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  • What are good reasons to use explicit interface implementation for the sole purpose of hiding members?

    - by Nathanus
    During one of my studies into the intricacies of C#, I came across an interesting passage concerning explicit interface implementation. While this syntax is quite helpful when you need to resolve name clashes, you can use explicit interface implementation simply to hide more "advanced" members from the object level. The difference between allowing the use of object.method() or requiring the casting of ((Interface)object).method() seems like mean-spirited obfuscation to my inexperienced eyes. The text noted that this will hide the method from Intellisense at the object level, but why would you want to do that if it was not necessary to avoid name conflicts?

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  • Identifying the best pattern

    - by Daniel Grillo
    I'm developing a software to program a device. I have some commands like Reset, Read_Version, Read_memory, Write_memory, Erase_memory. Reset and Read_Version are fixed. They don't need parameters. Read_memory and Erase_memory need the same parameters that are Length and Address. Write_memory needs Lenght, Address and Data. For each command, I have the same steps in sequence, that are something like this sendCommand, waitForResponse, treatResponse. I'm having difficulty to identify which pattern should I use. Factory, Template Method, Strategy or other pattern.

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  • Frames per Second and Updates per Second [on hold]

    - by matt murray
    So this is more a general resources question, as I am seeking knowledge on how best to conserve resources in a game (I am writing in Java, and please this is not a thread on what language I should write it in, I have already chosen Java) so that the updates and frames per second could be the highest they could be. In general I am just searching for any articles you may have, any personal experience, anything what so ever that could be of use to a pretty new Java game developer on the subject! Thanks in advance!

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  • Pattern for a class that does only one thing

    - by Heinzi
    Let's say I have a procedure that does stuff: void doStuff(initalParams) { ... } Now I discover that "doing stuff" is quite a compex operation. The procedure becomes large, I split it up into multiple smaller procedures and soon I realize that having some kind of state would be useful while doing stuff, so that I need to pass less parameters between the small procedures. So, I factor it out into its own class: class StuffDoer { private someInternalState; public Start(initalParams) { ... } // some private helper procedures here ... } And then I call it like this: new StuffDoer().Start(initialParams); or like this: new StuffDoer(initialParams).Start(); And this is what feels wrong. When using the .NET or Java API, I always never call new SomeApiClass().Start(...);, which makes me suspect that I'm doing it wrong. Sure, I could make StuffDoer's constructor private and add a static helper method: public static DoStuff(initalParams) { new StuffDoer().Start(initialParams); } But then I'd have a class whose external interface consists of only one static method, which also feels weird. Hence my question: Is there a well-established pattern for this type of classes that have only one entry point and have no "externally recognizable" state, i.e., instance state is only required during execution of that one entry point?

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  • Examples of Liskov Substitution

    - by james lewis
    I'm facilitating a session next week on the Liskov Substitution Principle and I was wondering if anyone had any examples of violations 'from the trenches'? I'm looking for something other than uncle Bob's rectangle - square problem and the persistent set problem he talks about in A-PPP (although that is a great example). So far I'm using the example of a (very simple) List and an IndexedList as the 'correct' use of inheritance. And the addition of a Set to this hierarchy as a violation (as a Set is distinct; strengthening the pre condition of the Add method). I've also taken this great example and it's solution from this question Both those examples are great but I'm looking for something more subtle and harder to spot. So far I've come up with nothing so if you've got a great, subtle example post it up. Also, any metaphors you've come across that helped you understand LSP would be really useful too.

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  • Does a mobile app need more access than the public API of a site?

    - by Iain
    I have a site with a public API, and some mobile app developers have been brought in to produce an iPhone app for the site. They insist they need to see the database schema, but as I understand it, they should only need access to the documented public API. Am I right? Is there something I've missed? I've told them that if there's a feature missing or data they require I can extend the API so that they can access it. I thought a web service API held to much the same principles as OOP object API's, in that the implementation details should be hidden as much as possible. I'm not a mobile app developer so if there is something I don't quite see then please let me know. Any insight or help will be much appreciated.

