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  • Functional Programming Equivalent of Design Patterns Book?

    - by JasonFruit
    Is there a functional-programming equivalent to the Gang of Four Design Patterns book? That is, is there a book that explains and gives examples of how commonly-needed code structures are implemented functionally? I think seeing that would give me a better idea of how to go about using in practice the functional concepts whose theory I understand.

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  • What are some good design patterns for CRUD?

    - by Extrakun
    I am working with a number of data entities which can be created, read, updated and deleted, and I find myself writing more or less the same code for them. For example, I need to sometimes output data as JSON, and sometimes in a table format. I am finding myself writing 2 different types of view to export the data to. Also, the creation of those entities within DB usually differs just by the SQL statements and the input parameters. I am thinking of creating a strategy pattern to represent different 'contexts'. For example, the read() method of an AJAX context will be to return the data as JSON. However, I wonder if others have deal with this problem beforehand and will like to know what design patterns are usually use for CRUD operations.

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  • Need some clarification with Patterns (DAO x Gateway)

    - by Marcos Placona
    Me and my colleagues got into this discussion early this morning, and our opinions started to clash a bit, so I decided to get some impartial advice here. One of my colleagues reckons that the DAO should return an object (populated bean). I think it's completely fine when you're returning a recordset with only one line, but think it's overkill if you have to return 10 lines, and create 10 separate objects. I on the other see that the difference between DAO and Gateway pattern is that the gateway pattern will allow you to return a recordset to your business class, which will therefore deal with the recordset data and do whatever it needs to do. My questions here are: Which assumptions are correct? What should the return type be for a DAO (i.e. getContact() - for one record) Should getContacts() (for multiple records) even be on the DAO, if so, what's it's returntype? We seem to be having some sort of confusion about DAO and Gateway Patterns. Should they be used together? Thanks in advance

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  • MVC & Design patterns in C++

    - by theunanonim
    I have an assignment (university level) in C++ The application that was done so far: - MVC agenda - the views are command-line - Agenda contains a list of contacts - a contact may be a friend or an acquiantance - Agenda may contain also a Company that is a contact and may contain other contacts (sorry the code is already too big as I tried to keep the MVC aspect of the application, and I can't post it here or request your time to study it..) To do: - implement factory method pattern - implement observer pattern - implement strategy pattern - implement visitor pattern The evaluation will depend on the number of added patterns and places they have been added. Am I an idiot or this is the stupidies possible assignement ? If not, please help me with some basic tips.. which one where ? Best Regards. P.S. Sorry for my English

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  • Looking for design patterns to isolate framework layers from each other

    - by T Reddy
    Hi, I'm wondering if anyone has any experience in "isolating" framework objects from each other (Spring, Hibernate, Struts). I'm beginning to see design "problems" where an object from one framework gets used in another object from a different framework. My fear is we're creating tightly coupled objects. For instance, I have an application where we have a DynaActionForm with several attributes...one of which is a POJO generated by the Hibernate Tools. This POJO gets used everywhere...the JSP populates data to it, the Struts Action sends it down to a Service Layer, the DAO will persist it...ack! Now, imagine that someone decides to do a little refactoring on that POJO...so that means the JSP, Action, Service, DAO all needs to be updated...which is kind of painful...There has got to be a better way?! There's a book called Core J2EE Patterns: Best Practices and Design Strategies (2nd Edition)...is this worth a look? I don't believe it touches on any specific frameworks, but it looks like it might give some insight on how to properly layer the application... Thanks!

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  • Comparing Design Patterns

    - by Lijo
    Hi, I am learning design patterns using C#. One of the challenges that I am facing is that they look similar. Could you please help me to distinguish them – basically when to use them? - Why not the other? Bridge and Strategy State and Strategy Façade and Strategy Composite and Strategy I understand that there are lots of resources available in the web. However they does not treat this special question. [Note: I am looking for implementation examples and rationale behind the selection; not mere explanations] It would be great if you are taking examples from any of the following 1) E-Commerce 2) Payroll system 3) Banking 4) Retailing Thanks for your understanding.. Thanks Lijo

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  • Progress Bar design patterns?

