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• Drawbacks of using an integer as a bitfield?

  - by Mark

  I have a bunch of boolean options for things like "accepted payment types" which can include things like cash, credit card, cheque, paypal, etc. Rather than having a half dozen booleans in my DB, I can just use an integer and assign each payment method an integer, like so PAYMENT_METHODS = ( (1<<0, 'Cash'), (1<<1, 'Credit Card'), (1<<2, 'Cheque'), (1<<3, 'Other'), ) and then query the specific bit in python to retrieve the flag. I know this means the database can't index by specific flags, but are there any other drawbacks?

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• Objective-C Objects Having Each Other as Properties

  - by mwt

  Let's say we have two objects. Furthermore, let's assume that they really have no reason to exist without each other. So we aren't too worried about re-usability. Is there anything wrong with them "knowing about" each other? Meaning, can each one have the other as a property? Is it OK to do something like this in a mythical third class: Foo *f = [[Foo alloc] init]; self.foo = f; [f release]; Bar *b = [[Bar alloc] init]; self.bar = b; [b release]; foo.bar = bar; bar.foo = foo; ...so that they can then call methods on each other? Instead of doing this, I'm usually using messaging, etc., but sometimes this seems like it might be a tidier solution. I hardly ever see it in example code (maybe never), so I've shied away from doing it. Can somebody set me straight on this? Thanks.

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• how to implement this observer pattern?

  - by lethal

  Hello. I have 4 classes, that describe state diagram. Node, Edge, ComponentOfNode, ComponentOfEdge. ComponentOfEdge compounds from ComponentsOfNode. Node can have 0..n outgoing edges. Edge can have only 2 nodes. Edge should be able to offer ComponentOfNode, but only from nodes that Edge has, in form ComponentOfEdge. The user can change ComponentsOfNode. I need this change spreads to all Edge. Hw to do it? I expect the observer should be used. Can you give me example in pseudocode please?

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• PHP Access property of a class from within a class instantiated in the original class.

  - by Iain

  I'm not certain how to explain this with the correct terms so maybe an example is the best method... $master = new MasterClass(); $master->doStuff(); class MasterClass { var $a; var $b; var $c; var $eventProccer; function MasterClass() { $this->a = 1; $this->eventProccer = new EventProcess(); } function printCurrent() { echo '<br>'.$this->a.'<br>'; } function doStuff() { $this->printCurrent(); $this->eventProccer->DoSomething(); $this->printCurrent(); } } class EventProcess { function EventProcess() {} function DoSomething() { // trying to access and change the parent class' a,b,c properties } } My problem is i'm not certain how to access the properties of the MasterClass from within the EventProcess-DoSomething() method? I would need to access, perform operations on and update the properties. The a,b,c properties will be quite large arrays and the DoSomething() method would be called many times during the execuction of the script. Any help or pointers would be much appreciated :)

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• Arrow in nav menus in CSS/JS (e.g. playframework.org)

  - by manmal

  The navigation menu at the top of the www.playframework.org site features a small arrow pointing upward for the currently selected section (Home, Learn, Download,...). I tried to get behind the implementation they used, but I can't wrap my head around it - the resource does not show up in Chrome's Resources window, and an inspection of the elements did not show any signs of a background image, nor a JS interceptor (although I might have missed that). What in hellhound's name is going on there? :)

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• Elegant and 'correct' multiton implementation in Objective C?