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  • Where can I hire local programmers with very specific skillsets?

    - by Lostsoul
    I have been browsing the site and haven't found a exact fit to this question so I'll post it but if its already answered(since I'm sure its a common problem, then let me know). I have a business and want to create a totally different product in a different industry than I'm currently in, so I learned how to program and created a working prototype. I have a bit of savings and am getting some cash flow from my current business so I can go out and hire a developer(in the future hopefully it can be permenant but right now I just need a person willing to work on contract and code on weekends or their spare time and I just want to pay in cash instead of equity or future promises). At first I wasn't sure what kind of developer to hire but this question helped me understand I should target specific skills I need as opposed to general programmers. This poses a problem for me since general programmers are everywhere but if I want specific skills I'm unsure how to get them. I thought about a list of approaches but it doesn't feel complete or effective since it seems to be assuming good developers are actively looking. If it helps I want someone local(since this is my first developer hire) and looking for skills like cuda, hadoop, hbase, java and c. Any suggestions? As a FYI, I have been thinking of approaching it as: Go to meet ups for one or more skills I need. Use LinkedIn to find people with the skills I need Search for job postings that contain skills I need and then use linkedIn to reach out to that firms employees since many profiles on linkedin are not very updated or detailed but job postings generally are. Send postings to universities and maybe find a student who loves technology so much they learned these tools on their own. Post on job board. Not sure how successful it will be to post to monster. Use Craigslist, not sure if a highly skilled developer would go here for work. What am I missing? I could be wrong but it seems like good/smart/able developers aren't hunting for work non-stop(especially in this tech job market). Plus most successful people I know have work/life balance so I'm not sure if the best ones really care about code after work. Lastly, most of the skills I need aren't used in big corporations so not sure how aggressively smart developers at small shops look for work. I don’t really know any developers personally, so but should I be using the above plan or if they live balanced lives should I be looking outside of the regular resources(and instead focus on asking around my gym or my accountant or something)? Sorry, I'm making huge assumptions here, I guess because developers are a total mystery to me. I kind of wish Jane Goodall wrote a book on understanding developers social behaviour better :-p

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  • Can you point me to a nontrivial strategy pattern implementation?

    - by Eugen Martynov
    We are faced implementing a registration workflow with many branches. There are three main flows which in some conditions lead to one another. Each flow has at least four different steps; some steps interact with the server, and every step adds more information to the state. Also the requirement is to have it persistent between sessions, so if the user closes the app (this is a mobile app), it will restore the process from the last completed step with the state from the previous session. I think this could benefit from the use of the strategy pattern, but I've never had to implement it for such a complex case. Does anyone know of any examples in open source or articles from which I could find inspiration? Preferably the examples would be from a live/working/stable application. I'm interested in Java implementation mostly; we are developing for Java mobile phones: android, blackberry and J2ME. We have an SDK which is quite well separated from platform specific implementations, but examples in C++, C#, Objective-C or Python would be acceptable.

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  • Which is the most practical way to add functionality to this piece of code?

