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• Setting a form field's value during validation

  - by LaundroMat

  I read about this issue already, but I'm having trouble understanding why I can't change the value of a form's field during validation. I have a form where a user can enter a decimal value. This value has to be higher than the initial value of the item the user is changing. During clean(), the value that was entered is checked against the item's previous value. I would like to be able to re-set the form field's value to the item's initial value when a user enters a lower value. Is this possible from within the clean() method, or am I forced to do this in the view? Somehow, it doesn't feel right to do this in the view... (To make matters more complicated, the form's fields are built up dynamically, meaning I have to override the form's clean() method instead of using the clean_() method).

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• Implementing Clonable in Java

  - by Artium

  In which cases should I use this way: public A clone() throws CloneNotSupportedException { A clone = (A)super.clone(); clone.x= this.x; return clone; } And in which cases should I use that way: public ShiftedStack clone() throws CloneNotSupportedException { return new A(this.x); } What should I do if x is final and I want to use the first way? Regarding the first way, I understand it like this: we clone the super class and up-cast it, leading to some members uninitialized. After this initialize these members. Is my understanding correct? Thank you.

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• SQL Server Mapping a user to a login and adding roles programmatically

  - by user163457

  In my SQL Server 2005 server I create databases and logins using Management Studio. My application requires that I give a newly created user read and write permissions to another database. To do this I right-click the newly created login, select properties and go to User Mapping. I put a check beside the database to map this login to the db and select db_datareader and db_datawriter as the roles to map. Can this be done programmatically? I've read about using Alter User and sp_change_users_login but I'm having problems getting these to work, since sp_change_users_login has been deprecated so I'd prefer to use Alter User. Please note my understanding of SQL Server database users/logins/roles is basic

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• What can't the NDK be used for?

  - by Android Eve

  From the official NDK site: The Android NDK... provides headers and libraries that allow you to build activities, handle user input, use hardware sensors, access application resources, and more, when programming in C or C++. If you write native code, your applications are still packaged into an .apk file and they still run inside of a virtual machine on the device. The fundamental Android application model does not change. Yet, it is always described as a companion tool to the Android SDK and as a toolset that allows to "implement parts of your applications using native-code languages such as C and C++". My understanding from this is that, unlike the Java based SDK, the NDK is not designed to implement certain parts of an Android application. Is this correct? If so, what parts doesn't the NDK allow implementing?

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• geom_rect and NULL

  - by csgillespie

  I've been looking at the geom_rect example in section 5.10 of the ggplot2 book and don't understand the purpose of the NULL's in the aes function. For example, using the mpg data: g = ggplot(data=mpg, aes(x=displ, y=hwy)) + geom_point() #Produces a plot with a transparent filled region g + geom_rect(aes(NULL, NULL), alpha=0.1,xmin=5, xmax=7, ymin=10, ymax=45, fill="blue") #Solid filled region (v0.9) or nothing in v0.8 g + geom_rect(alpha=0.1,xmin=5, xmax=7, ymin=10, ymax=45, fill="blue") My understanding is that the NULL's are resetting the x & y mapping, but I don't see why this should affect the transparency.

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• Casting to specific asp.net page type

  - by DEH

  I have an asp.net page with a code-behind class definition as follows: public partial class examplepage : System.Web.UI.Page I'd like to set a public property within the page that I can reference from other classes. My understanding is that if I cast to examplepage then I should be able to get at the public property that is specific to example page, as in: string test=((examplepage)HttpContext.Current.Handler).propertyX; However, when I try casting as above the compiler does not recognise examplepage. Can anyone tell me how I can cast? I have no specific namespaces defined. Thanks

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• Is the offical Sun Java EE tutorial the best way to learn how to make Java web apps?

  - by Nick

  I've been a web developer for almost a decade. I've mostly used classic ASP/JavaScript and I'd like to move into Java based apps. I have a decent understanding of Java itself (enough to know how to lookup what I don't know) and I spent some time doing minor work on a JSF/Spring/Hibernate app, but from what a trusted coworker told me, this application is the example of what not to do. I want to learn the really hardcore stuff (EJBs, HA Clustering, etc), but I know I have to walk before I can run. Is the Sun Tutorial the best place to start? Or is there an definitive book (like K&R for C or Gang of Four for design patterns) that I should buy?

