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  • Connecting data to a GUI - OOP

    - by tau
    I have an application with several graphs and tables on it. I worked fast and just made classes like Graph and Table that each contained a request object (pseudo-code): class Graph { private request; public function setDateRange(dateRange) { request.setDateRange(dateRange); } public function refresh() { request.getData(function() { //refresh the display }); } } Upon a GUI event (say, someone changes the date range dropdown), I'd just call the setters on the Graph instance and then refresh it. Well, when I added other GUI elements like tables and whatnot, they all basically had similar methods (setDateRange and other things common to the request). What are some more elegant OOP ways of doing this? The application is very simple and I don't want to over-architect it, but I also don't want to have a bunch of classes with basically the same methods that are just routing to a request object. I also don't want to set up each GUI class as inheriting from the request class, but I'm open to any ideas really.

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  • C++ error message output format

    - by sub
    If I want to trigger an error in my interpreter I call this function: Error( ErrorType type, ErrorSeverity severity, const char* msg, int line ); However, with that I can only output Name error: Undefined variable in line 1 instead of Name error: Undefined variable 'someVariableName' in line 1 I'm working entirely with strings (except for the error messages as they all are constant at the moment), so sprintf won't work. What is the best way to create an efficient error function that can output a constant message combined with a string that describes which object, e.g.: a non-existing variable, triggered the error?

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  • Ignoring (serious) errors to keep the program alive?

    - by SQuirreL bites
    One of the main things I wanted to achieve in my experimental programming language was: When errors occur (Syntax, Name, Type, etc.) keep the program running, no matter how serious or devastating it is. I know that this is probably very bad, but I just wanted something that doesn't kill itself on every error - I find it interesting what happens when a serious error occurs but the program continues. Does this "paradigm" have a name? I mean expect for How bad is it to do the above? Are there programs in use out there that just follow: "Hey, this is a fatal, unexpected error - but you know what? I don't care!"?

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  • Using a regex pattern to find revision numbers from a svn merge

    - by zyzy
    svn diff -rXX:HEAD Will give me a format like this, if there has been a merge between those revisions: Merged /<branch>:rXXX,XXX-XXX or Merged /<branch>:rXXX I'm not very familiar with regex and am trying to put together a pattern which will match all the numbers (merged revision numbers) AFTER matching the "Merged /branch:r" part. So far I have this to match the first part: [Mm]erged.*[a-zA-Z]:r Thanks in adv. for the help :)

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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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  • Is this the correct why of speaking to a "Content Manager" Class?

    - by DeanMc
    I am creating a silverlight site. I am currently breaking out my ideas into pieces of functionality. One of the idea's I have is the concept of a content manager. This is essentially a UI control with 4 regions. Top, Bottom, Right & Left. I also have a collection of objects that are considered "Menu Items". These are controls that function as a way to navigate around, similar to links. The idea I have is to implement an IMenuItem interface. Among the standard pieces of information (Text, PageReference, etc) I was also going to hold a reference to the content manager. My idea behind this thinking is that I can pass the PageReference to a property on the ContentManager and then call a method which knows how to update the content manager accordingly. Is this the best way of implementing this or is their some sort of pattern for it?

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  • Using an interface as a constructor parameter in Java?

    - by aperson
    How would I be able to accomplish the following: public class testClass implements Interface { public testClass(Interface[] args) { } } So that I could declare Interface testObject = new testClass(new class1(4), new class2(5)); Where class1 and class2 are also classes that implement Interface. Also, once I accomplish this, how would I be able to refer to each individual parameter taken in to be used in testClass? Thanks :)

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  • Files mapping architecture

    - by user326198
    I need to know How I can achieve this goal by classes : we have two different applications in the company (App1 , App2) Appl can export xml with know items ( ID , Name) we need app2 to import this data but App2 display different items (CarID, CarName) and this items defined like this with the mapping info <CarID> <Mapping name="ID"/> </CarID> <CarNAme> <Mapping name="Name"/> </CarNAme>" How I can achieve this as classes or ARCHITECTURE , i will develop this with c# I need one interface because we may support different type of files not just xml

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  • Help with database design

    - by Jonny
    Hey im new to database design and having trouble trying to figure this one out. I have two tables Team and Fixtures. Team has rows of football teams and Fixture has 2 of those football teams in each row (home and away team). I want to link team id to home_team and away_team but it doesnt allow me to. Please tell me how i can solve this. Here is an image of my tables/relationships http://i49.tinypic.com/288qwpg.jpg

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  • Will my app get rejected because of this ???

