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  • Best Practices in .NET XML Serialization of Complex Classes

    This article will show you XML serialization, so simply added in code, is not a magical stick. Serialization must be planned in full detail when working with complex classes, rather than expected to work by itself. Loss of planning work leads to redesign work later on, when maintaining serialization of original classes becomes too expensive or even hits the limit after which serialization of original classes is not possible without loss of data.

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  • How can I cleanly and elegantly handle data and dependancies between classes

    - by Neophyte
    I'm working on 2d topdown game in SFML 2, and need to find an elegant way in which everything will work and fit together. Allow me to explain. I have a number of classes that inherit from an abstract base that provides a draw method and an update method to all the classes. In the game loop, I call update and then draw on each class, I imagine this is a pretty common approach. I have classes for tiles, collisions, the player and a resource manager that contains all the tiles/images/textures. Due to the way input works in SFML I decided to have each class handle input (if required) in its update call. Up until now I have been passing in dependencies as needed, for example, in the player class when a movement key is pressed, I call a method on the collision class to check if the position the player wants to move to will be a collision, and only move the player if there is no collision. This works fine for the most part, but I believe it can be done better, I'm just not sure how. I now have more complex things I need to implement, eg: a player is able to walk up to an object on the ground, press a key to pick it up/loot it and it will then show up in inventory. This means that a few things need to happen: Check if the player is in range of a lootable item on keypress, else do not proceed. Find the item. Update the sprite texture on the item from its default texture to a "looted" texture. Update the collision for the item: it might have changed shape or been removed completely. Inventory needs to be updated with the added item. How do I make everything communicate? With my current system I will end up with my classes going out of scope, and method calls to each other all over the place. I could tie up all the classes in one big manager and give each one a reference to the parent manager class, but this seems only slightly better. Any help/advice would be greatly appreciated! If anything is unclear, I'm happy to expand on things.

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  • Entity Framework equivalence for NHibernte SchemaExport

    - by jbandi
    Is there an equivalence in Entity Framework to NHibernate SchemaExport? Given I have a working Entity-Model, I would like to programmatically initialize a database. I would like to use this functionality in the setup of my integration tests. Creating the matching DDL for an Entity-Model would also suffice.

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  • How to Buy an SD Card: Speed Classes, Sizes, and Capacities Explained

    - by Chris Hoffman
    Memory cards are used in digital cameras, music players, smartphones, tablets, and even laptops. But not all SD cards are created equal — there are different speed classes, physical sizes, and capacities to consider. Different devices require different types of SD cards. Here are the differences you’ll need to keep in mind when picking out the right SD card for your device. Speed Class In a nutshell, not all SD cards offer the same speeds. This matters for some tasks more than it matters for others. For example, if you’re a professional photographer taking photos in rapid succession on a DSLR camera saving them in high-resolution RAW format, you’ll want a fast SD card so your camera can save them as fast as possible. A fast SD card is also important if you want to record high-resolution video and save it directly to the SD card. If you’re just taking a few photos on a typical consumer camera or you’re just using an SD card to store some media files on your smartphone, the speed isn’t as important. Manufacturers use “speed classes” to measure an SD card’s speed. The SD Association that defines the SD card standard doesn’t actually define the exact speeds associated with these classes, but they do provide guidelines. There are four different speed classes — 10, 8, 4, and 2. 10 is the fastest, while 2 is the slowest. Class 2 is suitable for standard definition video recording, while classes 4 and 6 are suitable for high-definition video recording. Class 10 is suitable for “full HD video recording” and “HD still consecutive recording.” There are also two Ultra High Speed (UHS) speed classes, but they’re more expensive and are designed for professional use. UHS cards are designed for devices that support UHS. Here are the associated logos, in order from slowest to fastest:       You’ll probably be okay with a class 4 or 6 card for typical use in a digital camera, smartphone, or tablet. Class 10 cards are ideal if you’re shooting high-resolution videos or RAW photos. Class 2 cards are a bit on the slow side these days, so you may want to avoid them for all but the cheapest digital cameras. Even a cheap smartphone can record HD video, after all. An SD card’s speed class is identified on the SD card itself. You’ll also see the speed class on the online store listing or on the card’s packaging when purchasing it. For example, in the below photo, the middle SD card is speed class 4, while the two other cards are speed class 6. If you see no speed class symbol, you have a class 0 SD card. These cards were designed and produced before the speed class rating system was introduced. They may be slower than even a class 2 card. Physical Size Different devices use different sizes of SD cards. You’ll find standard-size CD cards, miniSD cards, and microSD cards. Standard SD cards are the largest, although they’re still very small. They measure 32x24x2.1 mm and weigh just two grams. Most consumer digital cameras for sale today still use standard SD cards. They have the standard “cut corner”  design. miniSD cards are smaller than standard SD cards, measuring 21.5x20x1.4 mm and weighing about 0.8 grams. This is the least common size today. miniSD cards were designed to be especially small for mobile phones, but we now have a smaller size. microSD cards are the smallest size of SD card, measuring 15x11x1 mm and weighing just 0.25 grams. These cards are used in most cell phones and smartphones that support SD cards. They’re also used in many other devices, such as tablets. SD cards will only fit into marching slots. You can’t plug a microSD card into a standard SD card slot — it won’t fit. However, you can purchase an adapter that allows you to plug a smaller SD card into a larger SD card’s form and fit it into the appropriate slot. Capacity Like USB flash drives, hard drives, solid-state drives, and other storage media, different SD cards can have different amounts of storage. But the differences between SD card capacities don’t stop there. Standard SDSC (SD) cards are 1 MB to 2 GB in size, or perhaps 4 GB in size — although 4 GB is non-standard. The SDHC standard was created later, and allows cards 2 GB to 32 GB in size. SDXC is a more recent standard that allows cards 32 GB to 2 TB in size. You’ll need a device that supports SDHC or SDXC cards to use them. At this point, the vast majority of devices should support SDHC. In fact, the SD cards you have are probably SDHC cards. SDXC is newer and less common. When buying an SD card, you’ll need to buy the right speed class, size, and capacity for your needs. Be sure to check what your device supports and consider what speed and capacity you’ll actually need. Image Credit: Ryosuke SEKIDO on Flickr, Clive Darra on Flickr, Steven Depolo on Flickr