  - by submachine

  Would you call this implementation of a multiton in objective-c 'elegant'? I have programmatically 'disallowed' use of alloc and allocWithZone: because the decision to allocate or not allocate memory needs to be done based on a key. I know for sure that I need to work with only two instances, so I'm using 'switch-case' instead of a map. #import "Multiton.h" static Multiton *firstInstance = nil; static Multiton *secondInstance = nil; @implementation Multiton + (Multiton *) sharedInstanceForDirection:(char)direction { return [[self allocWithKey:direction] init]; } + (id) allocWithKey:(char)key { return [self allocWithZone:nil andKey:key]; } + (id)allocWithZone:(NSZone *)zone andKey:(char)key { Multiton **sharedInstance; @synchronized(self) { switch (key) { case KEY_1: sharedInstance = &firstInstance; break; case KEY_2: sharedInstance = &secondInstance; break; default: [NSException raise:NSInvalidArgumentException format:@"Invalid key"]; break; } if (*sharedInstance == nil) *sharedInstance = [super allocWithZone:zone]; } return *sharedInstance; } + (id) allocWithZone:(NSZone *)zone { //Do not allow use of alloc and allocWithZone [NSException raise:NSObjectInaccessibleException format:@"Use allocWithZone:andKey: or allocWithKey:"]; return nil; } - (id) copyWithZone:(NSZone *)zone { return self; } - (id) retain { return self; } - (unsigned) retainCount { return NSUIntegerMax; } - (void) release { return; } - (id) autorelease { return self; } - (id) init { [super init]; return self; } PS: I've not tried out if this works as yet, but its compiling cleanly :)

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• Using a user-defined type as a primary key

  - by Chris Kaminski

  Suppose I have a system where I have metadata such as: table: ====== key name address ... Then suppose I have a user-defined type described as so: datasource datasource-key A) are there systems where it's possible to have keys based on user-defined types? B) if so, how do you decompose the keys into a form suitable for querying? C) is this a case where I'm just better off with a composite primary key?

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• How can I build a voting system to support multiple types of objects to vote on?

  - by Kyle Hayes

  I'm really looking for something very similar to the way SO is setup where a few different kinds of things can be voted on (questions AND answers). What kind of DB schema, generally, could I use to support voting on many different kinds of objects? Would I have a single Vote table that would have references to other objects in the database? Or do I have to have or should have a separate vote table for each of the objects I would like to vote on.

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• Can I access elements/methods named "button1" "button2" "button3" etc. using "buttoni" inside a for-

  - by cksubs

  I have a bunch of buttons named: button1 button2 button3 etc. Is there a way to basically do this? pseudocode for(int i = 1, i < 15, i++) { button{i}.selected = YES; } This also goes for method calls, etc. I've often thought such a way of calling methods would be very convenient, but I don't think I've ever seen it done when using compiled languages. But I have done it using PHP. Is there any way to do this in Objective-C? (That's where my problem is now, but I'd also be interested in if you can do this in other languages.) Alternately, is there a reason why this is NOT a good way to go about accessing all the UI elements? Thanks!

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• How does an operating system accomodate for USB 2.0's inability to provide interrrupts for connected

  - by user354822

  That's it. ffffffffffff

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• How do I write a Java text file viewer for big log files

  - by Hannes de Jager

  I am working on a software product with an integrated log file viewer. Problem is, its slow and unstable for really large files because it reads the whole file into memory when you view a log file. I'm wanting to write a new log file viewer that addresses this problem. What are the best practices for writing viewers for large text files? How does editors like notepad++ and VIM acomplish this? I was thinking of using a buffered Bi-directional text stream reader together with Java's TableModel. Am I thinking along the right lines and are such stream implementations available for Java?

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• How to handle injecting dependencies into rich domain models?

  - by Arne

  In a web server project with a rich domain model (application logic is in the model, not in the services) how do you handle injecting the dependencies into the model objects? What are your experiences? Do you use some form of AOP? Like Springs @Configurable annotation? Load time or build time weawing? Problems you encountered? Do you use manual injection? Then how do you handle different instantiation scenarios (creating of the objects through an library [like Hibernate], creating objects with "new" ...)? Or do you use some other way of injecting the dependencies?