    - by Adam Arold
    I'm writing an open source library which handles hexagonal grids. It mainly revolves around the HexagonalGrid and the Hexagon class. There is a HexagonalGridBuilder class which builds the grid which contains Hexagon objects. What I'm trying to achieve is to enable the user to add arbitrary data to each Hexagon. The interface looks like this: public interface Hexagon extends Serializable { // ... other methods not important in this context <T> void setSatelliteData(T data); <T> T getSatelliteData(); } So far so good. I'm writing another class however named HexagonalGridCalculator which adds some fancy pieces of computation to the library like calculating the shortest path between two Hexagons or calculating the line of sight around a Hexagon. My problem is that for those I need the user to supply some data for the Hexagon objects like the cost of passing through a Hexagon, or a boolean flag indicating whether the object is transparent/passable or not. My question is how should I implement this? My first idea was to write an interface like this: public interface HexagonData { void setTransparent(boolean isTransparent); void setPassable(boolean isPassable); void setPassageCost(int cost); } and make the user implement it but then it came to my mind that if I add any other functionality later all code will break for those who are using the old interface. So my next idea is to add annotations like @PassageCost, @IsTransparent and @IsPassable which can be added to fields and when I'm doing the computation I can look for the annotations in the satelliteData supplied by the user. This looks flexible enough if I take into account the possibility of later changes but it uses reflection. I have no benchmark of the costs of using annotations so I'm a bit in the dark here. I think that in 90-95% of the cases the efficiency is not important since most users wont't use a grid where this is significant but I can imagine someone trying to create a grid with a size of 5.000.000.000 X 5.000.000.000. So which path should I start walking on? Or are there some better alternatives? Note: These ideas are not implemented yet so I did not pay too much attention to good names.

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  • Get Info From Database, or Build Inferred Info?

    - by Zaemz
    Does it make more sense to store and retrieve properties or information directly related to an item in a database, or, say in such a case that a product's ID could describe information about it, should the information be gathered from that? Example: Item SKU -- 4HBU12 4 - is the number of motors H - the voltage B - the color, blue U - the model 12 - the length Should I store those individual attributes as well as the SKU, or should I store only the SKU and build the attributes from it?

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  • Ensuring non conflicting components in a modular system

    - by Hailwood
    So lets say we are creating a simple "modular system" framework. The bare bones might be the user management. But we want things like the Page Manager, the Blog, the Image Gallery to all be "optional" components. So a developer could install the Page Manager to allow their client to add a static home page and about page with content they can easily edit with a wysiwyg editor. The developer could then also install the Blog component to allow the client to add blog entries. The developer could then also install the Gallery component to allow the client to show off a bunch of images. The thing is, all these components are designed to be independent, so how do we go about ensuring they don't clash? E.g. ensuring the client doesn't create a /gallery page with the Page Manager and then wonder why the gallery stopped working, or the same issue with the Blog component, assuming we allow the users to customize the URL structure of the blog (because remember, the Page Manager doesn't necessarily have to be there, so we might not wan't our blog posts to be Date/Title formatted), likewise our clients aren't always going to be happy to have their pages under pages/title formatting. My core question here is, when building a modular system how to we ensure that the modules don't conflict without restricting functionality? Do we just leave it up to the clients/developer using the modules to ensure they get setup in a way that does not conflict?

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  • What's a good tool for Scrum Project Management in game development? [closed]

    - by BleakCabalist
    I'm looking for an efficient, easy-to-learn tool for Scrum project management not for proffesional use but to use it in my thesis concerning the use of Scrum in game development. Basically I want to visualize a production process of a hypothetical game. Some fragments of the production process should be really detailed to make my point, so basically user stories, tasks, burndown charts etc. are a must. I'm using Scrum, Kanban and some Lean practices for eliminating waste. I also want to use Extreme Programming practices in this production process including TDD and Continuous Integration. I have zero experience in proffesional project management so I need something that's fairly simple to use for a newb like me. Anyone can recommend a tool like that? For now I was thinking about TargetProcess and ScrumWorks. Thanks.

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  • Is is common to use the command pattern for property get/sets?

    - by k rey
    Suppose I have a controller class with a bunch of properties. Each time a property is changed, I would like to update the model. Now also suppose that I use the command pattern to perform model updates. Is it common to use command classes within property get and sets of the controller class or is there a better way? Here is an example of what I am currently using: class MyController { private int _myInt; public int MyInt { get { return _myInt; } set { MyCommand cmd = new MyCommand(); cmd.Argument = _myInt; cmd.Execute(); // Command object updates the model } } }

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  • What is the best way to diagrammatically represent a system threading architecture?