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• Hibernate entities stored as HttpSession attribute values

  - by njudge

  I'm dealing with a legacy Java application with a large, fairly messy codebase. There's a fairly standard 'User' object that gets stored in the HttpSession between requests, so the servlets do stuff like this at the top: HttpSession session = request.getSession(true); User user = (User)session.getAttribute("User"); The old user authentication layer (which I won't describe; suffice to say, it did not use a database) is being replaced with code mapped to the DB with Hibernate. So 'User' is now a Hibernate entity. My understanding of Hibernate object life cycles is a little fuzzy, but it seems like storing 'User' in the HttpSession now becomes a problem, because it will be retrieved in a different transaction during the next request. What is the right thing to be doing here? Can I just use the Hibernate Session object's update() method to reattach the User instance the next time around? Do I need to?

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• How to Vertically Center Images on a Line?

  - by jeremy

  What's the best way to center icons on a line when the images are smaller than the line height? For example (styles inline for easier reading): <div style="line-height: 20px"> <img style="width: 12px; height: 12px;"/> Blah blah blah </div> Here's a jsFiddle example. This example also shows why vertical-align: middle does not work. I want the img to be centered against the text of the div. That is, even if the text wrapped to multiple lines, the image would be centered against a single line. Ideally, the solution would not involve setting margings/paddings on the image and would work even if I didn't know the line-height. Things I've read: How do I vertically align text next to an image with CSS? (deals with case where image is larger, doesn't seem to apply here) Understanding vertical-align

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• Replacing a C++ ActiveX component with a .NET implementation?

  - by Leon Breedt

  I have existing managed and unmanaged software using an ActiveX component supplied by a third party to perform some communications, but it is now required that this communication be routed through my application. Ideally I'd be able to install a .NET component which will expose exactly the same interface, and will be usable as a drop-in replacement. However, I am running into the limits of my understanding of COM, which admittedly is quite minimal. How best to ensure that my implementation of the interface is 100% binary compatible with the existing object? How do I ensure that applications use my implementation of the interface instead of the legacy implementation? Is it simply a matter of registering my implementation, and unregistering the legacy one? How do I ensure it's a "drop-in" replacement, and requires no changes to existing software? How do I ensure unmanaged code can use it without issue? Note: I am able to require that .NET 4.0 be used, if that will make things simpler.

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• C++ - defining static const integer members in class definition

  - by HighCommander4

  My understanding is that C++ allows static const members to be defined inside a class so long as it's an integer type. Why, then, does the following code give me a linker error? #include <algorithm> #include <iostream> class test { public: static const int N = 10; }; int main() { std::cout << test::N << "\n"; std::min(9, test::N); } The error I get is: test.cpp:(.text+0x130): undefined reference to `test::N' collect2: ld returned 1 exit status Interestingly, if I comment out the call to std::min, the code compiles and links just fine (even though test::N is also referenced on the previous line). Any idea as to what's going on? My compiler is gcc 4.4 on Linux.

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• WPF UserControl event called only once?

  - by 742

  Hi Everyone, I need to bind two-way a property of a user control to a property of a containing user control. I also need to set a default value to the property from code in the child (cannot be done easily from XAML tags). If I call my code from the child constructor, the value is set in the parent but the change callback routine is not triggered (my understanding is that the parent doesn't yet exist at the time the child is created). My current workaround is to catch the Loaded event of the child and to call the code from the handler. Howver as Loaded is called more than once, I need to set a flag to set the property only the first time. I don't like this way, but I don't know if there is a single shot event that could be used, or if this can be done otherwise. Any feedback based on your experience?