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• using partials in view helpers

  - by takeshin

  Creating custom Zend View helpers I often end up with something like: // logic here if ($condition) { $output = <<<EOS... } else { $output = <<<EOS... } or using switch. Then to eliminate this, I create setPartial(), getPartial() and htmlize() for using external .phtml's. This is not the best solution, because partials do not support doctype changing. Is there any better solution, than creating abstract class handling this common case? Are there any ready Zend solutions for this case? Separate view helper for each case? And where to put common code?

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• Java: refactoring static constants

  - by akf

  We are in the process of refactoring some code. There is a feature that we have developed in one project that we would like to now use in other projects. We are extracting the foundation of this feature and making it a full-fledged project which can then be imported by its current project and others. This effort has been relatively straight-forward but we have one headache. When the framework in question was originally developed, we chose to keep a variety of constant values defined as static fields in a single class. Over time this list of static members grew. The class is used in very many places in our code. In our current refactoring, we will be elevating some of the members of this class to our new framework, but leaving others in place. Our headache is in extracting the foundation members of this class to be used in our new project, and more specifically, how we should address those extracted members in our existing code. We know that we can have our existing Constants class subclass this new project's Constants class and it would inherit all of the parent's static members. This would allow us to effect the change without touching the code that uses these members to change the class name on the static reference. However, the tight coupling inherent in this choice doesn't feel right. before: public class ConstantsA { public static final String CONSTANT1 = "constant.1"; public static final String CONSTANT2 = "constant.2"; public static final String CONSTANT3 = "constant.3"; } after: public class ConstantsA extends ConstantsB { public static final String CONSTANT1 = "constant.1"; } public class ConstantsB { public static final String CONSTANT2 = "constant.2"; public static final String CONSTANT3 = "constant.3"; } In our existing code branch, all of the above would be accessible in this manner: ConstantsA.CONSTANT2 I would like to solicit arguments about whether this is 'acceptable' and/or what the best practices are.

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• .Net Template Engine/Report Solution

  - by runxc1 Bret Ferrier

  I am looking to add custom reports/forms to a web application. I want users to be able to upload a report definition/template file and then be able to print out a PDF or word document (one or the other it doesn't need to be both) for each of their widgets based off of the template they uploaded. I can't install anything on the server and am looking for an open source/free solution. Data Source- The data will be in the form of a datatable or dataset that the application fetches itself. The report tool does will not be able to connect to any database.

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• Should we avoid to use Object as the input parameter/ output value of a method?

  - by developer.cyrus

  Take Java syntax as an example, though the question itself is language independent. If the following snippet takes an object MyAbstractEmailTemplate as input argument in the method setTemplate, the class MyGateway will then become tightly-coupled with the object MyAbstractEmailTemplate, which lessens the re-usability of the class MyGateway. A compromise is to use dependency-injection to ease the instantiation of MyAbstractEmailTemplate. This might solve the coupling problem to some extent, but the interface is still rigid, hardly providing enough ?exibility to other developers/ applications. So if we only use primitive data type (or even plain XML in web service) as the input/ output of a method, it seems the coupling problem no longer exists. So what do you think? public class MyGateway { protected MyAbstractEmailTemplate template; publoc void setTemplate(MyAbstractEmailTemplate template) { this.template = template; } }

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• Why Are Ruby Programmers So Full of Themselves? [closed]

  - by Pierreten

  I've noticed this culture surrounding Ruby where developers truly believe that they are somehow more gifted than developers of other languages, regardless of experience and talent (even when that isn't the case, I've met some extremely junior Ruby developers come up with some pretty basic constructs, and pass them off as some sort of revolutionary idea). The derision of strongly typed languages seems to be a common theme as well; regardless of its merits. Is there something particular to the Ruby syntax in general that is to account for this? Is there a socialogical component to it?

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• Would it be useful to change java to support both static and dynamic types?