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  • Free C# Online Classes

    Now you can learn C language online from expert teachers of WiZiQ. These are Free Online Classes on C# which are scheduled on different timings. You can join the class as per your convenience.  Below are some of the topics which are covered in the classes:Programming with Collections in C#.NETIntroduction to Complex NumbersC++ Fundamental 2C++ ProgrammingThe recordings of these classes are also available which you can view anytime. ...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Where should instantiated classes be stored?

    - by Eric C.
    I'm having a bit of a design dilemma here. I'm writing a library that consists of a bunch of template classes that are designed to be used as a base for creating content. For example: public class Template { public string Name {get; set;} public string Description {get; set;} public string Attribute1 {get; set;} public string Attribute2 {get; set;} public Template() { //constructor } public void DoSomething() { //does something } ... } The problem is, not only is the library providing the templates, it will also supply quite a few predefined templates which are instances of these template classes. The question is, where do I put these instances of the templates? The three solutions I've come up with so far are: 1) Provide serialized instances of the templates as files. On the one hand, this solution would keep the instances separated from the library itself, which is nice, but it would also potentially add complexity for the user. Even if we provided methods for loading/deserializing the files, they'd still have to deal with a bunch of files, and some kind of config file so the app knows where to look for those files. Plus, creating the template files would probably require a separate app, so if the user wanted to stick with the files method of storing templates, we'd have to provide some kind of app for creating the template files. Also, this requires external dependencies for testing the templates in the user's code. 2) Add readonly instances to the template class Example: public class Template { public string Name {get; set;} public string Description {get; set;} public string Attribute1 {get; set;} public string Attribute2 {get; set;} public Template PredefinedTemplate { get { Template templateInstance = new Template(); templateInstance.Name = "Some Name"; templateInstance.Description = "A description"; ... return templateInstance; } } public Template() { //constructor } public void DoSomething() { //does something } ... } This method would be convenient for users, as they would be able to access the predefined templates in code directly, and would be able to unit test code that used them. The drawback here is that the predefined templates pollute the Template type namespace with a bunch of extra stuff. I suppose I could put the predefined templates in a different namespace to get around this drawback. The only other problem with this approach is that I'd have to basically duplicate all the namespaces in the library in the predefined namespace (e.g. Templates.SubTemplates and Predefined.Templates.SubTemplates) which would be a pain, and would also make refactoring more difficult. 3) Make the templates abstract classes and make the predefined templates inherit from those classes. For example: public abstract class Template { public string Name {get; set;} public string Description {get; set;} public string Attribute1 {get; set;} public string Attribute2 {get; set;} public Template() { //constructor } public void DoSomething() { //does something } ... } and public class PredefinedTemplate : Template { public PredefinedTemplate() { this.Name = "Some Name"; this.Description = "A description"; this.Attribute1 = "Some Value"; ... } } This solution is pretty similar to #2, but it ends up creating a lot of classes that don't really do anything (none of our predefined templates are currently overriding behavior), and don't have any methods, so I'm not sure how good a practice this is. Has anyone else had any experience with something like this? Is there a best practice of some kind, or a different/better approach that I haven't thought of? I'm kind of banging my head against a wall trying to figure out the best way to go. Thanks!

