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  • When should you use intermediate variables for expressions?

    - by froadie
    There are times that one writes code such as this: callSomeMethod(someClass.someClassMethod()); And other times when one would write the same code like this: int result = someClass.someClassMethod(); callSomeMethod(result); This is just a basic example to illustrate the point. My question isn't if you should use an intermediate variable or not, as that depends on the code and can sometimes be a good design decision and sometimes a terrible one. The question is - when would you choose one method over the other? What factors would you consider when deciding whether to use an intermediate step? (I'd assume length and understandability of the fully inlined code would have something to do with it...)

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  • Is testability alone justification for dependency injection?

    - by fearofawhackplanet
    The advantages of DI, as far as I am aware, are: Reduced Dependencies More Reusable Code More Testable Code More Readable Code Say I have a repository, OrderRepository, which acts as a repository for an Order object generated through a Linq to Sql dbml. I can't make my orders repository generic as it performs mapping between the Linq Order entity and my own Order POCO domain class. Since the OrderRepository by necessity is dependent on a specific Linq to Sql DataContext, parameter passing of the DataContext can't really be said to make the code reuseable or reduce dependencies in any meaningful way. It also makes the code harder to read, as to instantiate the repository I now need to write new OrdersRepository(new MyLinqDataContext()) which additionally is contrary to the main purpose of the repository, that being to abstract/hide the existence of the DataContext from consuming code. So in general I think this would be a pretty horrible design, but it would give the benefit of facilitating unit testing. Is this enough justification? Or is there a third way? I'd be very interested in hearing opinions.

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  • Saving data to server with user accounts.

    - by AKRamkumar
    Ok, so for an app I am making, I want the user to be able to save data online. On my website, I will provide a web server with tables of UserName/Password/SaveData. How can I do this without crashing the server load? How can I guarantee security ? Is there a Design Pattern for this?Is there a better way of doing this? This is going to be a free application, available to the public and I would like for their settings to be available, no matter the computer they are using. Is there a better way of doing this? I am using MEF for plugins so is there a way I can save plugin data as well?

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  • howto hide outline on a form

    - by justjoe
    i have to design a form with an input inside it. i use background image on the input so it would look like a button. so every time somebody click it, then it would send $POST, a behavior i want to achieve. But the problem is about the outline around the form. The outline show when we click the form. It's minor, but it would be great to make the form (or input) lost it outline. i test it using Firefox 3.6 and flock. Both of them show the outline behavior that i want to avoid

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  • What kind of icon should I deploy with my Android 1.x and 2.x application?

    - by licorna
    The thing is this, in Android 1.5 and 1.6 we had the Icon Design Guidelines. In this guide there are specifications for application icons. Every application should conform to this. However, in recent Android versions (2.0 and 2.1) icons have changed from the old to this new flat 2D style. Every icon in Nexus One has this style, so not even Google is conforming to the guideline. To see the differences between high and low density icons see this image and compare Evernote icon with the rest. I've been able to use different icons by using two directories with different icons: drawables-hdpi/icon.png and drawables/icon.png, BUT not every Android 2.x is going to be HDPI and not every 1.x Android device is going to be low pixel density. So the question is: Should I deploy different icons for different Android platform version within my apk file? and if I should, How do I do it?

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  • logic of button to be disabled or not in mvc

    - by rod
    Hi All, Here's an excerpt from a book I'm reading about application design with MVC: Ideally, the view is so simple and logic-free as to need virtually no testing. Users (and developers before users) can reasonably test the view by simply looking at the pixels on the screen. Anything else beyond pure graphical rendering should ideally be taken out of the view and placed in the controller and model. This includes, for example, the logic that determines whether a certain button should be enabled or grayed out at some point. what does the bold statement mean to you? what would this look like? thanks, rod.

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  • JPanel.addComponentListener does not work when the listener is a class variable

    - by Coder
    I have a public class which has the following method and instance variable: public void setImagePanel(JPanel value) { imagePanel = value; if (imagePanel != null) { //method 1 : works imagePanel.addComponentListener(new ComponentAdapter() { public void componentResized(ComponentEvent evt) { System.out.println("Here 1"); } }); //method 2 : does not work panelResizeListener = new ResizeListener(); imagePanel.addComponentListener(panelResizeListener); //method 3 : works //ResizeListener listener = new ResizeListener(); //imagePanel.addComponentListener(listener); //method 4 : works //imagePanel.addComponentListener(new ResizeListener()); //method 5 : does not work -- THIS IS THE DESIRED CODE I WANT TO USE imagePanel.addComponentListener(panelResizeListener); } } public class ResizeListener extends ComponentAdapter { @Override public void componentResized(ComponentEvent evt) { System.out.println("RESIZE 3"); } } private ResizeListener panelResizeListener = new ResizeListener(); Each of the methods above correspond the to code immediately below until the next //method comment. What i don't understand is why i can't use the class instance variable and add that to the JPanel as a component listener. What happens in the cases above where i say that the method does not work is that i don't get the "RESIZE 3" log messages. In all cases where i list that it works, then i get the "RESIZE 3" messages. The outer class is public with no other modification except that it implements an interface that i created (which has no methods or variables in common with the methods and variables listed above). If anyone can help me i would greatly appreciate it. This problem makes no sense to me, the code should be identical.