    - by A for Alpha
    hi guys... i am developing a ebook reader app for iPad and i am facing a issue related to the design aspects of the bookshelf. I am posting a sample photo of my bookshelf here. I want the book shelf to have a horizontal navigation similar to that of the iBooks. Will this come under violation of Apple's HIG?? Will they consider this design to be a imitation of their iBooks design and reject it?? I'm worried...

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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 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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  • Writing my own implementation of stl-like Iterator in C++.

    - by Negai
    Good evening everybody, I'm currently trying to understand the intrinsics of iterators in various languages i.e. the way they are implemented. For example, there is the following class exposing the list interface. template<class T> class List { public: virtual void Insert( int beforeIndex, const T item ) throw( ListException ) =0 ; virtual void Append( const T item ) =0; virtual T Get( int position ) const throw( ListException ) =0; virtual int GetLength() const =0; virtual void Remove( int position ) throw( ListException ) =0; virtual ~List() =0 {}; }; According to GoF, the best way to implement an iterator that can support different kinds of traversal is to create the base Iterator class (friend of List) with protected methods that can access List's members. The concrete implementations of Iterator will handle the job in different ways and access List's private and protected data through the base interface. From here forth things are getting confusing. Say, I have class LinkedList and ArrayList, both derived from List, and there are also corresponding iterators, each of the classes returns. How can I implement LinkedListIterator? I'm absolutely out of ideas. And what kind of data can the base iterator class retrieve from the List (which is a mere interface, while the implementations of all the derived classes differ significantly) ? Sorry for so much clutter. Thanks.

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  • How many variables is to many when storing in _SESSION?

    - by steve
    Hi - I'm looking for an idea of best practices here. I have a web based application that has a number of hooks into other systems. Let's say 5, and each of these 5 systems has a number of flags to determine different settings the user has selected in said systems, lets say 5 settings per system (so 5*5). I am storing the status of these settings in the user sesion variables and was wondering is that a sufficient way of doing it? I'm learning php as I go along so not sure about any pitfalls that this could run me into!

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  • C++ Iterator Pipelining Designs

    - by Kirakun
    Suppose we want to apply a series of transformations, int f1(int), int f2(int), int f3(int), to a list of objects. A naive way would be SourceContainer source; TempContainer1 temp1; transform(source.begin(), source.end(), back_inserter(temp1), f1); TempContainer2 temp2; transform(temp1.begin(), temp1.end(), back_inserter(temp2), f2); TargetContainer target; transform(temp2.begin(), temp2.end(), back_inserter(target), f3); This first solution is not optimal because of the extra space requirement with temp1 and temp2. So, let's get smarter with this: int f123(int n) { return f3(f2(f1(n))); } ... SourceContainer source; TargetContainer target; transform(source.begin(), source.end(), back_inserter(target), f123); This second solution is much better because not only the code is simpler but more importantly there is less space requirement without the intermediate calculations. However, the composition f123 must be determined at compile time and thus is fixed at run time. How would I try to do this efficiently if the composition is to be determined at run time? For example, if this code was in a RPC service and the actual composition--which can be any permutation of f1, f2, and f3--is based on arguments from the RPC call.

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  • Adding behaviour to a set of classes

    - by devoured elysium
    I have defined an Event class: Event and all the following classes inherit from Event: SportEventType1 SportEventType2 SportEventType3 SportEventType4 Right now I will only have SportEvents but I don't know if in the future I'll want some other kind of events that doesn't even have anything to do with Sports. Later, I will want to draw some graphics with info taken from Events, and the drawing logic can be a bit complex. But, for the moment, I think I shouldn't think of how the drawing will be done and I believe that maybe it'd be better if that drawing part was not put as an integral part of the Event/SportEventX class chain. I am looking for solutions for this problem. I know I could just make Event have an instance variable(attribute, for the java crowds) pointing to something as an IDrawInterface, but that would make the Event class "assume" it will be later used for drawing. I would like to make the Event class oblivious to this if possible. Thanks!

