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  • Good case for a Null Object Pattern? (Provide some service with a mailservice)

    - by fireeyedboy
    For a website I'm working on, I made an Media Service object that I use in the front end, as well as in the backend (CMS). This Media Service object manipulates media in a local repository (DB); it provides the ability to upload/embed video's and upload images. In other words, website visitors are able to do this in the front end, but administrators of the site are also able to do this in the backend. I'ld like this service to mail the administrators when a visitor has uploaded/embedded a new medium in the frontend, but refrain from mailing them when they upload/embed a medium themself in the backend. So I started wondering whether this is a good case for passing a null object, that mimicks the mail funcionality, to the Media Service in the backend. I thought this might come in handy when they decide the backend needs to have implemented mail functionality as well. In simplified terms I'ld like to do something like this: Frontend: $mediaService = new MediaService( new MediaRepository(), new StandardMailService() ); Backend: $mediaService = new MediaService( new MediaRepository(), new NullMailService() ); How do you feel about this? Does this make sense? Or am I setting myself up for problems down the road?

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  • [Delphi] How would you refactor this code?

    - by Al C
    This hypothetical example illustrates several problems I can't seem to get past, even though I keep trying!! ... Suppose the original code is a long event handler, coded in the UI, triggered when a user clicks a cell in a grid. Expressed as pseudocode it's: if Condition1=true then begin //loop through every cell in row, //if aCell/headerCellValue>1 then //color aCell red end else if Condition2=true then begin //do some other calculation adding cell and headerCell values, and //if some other product>2 then //color the whole row green end else show an error message I look at this and say "Ah, refactor to the strategy pattern! The code will be easier to understand, easier to debug, and easier to later extend!" I get that. And I can easily break the code into multiple procedures. The problem is ultimately scope related. Assume the pseudocode makes extensive use of grid properties, values displayed in cells, maybe even built-in grid methods. How do you move all that to another unit, without referencing the grid component in the UI--which would break all the "rules" about loose coupling that make OOP valuable? ... I'm really looking forward to responses. Thanks, as always -- Al C.

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  • WPF buttons same/recommended width

    - by rwallace
    Suppose you have a window with multiple buttons such as Ok/Cancel or Yes/No/Cancel. All the buttons need to be the same width. Obviously this could be done by just guessing a number and hardwiring all of them to that number. Is there a better way to do it, one that would take into account preferred/recommended sizes (just how wide should an Ok button be anyway? This is not a rhetorical question, I actually don't know the answer!), what's needed by the text of the longest caption, what happens if the font size is increased etc?

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  • Handling Dialogs in WPF with MVVM

    - by Ray Booysen
    In the MVVM pattern for WPF, handling dialogs is one of the more complex operations. As your view model does not know anything about the view, dialog communication can be interesting. I can expose an ICommand that when the view invokes it, a dialog can appear. Does anyone know of a good way to handle results from dialogs? I am speaking about windows dialogs such as MessageBox. One of the ways we did this was have an event on the viewmodel that the view would subscribe to when a dialog was required. public event EventHandler<MyDeleteArgs> RequiresDeleteDialog; This is OK, but it means that the view requires code which is something I would like to stay away from.

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  • Cocoa framework development: sharing between projects

    - by e.James
    I am currently developing a handful of similar Cocoa desktop apps. In an effort to share code between them, I have identified a set of core classes and functions that can be common across all of these applications. I would like to bundle this common code into a framework which all of my current applications (and any future ones) can link against. Now, here's the hard part: I'm going to be developing this framework as I go, so I need each of my desktop apps to have a reference to it, but I want to be able to edit the framework source code from within each of the app projects and have the framework automatically rebuilt as required. For example, let's say I have the Xcode project for DesktopAppNumberOne open, and I decide that one of my framework classes needs to be changed. I would like to: Open and edit the source file for that framework class without having to open the framework project in Xcode. Hit "build" on DesktopAppNumberOne, and see the framework rebuilt first (because one of its sources has changed), then see parts of DesktopAppNumberOne rebuilt (because one of the frameworks it links against has changed). I can see how to do this with only one app and one framework, but I'm having trouble figuring out how to do it with multiple apps that share a single framework. Has anyone had success with this approach? Am I perhaps going about this the wrong way? Any help would be appreciated.

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  • How to make some functions of a class as private for third level of inheritance.

    - by Shantanu Gupta
    I have created a class say A which has some functions defined as protected. Now Class B inherits A and class C inherits B. Class A has private default constructor and protected parameterized constructor. I want Class B to be able to access all the protected functions defined in Class A but class C can have access on some of the functions only not all the functions and class C is inheriting class B. How can I restrict access to some of the functions of Class A from Class C ? Class A { private A(){} protected A(int ){} protected calc(){} protected allow(){} } Class B : A {} // calc() and allow() should be accessible here CLass C:B { // calc() should not be accessible here but allow() should be accessible here. }

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  • C++. How to define template parameter of type T for class A when class T needs a type A template parameter?