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• How does SWTBOT run a custom eclipse based application? I don't know how to specify my target application

  - by jlisam13

  I have an eclipse based application. I have heard of swtbot however I am having a hard time understanding how exactly does this tool run my application and how would I specify that. This eclipse based application has an executable and various configuration/plugin/features files. I have done the tutorials about swtbot and I have successfully completed them but they all just create a template application to test on. Is this even possible? If not do you guys have any alternatives for UI automation testing on eclipse based apps? Thanks.

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• How to remove thie ".svc" extension in RESTful WCF service?

  - by Morgan Cheng

  In my knowledge, the RESTful WCF still has ".svc" in its URL. For example, if the service interface is like [OperationContract] [WebGet(UriTemplate = "/Value/{value}")] string GetDataStr(string value); The access URI is like "http://machinename/Service.svc/Value/2". In my understanding, part of REST advantage is that it can hide the implementation details. A RESTful URI like "http://machinename/Service/value/2" can be implemented by any RESTful framework, but a "http://machinename/Service.svc/value/2" exposes its implementation is WCF. How can I remove this ".svc" host in the access URI?

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• Zend_Form: Is this really the way we should be doing things?

  - by Francis Daigle

  OK. I understand how to use Zend_Form and it's implementation of the decorator pattern. My question is, is this the best way to be going about creating forms? Shouldn't a documents forms be left to to the front-end rather than generating forms programmatically? Doesn't this kinda violate the whole idea of keeping things separate? I mean, really, even providing that you have a good understanding of the methodology being employed, does it really save one that much time? I guess what I'm looking for is some guidance as to what might be considered 'best practice'. I'm not saying that Zend_Form doesn't have it's place, I'm just wondering if it should be used in all cases (or not). And this has nothing to do with validation. I'm just thinking that something more akin to using the 'ViewScript' approach might be more appropriate in most cases. Your thoughts?

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• "Othello" game needs some clarification

  - by pappu

  I am trying to see if my understanding of "othello" fame is correct or not. According to the rules, we flip the dark/light sides if we get some sequence like X000X = XXXXX. The question I have is if in the process of flipping 0-X or X- 0, do we also need to consider the rows/columns/diagonals of newly flipped elements? e.g. consider board state as shown in above image(New element X is placed @ 2,3) When we update board, we mark elements from 2,3 to 6,3 as Xs but in this process elements like horizontal 4,3 to 4,5 and diagonal 2,3 to 4,5 are also eligible for update? so do we update those elements as well? or just the elements which have starting as 2,3 (i.e update rows/column/diagonal whose starting point is the element we are dealing with, in our case 2,3?) Please help me understand it

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• Problems with dynamic programming

  - by xan

  I've got difficulties with understanding dynamic programming, so I decided to solve some problems. I know basic dynamic algorithms like longest common subsequence, knapsack problem, but I know them because I read them, but I can't come up with something on my own :-( For example we have subsequence of natural numbers. Every number we can take with plus or minus. At the end we take absolute value of this sum. For every subsequence find the lowest possible result. in1: 10 3 5 4; out1: 2 in2: 4 11 5 5 5; out2: 0 in3: 10 50 60 65 90 100; out3: 5 explanation for 3rd: 5 = |10+50+60+65-90-100| what it worse my friend told me that it is simple knapsack problem, but I can't see any knapsack here. Is dynamic programming something difficult or only I have big problems with it?

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• Display values and how many times they occured using a Dictionary

  - by user1730056

  I've been told to By using a dictionary (or your solution to Part 4), write a method at_least(a, n) that takes a list, a, and an integer, n, as arguments and returns a list containing only the elements of a that occur at least n times. For complete marks, the list should contain the elements in order of their first occurrence in a. I was able to figure this without using a dictionary, with def at_least2(a, n): return [x for x in a if a.count(x) is n] I was wondering how I can write this using a dictionary? The input is: a = [-6, 8, 7, 3, 2, -9, 1, -3, 2, -4, 4, -8, 7, 8, 2, -2, -7, 0, 1, -9, -3, -7, -3, -5, 6, -3, 6, -3, -10, -8] def at_least(a, 2): and the output: [8, 7, 2, -9, 1, -3, 2, -8, 7, 8, 2, -7, 1, -9, -3, -7, -3, 6, -3, 6, -3, -8] Edit: I don't understand how a dictionary is being used, yet the output isn't in dictionary form? My understanding is that dictionaries have values for each object. I'm not sure if I'm using the right terms.