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  • Which method should I use ?

    - by Ivan
    I want to do this exercise but I don't know exactly which method should I use for an exercise like this and what data will I use to test the algorithm. The driving distance between Perth and Adelaide is 1996 miles. On the average, the fuel consumption of a 2.0 litre 4 cylinder car is 8 litres per 100 kilometres. The fuel tank capacity of such a car is 60 litres. Design and implement a JAVA program that prompts for the fuel consumption and fuel tank capacity of the aforementioned car. The program then displays the minimum number of times the car’s fuel tank has to be filled up to drive from Perth to Adelaide. Note that 62 miles is equal to 100 kilometres. What data will you use to test that your algorithm works correctly?

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  • Shouldn't ObjectInputStream extend FilterInputStream?

    - by Vaibhav Bajpai
    The block quotes are from the Java Docs - A FilterInputStream contains some other input stream, which it uses as its basic source of data, possibly transforming the data along the way or providing additional functionality. A DataInputStream lets an application read primitive Java data types from an underlying input stream in a machine-independent way. The DataInputStream therefore extends FilterInputStream An ObjectInputStream deserializes primitive data and objects previously written using an ObjectOutputStream. However, for some reason the ObjectInputStream does NOT extend FilterInputStream even though it is also reading objects (this time and not primitive types) from the underlying input stream. Here is the branching of the concerned classes. Is there is a design reasoning for the same?

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  • State pattern: Why doesn't the context class implement or inherit the State abstract interface/class

    - by Ricket
    I'm reading about the State pattern. I have only just begun, so of course I begin by reading the entire Wikipedia article on it. I noticed that both of the examples in the article have some base abstract class or Java interface for a generic State's methods/functions. Then there are some states which inherit from the base and implement those methods/functions in different ways. Then there's a Context class which has a private member of type State and which, at any time, can be equal to an instance of one of the implementations. That context class also implements the same methods, and passes them onto the current state instance, and then has an additional method to change the state (or depending on design I understand the change of state could be a reaction to one of the implemented methods). Why doesn't this context class specifically "extend" or "implement" the generic State base class/interface?

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  • How to promote/market an event that needs many people?

    - by stjowa
    My team is about to launch a new web application, http://wethepixels.com, that requires a lot of people to be on the site at the same time for the concept to be successful. Our team is preparing to promote/market an event for a specific date and time, in order to try to grab a large group of people to the site at once. For those who have gone through a similar web launch, we would love to hear ideas on the best way to market for a large group in a relatively short period of time. We have created a Facebook page and a Facebook event, but it has yet to grab much attention (surprisingly to us). Is there a better way to attract a large number of users in a short period of time? Thanks

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  • Views performance in MySQL

    - by Gianluca Bargelli
    I am currently writing my truly first PHP Application and i would like to know how to project/design/implement MySQL Views properly; In my particular case User data is spread across several tables (as a consequence of Database Normalization) and i was thinking to use a View to group data into one large table: CREATE VIEW `Users_Merged` ( name, surname, email, phone, role ) AS ( SELECT name, surname, email, phone, 'Customer' FROM `Customer` ) UNION ( SELECT name, surname, email, tel, 'Admin' FROM `Administrator` ) UNION ( SELECT name, surname, email, tel, 'Manager' FROM `manager` ); This way i can use the View's data from the PHP app easily but i don't really know how much this can affect performance. For example: SELECT * from `Users_Merged` WHERE role = 'Admin'; Is the right way to filter view's data or should i filter BEFORE creating the view itself? (I need this to have a list of users and the functionality to filter them by role).

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  • Capturing USB Plug/Unplug events in Firemonkey

    - by radsdau
    [RAD Studio XE3 / C++] I have a FMX project running in Windows only at this stage, but I need to detect events when USB devices are connected and disconnected. I have a similar VCL app that can do this fine, but the Application-HookMainWindow is not exposed in FMX (only VCL). Is there an elegant way to handle this? Or do I have to hack some VCL stuff into my FMX app to make that work? I'd imagine I have to abstract it so I can support other platforms down the track. For the meantime though I need to get the Windows solution working. If the 'VCL hack' thing is required, how would I reference the vcl::Forms::Application from within my Fmx app? Cheers.

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  • How to simulate a mouse click in Cocoa for the iPhone?

    - by eagle
    I'm trying to setup automated unit tests for an iPhone application. I'm using a UIWebBrowser and need to simulate clicks on different links. I've tried doing this with JavaScript, but it doesn't produce the same results as when the I manually click on the links. The main problem is with links that have their target property set. I believe the only way for this automated unit test to work correctly is to simulate a mouse click at a specific x/y coordinate (i.e. where the link is located). Since the unit testing will only be used internally, private API calls are fine. It seems like this should be possible since the iPhone app isimulate seems to do something similar. Is there any way to do this in the framework?

