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• Should programmers do Pro Bono work? where are the code public defenders?

  - by Tj Kellie

  How many projects are people doing based on the Bro Bono publico ideals versus working for the highest wage or potential for a cash-in-buy-out payday? For years lawyers have been called out for excessive gathering of wealth from high bill rates and huge settlement deals, hiring out their knowledge and skills to the highest bidders. People call for them to do more for free, use the laws and their time to defend or further some cause thats in the public's best interest. Is professional software development that different? So many bright people and so much knowledge of complex systems. Do you think that there is enough of a "Pro Bono" movement to solve the social and public problems in the industry right now? If so what are the examples to point to? OLPC? NOTE: Saying that open source software is the same as pro bono misses the point completely. I was looking for specific projects with a social context, not just group-sourcing for free software. Just because your not making anyone pay for your software does not mean its doing anyone any good. I'm not calling out manual enforcement of pro bono work for programmers, really just want some objective opinions and concrete examples of social-minded software/tech development projects like the One Laptop Per Child project. I'm sure open source would be a natural tie-in for some.

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• Program Structure Design Tools? (Top Down Design)

  - by Lee Olayvar

  I have been looking to expand my methodologies to better involve Unit testing, and i stumbled upon Behavioral Driven Design (Namely Cucumber, and a few others). I am quite intrigued by the concept as i have never been able to properly design top down, only because keeping track of the design gets lost without a decent way to record it. So on that note, in a mostly language agnostic way, are there any useful tools out there i am (probably) unaware of? Eg, i have often been tempted to try building flow charts for my programs, but i am not sure how much that will help, and it seems a bit confusing to me how i could make a complex enough flow chart to handle the logic of a full program, and all its features.. ie, it just seems like flow charts would be limiting in the design scheme.. or possibly grow to an unmaintainable scale. BDD methods are nice, but with a system that is so tied to structure, tying into the language and unit testing seems like a must (for it to be worth it) and it seems to be hard to find something to work well with both Python and Java (my two main languages). So anyway.. on that note, any comments are much appreciated. I have searched around on here and it seems like top down design is a well discussed topic, but i haven't seen too much reference to tools themselves, eg, flow chart programs, etc. I am on Linux, if it matters (in the case of programs).

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• Make WebStart Java desktop application to start on system startup on Windows and Mac

  - by parxier

  I developed small cross-platform (Windows and Mac) SWT desktop application. It is distributed with WebStart. So far so good, everything works. I've got a new requirement to make my app start on system startup (with no user interaction). What is the best way to accomplish that? In JNLP file I've got this: <shortcut online="false"> <desktop/> <menu submenu="CompanyName"/> </shortcut> On Windows WebStart creates a desktop link [app_name].lnk and it points to javaws.exe and then some Java cache file as a parameter with funny name like ..\Sun\Java\Deployment\cache\6.0\4\2c0a6a781-213476. I can possibly programmatically find that link on user's machine by name... erm... and then copy it into user's Startup folder. I can see a problem here though as user can disable WebStart desktop shortcut creation option all together. On Mac WebStart pops up a dialog to prompt user for the location where to create an [app_name].app (user is allowed to change link name there!) file that launches an application. On Mac I don't event know where the Startup folder is located (and it seems to be much more complex there). Is there Java library out there that abstracts start app on system startup concept on different platforms as SWT does for GUI abstraction?

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• rename files with the same name

  - by snorpey

  Hi. I use the following function to rename thumbnails. For example, if I upload a file called "image.png" to an upload folder, and this folder already has a file named "image.png" in it, the new file automatically gets renamed to "image-copy-1.png". If there also is a file called "image-copy-1.png" it gets renamed to "image-copy-2.png" and so on. The following function returns the new filename. At least that's what it is supposed to do... The renaming doesn't seeem to work correctly, though. Sometimes it produces strange results, like: 1.png 1-copy-1.png 1-copy-2.png 1-copy-2-copy-1.png 1-copy-2-copy-3.png I hope you understand my problem, despite my description being somewhat complex... Can you tell me what went wrong here? (bonus question: Is regular expressions the right tool for doing this kind of stuff?) <?php function renameDuplicates($path, $file) { $fileName = pathinfo($path . $file, PATHINFO_FILENAME); $fileExtension = "." . pathinfo($path . $file, PATHINFO_EXTENSION); if(file_exists($path . $file)) { $fileCopy = $fileName . "-copy-1"; if(file_exists($path . $fileCopy . $fileExtension)) { if ($contains = preg_match_all ("/.*?(copy)(-)(\\d+)/is", $fileCopy, $matches)) { $copyIndex = $matches[3][0]; $fileName = substr($fileCopy, 0, -(strlen("-copy-" . $copyIndex))) . "-copy-" . ($copyIndex + 1); } } else { $fileName .= "-copy-1"; } } $returnValue = $fileName . $fileExtension; return $returnValue; }?>