    - by shoosh
    The application I'm writing performs a length algorithm which usually takes a few minutes to finish. During this time I'd like to show the user a progress bar which indicates how much of the algorithm is done as precisely as possible. The algorithm is divided into several steps, each with its own typical timing. For instance- initialization (500 milli-sec) reading inputs (5 sec) step 1 (30 sec) step 2 (3 minutes) writing outputs (7 sec) shutting down (10 milli-sec) Each step can report its progress quite easily by setting the range its working on, say [0 to 150] and then reporting the value it completed in its main loop. What I currently have set up is a scheme of nested progress monitors which form a sort of implicit tree of progress reporting. All progress monitors inherit from an interface IProgressMonitor: class IProgressMonitor { public: void setRange(int from, int to) = 0; void setValue(int v) = 0; }; The root of the tree is the ProgressMonitor which is connected to the actual GUI interface: class GUIBarProgressMonitor : public IProgressMonitor { GUIBarProgressMonitor(ProgressBarWidget *); }; Any other node in the tree are monitors which take control of a piece of the parent progress: class SubProgressMonitor : public IProgressMonitor { SubProgressMonitor(IProgressMonitor *parent, int parentFrom, int parentLength) ... }; A SubProgressMonitor takes control of the range [parentFrom, parentFrom+parentLength] of its parent. With this scheme I am able to statically divide the top level progress according to the expected relative portion of each step in the global timing. Each step can then be further subdivided into pieces etc' The main disadvantage of this is that the division is static and it gets painful to make changes according to variables which are discovered at run time. So the question: are there any known design patterns for progress monitoring which solve this issue?

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  • Programming habits, patterns, and standards that have developed out of appeal to tradition/by mistake? [closed]

    - by user828584
    Being self-taught, the vast majority of what I know about programming has come from reading other peoples' code on websites like this. I'm starting to wonder if I've developed bad or otherwise pointless habits from other people, or even just made invalid assumptions. For example, in javascript, void 0 is used in a lot of places, and until I saw this, I just assumed it was necessary and that 0 had some significance. Also, the http header, referer is misspelled but hasn't been changed because it would break a lot of applications. Also mentioned in Code Complete 2: The architecture should describe the motivations for all major decisions. Be wary of “we’ve always done it that way” justifications. One story goes that Beth wanted to cook a pot roast according to an award-winning pot roast recipe handed down in her husband’s family. Her husband, Abdul, said that his mother had taught him to sprinkle it with salt and pepper, cut both ends off, put it in the pan, cover it, and cook it. Beth asked, “Why do you cut both ends off?” Abdul said, “I don’t know. I’ve always done it that way. Let me ask my mother.” He called her, and she said, “I don’t know. I’ve always done it that way. Let me ask your grandmother.” She called his grandmother, who said, “I don’t know why you do it that way. I did it that way because it was too big to fit in my pan.” What are some other examples of this?

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  • In PHP, what are the different design patterns to implement OO controllers as opposed to procedural controllers?

    - by Ryan
    For example, it's very straightforward to have an index.php controller be a procedural script like so: <?php //include classes and functions //get some data from the database //and/or process a form submission //render HTML using your template system ?> Then I can just navigate to http://mysite.com/index.php and the above procedural script is essentially acting as a simple controller. Here the controller mechanism is a basic procedural script. How then do you make controllers classes instead of procedural scripts? Must the controller class always be tied to the routing mechanism?

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  • Patterns for a tree of persistent data with multiple storage options?