    - by thegreendroid
    I am yet to find the perfect way to diagrammatically represent the overall threading architecture for a system (using UML or otherwise). I am after a diagramming technique that would show all the threads in a given system and how they interact with each other. There are a few similar questions - Drawing Thread Interaction, UML Diagrams of Multithreaded Applications and Intuitive UML Approach to Depict Threads but they don't fully answer my question. What are some of the techniques that you've found useful to depict the overall threading architecture for a system?

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  • How do I know when should I package my classes in Ruby?

    - by Omega
    In Ruby, I'm creating a small game development framework. Just some personal project - a very small group of friends helping. Now I am in need of handling geometric concepts. Rectangles, Circles, Polygons, Vectors, Lines, etc. So I made a class for each of these. I'm stuck deciding whether I should package such classes in a module, such as Geometry. So I'd access them like Geometry::Rectangle, or just Rectangle if I include the module. Now then, my question isn't about this specific scenario. I'd like to know, when is it suitable to package similar classes into one module in Ruby? What factors should I consider? Amount of classes? Usage frequency? Complexity?

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  • How do I start correctly in building database classes in c#?

    - by e4rthdog
    I am new in C# programming and in OOP. I need to dive into web applications for my company, and I need to do it fast and correct. So even that I know ASP.NET MVC is the way to go, I want to start with some simple applications with ASP.NET Webforms and then advance to MVC logic. Also regarding my db classes: I plan to create common database classes in order to be able to use them either from WinForms or ASP.NET applications. I also know that the way to go is to learn about ORM and EF. BUT I also want to start from where I am feeling comfortable and that is the traditional ADO.NET way. So about my Data Access Layer classes: Should I return my results in datasets or arraylists/lists? Should my methods do their own connect/disconnect from the db, or have separate methods and let the application maintain the connection?

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  • Comparison of languages by usage type?

    - by Tom
    Does anyone know of a good place to go find comparisons of programming languages by the intended platform/usage? Basically, what I want to know, is of the more popular languages, which ones are meant for high level application development, low level system development, mobile development, web, etc. If there's a good listing out there already, I'm not finding it so far. Does anyone know of a place that would have this? Thanks.

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  • When do domain concepts become application constructs?

    - by Noren
    I recently posted a question regarding recovering a DDD architecture that became an anemic domain model into a multitier architecture and this question is a follow-on of sorts. My question is when do domain concepts become application constructs. My application is a local client C# 4/WPF with the following architecture: Presentation Layer Views ViewModels Business Layer ??? Domain Layer Classes that take the POCOs with primitive types and create domain concepts (e.g. image, layer, etc) Sanity checks values (e.g. image width 0) Interfaces for DTOs Interface for a repository that abstracts the filesystem Data Access Layer Classes that parse the proprietary binary files into POCOs with primitive types by explicit knowledge of the file format Implementation of domain DTOs Implementation of domain repository class Local Filesystem Proprietary binary files When does the MyImageType domain class with Int32 width, height, and Int32[] pixels become a System.Windows.Media.ImageDrawing? If I put it in the domain layer, it seems like implemenation details are being leaked (what if I didn't want to use WPF?). If I put it in the presentation layer, it seems like it's doing too much. If I create a business layer, it seems like it would be doing too little since there are few "rules" given the CRUD nature of the application. I think all of my reading has lead to analysis paralysis, so I thought fresh eyes might lend some perspective.

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  • What Type of Options should be on the Game Settings Menu?

    - by A13X
    I have seen a post about the main menu options here: UI: Main Menu options for mobile games. What options should be listed? What do users want to see? But I want to know what kind of options should/need to be available on the settings screen. I am making a rather simple 2D game for Android, but really I haven't found many aspects that warrant an options button or a check box besides turning the sound and music on/off. I was thinking graphics settings but then again, how many apps really need graphics settings besides immersive 3D ones?