    - by jaybny
    Executor class has template of type P and it takes a P object in constructor. Algo class has a template E and also has a static variable of type E. Processor class has template T and a collection of Ts. Question how can I define Executor< Processor<Algo> > and Algo<Executor> ? Is this possible? I see no way to defining this, its kind of an "infinite recursive template argument" See code. template <class T> class Processor { map<string,T> ts; void Process(string str, int i) { ts[str].Do(i); } } template <class P> class Executor { Proc &p; Executor(P &p) : Proc(p) {} void Foo(string str, int i) { p.Process(str,i); } Execute(string str) { } } template <class E> class Algo { static E e; void Do(int i) {} void Foo() { e.Execute("xxx"); } } main () { typedef Processor<Algo> PALGO; // invalid typedef Executor<PALGO> EPALGO; typedef Algo<EPALGO> AEPALGO; Executor<PALGO> executor(PALGO()); AEPALGO::E = executor; }

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  • Immutable classes in C++

    - by ereOn
    Hi, In one of my projects, I have some classes that represent entities that cannot change once created, aka. immutable classes. Example : A class RSAKey that represent a RSA key which only has const methods. There is no point changing the existing instance: if you need another one, you just create one. My objects sometimes are heavy and I enforced the use of smart pointers to avoid copy. So far, I have the following pattern for my classes: class RSAKey : public boost::noncopyable, public boost::enable_shared_from_this<RSAKey> { public: /** * \brief Some factory. * \param member A member value. * \return An instance. */ static boost::shared_ptr<const RSAKey> createFromMember(int member); /** * \brief Get a member. * \return The member. */ int getMember() const; private: /** * \brief Constructor. * \param member A member. */ RSAKey(int member); /** * \brief Member. */ const int m_member; }; So you can only get a pointer (well, a smart pointer) to a const RSAKey. To me, it makes sense, because having a non-const reference to the instance is useless (it only has const methods). Do you guys see any issue regarding this pattern ? Are immutable classes something common in C++ or did I just created a monster ? Thank you for your advices !

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  • MyController class must produce class according to the enum type.

    - by programmerist
    GenoTipController must produce class according to the enum type. i have 3 class: _Company,_Muayene,_Radyoloji. Also i have CompanyView Class GetPersonel method. if you look GenoTipController my codes need refactoring. Can you understand me? i need a class according to ewnum type must me produce class. For example; case DataModelType.Radyoloji it must return radyoloji= new Radyoloji . Everything must be one switch case? public class GenoTipController { public _Company GenerateCompany(DataModelType modeltype) { _Company company = null; switch (modeltype) { case DataModelType.Radyoloji: break; case DataModelType.Satis: break; case DataModelType.Muayene: break; case DataModelType.Company: company = new Company(); break; default: break; } return company; } public _Muayene GenerateMuayene(DataModelType modeltype) { _Muayene muayene = null; switch (modeltype) { case DataModelType.Radyoloji: break; case DataModelType.Satis: break; case DataModelType.Muayene: muayene = new Muayene(); break; case DataModelType.Company: break; default: break; } return muayene; } public _Radyoloji GenerateRadyoloji(DataModelType modeltype) { _Radyoloji radyoloji = null; switch (modeltype) { case DataModelType.Radyoloji: radyoloji = new Radyoloji(); break; case DataModelType.Satis: break; case DataModelType.Muayene: break; case DataModelType.Company: break; default: break; } return radyoloji; } } public class CompanyView { public static List GetPersonel() { GenoTipController controller = new GenoTipController(); _Company company = controller.GenerateCompany(DataModelType.Company); return company.GetPersonel(); } } public enum DataModelType { Radyoloji, Satis, Muayene, Company } }

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  • Passing an array for setting variable

    - by mathk
    Hi, I often see this idiom when reading php code: public function __construct($config) { if (array_key_exists('options', $config)) { ... } if (array_key_exists('driver_options', $config)) { ... } } Here I am concern with the way the parameter is used. If I were in lisp I would do: (defun ct (&key options driver_options) (do-something-with-option-and-driver_option)) But since I am in PHP I would rather have a constructor that take a list of parameter and let them be null if there a not require. So what do you guys think about having an array as parameter in other to do some initialization-or-whatever? In other to answer you have to take in account the point of view of the user of the function and the designer of the API. Also have you ever heard this has a code-smell? thanks

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  • Patterns for wrapping a command line tool in another language

    - by Tom Duckering
    I'm currently writing some Java to wrap around an extensive command line tool. It feels like I'm writing a lot of similar code. I'm wondering if there are any established patterns for wrapping command line tools - passing arguments and handling output and so on. Specific examples in Java would obviously be great, but any general suggestions or pointers are welcome too.