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• Convert 4 bytes to int

  - by Oscar Reyes

  I'm reading a binary file like this: InputStream in = new FileInputStream( file ); byte[] buffer = new byte[1024]; while( ( in.read(buffer ) > -1 ) { int a = // ??? } What I want to do it to read up to 4 bytes and create a int value from those but, I don't know how to do it. I kind of feel like I have to grab 4 bytes at a time, and perform one "byte" operation ( like << & FF and stuff like that ) to create the new int What's the idiom for this? EDIT Ooops this turn out to be a bit more complex ( to explain ) What I'm trying to do is, read a file ( may be ascii, binary, it doesn't matter ) and extract the integers it may have. For instance suppose the binary content ( in base 2 ) : 00000000 00000000 00000000 00000001 00000000 00000000 00000000 00000010 The integer representation should be 1 , 2 right? :- / 1 for the first 32 bits, and 2 for the remaining 32 bits. 11111111 11111111 11111111 11111111 Would be -1 and 01111111 11111111 11111111 11111111 Would be Integer.MAX_VALUE ( 2147483647 )

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• Linq: the linked objects are null, why?

  - by user46503

  Hello, I have several linked tables (entities). I'm trying to get the entities using the following linq: ObjectQuery<Location> locations = context.Location; ObjectQuery<ProductPrice> productPrice = context.ProductPrice; ObjectQuery<Product> products = context.Product; IQueryable<ProductPrice> res1 = from pp in productPrice join loc in locations on pp.Location equals loc join prod in products on pp.Product equals prod where prod.Title.ToLower().IndexOf(Word.ToLower()) > -1 select pp; This query returns 2 records, ProductPrice objects that have linked object Location and Product but they are null and I cannot understand why. If I try to fill them in the linq as below: res = from pp in productPrice join loc in locations on pp.Location equals loc join prod in products on pp.Product equals prod where prod.Title.ToLower().IndexOf(Word.ToLower()) > -1 select new ProductPrice { ProductPriceId = pp.ProductPriceId, Product = prod }; I have the exception "The entity or complex type 'PBExplorerData.ProductPrice' cannot be constructed in a LINQ to Entities query" Could someone please explain me what happens and what I need to do? Thanks

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• Audio stream mangement in Linux

  - by User1

  I have a very complicated audio setup for a project. Here's what we have: 3 applications playing sound 2 applications recording sound 2 sound cards I really don't really have the code to any of these applications. All I want to do is monitor and control the audio streams. Here are a few examples of operations I'd like to do while the applications are running: Mute one of the incoming audio streams. Have one of the incoming audio streams do a "solo" (be the only stream that can "talk"). Get a graph (about 30 seconds worth) of the audio that each stream produced. Send one of the audio streams to soundcard #1, but all three audio streams to soundcard #2. I would likely switch audio streams every 2 minutes or so with one of the operations listed above. A GUI would be preferred. I started looking at the sound systems in Linux and it gets extremely complex and I feel like there have been many new advances in the past few years. I see jack, pulseaudio, artsd, and several other packages. They all have some promise but where should I start? Is there something someone already built that can help?

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• Why does VBA Find loop fail when called from Evaluate?