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  • Improving Click and Drag with C++

    - by Josh
    I'm currently using SFML 2.0 to develop a game in C++. I have a game sprite class that has a click and drag method. The method works, but there is a slight problem. If the mouse moves too fast, the object the user selected can't keep up and is left behind in the spot where the mouse left its bounds. I will share the class definition and the given function implementation. Definition: class codePeg { protected: FloatRect bounds; CircleShape circle; int xPos, yPos, xDiff, yDiff, once; int xBase, yBase; Vector2i mousePos; Vector2f circlePos; public: void init(RenderWindow& Window); void draw(RenderWindow& Window); void drag(RenderWindow& Window); void setPegPosition(int x, int y); void setPegColor(Color pegColor); void mouseOver(RenderWindow& Window); friend int isPegSelected(void); }; Implementation of the "drag" function: void codePeg::drag(RenderWindow& Window) { mousePos = Mouse::getPosition(Window); circlePos = circle.getPosition(); if(Mouse::isButtonPressed(Mouse::Left)) { if(mousePos.x > xPos && mousePos.y > yPos && mousePos.x - bounds.width < xPos && mousePos.y - bounds.height < yPos) { if(once) { xDiff = mousePos.x - circlePos.x; yDiff = mousePos.y - circlePos.y; once = 0; } xPos = mousePos.x - xDiff; yPos = mousePos.y - yDiff; circle.setPosition(xPos, yPos); } } else { once = 1; xPos = xBase; yPos = yBase; xDiff = 0; yDiff = 0; circle.setPosition(xBase, yBase); } Window.draw(circle); } Like I said, the function works, but to me, the code is very ugly and I think it could be improved and could be more efficient. The only thing I can think of as to why the object cannot keep up with the mouse is that there are too many function calls and/or checks. The user does not really have to mouse the mouse "fast" for it to happen, I would say at an average pace the object is left behind. How can I improve the code so that the object remains with the mouse when it is selected? Any help improving this code or giving advice is greatly appreciated.

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  • Vernon's book Implementing DDD and modeling of underlying concepts

    - by EdvRusj
    Following questions all refer to examples presented in Implementing DDD In article we can see from Figure 6 that both BankingAccount and PayeeAccount represent the same underlying concept of Banking Account BA 1. On page 64 author gives an example of a publishing organization, where the life-cycle of a book goes through several stages ( proposing a book, editorial process, translation of the book ... ) and at each of those stages this book has a different definition. Each stage of the book is defined in a different Bounded Context, but do all these different definitions still represent the same underlying concept of a Book, just like both BankingAccount and PayeeAccount represent the same underlying concept of a BA? 2. a) I understand why User shouldn't exist in Collaboration Context ( CC ), but instead should be defined within Identity and Access Context IAC ( page 65 ). But still, do User ( IAC ), Moderator ( CC ), Author ( CC ),Owner ( CC ) and Participant ( CC ) all represent different aspects of the same underlying concept? b) If yes, then this means that CC contains several model elements ( Moderator, Author, Owner and Participant ), each representing different aspect of the same underlying concept ( just like both BankingAccount and PayeeAccount represent the same underlying concept of a BA ). But isn't this considered a duplication of concepts ( Evan's book, page 339 ), since several model elements in CC represent the same underlying concept? c) If Moderator, Author ... don't represent the same underlying concept, then what underlying concept does each represent? 3. In an e-commerce system, the term Customer has multiple meanings ( page 49 ): When user is browsing the Catalog, Customer has different meaning than when user is placing an Order. But do these two different definitions of a Customer represent the same underlying concept, just like both BankingAccount and PayeeAccount represent the same underlying concept of a BA? thanks

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  • How do I explain the importance of NUNIT Test cases to my Colleagues [duplicate]

    - by JNL
    This question already has an answer here: How to explain the value of unit testing 6 answers I am currently working in Software Development for applications including lot of Mathematical Calculations. As a result there are lot of test cases that we need to consider. We donot have any NUNIT Test case system, I am wonderring how should I get the advantages of implementing the NUNIT testing in front of my colleagues and my boss. I am pretty sure, it would be of great help for our team. Any help regarding the same, will be higly appreciated.