    - by Robin Winslow
    I have a real-world problem which I'll try to abstract into an illustrative example. So imagine I have data objects in a tree, where parent objects can access children, and children can access parents: // Interfaces interface IParent<TChild> { List<TChild> Children; } interface IChild<TParent> { TParent Parent; } // Classes class Top : IParent<Middle> {} class Middle : IParent<Bottom>, IChild<Top> {} class Bottom : IChild<Middle> {} // Usage var top = new Top(); var middles = top.Children; // List<Middle> foreach (var middle in middles) { var bottoms = middle.Children; // List<Bottom> foreach (var bottom in bottoms) { var middle = bottom.Parent; // Access the parent var top = middle.Parent; // Access the grandparent } } All three data objects have properties that are persisted in two data stores (e.g. a database and a web service), and they need to reflect and synchronise with the stores. Some objects only request from the web service, some only write to it. Data Mapper My favourite pattern for data access is Data Mapper, because it completely separates the data objects themselves from the communication with the data store: class TopMapper { public Top FetchById(int id) { var top = new Top(DataStore.TopDataById(id)); top.Children = MiddleMapper.FetchForTop(Top); return Top; } } class MiddleMapper { public Middle FetchById(int id) { var middle = new Middle(DataStore.MiddleDataById(id)); middle.Parent = TopMapper.FetchForMiddle(middle); middle.Children = BottomMapper.FetchForMiddle(bottom); return middle; } } This way I can have one mapper per data store, and build the object from the mapper I want, and then save it back using the mapper I want. There is a circular reference here, but I guess that's not a problem because most languages can just store memory references to the objects, so there won't actually be infinite data. The problem with this is that every time I want to construct a new Top, Middle or Bottom, it needs to build the entire object tree within that object's Parent or Children property, with all the data store requests and memory usage that that entails. And in real life my tree is much bigger than the one represented here, so that's a problem. Requests in the object In this the objects request their Parents and Children themselves: class Middle { private List<Bottom> _children = null; // cache public List<Bottom> Children { get { _children = _children ?? BottomMapper.FetchForMiddle(this); return _children; } set { BottomMapper.UpdateForMiddle(this, value); _children = value; } } } I think this is an example of the repository pattern. Is that correct? This solution seems neat - the data only gets requested from the data store when you need it, and thereafter it's stored in the object if you want to request it again, avoiding a further request. However, I have two different data sources. There's a database, but there's also a web service, and I need to be able to create an object from the web service and save it back to the database and then request it again from the database and update the web service. This also makes me uneasy because the data objects themselves are no longer ignorant of the data source. We've introduced a new dependency, not to mention a circular dependency, making it harder to test. And the objects now mask their communication with the database. Other solutions Are there any other solutions which could take care of the multiple stores problem but also mean that I don't need to build / request all the data every time?

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  • What are the best patterns/designs for stateful API development?

    - by Svante
    I am about to implement a API for my TCP/IP server written in Java. Right now I have a temporary method that takes a String, executes a command based on the String and returns a String basically like the following. public void communicate(BufferedReader in, PrintWriter out) { while(true) { out.println(handleCommand(in.readLine())); } } private String handleCommand(String command) { if (command.equals("command1") { // do stuff return "Command 1 executed"; } else if (command.equals("command2") { // do some other stuff return "Command 2 executed"; } } I really want to do something more extensible, smarter and stateful, so I could handle more complex and stateful commands and without the method/class getting bloated. How would you start? Suggestions, ideas, or links for further reading are very welcome.

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  • What patterns book for iOS development contains this specific information? [closed]

    - by Brett Ryan
    I've read several books on iOS development and Objective-C, however what a lot of them teach is how to work with interfaces and all contain the model inside the view controller, i.e. a UITableViewController based view will simply have an NSArray as it's model. I'm interested in what the best practices are for designing the structure of an application. Specifically I'm interested in best practices for the following: How to separate a model from the view controller. I think I know how to do this by simply replacing the NSArray style example with a specific model object, however what I do not know how to do is alert the view when the model changes. For example in .NET I would solve this by conforming to INotifyPropertyChanged and databinding, and similarly with Java I would use PropertyChangeListener. How to create a service model for my domain objects. For example I want to learn the best way to create a service for a hypothetical Widget object to manage an internal DB and also services for communicating with remote endpoints. I need to learn the best ways to do this in a way that interface components can subscribe to events such as widgetUpdated. These services should be singleton classes and some how dependency injected into model/controller objects. Books I've read so far are: Programming in Objective-C (4th Edition) Beginning iOS 5 Development: Exploring the iOS SDK The iOS 5 Developer's Cookbook: Expanded Electronic Edition: Essentials and Advanced Recipes for iOS Programmers Learn Objective-C on the Mac: For OS X and iOS I've also purchased the following updated books but not yet read them. The Core iOS 6 Developer's Cookbook (4th edition Programming in Objective-C (5th Edition) I come from a Java and C# background with 15 years experience, I understand that many of the ways I would do things in these languages may not fit to the ObjC way of developing applications. Would someone be able to provide me with the book on this topic containing this specific subject matter?