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  • Managing important runtime business logic with regard to a codebase

    - by Daniel Beardsley
    I'm working on a project which will end up have a lot of application information stored in the form of records in a database. In this case, it's the configuration of data views: which grid columns to show/hide default filters to apply to each grid view column titles sorting subtotaling ... This information is a big part of the value of the application and is essential to it's function. The data will be altered by admins a fair amount, so it's not static and it wouldn't be appropriate to have to deploy a new version of the app every time the data changes. The question is, Where should this data be stored? It will definitely live in the database because that's how it's accessed, but I feel like it needs to also be kept with the version controlled codebase because it's an integral part of functioning of the application. Has anyone dealt with an issue like this before? What did you end up doing?

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  • Building a wiki like data model in rails question.

    - by lillq
    I have a data model in which I would like to have an item that has a description that can be edited. I would like to also keep track of all edits to the item. I am running into issues with my current strategy, which is: class Item < ActiveRecord::Base has_one :current_edit, :class_name => "Edit", :foreign_key => "current_edit_id" has_many :edits end class Edit < ActiveRecord::Base belongs_to :item end Can the Item have multiple associations to the same class like this? I was thinking that I should switch to keeping track of the edit version in the Edit object and then just sorting the has_many relationship base on this version.

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  • PHP Frontpage/Page controller

    - by atno
    I using the following as Frontpage/Page Controller(s) and it's working ok so far, except two problems I'm facing which as you can see are the $pages array and the switch, which are actually much much longer as the one I've pasted here. Everytime there is a need for a new page controller I have to add it to $pages array and to switch which makes that list very long. How would you overcome this problem and do you see any other improvement on this code? loadLogic() in page controllers it is used to get functions under pages/controllername/logic/function.php. Frontpage Controller - index.php: include 'common/common.php'; if(!isset($_GET['p']) OR $_GET['p'] == ''){ $_GET['p'] = 'home'; header('Location: index.php?p=home'); } $pages = array('home','register','login','logout','page1','page2','page3'); $_GET['p'] = trim($_GET['p']); if(isset($_GET['p'])){ if(in_array($_GET['p'], $pages)){ switch ($_GET['p']) { case 'home': include 'home.php'; break; case 'register': include 'register.php'; break; case 'login': include 'login.php'; break; case 'logout': include 'logout.php'; break; case 'page1': include 'page1.php'; break; case 'page2': include 'page2.php'; break; case 'page3': include 'page3.php'; break; } }else{ echo '404!'; } } Page Controller - {home,register,login,logout,page1,page2,page3}.php: include 'tpl/common/header.php'; contentStart(); if(isset($_SESSION['logged'])){ loadLogic('dashboard'); }else{ loadLogic('nologin'); } //Display login form in logic page instead links // if(!isset($_SESSION['logged'])){ contentEnd(); loadLogic('nologinForm'); }else{ contentEnd(); include'tpl/common/rcol.php'; } include 'tpl/common/footer.php'; function loadLogic(): function loadLogic($logic) { $path = dirname(__DIR__) . '/pages'; $controller = preg_split('/&/',$_SERVER['QUERY_STRING']); $controller = trim($controller[0],"p="); $logicPath = 'logic'; $logic = $logic . '.php'; $err = 0; $logicFullPath = $path.'/'.$controller.'/'.$logicPath.'/'.$logic; if($err == '0'){ include "$logicFullPath"; } } Folder Structure: projectName | ---> common | ---> pages | | | --->home | | | --->register | | | --->login | | | --->logout | | | --->page1 | | | --->page2 | | | --->page3 | ---> tpl | | | ---> common | --> home.php | --> register.php | --> login.php | --> logout.php | --> page1.php | --> page2.php | --> page3.php

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  • internal implementation of database Queries

    - by harigm
    In my experience I have used many queries like select, order by, where clause etc.. in mysql, sql-server, oracle etc For a moment i have thought, 1)how is this internally written to implement the above queries 2) which language do they use? 3) is that programming language? if yes which language? 4)what kind of environment required to implement this kind of complex database

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  • Designing software interface for various screen sizes

    - by Tower
    Hi, Nowadays we have screens like 1920x1200 and 1680x1050 in popular use and some even use 2560x1600 resolution while some older systems still rely on a 800x600 resolution. I am writing a software that looks good on a 1680x1050, but too small on a 1920x1200 and too large on a 1024x768. Do you have suggestions how to go for designing an application for various screen sizes? Things were a lot simpler before when we had little differences in resolutions, but now it seems there's no good way of handling this. I know this question is more about designing / layout than programming, but I bet this is more or less part of programmers life so I made this post here.

