Enterprise Manager Extensibility Exchange, customers have access to an assortment of Oracle and Partner provided solutions through this Exchange, which is accessed at http://www.oracle.com/goto/emextensibility.  Currently, there are over 80 Oracle and partner provided plug-ins across the EM 11g and EM 12c versions.  Blue Medora is one of those contributing partners, for which you will find 3 of our solutions including our flagship plugin for VMware.  Let's look at Blue Medora’s VMware plug-in as an example to what I'm trying to convey.  Here is a common situation solved by true visibility into your entire stack:Symptoms•    My database is bogging down, however the database appears okay internally.  Maybe it’s starved for resources?•    My OS tooling is showing everything is “OK”.  Something doesn’t add up. Root cause•    Through the VMware plugin we can see the problem is actually on the virtualization layer Solution•    From within Enterprise Manager  -- the same tool you use for all of your database tuning -- we can overlay the data of the database target, host target, and virtual machine target for a true picture of the true root cause. Here is the console view: Perhaps your monitoring conditions are more specific to your environment.  No worries, Enterprise Manager still has you covered.  With Metric Extensions you have the “Next Generation” of User-Defined Metrics, which easily bring the power of your existing management scripts into a single console while leveraging the proven Enterprise Manager framework. Simply put, Oracle Enterprise manager boasts a growing ecosystem that provides the single pane of glass for your entire datacenter from the database and beyond.  Bryce can be contacted at [email protected]

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