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  • creating a contact listener with sprites from different classes

    - by wilM
    I've been trying to set a contact listener that creates a joint on contact between two sprites which have their own individual classes. Both sprites are inheriting from NSObject and their are initialized in their parentlayer (init method of HelloWorldLayer.mm). It is quite straightforward when everything is in the same class, but in a case like this where sprites have their own classes how will it be done. Please Help, I've been at it for days.

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  • Adding Attributes to Generated Classes

    ASP.NET MVC 2 adds support for data annotations, implemented via attributes on your model classes.  Depending on your design, you may be using an OR/M tool like Entity Framework or LINQ-to-SQL to generate your entity classes, and you may further be using these entities directly as your Model.  This is fairly common, and alleviates the need to do mapping between POCO domain objects and such entities (though there are certainly pros and cons to using such entities directly). As an example, the current version of the NerdDinner application (available on CodePlex at nerddinner.codeplex.com) uses Entity Framework for its model.  Thus, there is a NerdDinner.edmx file in the project, and a generated NerdDinner.Models.Dinner class.  Fortunately, these generated classes are marked as partial, so you can extend their behavior via your own partial class in a separate file.  However, if for instance the generated Dinner class has a property Title of type string, you cant then add your own Title of type string for the purpose of adding data annotations to it, like this: public partial class Dinner { [Required] public string Title { get;set; } } This will result in a compilation error, because the generated Dinner class already contains a definition of Title.  How then can we add attributes to this generated code?  Do we need to go into the T4 template and add a special case that says if were generated a Dinner class and it has a Title property, add this attribute?  Ick. MetadataType to the Rescue The MetadataType attribute can be used to define a type which contains attributes (metadata) for a given class.  It is applied to the class you want to add metadata to (Dinner), and it refers to a totally separate class to which youre free to add whatever methods and properties you like.  Using this attribute, our partial Dinner class might look like this: [MetadataType(typeof(Dinner_Validation))] public partial class Dinner {}   public class Dinner_Validation { [Required] public string Title { get; set; } } In this case the Dinner_Validation class is public, but if you were concerned about muddying your API with such classes, it could instead have been created as a private class within Dinner.  Having the validation attributes specified in their own class (with no other responsibilities) complies with the Single Responsibility Principle and makes it easy for you to test that the validation rules you expect are in place via these annotations/attributes. Thanks to Julie Lerman for her help with this.  Right after she showed me how to do this, I realized it was also already being done in the project I was working on. Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • When do you use a struct instead of a class?

    - by jkohlhepp
    What are your rules of thumb for when to use structs vs. classes? I'm thinking of the C# definition of those terms but if your language has similar concepts I'd like to hear your opinion as well. I tend to use classes for almost everything, and use structs only when something is very simplistic and should be a value type, such as a PhoneNumber or something like that. But this seems like a relatively minor use and I hope there are more interesting use cases.

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  • Design: classes with same implementation but different method names

    - by Dror Helper
    I have multiple classes that have similar implementation for different named methods: class MyClassX { public int MyClassXIntMethod(){} public string MyClassXStringMethod(){} } class MyClassY { public int MyClassYIntMethod(){} public string MyClassYStringMethod(){} } the methods inside the classes have similar implementation but because the method's names are different (due to 3rd party constraints) i cannot use inheritance. I'm looking for an elegant solution that would be better than implementing the same functionality over and over again.

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  • Chaining CSS classes in IE6 - Trying to find a jQuery solution?