  - by James A. N. Stauffer

  What if a Java allow both static and dynamic types. That might allow the best of both worlds. i.e.: String str = "Hello"; var temp = str; temp = 10; temp = temp * 5; Would that be possible? Would that be beneficial? Do any languages currently support both and how well does it work out? Here is a better example (generics can't be used but the program does know the type): var username = HttpServletRequest.getSession().getAttribute("username");//Returns a String if(username.length() == 0) { //Error }

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• Can I use the decorator pattern to wrap a method body?

  - by mgroves

  I have a bunch of methods with varying signatures. These methods interact with a fragile data connection, so we often use a helper class to perform retries/reconnects, etc. Like so: MyHelper.PerformCall( () => { doStuffWithData(parameters...) }); And this works fine, but it can make the code a little cluttery. What I would prefer to do is decorate the methods that interact with the data connection like so: [InteractsWithData] protected string doStuffWithData(parameters...) { // do stuff... } And then essentially, whenever doStuffWithData is called, the body of that method would be passed in as an Action to MyHelper.PerformCall(). How do I do this?

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• Building a structure/object in a place other than the constructor

  - by Vishal Naidu

  I have different types of objects representing the same business entity. UIObject, PowershellObject, DevCodeModelObject, WMIObject all are different representation to the same entity. So say if the entity is Animal then I have AnimalUIObject, AnimalPSObject, AnimalModelObject, AnimalWMIObject, etc. Now the implementations of AnimalUIObject, AnimalPSObject, AnimalModelObject are all in separate assemblies. Now my scenario is I want to verify the contents of business entity Animal irrespective of the assembly it came from. So I created a GenericAnimal class to represent the Animal entity. Now in GenericAnimal I added the following constructors: GenericAnimal(AnimalUIObject) GenericAnimal(AnimalPSObject) GenericAnimal(AnimalModelObject) Basically I made GenericAnimal depend on all the underlying assemblies so that while verifying I deal with this abstraction. Now the other approach to do this is have GenericAnimal with an empty constructor an allow these underlying assemblies to have a Transform() method which would build the GenericAnimal. Both approaches have some pros and cons: The 1st approach: Pros: All construction logic is in one place in one class GenericAnimal Cons: GenericAnimal class must be touched every-time there is a new representation form. The 2nd approach: Pros: construction responsibility is delegated to the underlying assembly. Cons: As construction logic is spread accross assemblies, tomorrow if I need to add a property X in GenericAnimal then I have to touch all the assemblies to change the Transform method. Which approach looks better ? or Which would you consider a lesser evil ? Is there any alternative way better than the above two ?

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• How do you manage web navigation info in your application?

  - by Dave

  I’m building an application where different users will have different menu items available to them depending on what they’ve paid for. There will also be multiple levels to the menu hierarchy. What’s the best approach to this problem? I’m assuming I need a database table that represents the menu hierarchy, including the parent-child relationships of the nodes in the navigation as well as the sorting of the items. Then another table which I use to manage whether a user is authorized to access a particular item in that table. When I render the view, I’d reference the menus, and the access rights of the user to output the menu, and I’d also need a function to check that same authorization from each controller in case a user manually types in a URL of a controller they’re not supposed to have access to. Is this the right approach? Any suggestions for caching this to prevent the constant look-ups of this type of info? I’m open to any suggestions on how you may have approached this type of requirement.

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• help me to choose between two designs