  - by Abiel

  I am having some problems running a find loop inside of a subroutine when the routine is called using the Application.Evaluate or ActiveSheet.Evaluate method. For example, in the code below, I define a subroutine FindSub() which searches the sheet for a string "xxx". The routine CallSub() calls the FindSub() routine using both a standard Call statement and Evaluate. When I run Call FindSub, everything will work as expected: each matching address gets printed out to the immediate window and we get a final message "Finished up" when the code is done. However, when I do Application.Evaluate "FindSub()", only the address of the first match gets printed out, and we never reach the "Finished up" message. In other words, an error is encountered after the Cells.FindNext line as the loop tries to evaluate whether it should continue, and program execution stops without any runtime error being printed. I would expect both Call FindSub and Application.Evaluate "FindSub()" to yield the same results in this case. Can someone explain why they do not, and if possible, a way to fix this? Thanks. Note: In this example I obviously do not need to use Evaluate. This version is simplified to just focus on the particular problem I am having in a more complex situation. Sub CallSub() Call FindSub Application.Evaluate "FindSub()" End Sub Sub FindSub() Dim rngFoundCell As Range Dim rngFirstCell As Range Set rngFoundCell = Cells.Find(What:="xxx", after:=ActiveCell, LookIn:=xlValues, _ LookAt:=xlPart, SearchOrder:=xlByRows, SearchDirection:=xlNext, _ MatchCase:=False, SearchFormat:=False) If Not rngFoundCell Is Nothing Then Set rngFirstCell = rngFoundCell Do Debug.Print rngFoundCell.Address Set rngFoundCell = Cells.FindNext(after:=rngFoundCell) Loop Until (rngFoundCell Is Nothing) Or (rngFoundCell.Address = rngFirstCell.Address) End If Debug.Print "Finished up" End Sub

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• Redraw and flicker issues

  - by AngryHacker

  I have an Outlook style app. So basically I have a sidebar on the left and on the right I have a panel control (pnlMainBody) that hosts content. The content is typically a user control that I add to the panel when user clicks appropriate button in the side bar. The way I add the user control to the panel is as follows: // _pnlEmails is the User Control that I am adding to the panel _pnlEmails = new pnlEmails(); _pnlEmails.Dock = DockStyle.Fill; this.pnlMainBody.Controls.Add(_pnlEmails); Some of the user controls that I add to the main panel are quite complex UI-wise. So when this.pnlMainBody.Controls.Add(_pnlEmails); fires, I see the control appear on the screen, then it resizes itself to fill the body of the panel control. It's quite ugly actually, so I was wondering whether there is a way to not show the resizing until it's actually done resizing? I've tried setting the user control's .Visible to false. I've tried doing .SuspendLayout, all to no avail. Is there a way to do this so the screen transitions are smooth?

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• Perl program - Dynamic Bootstrapping code

  - by mgj

  Hi.. I need to understand the working of this particular program, It seems to be quite complicated, could you please see if you could help me understanding what this program in Perl does, I am a beginner so I hardly can understand whats happening in the code given on the following link below, Any kind of guidance or insights wrt this program is highly appreciated. Thank you...:) This program is called premove.pl.c Its associated with one more program premove.pl, Its code looks like this: #!perl open (newdata,">newdata.txt") || die("cant create new file\n");#create passwd file $linedata = ""; while($line=<>){ chomp($line); #chop($line); print newdata $line."\n"; } close(newdata); close(olddata); __END__ I am even not sure how to run the two programs mentioned here. I wonder also what does the extension of the first program signify as it has "pl.c" extension, please let me know if you know what it could mean. I need to understand it asap thats why I am posting this question, I am kind of short of time else I would try to figure it out myself, This seems to be a complex program for a beginner like me, hope you understand. Thank you again for your time.

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• haskell: a data structure for storing ascending integers with a very fast lookup

  - by valya

  Hello! (This question is related to my previous question, or rather to my answer to it.) I want to store all qubes of natural numbers in a structure and look up specific integers to see if they are perfect cubes. For example, cubes = map (\x -> x*x*x) [1..] is_cube n = n == (head $ dropWhile (<n) cubes) It is much faster than calculating the cube root, but It has complexity of O(n^(1/3)) (am I right?). I think, using a more complex data structure would be better. For example, in C I could store a length of an already generated array (not list - for faster indexing) and do a binary search. It would be O(log n) with lower ?oefficient than in another answer to that question. The problem is, I can't express it in Haskell (and I don't think I should). Or I can use a hash function (like mod). But I think it would be much more memory consuming to have several lists (or a list of lists), and it won't lower the complexity of lookup (still O(n^(1/3))), only a coefficient. I thought about a kind of a tree, but without any clever ideas (sadly I've never studied CS). I think, the fact that all integers are ascending will make my tree ill-balanced for lookups. And I'm pretty sure this fact about ascending integers can be a great advantage for lookups, but I don't know how to use it properly (see my first solution which I can't express in Haskell).