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  • Is MVC a Design Pattern or Architectural pattern

    - by JCasso
    According to Sun and Msdn it is a design pattern. According to Wikipedia it is an architectural pattern In comparison to design patterns, architectural patterns are larger in scale. (Wikipedia - Architectural pattern) Or it is an architectural pattern that also has a design pattern ? Which one is true ?

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  • Patterns for dynamic CMS components (event driven?)

    - by CitrusTree
    Sorry my title is not great, this is my first real punt at moving 100% to OO as I've been procedural for more years than I can remember. I'm finding it hard to understand if what I'm trying to do is possible. Depending on people's thoughts on the 2 following points, I'll go down that route. The CMS I'm putting together is quote small, however focuses very much on different types of content. I could easily use Drupal which I'm very comfortable with, but I want to give myself a really good reasons to move myself into design patterns / OO-PHP 1) I have created a base 'content' class which I wish to be able to extend to handle different types of content. The base class, for example, handles HTML content, and extensions might handle XML or PDF output instead. On the other hand, at some point I may wish to extend the base class for a given project completely. I.e. if class 'content-v2' extended class 'content' for that site, any calls to that class should actually call 'content-v2' instead. Is that possible? If the code instantiates an object of type 'content' - I actually want it to instantiate one of type 'content-v2'... I can see how to do it using inheritance, but that appears to involve referring to the class explicitly, I can't see how to link the class I want it to use instead dynamically. 2) Secondly, the way I'm building this at the moment is horrible, I'm not happy with it. It feels very linear indeed - i.e. get session details get content build navigation theme page publish. To do this all the objects are called 1-by-1 which is all very static. I'd like it to be more dynamic so that I can add to it at a later date (very closely related to first question). Is there a way that instead of my orchestrator class calling all the other classes 1-by-1, then building the whole thing up at the end, that instead each of the other classes can 'listen' for specific events, then at the applicable point jump in and do their but? That way the orchestrator class would not need to know what other classes were required, and call them 1-by-1. Sorry if I've got this all twisted in my head. I'm trying to build this so it's really flexible.

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  • Game logic dynamically extendable architecture implementation patterns

    - by Vlad
    When coding games there are a lot of cases when you need to inject your logic into existing class dynamically and without making unnecessary dependencies. For an example I have a Rabbit which can be affected by freeze ability so it can't jump. It could be implemented like this: class Rabbit { public bool CanJump { get; set; } void Jump() { if (!CanJump) return; ... } } But If I have more than one ability that can prevent it from jumping? I can't just set one property because some circumstances can be activated simultanously. Another solution? class Rabbit { public bool Frozen { get; set; } public bool InWater { get; set; } bool CanJump { get { return !Frozen && !InWater; } } } Bad. The Rabbit class can't know all the circumstances it can run into. Who knows what else will game designer want to add: may be an ability that changes gravity on an area? May be make a stack of bool values for CanJump property? No, because abilities can be deactivated not in that order in which they were activated. I need a way to seperate ability logic that prevent the Rabbit from jumping from the Rabbit itself. One possible solution for this is making special checking event: class Rabbit { class CheckJumpEventArgs : EventArgs { public bool Veto { get; set; } } public event EventHandler<CheckJumpEvent> OnCheckJump; void Jump() { var args = new CheckJumpEventArgs(); if (OnCheckJump != null) OnCheckJump(this, args); if (!args.Veto) return; ... } } But it's a lot of code! A real Rabbit class would have a lot of properties like this (health and speed attributes, etc). I'm thinking of borrowing something from MVVM pattern where you have all the properties and methods of an object implemented in a way where they can be easily extended from outside. Then I want to use it like this: class FreezeAbility { void ActivateAbility() { _rabbit.CanJump.Push(ReturnFalse); } void DeactivateAbility() { _rabbit.CanJump.Remove(ReturnFalse); } // should be implemented as instance member // so it can be "unsubscribed" bool ReturnFalse(bool previousValue) { return false; } } Is this approach good? What also should I consider? What are other suitable options and patterns? Any ready to use solutions? UPDATE The question is not about how to add different behaviors to an object dynamically but how its (or its behavior) implementation can be extended with external logic. I don't need to add a different behavior but I need a way to modify an exitsing one and I also need a possibiliity to undo changes.

