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• How to find all initializations of instance variables in a Java package?

  - by Hank Gay

  I'm in the midst of converting a legacy app to Spring. As part of the transition, we're converting our service classes from an "instantiate new ones whenever you need one" style to a Springleton style, so I need a way to make sure they don't have any state. I'm comfortable on the *nix command-line, and I have access to IntelliJ (this strikes me as a good fit for Structural Search and Replace, if I could figure out how to use it), and I could track down an Eclipse install, if that would help. I just want to make absolutely sure I've found all the possible problems. UPDATE: Sorry for the confusion. I don't have a problem finding places where the old constructor was being called. What I'm looking for is a "bullet-proof" why to search all 100+ service classes for any sort of internal state. The most obvious one I could think of (and the only one I've really found so far) is cases where we use memoization in the classes, so they have instance variables that get initialized internally instead of via Spring. This means that when the same Springleton gets used for different requests, data can leak between them. Thanks.

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• in .net, what programming model would be good for prototyping, but then reusable for production (for

  - by Greg

  Hi, In .NET land what would be a good approach for quick prototyping of a concept (i.e. development just on my PC) that could then be extended out to product (users across LAN/WAN), BUT in a fashion that the model/business logic code and data access layer code can be used as is? One thought for example I had as to do: (a) WinForms with business logic and Entity Framework layer to SQL Server Express on my PC, then (b) Go then to ASP.net (using the business logic / data library) with SQL Server/IIS Any comments? Other suggestions?

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• Point covering problem

  - by Sean

  I recently had this problem on a test: given a set of points m (all on the x-axis) and a set n of lines with endpoints [l, r] (again on the x-axis), find the minimum subset of n such that all points are covered by a line. Prove that your solution always finds the minimum subset. The algorithm I wrote for it was something to the effect of: (say lines are stored as arrays with the left endpoint in position 0 and the right in position 1) algorithm coverPoints(set[] m, set[][] n): chosenLines = [] while m is not empty: minX = min(m) bestLine = n[0] for i=1 to length of n: if n[i][0] <= m and n[i][1] > bestLine[1] then bestLine = n[i] add bestLine to chosenLines for i=0 to length of m: if m <= bestLine[1] then delete m[i] from m return chosenLines I'm just not sure if this always finds the minimum solution. It's a simple greedy algorithm so my gut tells me it won't, but one of my friends who is much better than me at this says that for this problem a greedy algorithm like this always finds the minimal solution. For proving mine always finds the minimal solution I did a very hand wavy proof by contradiction where I made an assumption that probably isn't true at all. I forget exactly what I did. If this isn't a minimal solution, is there a way to do it in less than something like O(n!) time? Thanks

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• how to get a specific class object

  - by user1275129

  I am still quite new to class concept. I have a problem here. for example, i have a class called class p{ int id; p(id){ //constructor } } now, i want to make instances of class p. After i have all the instances. i want to build a function get_p(pid) to return the specific class p which id=pid, how can i write this part? I have read c++ and java class tutorials, but i cant sort this out. please help me.

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• Pass a class as a parameter?

  - by JuBu1324

  I have been lead to believe that it is possible to pass a class as a method parameter, but I'm having trouble implementing the concept. Right now I have something like: - (id)navControllerFromView:(Class *)viewControllerClass title:(NSString *)title imageName:(NSString *)imageName { viewControllerClass *viewController = [[viewControllerClass alloc] init]; UINavigationController *thisNavController = [[UINavigationController alloc] initWithRootViewController: viewController]; thisNavController.tabBarItem = [[UITabBarItem alloc] initWithTitle: title image: [UIImage imageNamed: imageName] tag: 3]; return thisNavController; } and I call it like this: rootNavController = [ self navControllerFromView:RootViewController title:@"Contact" imageName:@"my_info.png" ]; What's wrong with this picture?

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• Where's the definitive resource online about how to carry out Agile development?

  - by jdk

  I want to start Agile practices in a team. I'm assuming the information is available for free online about how to specifically carry it out. Online I can locate the manifesto, the alliances and corporations involved but where is the actual central guide or root instruction set about how to do it? (Maybe the practices themselves are more ethereal or subjective than I expect and it's found in multiple places?) Edit to summarize solutions: Agile is a concept so that's what's to be found online about it. However specific processes or methods of Agile development have been created like Scrum and Extreme programming to provide concrete solutions to teams who want to adopt Agile and reap its proposed benefits. Find the shoe (or method) that fits best. Maybe create it. If looking for solutions online to implement Agile development in your organization or for your project, seek out the specific methods too and decide among them.