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• How to remove all ListBox items?

  - by Nano HE

  Hi, I created two RadioButton (Weight and Height). I will do switch between the two categories. But the they share the same ListBox Controllers (listBox1 and listBox2). Is there any good method to clear all the ListBox items simpler? I didn't find the removeAll() for ListBox. I don't like my complex multi-lines style which I posted here. private void Weight_Click(object sender, RoutedEventArgs e) { // switch between the radioButton "Weith" and "Height" // Clear all the items first listBox1.Items.Remove("foot"); listBox1.Items.Remove("inch"); listBox1.Items.Remove("meter"); listBox2.Items.Remove("foot"); listBox2.Items.Remove("inch"); listBox2.Items.Remove("meter"); // Add source units items for listBox1 listBox1.Items.Add("kilogram"); listBox1.Items.Add("pound"); // Add target units items for listBox2 listBox2.Items.Add("kilogram"); listBox2.Items.Add("pound"); } private void Height_Click(object sender, RoutedEventArgs e) { // switch between the radioButton "Weith" and "Height" // Clear all the items first listBox1.Items.Remove("kilogram"); listBox1.Items.Remove("pound"); listBox2.Items.Remove("kilogram"); listBox2.Items.Remove("pound"); // Add source units items for listBox1 listBox1.Items.Add("foot"); listBox1.Items.Add("inch"); listBox1.Items.Add("meter"); // Add target units items for listBox2 listBox2.Items.Add("foot"); listBox2.Items.Add("inch"); listBox2.Items.Add("meter"); }

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• How you would you describe the Observer pattern in beginner language?

  - by Sheldon

  Currently, my level of understanding is below all the coding examples on the web about the Observer Pattern. I understand it simply as being almost a subscription that updates all other events when a change is made that the delegate registers. However, I'm very unstable in my true comprehension of the benefits and uses. I've done some googling, but most are above my level of understanding. I'm trying to implement this pattern with my current homework assignment, and to truly make sense on my project need a better understanding of the pattern itself and perhaps an example to see what its use. I don't want to force this pattern into something just to submit, I need to understand the purpose and develop my methods accordingly so that it actually serves a good purpose. My text doesn't really go into it, just mentions it in one sentence. MSDN was hard for me to understand, as I'm a beginner on this, and it seems more of an advanced topic. How would you describe this Observer pattern and its uses in C# to a beginner? For an example, please keep code very simple so I can understand the purpose more than complex code snippets. I'm trying to use it effectively with some simple textbox string manipulations and using delegates for my assignment, so a pointer would help!

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• What ever happened to APL?

  - by lkessler

  When I was at University 30 years ago, I used a programming language called APL. I believe the acronym stood for "A Programming Language", This language was interpretive and was especially useful for array and matrix operations with powerful operators and library functions to help with that. Did you use APL? Is this language still in use anywhere? Is it still available, either commercially or open source? I remember the combinatorics assignment we had. It was complex. It took a week of work for people to program it in PL/1 and those programs ranged from 500 to 1000 lines long. I wrote it in APL in under an hour. I left it at 10 lines for readability, although I should have been a purist and worked another hour to get it into 1 line. The PL/1 programs took 1 or 2 minutes to run on the IBM mainframe and solve the problem. The computer charge was $20. My APL program took 2 hours to run and the charge was $1,500 which was paid for by our Computer Science Department's budget. That's when I realized that a week of my time is worth way more than saving some $'s in someone else's budget. I got an A+ in the course. p.s. Don't miss this presentation entitled: "APL one of the greatest programming languages ever"

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• Generics with constraints hierarchy