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  • To join or not to join - database structure

    - by Industrial
    Hi! We're drawing up the database structure with the help of mySQL Workbench for a new app and the number of joins required to make a listing of the data is increasing drastically as the many-to-many relationships increases. The questions: Is it really that bad to merge tables where needed and thereby reducing joins? Is there a better way then pivot tables to take care of many-to-many relationships? We discussed about instead storing all data in serialized text columns and having the application make the sorting instead of the database, but this seems like a very bad idea, even though that the database will be heavily cached. What do you think? Thanks!

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  • Entity framework and database logic.

    - by Xavier Devian
    Hi all, i have a question that's being around for several years. As all you know entity framework is an ORM tool that tries to model the database to an object oriented access model. All the samples I've seen are quering directly to the database tables. So, which is the role of the views in the database now?. The views were used to model the database in a more friendly way, that is, several physical tables, one logic table. This was great for example in hidding the complex relational model on stored procedures as queryng the views inside them was much easier than reproducing the query joins over and over on each stored procedure. So the question is, why is entity framework so good if stored procedures can not take benefit of it?

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  • Why does C++ mandate that complex only be instantiated for float, double, or long double?

    - by templatetypedef
    According to the C++ ISO spec, §26.2/2: The effect of instantiating the template complex for any type other than float, double or long double is unspecified. Why would the standard authors explicitly add this restriction? This makes it unspecified, for example, what happens if you make complex<int> or a complex<MyCustomFixedPointType> and seems like an artificial restriction. Is there a reason for this limitation? Is there a workaround if you want to instantiate complex with your own custom type? I'm primarily asking this question because of this earlier question, in which the OP was confused as to why abs was giving bizarre outputs for complex<int>. That said, this still doesn't quite make sense given that we also might want to make complex numbers out of fixed-points types, higher-precision real numbers, etc. Thanks!

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  • I want define tables from a part of my ER Diagram.

    - by M R Jafari
    I have a ER-Diagram (Show in http://www.4freeimagehost.com/show.php?i=f82997ca4d5d.png). In the diagram you see 2 entities and a 1:N relataion together. Project has 2 columns as ProjectID, ProjectName. Employee has 3 colums as EmployeeID, EmployeeName and ProjectID. A project has ONLY 1 project-manager and project-manager is a employee. What columns add them?

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  • Spring 2.0.0/2.0.6 to 3.0.5 migration stories

    - by Pangea
    We are in the process of migrating to 3.0.5 of spring from 2.0.x. We mainly use spring in below scenarios custom scope: thread local scope persistence: jdbc+hibernate 3.6 (but moving to mix of ejb 3.0+jpa 2.0+hibernate, not sure if all 3 can co-exist in 1 app) transactions: local (but planning to use jta due to the necessity of using multiple persistence inits, and has to use ejb+jpa+hibernate in 1 single trans), declarative trans mgmt parent-child contexts cxf annotations+xml OracleLobHandler Resource/ResourceBundleMessageResource JSF/Facelets with FacesSpringVariableResolver ActiveMQ integration Quartz integration TaskExecutor JMX exporter HttpExporter/Invoker Appreciate if someone can share their experiences like what to watch out for head aches/pain points which ones to drop for better alternate choices in new 3.0.5 release Is it better to switch from commons/iscreen validator to Hibernate Validator (Spec impl) or Spring Validator Is there a bean mapping framework in spring that i can use instead of Dozer XSLT transformation helper: currently we have small homegrown framework to cache xslts during load. if spring can do that for me then I would like to drop this Encryption/Decryption support. Password generation support. Authentication with SALT any SAML (or claims based secur New ideas Suggestions Switch to latest version of aspectj Upgrade guide from 2.5 to 3.0.5

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  • Is there any danger in committing to a component library such as SmartGwt or Swing?

    - by Banang
    Since February this year I have been working on an app that's built using SmartGWT components. Generally, I find the components very nice to work with, and the fact that they're open source and free to use is just fantastic. However, I can't seem to shake the feeling that it's not a durable way of developing, but I can't quite explain why. Maybe it's because I know that any minute now the team developing it could decide to stop, which would leave me and my team in a bit of a pickle, but I'm sure there must be something more. I have been trying to find ways of explaining this feeling to myself, but to no avail. Therefore I turn to you, dear community, to ask if you can come up with a good reason why committing to building your app (that's supposed to be around for many more years to come) using a component library such as SmartGWT is a bad idea? Is there any reason I should just have developed the components myself? Or did I make the right choice when deciding not to reinvent the wheel and just go for what was readily available?

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