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• How to start coding the "Dining Philosophers" simulation?

  - by GrizzlyGuru

  I'm not a beginner at C# but I really need to increase my understanding, so I've picked a classic deadlock problem to code to help teach myself some of the more advanced concepts of C#. The Dining Philosophers Problem seems like a good one, but I need a little help to get started. I know I need to approach the "diners" as objects, but to simulate the random delays between eating, should I look to threading with each diner in a separate thread? Do I need some kind of "master" to monitor all the actions? Any general design concept advice is welcome, but I'd like to do the grunt programming as an exercise. Thanks!

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• Creating a computer with pencil and paper [closed]

  - by Justian Meyer

  This concept has been brought to my attention before, but many people might know it from this popular comic here, where he uses stones instead of points on a paper. This concept is so abstract to me. A full-functioning computer that can manage algorithms, input, output, etc. without electricity? Surely, it's difficult to visualize because my definition of a computer is not exactly what the word sounds like COMPUTE-ER. Can someone help me bring the concept to light - the understanding, how to make one, etc? It seems like it'd be an interesting read, although I think I wouldn't be able to make it do anything. Many thanks in advance for responses. I've tried searching Google, but all I got were ways to diagram code and chart ideas. -.Justian.

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• How To: Call a web service from ajax

  - by Kolten

  I have a simple Web Service that send email and is called via: public bool SendMail(string format, string from, string to, string cc, string bcc, string subject, string body, string replyTo) I have never used ajax before, and find I need to call this service and pass form contents to it from a simple html page (I cannot use asp or asp.net unfortunately). Can I get a quick rundown of what is required? I have searched for simple examples, but find I am having difficulty understanding how to call it and pass the parameters required of the Web Service. Thanks all!

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• How can I load an MP3 or similar music file for display and anaysis in wxWdigets?

  - by Jon Cage

  I'm developing a GUI in wxPython which allows a user to generate sequences of colours for some toys I'm building. Part of the program needs to load an MP3 (and potentially other formats further down the line) and display it to the user. That shuold be sufficient to get started but later I'd like to add features like identifying beats and some crude frequency analysis. Is there any simple way of loading / understanding an MP3's contents to display a plot of it's amplitudes to the screen using wxWidgets? I later intend to port to C++/wxWidgets for speed and to avoid having to distribute wxPython.

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• Cocoa Interface Builder object initialization

  - by Stanley

  Base on the documentation and sample code that I have gone through, I got an impression that when a class defined in xcode is read into and configured in Interface Builder, an object based on the class is effectively created and stored in an xib or nib file. So the object is ready to be used when the corresponding application is launched. Alternatively, for classes that have not been handled by Interface Builder, code such as the "new" statements have to be written in xcode explicitly in order for the associated objects to be created and used. It will be very nice to have people who are more knowledgable than me to confirm or to correct my very naive understanding of Interface Builder ...

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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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• How to work around a site forbidding me to scrape their images with PHP

  - by Petruza

  I'm scraping a site, searching for JPGs to download. Scraping the site's HTML pages works fine. But when I try getting the JPGs with CURL, copy(), fopen(), etc., I get a 403 forbiden status. I know that's because the site owners don't want their images scraped, so I understand a good answer would be just don't do it, because they don't want you to. Ok, but let's say it's ok and I try to work around this, how could this be achieved? If I get the same URL with a browser, I can open the image perfectly, it's not that my IP is banned or anything, and I'm testing the scraper one file at a time, so it's not blocking me because I make too many requests too often. From my understanding, it could be that either the site is checking for some cookies that confirm that I'm using a browser and browsing their site before I download a JPG. Or that maybe PHP is using some user agent for the requests that the server can detect and filter out. Anyway, have any idea?

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