  - by devoured elysium

  I am currently facing a very disturbing problem: interface IStateSpace<Position, Value> where Position : IPosition // <-- Problem starts here where Value : IValue // <-- and here as I don't { // know how to get away this // circular dependency! // Notice how I should be // defining generics parameters // here but I can't! Value GetStateAt(Position position); void SetStateAt(Position position, State state); } As you'll down here, both IPosition, IValue and IState depend on each other. How am I supposed to get away with this? I can't think of any other design that will circumvent this circular dependency and still describes exactly what I want to do! interface IState<StateSpace, Value> where StateSpace : IStateSpace where Value : IValue { StateSpace StateSpace { get; }; Value Value { get; set; } } interface IPosition { } interface IValue<State> where State : IState { State State { get; } } Basically I have a state space IStateSpace that has states IState inside. Their position in the state space is given by an IPosition. Each state then has one (or more) values IValue. I am simplifying the hierarchy, as it's a bit more complex than described. The idea of having this hierarchy defined with generics is to allow for different implementations of the same concepts (an IStateSpace will be implemented both as a matrix as an graph, etc). Would can I get away with this? How do you generally solve this kind of problems? Which kind of designs are used in these cases? Thanks

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• Subclassing an NSTextField

  - by Hooligancat

  Given all the complex things I seem to cover every day, this appears to be a "what the heck am I doing wrong that seems to simple?" scenario! I would like to subclass an NSTextField to change the background color and text color. For simplicity sake (and to help anyone who hasn't ever subclassed anything before), here is the example of my (simplified) subclass MyNSTextFieldSubclass... Step 1: Create the subclass file: First the header file @interface MyTextFieldSubclass : NSTextField { } @end And the method file @implementation MyTextFieldSubclass -(NSColor *)backgroundColor { return [NSColor redColor]; } -(NSColor *)textColor { return [NSColor yellowColor]; } @end Step 2: Drag an NSTextField to a window in Interface Builder, select the Identity tab in the inspector and select the class MyTextFieldSubclass Step 3: Save the IB file, build and run the application Problem When I run the build, the text field does not reflect the color subclassing. However, I know the subclass is being called because if I add the following method, it gets called on text changes. -(void)textDidChange:(NSNotification *)notification { NSLog(@"My text changed"); } So why does the color change not occur on the text fields? I know that I can set the color in IB, but for anyone who has dealt with a lot of UI elements that all need the same styling, subclassing makes life way, way easier. Ironically, I have never had to subclass an NSTextField before and this one has me stumped. As usual, any and all help very much appreciated. I'm sure it will turn out to be a "Doh!" moment - just cant see the wood for the trees right now (plus I'm exhausted from watching too much World Cup Football early in the morning which never helps).

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• What is Adobe Flex? Is it just Flash II?

  - by Adam Davis

  Question Alright, I'm confused by all the buzzwords and press release bingo going on. What is the relationship between flash and flex: Replace flash (not really compatible) Enhance flash The next version of flash but still basically compatible Separate technology altogether ??? If I'm starting out in Flash now, should I just skip to Flex? Follow up Ok, so what I'm hearing is that there's three different parts to the puzzle: Flash The graphical editor used to make "Flash Movies", ie it's an IDE that focuses on the visual aspect of "Flash" (Officially Flash CS3?) The official name for the display plugins (ie, "Download Flash Now!") A general reference to the entire technology stack In terms of the editor, it's a linear timeline based editor, best used for animations with complex interactivity. Actionscript The "Flash" programming language Flex An Adobe Flash IDE that focuses on the coding/programming aspect of "Flash" (Flex Builder?) A Flash library that enhances Flash and makes it easier to program for (Flex SDK?) Is not bound to a timeline (as the Flash IDE is) and so "standard" applications are more easily accomplished. Is this correct?

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• Convert function to read from string instead of file in C