  - by alex

  // stupid title, but I could not think anything smarter I have a code (see below, sorry for long code but it's very-very simple): namespace Option1 { class AuxClass1 { string _field1; public string Field1 { get { return _field1; } set { _field1 = value; } } // another fields. maybe many fields maybe several properties public void Method1() { // some action } public void Method2() { // some action 2 } } class MainClass { AuxClass1 _auxClass; public AuxClass1 AuxClass { get { return _auxClass; } set { _auxClass = value; } } public MainClass() { _auxClass = new AuxClass1(); } } } namespace Option2 { class AuxClass1 { string _field1; public string Field1 { get { return _field1; } set { _field1 = value; } } // another fields. maybe many fields maybe several properties public void Method1() { // some action } public void Method2() { // some action 2 } } class MainClass { AuxClass1 _auxClass; public string Field1 { get { return _auxClass.Field1; } set { _auxClass.Field1 = value; } } public void Method1() { _auxClass.Method1(); } public void Method2() { _auxClass.Method2(); } public MainClass() { _auxClass = new AuxClass1(); } } } class Program { static void Main(string[] args) { // Option1 Option1.MainClass mainClass1 = new Option1.MainClass(); mainClass1.AuxClass.Field1 = "string1"; mainClass1.AuxClass.Method1(); mainClass1.AuxClass.Method2(); // Option2 Option2.MainClass mainClass2 = new Option2.MainClass(); mainClass2.Field1 = "string2"; mainClass2.Method1(); mainClass2.Method2(); Console.ReadKey(); } } What option (option1 or option2) do you prefer ? In which cases should I use option1 or option2 ? Is there any special name for option1 or option2 (composition, aggregation) ?

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• What is a good measure of strength of a link and influence of a node?

  - by Legend

  In the context of social networks, what is a good measure of strength of a link between two nodes? I am currently thinking that the following should give me what I want: For two nodes A and B: Strength(A,B) = (neighbors(A) intersection neighbors(B))/neighbors(A) where neighbors(X) gives the total number of nodes directly connected to X and the intersection operation above gives the number of nodes that are connected to both A and B. Of course, Strength(A,B) != Strength(B,A). Now knowing this, is there a good way to determine the influence of a node? I was initially using the Degree Centrality of a node to determine its "influence" but I somehow think its not a good idea because just because a node has a lot of outgoing links does not mean anything. Those links should be powerful as well. In that case, maybe using an aggregate of the strengths of each node connected to this node is a good idea to estimate its influence? I'm a little confused. Does anyone have any suggestions?

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• Which pattern to use for logging? Dependency Injection or Service Locator?

  - by andlju

  Consider this scenario. I have some business logic that now and then will be required to write to a log. interface ILogger { void Log(string stuff); } interface IDependency { string GetInfo(); } class MyBusinessObject { private IDependency _dependency; public MyBusinessObject(IDependency dependency) { _dependency = dependency; } public string DoSomething(string input) { // Process input var info = _dependency.GetInfo(); var intermediateResult = PerformInterestingStuff(input, info); if (intermediateResult== "SomethingWeNeedToLog") { // How do I get to the ILogger-interface? } var result = PerformSomethingElse(intermediateResult); return result; } } How would you get the ILogger interface? I see two main possibilities; Pass it using Dependency Injection on the constructor. Get it via a singleton Service Locator. Which method would you prefer, and why? Or is there an even better pattern? Update: Note that I don't need to log ALL method calls. I only want to log a few (rare) events that may or may not occur within my method.

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• Repository Pattern Standardization of methods

  - by Nix

  All I am trying to find out the correct definition of the repository pattern. My original understanding was this (extremely dubmed down) Separate your Business Objects from your Data Objects Standardize access methods in data access layer. I have really seen 2 different implementations. Implementation 1 : public Interface IRepository<T>{ List<T> GetAll(); void Create(T p); void Update(T p); } public interface IProductRepository: IRepository<Product> { //Extension methods if needed List<Product> GetProductsByCustomerID(); } Implementation 2 : public interface IProductRepository { List<Product> GetAllProducts(); void CreateProduct(Product p); void UpdateProduct(Product p); List<Product> GetProductsByCustomerID(); } Notice the first is generic Get/Update/GetAll, etc, the second is more of what I would define "DAO" like. Both share an extraction from your data entities. Which I like, but i can do the same with a simple DAO. However the second piece standardize access operations I see value in, if you implement this enterprise wide people would easily know the set of access methods for your repository. Am I wrong to assume that the standardization of access to data is an integral piece of this pattern ? Rhino has a good article on implementation 1, and of course MS has a vague definition and an example of implementation 2 is here.

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