    - by Mike Baxter
    Right, perhaps I ask the impossible? I consider myself fairly new to Javscript and jQuery, but that being said, I have written some fairly complex code recently so I am definitely getting there... however I am now possed with a rather interesting issue at my current freelance contract. The previous web coder has taken a Grid-960 approach to the HTML and as a result has used chained classes to style many of the elements. The example below is typical of what can be found in the code: <div class='blocks four-col-1 orange highlight'>Some content</div> And in the css there will be different declarations for: (not actual css... but close enough) .blocks {margin-right:10px;} .orange {background-image:url(someimage.jpg);} .highlight {font-weight:bold;} .four-col-1 {width:300px;} and to make matters worse... this is in the CSS: .blocks.orange.highlight {background-colour:#dd00ff;} Anyone not familiar with this particular bug can read more on it here: http://www.ryanbrill.com/archives/multiple-classes-in-ie/ it is very real and very annoying. Without wanting to go into the merrits of not chaining classes (I told them this, but it is no longer feasible to change their approach... 100 hand coded pages into a 150 page website, no CMS... sigh) and without the luxury of being able to change the way these blocks are styled... can anyone advise me on the complexity and benefits between any of my below proposed approaches or possible other options that would adequately solve this problem. Potential Solution 1 Using conditional comments I am considering loading a jquery script only for IE6 that: Reads the class of all divs in a certain section of the page and pushes to an array creates empty boxes off screen with only one of the classes applied at a time Reads the applied CSS values for each box Re-applies these styles to the individual box, somehow bearing in mind the order in which they are called and overwriting conflicting instructions as required Potential Solution 2 read the class of all divs in a certain section of the page and push to an array Scan the document for links to style sheets Ajax grab the stylesheets and traverse looking for matching names to those in class array Apply styles as needed Potential Solution 3 Create an IE6 only stylesheet containing the exact style to be applied as a unique name (ie: class='blocks orange highlight' becomes class='blocks-orange-highlight') Traverse the document in IE6 and convert all spaces in class declarations to hyphens and reapply classes based on new style name Summary: Solution 1 allows the people at this company to apply any styles in the future and the script will adjust as needed. However it does not allow for the chained style to be added, only the individual style... it is also processor intensive and time consuming, but also the most likely to be converted into a plugin that could be used the world over Solution 2 is a potential nightmare to code. But again will allow for an endless number of updates without breaking Solution 3 will require someone at the companty to hardcode the new styles every time they make a change, and if they don't, IE6 will break. Ironically the site, whilst needing to conform to IE6 in a limited manner, does not need to run wihtout javascript (they've made the call... have JS or go away), so consider all jQuery and JS solutions to be 'game on'. Did I mention how much i hate IE6? Anyway... any thoughts or comments would be appreciated. I will continue to develop my own solution and if I discover one that can be turned into a jQuery plugin I will post it here in the comments. Regards, Mike.

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  • Python's equivalence?

    - by user304014
    Is there anyway to transform the following code in Java to Python's equivalence? public class Animal{ public enum AnimalBreed{ Dog, Cat, Cow, Chicken, Elephant } private static final int Animals = AnimalBreed.Dog.ordinal(); private static final String[] myAnimal = new String[Animals]; private static Animal[] animal = new Animal[Animals]; public static final Animal DogAnimal = new Animal(AnimalBreed.Dog, "woff"); public static final Animal CatAnimal = new Animal(AnimalBreed.Cat, "meow"); private AnimalBreed breed; public static Animal myDog (String name) { return new Animal(AnimalBreed.Dog, name); } }

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  • Code equivalence between Javascript and PHP

    - by xdevel2000
    I'm trying to learn PHP and I wish to know if there are some function equivalence constructs: In JS I can do: var t = function() {}; t(); myObj.DoStuff = function() {} // here I add a method at run-time myObj.DoStuff(); myObj["DoStuff"](); var j = myObj.DoStuff; j(); and so other things with function evaluation. In Js objects are associative arrays so every properties is accessible with the subscript notation... Can I add a method at run-time to a class template so next its object instances can have it? In JS I can do that via a prototype function property.

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  • Why are static classes considered “classes” and “reference types”?

    - by Timwi
    I’ve been pondering about the C# and CIL type system today and I’ve started to wonder why static classes are considered classes. There are many ways in which they are not really classes: A “normal” class can contain non-static members, a static class can’t. In this respect, a class is more similar to a struct than it is to a static class, and yet structs have a separate name. You can have a reference to an instance of a “normal” class, but not a static class (despite it being considered a “reference type”). In this respect, a class is more similar to an interface than it is to a static class, and yet interfaces have a separate name. The name of a static class can never be used in any place where a type name would normally fit: you can’t declare a variable of this type, you can’t use it as a base type, and you can’t use it as a generic type parameter. In this respect, static classes are somewhat more like namespaces. A “normal” class can implement interfaces. Once again, that makes classes more similar to structs than to static classes. A “normal” class can inherit from another class. It is also bizarre that static classes are considered to derive from System.Object. Although this allows them to “inherit” the static methods Equals and ReferenceEquals, the purpose of that inheritance is questionable as you would call those methods on object anyway. C# even allows you to specify that useless inheritance explicitly on static classes, but not on interfaces or structs, where the implicit derivation from object and System.ValueType, respectively, actually has a purpose. Regarding the subset-of-features argument: Static classes have a subset of the features of classes, but they also have a subset of the features of structs. All of the things that make a class distinct from the other kinds of type, do not seem to apply to static classes. Regarding the typeof argument: Making a static class into a new and different kind of type does not preclude it from being used in typeof. Given the sheer oddity of static classes, and the scarcity of similarities between them and “normal” classes, shouldn’t they have been made into a separate kind of type instead of a special kind of class?