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  • What's the difference between these design pattern books? [on hold]

    - by BSara
    I'm currently looking for a good reference/guide for design patterns and in my search I've found the following three books highly recommended: Design Patterns: Elements of Reusable Object-Oriented Software Pattern Hatching: Design Patterns Applied Design Patterns Explained: A New Perspective on Object-Oriented Design I can't decide which book (if any) to purchase. So, my question is this: What are the fundamental differences between these books?

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  • Top Fusion Apps User Experience Guidelines & Patterns That Every Apps Developer Should Know About

    - by ultan o'broin
    We've announced the availability of the Oracle Fusion Applications user experience design patterns. Developers can get going on these using the Design Filter Tool (or DeFT) to select the best pattern for their context of use. As you drill into the patterns you will discover more guidelines from the Applications User Experience team and some from the Rich Client User Interface team too that are also leveraged in Fusion Apps. All are based on the Oracle Application Development Framework components. To accelerate your Fusion apps development and tailoring, here's some inside insight into the really important patterns and guidelines that every apps developer needs to know about. They start at a broad Fusion Apps information architecture level and then become more granular at the page and task level. Information Architecture: These guidelines explain how the UI of an Oracle Fusion application is constructed. This enables you to understand where the changes that you want to make fit into the oveall application's information architecture. Begin with the UI Shell and Navigation guidelines, and then move onto page-level design using the Work Areas and Dashboards guidelines. UI Shell Guideline Navigation Guideline Introduction to Work Areas Guideline Dashboards Guideline Page Content: These patterns and guidelines cover the most common interactions used to complete tasks productively, beginning with the core interactions common across all pages, and then moving onto task-specific ones. Core Across All Pages Icons Guideline Page Actions Guideline Save Model Guideline Messages Pattern Set Embedded Help Pattern Set Task Dependent Add Existing Object Pattern Set Browse Pattern Set Create Pattern Set Detail on Demand Pattern Set Editing Objects Pattern Set Guided Processes Pattern Set Hierarchies Pattern Set Information Entry Forms Pattern Set Record Navigation Pattern Set Transactional Search and Results Pattern Group Now, armed with all this great insider information, get developing some great-looking, highly usable apps! Let me know in the comments how things go!

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  • General Availability: Simplified User Experience Design Patterns eBook

    - by ultan o'broin
    Karen Scipi (@karenscipi) writes: The Oracle Applications User Experience team is delighted to announce that our Simplified User Experience Design Patterns for the Oracle Applications Cloud Service eBook is available for free. Working with publishers McGraw-Hill, we're pleased to make the eBook available in EPUB (for use on Apple iOS devices), MOBI (ideal for Amazon Kindle), and PDF (for anything with Adobe Reader) versions. The Simplified User Experience Design Patterns for the Oracle Applications Cloud Service eBook We’re sharing the same user experience design patterns, and their supporting guidance on page types and Oracle ADF components that Oracle uses to build simplified user interfaces (UIs) for the Oracle Sales Cloud and Oracle Human Capital Management (HCM) Cloud, with you so that you can build your own simplified UI solutions. Click to register and download your free copy of the eBook Design patterns offer big wins for applications builders because they are proven, reusable, and based on Oracle technology. They enable developers, partners, and customers to design and build the best user experiences consistently, shortening the application's development cycle, boosting designer and developer productivity, and lowering the overall time and cost of building a great user experience. Developers use the eBook to build their own simplified UIs with Oracle ADF and Oracle JDeveloper Now, Oracle partners, customers and the Oracle ADF community can share further in the Oracle Applications User Experience science and design expertise that brought the acclaimed simplified UIs to the Cloud and they can build their own UIs, simply and productively too!