  - by Dusty

  I've been tasked with updating a function which currently reads in a configuration file from disk and populates a structure: static int LoadFromFile(FILE *Stream, ConfigStructure *cs) { int tempInt; ... if ( fscanf( Stream, "Version: %d\n",&tempInt) != 1 ) { printf("Unable to read version number\n"); return 0; } cs->Version = tempInt; ... } to one which allows us to bypass writing the configuration to disk and instead pass it directly in memory, roughly equivalent to this: static int LoadFromString(char *Stream, ConfigStructure *cs) A few things to note: The current LoadFromFile function is incredibly dense and complex, reading dozens of versions of the config file in a backward compatible manner, which makes duplication of the overall logic quite a pain. The functions that generate the config file and those that read it originate in totally different parts of the old system and therefore don't share any data structures so I can't pass those directly. I could potentially write a wrapper, but again, it would need to handle any structure passed in in a backwards compatible manner. I'm tempted to just pass the file as is in as a string (as in the prototype above) and convert all the fscanf's to sscanf's but then I have to handle incrementing the pointer along (and potentially dealing with buffer overrun errors) manually. This has to remain in C, so no C++ functionality like streams can help here Am I missing a better option? Is there some way to create a FILE * that actually just points to a location in memory instead of on disk? Any pointers, suggestions or other help is greatly appreciated.

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• dynamically horizontal scalable key value store

  - by Zubair

  Hi, Is there a key value store that will give me the following: Allow me to simply add and remove nodes and will redstribute the data automatically Allow me to remove nodes and still have 2 extra data nodes to provide redundancy Allow me to store text or images up to 1GB in size Can store small size data up to 100TB of data Fast (so will allow queries to be performed on top of it) Make all this transparent to the client Works on Ubuntu/FreeBSD or Mac Free or open source I basically want something I can use a "single", and not have to worry about having memcached, a db, and several storage components so yes, I do want a database "silver bullet" you could say. Thanks Zubair Answers so far: MogileFS on top of BackBlaze - As far as I can see this is just a filesystem, and after some research it only seems to be appropriate for large image files Tokyo Tyrant - Needs lightcloud. This doesn't auto scale as you add new nodes. I did look into this and it seems it is very fast for queries which fit onto a single node though Riak - This is one I am looking into myself, but I don't have any results yet Amazon S3 - Is anyone using this as their sole persistance layer in production? From what I have seen it seems to be used for storage of images as complex queries are too expensive @shaman suggested Cassandra - definitely one I am looking into So far it seems that there is no database or key value store that fulfills the criteria I mentioned, not even after offering a bounty of 100 points did the question get answered!

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• How to get interpolated message in NHibernate.Validator

  - by SztupY

  Hi! I'm trying to integrate NHibernate.Validator with ASP.NET MVC client side validations, and the only problem I found is that I simply can't convert the non-interpolated message to a human-readable one. I thought this would be an easy task, but turned out to be the hardest part of the client-side validation. The main problem is that because it's not server-side, I actually only need the validation attributes that are being used, and I don't actually have an instance or anything else at hand. Here are some excerpts from what I've been already trying: // Get the the default Message Interpolator from the Engine IMessageInterpolator interp = _engine.Interpolator; if (interp == null) { // It is null?? Oh, try to create a new one interp = new NHibernate.Validator.Interpolator.DefaultMessageInterpolator(); } // We need an instance of the object that needs to be validated, se we have to create one object instance = Activator.CreateInstance(Metadata.ContainerType); // we enumerate all attributes of the property. For example we have found a PatternAttribute var a = attr as PatternAttribute; // it seems that the default message interpolator doesn't work, unless initialized if (interp is NHibernate.Validator.Interpolator.DefaultMessageInterpolator) { (interp as NHibernate.Validator.Interpolator.DefaultMessageInterpolator).Initialize(a); } // but even after it is initialized the following will throw a NullReferenceException, although all of the parameters are specified, and they are not null (except for the properties of the instance, which are all null, but this can't be changed) var message = interp.Interpolate(new InterpolationInfo(Metadata.ContainerType, instance, PropertyName, a, interp, a.Message)); I know that the above is a fairly complex code for a seemingly simple question, but I'm still stuck without solution. Is there any way to get the interpolated string out of NHValidator?