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• <= vs < when proving big-o notation

  - by user600197

  We just started learning big-o in class. I understand the general concept that f(x) is big-o of g(x) if there exists two constants c,k such that for all xk |f(x)|<=c|g(x)|. I had a question whether or not it is required that we include the <= to sign or whether it is just sufficient to put the < sign? For example: suppose f(x)=17x+11 and we are to prove that this is O(x^2). Then if we take c=28 and xk=1 we know that 17x+11<=28x^2. So since we know that x will always be greater than 1 this implies that 28x^2 will always be greater than 17x+11. So, do we really need to include the equal sign (<=) or is it okay if we just write (<)? Thanks in advance.

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• Significance of date 02/31/2157?

  - by dpatchery

  I work in a large scale IT support environment. Twice now we have seen an invalid date of 02/31/2157 being inserted in an Oracle DATE column. So far I have not been able to reproduce this problem, but it appears to be happening occasionally when a user attempts to save '00/00/0000' into the column. I believe the value is originating from a PowerBuilder DataWindow update. The application uses myriad libraries for all sorts of technologies, so this question may be a bit vague, but... Has anyone seen the date 02/31/2157 in some established library that Oracle could be defaulting to when some other invalid date is entered? Perhaps an end-of-time concept analogous to the beginning-of-time date of 1/1/1970?

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• Learning C++ from AS3

  - by grey

  I'm a decent AS3 programmer. I work in games, and that is my reason for programming. While there is much I can accomplish with Adobe AIR, my understanding at this point is that learning C++ is probably a good direction to take. I would learn a lot of valuable lower level programming if I needed it down the road, and I would have an easier time learning other C oriented languages. I see a lot of information for people looking to learn AS3 who know C++, but not the other way around. Why C++? Cross platform compatibility is important to me, so I'm not particularly interested in C# or Objective-C at this junction. I'm also aware of HaXe, and while I love the concept, after doing some research I'm worried about investing a lot of time into something so recent with limited learning resources and documentation. I'm looking for advice and resources (books, articles) related to this topic. Thanks in advance!

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• is it better to use a "natural" language to write codes ?

  - by M.H

  I recently saw a programming language called supernova and they said in the web page : The Supernova Programming language is a modern scripting language and the First one presents the concept of programming with direct Fiction Description using Clear subset of pure Human Language. and you can write codes like : i want window and the window title is Hello World. i want button and button caption is Close. and button name is btn1. btn1 mouse click. instructions are you close window end of instructions my question is not about the language itself but it is that are we need such languages and did they make writing codes more easier or not ?

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• Get access to a lot of iPhone and iPad Quality Source Codes for only $89

  - by Pixmator

  Hi developers and coming developers! We are happy to release this new concept from Pixmator.com, where you can get access to a lot of iPhone and iPad source codes for only $89. Start making a pro-developed application by these great application examples with is followed with a Source Code, so you can get everything out of it! These applications is present with a fully professionally designed graphic. The engine and the code is as well, as the graphic! It looks awesome. It is awesome. Take a look, it doesn't hurt anyone. Hope you guys like it! It will be available for purchase soon! Check out the link below: Check it out here!

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• What's the deal with all of the abstract stuff?

  - by JustVenting

  I see a lot of talk about MVVM, MVC, Design Patterns etc... You know, some guy has a blog, and he spent the last six months learning about one these things and desiging a program centered around that concept and then he goes on and on about it like its better than sliced bread. I read all of this crap and I wonder, whatever happened to simple logical programming? Not self-absorbed huge frameworks of design patterns and mvc and whatever else you can think of... just simple linear programming, perhaps a few classes to encapsulate things here and there.

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• What are the differences between MVP, Presentation Model, MVVM and MVC?

  - by Nicholas

  I have a pretty good idea how each of these patterns work some of the minor differences between them, but are they really all that different from each other? It seems to me that the Presenter, Presentation Model, ViewModel and Controller are essentially the same concept. Why couldn't I classify all of these concepts as controllers? I feel like it might simplify the entire idea a great deal. Can anyone give a clear description of their differences? I want to clarify that I do understand how the patterns work, and have implemented most of them in one technology or another. What I am really looking for is someone's experience with one of these patterns, and why they would not consider their ViewModel a controller for instance.