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  • Classes. Whats the point?

    - by Ben Shelock
    I'm fairly new to OOP in PHP, I've made a couple of basic scripts but nothing impressive. All I've really taken from it is that it would probably be easier just make a collection of functions and include them. The structure of classes seems to just confuse what was otherwise a simple process. And in collating everything into a class it doesn't really add any functionality. So I'm clearly missing something. Could someone explain what functionality is added by creating classes

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  • What should I put into classes and what stuff I shouldnt?

    - by jpjp
    I am learning about classes right now in PHP and their examples are like.. class table { //makes a table private $tag ; function Begin($border=0, $align="center", $width='100%', $cellpadding=2, $cellspacing=2, $class='', $id='', $bgcolor='', $style='') { $this->tag = '<table ' ; if ($align) $this->tag .= 'align="' . $align . '" ' ; if ($width) $this->tag .= 'width="' . $width . '" ' ; if ($border > 0) $this->tag .= 'border="' . $border . '" ' ; if ($cellpadding > 0) $this->tag .= 'cellpadding="' . $cellpadding . '" ' ; if ($cellspacing > 0) $this->tag .= 'cellspacing="' . $cellspacing . '" ' ; if ($class) $this->tag .= 'class="' . $class . '" ' ; if ($id) $this->tag .= 'id="' . $id . '" ' ; if ($bgcolor) $this->tag .= 'bgcolor="' . $bgcolor . '" ' ; if ($style) $this->tag .= 'style="' . $style . '" ' ; $this->tag .= ">" ; return $this->tag ; } Then you just instantiate it and make a table by $table =new table; $table->$table($border=2, $align='center', etc); Should I be coding like this where html, css are in classes? i feel making tables and forms this way is more confusing then actually just typing . Should I only put like validation, getting data from db, and the logic stuff in classes? What should I use classes for and not?

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  • How to avoid general names for abstract classes?

    - by djechlin
    In general it's good to avoid words like "handle" or "process" as part of routine names and class names, unless you are dealing with (e.g.) file handles or (e.g.) unix processes. However abstract classes often don't really know what they're going to do with something besides, say, process it. In my current situation I have an "EmailProcessor" that logs into a user's inbox and processes messages from it. It's not really clear to me how to give this a more precise name, although I've noticed the following style matter arises: better to treat derived classes as clients and named the base class by the part of the functionality it implements? Gives it more meaning but will violate is-a. E.g. EmailAcquirer would be a reasonable name since it's acquiring for the derived class, but the derived class won't be acquiring for anyone. Or just really vague name since who knows what the derived classes will do. However "Processor" is still too general since it's doing many relevant operations, like logging in and using IMAP. Any way out of this dilemma? Problem is more evident for abstract methods, in which you can't really answer the question "what does this do?" because the answer is simply "whatever the client wants."

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  • Html 5 clock, part ii - CSS marker classes and getElementsByClassName

    - by Norgean
    The clock I made in part i displays the time in "long" - "It's a quarter to ten" (but in Norwegian). To save space, some letters are shared, "sevenineight" is four letters shorter than "seven nine eight". We only want to highlight the "correct" parts of this, for example "sevenineight". When I started programming the clock, each letter had its own unique ID, and my script would "get" each element individually, and highlight / hide each element according to some obscure logic. I quickly realized, despite being in a post surgery haze, …this is a stupid way to do it. And, to paraphrase NPH, if you find yourself doing something stupid, stop, and be awesome instead. We want an easy way to get all the items we want to highlight. Perhaps we can use the new getElementsByClassName function? Try to mark each element with a classname or two. So in "sevenineight": 's' is marked as 'h7', and the first 'n' is marked with both 'h7' and 'h9' (h for hour). <div class='h7 h9'>N</div><div class='h9'>I</div> getElementsByClassName('h9') will return the four letters of "nine". Notice that these classes are not backed by any CSS, they only appear directly in html (and are used in javascript). I have not seen classes used this way elsewhere, and have chosen to call them "marker classes" - similar to marker interfaces - until somebody comes up with a better name.

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