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  • Is there a case for parameterising using Abstract classes rather than Interfaces?

    - by Chris
    I'm currently developing a component based API that is heavily stateful. The top level components implement around a dozen interfaces each. The stock top-level components therefore sit ontop of a stack of Abstract implementations which in turn contain multiple mixin implementations and implement multiple mixin interfaces. So far, so good (I hope). The problem is that the base functionality is extremely complex to implement (1,000s of lines in 5 layers of base classes) and therefore I do not wish for component writers to implement the interfaces themselves but rather to extend my base classes (where all the boiler plate code is already written). If the API therefore accepts interfaces rather than references to the Abstract implementation that I wish for component writers to extends, then I have a risk that the implementer will not perform the validation that is both required and assumed by other areas of code. Therefore, my question is, is it sometimes valid to paramerise API methods using an abstract implementation reference rather than a reference to the interface(s) that it implements? Do you have an example of a well-designed API that uses this technique or am I trying to talk myself into bad-practice?

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  • How to proxy calls to the instance of an object

    - by mr.b
    Edit: Changed question title from "Does C# allow method overloading, PHP style (__call)?" - figured out it doesn't have much to do with actual question. Also edited question text. What I want to accomplish is to proxy calls to a an instance of an object methods, so I could log calls to any of its methods. Right now, I have code similar to this: class ProxyClass { static logger; public AnotherClass inner { get; private set; } public ProxyClass() { inner = new AnotherClass(); } } class AnotherClass { public void A() {} public void B() {} public void C() {} // ... } // meanwhile, in happyCodeLandia... ProxyClass pc = new ProxyClass(); pc.inner.A(); // need to write log message like "method A called" pc.inner.B(); // need to write log message like "method B called" // ... So, how can I proxy calls to an object instance in extensible way? Method overloading would be most obvious solution (if it was supported in PHP way). By extensible, meaning that I don't have to modify ProxyClass whenever AnotherClass changes. In my case, AnotherClass can have any number of methods, so it wouldn't be appropriate to overload or wrap all methods to add logging. I am aware that this might not be the best approach for this kind of problem, so if anyone has idea what approach to use, shoot. Thanks!

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  • Where does the query language sit within the MVC pattern?

    - by weesilmania
    I'd assume that since the query language sits within the controller (typically) that it belongs to that component, but if I play devil's advocate I'd argue that the query language is execute within the domain of the model, and is tightly coupled to that component so it might also be a part of it. Anyone know the answer? Is there a straight answer or is it technology specific?

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  • Instantiating and referencing models in MVC

    - by fig-gnuton
    In MVC, should each model be a globally accessible singleton accessible to any view/controller? Or should the models be singletons that are dependency injected into any component that requires them? Or should a new model instance be created for each component that needs one, in which case events would be used to propagate changes across model instances of the same class?

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  • C# Class Factories

    - by Andy
    I have a class called Foo that has a function that looks like the following List<Bar> LoadData(); Both Foo and Bar are in a library that I want to reuse in other projects. Now I am working on a new project and I want to subclass Bar. Let's call it NewBar. What is a simple and flexible way to get Foo.LoadData to return a list of NewBar? I think that a factory is needed or perhaps just a delegate function. Can anyone provide an example? Thanks, Andy

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  • How to separate model and view with Core Data?

    - by andrewebling
    I have a subclass of UIView which draws itself based on data held in a corresponding model class, which is a subclass of NSManagedObject. The problem is, some fields in the data model (e.g. the position of the view) are already held in the view (i.e. the frame property in this case). I then have a data duplication/synchronization problem to solve. To complicate matters further, the view needs to update in response to changes made to the data model and the data model needs to be updated in responses made to the view (e.g. the user dragging it to a new location). What's the best way to solve this? Using KVO and references in both directions? Or is there a better approach?

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