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• is there some lightweight tecnique for adding type safety to identifier properties?

  - by shoren

  After using C++ I got used to the concept of Identifier which can be used with a class for the type, provides type safety and has no runtime overhead (the actual size is the size of the primitive). I want to do something like that, so I will not make mistakes like: personDao.find(book.getId());//I want compilation to fail personDao.find(book.getOwnerId());//I want compilation to succeed Possible solutuions that I don't like: For every entity have an entity id class wrapping the id primitive. I don't like the code bloat. Create a generic Identifier class. Code like this will not compile: void foo(Identifier book); void foo(Identifier person); Does anyone know of a better way? Is there a library with a utility such as this? Is implementing this an overkill? And the best of all, can this be done in Java without the object overhead like in C++?

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• Are there really safe and legal resources for sound effects to use in applications?

  - by mystify

  For those who want to opt for "close" immediately: Great user interfaces need great sound effects, right? User interfaces are programmed by programmers, right? So this is a programming question, ok? I had a very hard time to find good and legal sound resources. I am not looking for free sounds. Proper licensing is absolutely crucial, and I don't want to get sued by multibilliondollar music companies, hollywood sound studios and their highly overpaid lawyers. They cry about people downloading their stuff in file sharing sites but when someone comes and wants to really license stuff, the market is so empty like an open and unwatched gold mine. Trust me, whatever I type into google, I always end up getting sort of opaque and strange music libraries that do charge money, but refuse to provide proper licensing evidence to the licensee. When you pay money and they only count how many files you downloaded, that can never be a valid license, nor any evidence for you that you did license the sounds. Imagine that contributor suing you and you say: "I licensed it at xy", and his lawyer just smiles: "Show me proof, mofo!". So you loose a million dollars, or 1 for every downloaded app. Congrats. But that's the way all those "hey we're the worlds largest sound effect library" libraries are doing it. It's really annoying. And I hope someone here is able to point out a sound effects ressource which is A) big B) used by professinals C) has a reasonable pricing and licensing model D) provides the licensee with proper legal evidence about licensed sounds You know, I'm not from the US and typically you US folks are the ones who invent the cool stuff on the net, and maybe I just missed a new great start up. So?

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• PHP OOP: Unique method per argument type?

  - by sunwukung

  I'm writing a little homebrew ORM (academic interest). I'm trying to adhere to the TDD concept as a training exercise, and as part of that exercise I'm writing documentation for the API as I develop the class. Case in point - I'm working on a classic "getCollection" type mapper class. I want it to be able to retrieve collections of asset X (let's say blog posts) for a specific user, and also collections based on an arbitrary array of numeric values. So - you might have a method like any one of these $User = $UserMapper->load(1); $ArticleCollection = $ArticleMapper->getCollection(range(10,20)); $ArticleCollection = $ArticleMapper->getCollection($User); $ArticleCollection = $ArticleMapper->getCollection($User->getId()); So, in writing the documentation for the getCollection method - I want to declare the @param variable in the Docblock. Is it better to have a unique method for each argument type, or is it acceptable to have a method that delegates to the correct internal method/class based on argument type?

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• DRY vs Security and Maintainability with MVC and View Models

  - by Mystere Man

  I like to strive for DRY, and obviously it's not always possible. However, I have to scratch my head over a concept that seems pretty common in MVC, that of the "View Model". The View Model is designed to only pass the minimum amount of information to the view, for both security, maintainability, and testing concerns. I get that. It makes sense. However, from a DRY perspective, a View Model is simply duplicating data you already have. The View Model may be temporary, and used only as a DTO, but you're basically maintaing two different versions of the same model which seems to violate the DRY principal. Do View Models violate DRY? Are they a necessary evil? Do they do more good than bad?

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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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• How to use TestAndSet() for solving the critical section problem?

  - by Dan Mantyla

  I'm studying for an exam and I'm having difficulty with a concept. This is the pseudo code I am given: int mutex = 0; do { while (TestAndSet(&mutex)); // critical section mutiex = 0; // remainder section } while (TRUE); My instructor says that only two of the three necessary conditions (mutual exclusion, progress, and bounded waiting) are met with this code, but I don't understand which one isn't being met...?? How should the code be modified to support the missing condition to solve the critical region problem? Thanks in advance for any insight!