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  • Design Patterns Recommendation for Filtering Option

    - by Tarik
    Hi people, I am thinking to create a filter object which filters and delete everything like html tags from a context. But I want it to be independent which means the design pattern I can apply will help me to add more filters in the future without effecting the current codes. I thought Abstract Factory but it seems it ain't gonna work out the way I want. So maybe builder but it looks same. I don't know I am kinda confused, some one please recommend me a design pattern which can solve my problem but before that let me elaborate the problem a little bit. Lets say I have a class which has Description field or property what ever. And I need filters which remove the things I want from this Description property. So whenever I apply the filter I can add more filter in underlying tier. So instead of re-touching the Description field, I can easily add more filters and all the filters will run for Description field and delete whatever they are supposed to delete from the Description context. I hope I could describe my problem. I think some of you ran into the same situation before. Thanks in advance...

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  • BPM Business Value Patterns

    - by JuergenKress
    Together with Matthias Ziegler from Accenture we presented the BPM Business Value Patterns at the SOA & BPM Integration Days in Germany in October: BPM Business Value Patterns View more presentations by Jürgen Kress Please visit the website http://soa-bpm-days.de/  for the next SOA & BPM Integration Days III February 29th & March 1st in Munich If you'd like to learn more please feel free to contact us any time: Matthias Ziegler Jürgen Kress For regular information on Oracle SOA Suite become a member of the SOA Partner Community. To register please visit  www.oracle.com/goto/emea/soa (OPN account required) Blog Twitter LinkedIn Mix Forum Technorati Tags: Matthias Ziegler,Jürgen Kress,SOA & BPM Integration Days,BPM,BPM Value Patterns,BPM ROI,Oracle,OPN,Accenture

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  • Patterns for implementing field change tracking.

    - by David
    Hi all For one of my recent projects, I had to implement field change tracking. So anytime the user changed a value of a field, the change was recorded in order to allow full auditing of changes. In the database, I implemented this as a single table 'FieldChanges' with the following fields: TableName, FieldName, RecordId, DateOfChange, ChangedBy, IntValue, TextValue, DateTimeValue, BoolValue. The sproc saving changes to an object determines for each field whether it has been changed and inserts a record into FieldChanges if it has: if the type of the changed field is int, it records it in the IntValue field in the FieldChanges table, etc. This means that for any field in any table with any id value, I can query the FieldChanges table to get a list of changes. This works quite well but is a bit clumsy. Can anyone else who has implemented similar functionality suggest a better approach, and why they think it's better? I'd be really interested - thanks. David

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  • Parallel programming patterns for C#?

    - by VoidDweller
    With Intel's launch of a Hexa-Core processor for the desktop, it looks like we can no longer wait for Microsoft to make many-core programming "easy". I just order a copy of Joe Duffy's book Concurrent Programming on Windows. This looks like a great place to start, though, I am hoping some of you who have been targeting multi/many core systems would point me to some good resources that have or would have helped on your projects?

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  • Mutability design patterns in Objective C and C++

    - by Mac
    Having recently done some development for iPhone, I've come to notice an interesting design pattern used a lot in the iPhone SDK, regarding object mutability. It seems the typical approach there is to define an immutable class NSFoo, and then derive from it a mutable descendant NSMutableFoo. Generally, the NSFoo class defines data members, getters and read-only operations, and the derived NSMutableFoo adds on setters and mutating operations. Being more familiar with C++, I couldn't help but notice that this seems to be a complete opposite to what I'd do when writing the same code in C++. While you certainly could take that approach, it seems to me that a more concise approach is to create a single Foo class, mark getters and read-only operations as const functions, and also implement the mutable operations and setters in the same class. You would then end up with a mutable class, but the types Foo const*, Foo const& etc all are effectively the immutable equivalent. I guess my question is, does my take on the situation make sense? I understand why Objective-C does things differently, but are there any advantages to the two-class approach in C++ that I've missed? Or am I missing the point entirely? Not an overly serious question - more for my own curiosity than anything else.

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  • Video Synthesis - Making waves, patterns, gradients...

    - by Nathan
    I'm writing a program to generate some wild visuals. So far I can paint each pixel with a random blue value: for (y = 0; y < YMAX; y++) { for (x = 0; x < XMAX; x++) { b = rand() % 255; setPixelColor(x,y,r,g,b); } } I'd like to do more than just make blue noise, but I'm not sure where to start (Google isn't helping me much today), so it would be great if you could share anything you know on the subject or some links to related resources.

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