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  • How to manage long running background threads and report progress with DDD

    - by Mr Happy
    Title says most of it. I have found surprising little information about this. I have a long running operation of which the user wants to see the progress (as in, item x of y processed). I also need to be able to pause and stop the operation. (Stopping doesn't rollback the items already processed.) The thing is, it's not that each item takes a long time to get processed, it's that that there are usually a lot of items. And what I've read about so far is that it's somewhat of an anti-pattern to put something like a queue in the DB. I currently don't have any messaging system in place, and I've never worked with one either. Another thing I read somewhere is that progress reporting is something that belongs in the application layer, but it didn't go into the details. So having said all this, what I have in mind is the following. User request with list of items enters the application layer. Application layer gets some information from the domain needed to process the items. Application layer passes the items and the information off to some domain service (should the implementation of this service belong in the infrastructure layer?) This service spins up a worker thread with callbacks for both progress reporting and pausing/stopping it. This worker thread will process each item in it's own UoW. This means the domain information from earlier needs to be stored in some DTO. Since nothing is really persisted, the service should be singleton and thread safe Whenever a user requests a progress report or wants to pause/stop the operation, the application layer will ask the service. Would this be a correct solution? Or am I at least on the right track with this? Especially the singleton and thread safe part makes the whole thing feel icky.

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  • Best Creational Pattern for loggers in a multi-threaded system?

    - by Dipan Mehta
    This is a follow up question on my past questions : Concurrency pattern of logger in multithreaded application As suggested by others, I am putting this question separately. As the learning from the last question. In a multi-threaded environment, the logger should be made thread safe and probably asynchronous (where in messages are queued while a background thread does writing releasing the requesting object thread). The logger could be signleton or it can be a per-group logger which is a generalization of the above. Now, the question that arise is how does logger should be assigned to the object? There are two options I can think of: 1. Object requesting for the logger: Should each of the object call some global API such as get_logger()? Such an API returns "the" singleton or the group logger. However, I feel this involves assumption about the Application environment to implement the logger -which I think is some kind of coupling. If the same object needs to be used by other application - this new application also need to implement such a method. 2. Assign logger through some known API The other alternative approach is to create a kind of virtual class which is implemented by application based on App's own structure and assign the object sometime in the constructor. This is more generalized method. Unfortunately, when there are so many objects - and rather a tree of objects passing on the logger objects to each level is quite messy. My question is there a better way to do this? If you need to pick any one of the above, which approach is would you pick and why? Other questions remain open about how to configure them: How do objects' names or ID are assigned so that will be used for printing on the log messages (as the module names) How do these objects find the appropriate properties (such as log levels, and other such parameters) In the first approach, the central API needs to deal with all this varieties. In the second approach - there needs to be additional work. Hence, I want to understand from the real experience of people, as to how to write logger effectively in such an environment.

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  • What is meant by, "A user shouldn't decide whether it is an Admin or not. The Privileges or Security system should."

    - by GlenPeterson
    The example used in the question pass bare minimum data to a function touches on the best way to determine whether the user is an administrator or not. One common answer was: user.isAdmin() This prompted a comment which was repeated several times and up-voted many times: A user shouldn't decide whether it is an Admin or not. The Privileges or Security system should. Something being tightly coupled to a class doesn't mean it is a good idea to make it part of that class. I replied, The user isn't deciding anything. The User object/table stores data about each user. Actual users don't get to change everything about themselves. But this was not productive. Clearly there is an underlying difference of perspective which is making communication difficult. Can someone explain to me why user.isAdmin() is bad, and paint a brief sketch of what it looks like done "right"? Really, I fail to see the advantage of separating security from the system that it protects. Any security text will say that security needs to be designed into a system from the beginning and considered at every stage of development, deployment, maintenance, and even end-of-life. It is not something that can be bolted on the side. But 17 up-votes so far on this comment says that I'm missing something important.

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