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  • How to make addValueChangeHandler act just like addChangeHandler

    - by Konoplianko
    Hi. I have a problem. I made a wrap widget that implements interface HasChangeHandlers But i just can't fit events to each other. public HandlerRegistration addChangeHandler( final ChangeHandler handler ) { HandlerRegistration registration1 = dateFrom.addValueChangeHandler( handler );// Compile error HandlerRegistration registration2 = dateTo.addValueChangeHandler( new ValueChangeHandler<Date>() { @Override public void onValueChange( ValueChangeEvent<Date> dateValueChangeEvent ) { //have to fire handler ?? } } ); return null; // what i should return here? } Thanks in advance !

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  • jQuery Flip! links inside divs

    - by JLee
    Hey there. I want to use Flip (http://lab.smashup.it/flip/) for one of my projects. But I want the links to make the flip action inside the divs that are going to be flipped. I stumbled across a question here and the reply was very helpful, and by using that codes I managed to achieve what I want. But now the issue is when the page first loads it automatically flips before clicking any link. I don't know much about jQuery. So I would appreciate any help.

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  • Separate functionality depending on Role in ASP.NET MVC

    - by Andrew Bullock
    I'm looking for an elegant pattern to solve this problem: I have several user roles in my system, and for many of my controller actions, I need to deal with slightly different data. For example, take /Users/Edit/1 This allows a Moderator to edit a users email address, but Administrators to edit a user's email address and password. I'd like a design for separating the two different bits of action code for the GET and the POST. Solutions I've come up with so far are: Switch inside each method, however this doesn't really help when i want different model arguments on the POST :( Custom controller factory which chooses a UsersController_ForModerators and UsersController_ForAdmins instead of just UsersController from the controller name and current user role Custom action invoker which choose the Edit_ForModerators method in a similar way to above Have an IUsersController and register a different implementation of it in my IoC container as a named instance based on Role Build an implementation of the controller at runtime using Castle DynamicProxy and manipulate the methods to those from role-based implementations Im preferring the named IoC instance route atm as it means all my urls/routing will work seamlessly. Ideas? Suggestions?

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  • jQuery stopPropagation bubble down

    - by Jasie
    I have a div with a link inside of it: <div id="myDiv"> <a href="http://www.lol.com">Lol</a> </div> Clicking the <div /> should go somewhere, but clicking the child <a /> should go to www.lol.com. I've seen from previous questions and the jQuery website that .stopPropagation prevents bubbling upwards, but how do I prevent a bubble downwards (isn't that what's necessary here?).

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  • How to listen to keyboard events in GWT table?

    - by Olaf Mertens
    In my GWT program I have a table that has a selected row. I'd like to move the row selection with the up- and down-keys on the keyboard. So I have to catch the key events somehow. The GWT docs handle key events in input fields only. But I don't have an input field! Is this possible at all? Maybe it is a DOM/Javascript restriction that GWT cannot work around...

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  • Race condition firing events in AS3

    - by crispclean
    Hello I have some troubles firing and removing events in the right chronicle order. The code below gives the following output: save poster into db, and dispatch event calling service, dispatch event removed = false calling service, dispatch event removed = false calling service, dispatch event removed = true save poster into db, and dispatch event save poster into db, and dispatch event of course this should be more something like: save poster into db, and dispatch event calling service, dispatch event removed = true save poster into db, and dispatch event calling service, dispatch event removed = true save poster into db, and dispatch event calling service, dispatch event removed = true Can someone help me with this? I'm running out of ideas on how to tackle this. thx! for(var i:int = 0;i< 3;i++){ createPoster(); } function createPoster(){ Main.db.savePoster(); Main.db.addEventListener(Config.evt_SAVEPOSTER_READY, callService); } function callService(){ Main.db.removeEventListener(Config.evt_SAVEPOSTER_READY, callService); }

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  • Why does Excel expose an 'Evaluate' method at all?

    - by jtolle
    A few questions have come up recently involving the Application.Evaluate method callable from Excel VBA. The old XLM macro language also exposes an EVALUATE() function. Both can be quite useful. Does anyone know why the general expression evaluator is exposed, though? My own hunch is that Excel needed to give people a way to get ranges from string addresses, and to get the value of named formulas, and just opening a portal to the expression evaluator was the easiest way. But of course you don't need the ability to evaluate arbitrary expressions just to do that. Application.Evaluate seems kind of...unfinished. It isn't very well documented, and there are quite a few quirks and limitations (as described by Charles Williams here: http://www.decisionmodels.com/calcsecretsh.htm) with what is exposed. I suppose the answer could be simply "why not expose it?", but I'd be interested to know what design decisions led to this feature. Failing that, I'd be interested to hear other hunches.

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  • A general question about inheritence in the .NET framework

    - by Grant
    I have a general question about inheritance in the .NET framework, lets say you have 2 classes, the first is called Parent and the second is called Child. Child inherits from Parent. Parent wants to ensure that each instance of child executes a specific piece of code when it loads irrespective of whether the child has their own onLoad code explicitly specified. From my experience, if i handle onLoad in the parent and not in the child, the parents onLoad code will fire but if its handled in both classes only the child's code will fire. Is this correct? and if so how can i ensure the parents code will always fire for the child...

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