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• Presentation to under privileged students about what programming is. How? Any ideas.

  - by Quigrim

  Next week I have to give a presentation to a group of under privileged college students about the possibilities of a career in software development. These students have no exposure to programming what-so-ever. I have a good idea of how to tackle the non-technical, general portion of the presentation. However, notwithstanding my decade of experience, I am finding myself at somewhat of a loss how to convey the concept of programming in a meaningful way in under 20 minutes. Do I demonstrate actual simple code, or do I stick with concepts? I need to be able to scratch the surface of the vastness of the programming realm, to create just enough of a handle to those students, to peak the interest of those who might have the aptitude for it. Any ideas that are concise and clear would be greatly appreciated. Also, if anybody knows of online resources that addresses this topic, please share. Looking forward to some great input from this community. Thank you.

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• What are good uses for Python3's "Function Annotations"

  - by agscala

  Function Annotations: PEP-3107 I ran across a snippet of code demonstrating Python3's function annotations. The concept is simple but I can't think of why these were implemented in Python3 or any good uses for them. Perhaps SO can enlighten me? How it works: def foo(a: 'x', b: 5 + 6, c: list) -> max(2, 9): ... function body ... Everything following the colon after an argument is an 'annotation', and the information following the -> is an annotation for the function's return value. foo.func_annotations would return a dictionary: {'a': 'x', 'b': 11, 'c': list, 'return': 9} What's the significance of having this available?

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• Sync data between a windows desktop app and windows mobile client app

  - by Chris W

  I need to knock up a very quick prototype/proof of concept application to demo to someone within the next couple of days so I've minimal time to research this as fully as I normally would. The set-up is a very simple database application running on a laptop - will only ever be a single user updating a couple of tables so I was thinking of knocking up a basic Win Forms app against SQL Compact. Visual Studio's auto generated data grid edit screens will be fine with a little customisation. The second aspect is to then add a windows mobile client application that can pull data from both tables stored on the laptop, edit some data and insert some extra rows before sending the changes back to the laptop copy of the database. I've not done any WinMo development so what's the best approach for me to look at. Is it easy enough to sync data between the two databases when the WinMo device is connected to the laptop with USB? Most of the samples I've looked at so far seem to be syncing SQL Compact with SQL Standard using IIS which seems a bit overkill. The volumes of data to be synced are so small that I can easily write some manual sync code if it's easy for me to query/update the Compact DB from the laptop application when the device is connected.

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• Use count or have a field that tallies?

  - by Dan LaManna

  Fairly simple concept, making an extremely basic message board system and I want users to have a post count. Now I was debating on whether or not to have a tally in their row that is added each time a post by them is created, or subtracted by one each time a post of theirs is deleted. However I'm sure that performing a count query when the post count is requested would be more accurate due to unforseen circumstances (say a thread gets deleted and it doesn't lower their tally properly), however this seems like it would be less efficient to run a query EVERY time their post count is loaded, especially in the case of them having 10 posts on the same page and it lists their post count each post. Thoughts/Advice? Thanks

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• Capturing system command output as a string

  - by dreeves

  Perl and PHP do this with backticks. For example: $output = `ls`; This code returns a directory listing into the variable $output. A similar function, system("ls"), returns the operating system return code for the given command. I'm talking about a variant that returns whatever the command prints to stdout. (There are better ways to get the list of files in a directory; the example code is an example of this concept.) How do other languages do this? Is there a canonical name for this function? (I'm going with "backtick"; though maybe I could coin "syslurp".)

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• Which web solution should I use for my project?

  - by BenIOs

  I'm going to create a fairly large (from my point of view anyway) web project with a friend. We will create a site with roads and other road related info. Our calculations is that we will have around 100k items in our database. Each item will contain some information like location, name etc. (about 30 thing each). We are counting on having a few hundred thousand unique visitors per month. The 100k items and their locations (that will be searchable) will be the main part of the page but we will also have some articles, comments, news and later on some more social functions (accounts, forums, picture uploads etc.). We were going to use Google AppEngine to develop our project since it is really scalable and free (at least for a while). But I'm actually starting to doubt that AppEngine is right for us. It seems to be for webbapps and not sites like ours. Which system (language/framework etc.) would you guys recommend us to use? It doesn't really mater if we know the language since before (we like learning new stuff) but it would be good if it's something that is future proof.

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