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• Hibernate : Opinions in Composite PK vs Surrogate PK

  - by Albert Kam

  As i understand it, whenever i use @Id and @GeneratedValue on a Long field inside JPA/Hibernate entity, i'm actually using a surrogate key, and i think this is a very nice way to define a primary key considering my not-so-good experiences in using composite primary keys, where : there are more than 1 business-value-columns combination that become a unique PK the composite pk values get duplicated across the table details cannot change the business value inside that composite PK I know hibernate can support both types of PK, but im left wondering by my previous chats with experienced colleagues where they said that composite PK is easier to deal with when doing complex SQL queries and stored procedure processes. They went on saying that when using surrogate keys will complicate things when doing joining and there are several condition when it's impossible to do some stuffs when using surrogate keys. Although im sorry i cant explain the detail here since i was not clear enough when they explain it. Maybe i'll put more details next time. Im currently trying to do a project, and want to try out surrogate keys, since it's not getting duplicated across tables, and we can change the business-column values. And when the need for some business value combination uniqueness, i can use something like : @Table(name="MY_TABLE", uniqueConstraints={ @UniqueConstraint(columnNames={"FIRST_NAME", "LAST_NAME"}) // name + lastName combination must be unique But im still in doubt because of the previous discussion about the composite key. Could you share your experiences in this matter ? Thank you !

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• iPhone programming - problem with CoreFoundation forking

  - by Tom

  Hello all, I've been working on an iPhone for several months. It's a 2d shooting game akin to the old Smash TV type games. I'm doing everything alone and it has come out well so far, but now I am getting unpredictable crashes which seem to be related to CoreFoundation forking and not exec()ing, as the message __THE_PROCESS_HAS_FORKED_AND_YOU_CANNOT_USE_THIS_COREFOUNDATION_FUNCTIONA LITY___YOU_MUST_EXEC__ always shows up somewhere in the debugger. Usually it shows up around a CFRunLoopRunSpecific and is related to either a timer firing or _InitializeTouchTapCount. I cannot figure out exactly what is causing the fork to occur. My main game loop is running on a timer, first updating all the logic and then drawing everything with openGL. There is nothing highly complex or unusual. I understand you cannot make CF calls on the childside of a fork, or access shared memory and things like that. I am not explicitly trying to fork anything. My question is: can anyone tell me what type of activity might cause CoreFoundation to randomly fork like this? I'd really like to finish this game and I don't know how to solve this problem. Thanks for any help.

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• C - Complicated pointer declarations - help understanding

  - by Emmel

  In my burgeoning new self-education in the C language, I've come across a set of declarations that I do not understand how to read. I'd love for someone to break these down. I'll explain at the bottom where I got these examples from. 1. char (*(*x())[])() "x: function returning pointer to array[] of pointer to function returning char" - huh? 2. char (*(*x[3])())[5] "x: array[3] of pointer to function returning pointer to array[5] of char" - come again? 3. char **argv This I understand. "Pointer to pointer to char." But what I don't understand is -- what's the use case for a pointer to a pointer? Follow-up question: does anyone every use declarations this complex or is this just academic fun on the part of the authors of the examples I got this from? These examples are from section 5.12 of the K&R book. This is the first time I'm genuinely stumped by an explanation, in an otherwise well-written classic. Thanks.

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• Connect two client sockets

  - by Hernán Eche

  Good morning, let's say Java has two kind of sockets... server sockets "ServerSocket" client sockets or just "Socket" ////so Simple ! Imagine the situation of two processes: X Client <-- Y Server The server process Y : has a "ServerSocket", that is listening to a TCP port The client process X : send a connection request through a -client type- "Socket" X ////so Simple ! then the accept() method (in server Y) returns a new client type "Socket", when it occurs, great the two Sockets get "interconected", so the -client socket- in client process, is connected with the -client socket- in the server process then (reading/writing in socket X is like reading/writing in socket Y, and viceversa. ) TWO CLIENT SOCKETS GET INTERCONECTED!! ////so Simple ! BUT... (there is always a But..) What if I create the two CLIENT sockets in same process, and I want to get them "interconected" ? ////mmm Complex =(... even posible? Let's say how to have TWO CLIENT SOCKETS GET INTERCONECTED WITHOUT using an intermediate ServerSocket ? I 've solved it.. by creating two threads for continuously reading A and writing B, and other for reading B and writng A... but I think could be a better way..(or should!) (Those world-energy-consuming threads are not necessary with the client-server aproach) Any help or advice would be appreciated!! Thanks

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• How to implement properly plugins in C#?

  - by MartyIX

  I'm trying to add plugins to my game and what I'm trying to implement is this: Plugins will be either mine or 3rd party's so I would like a solution where crashing of the plugin would not mean crashing of the main application. Methods of plugins are called very often (for example because of drawing of game objects). What I've found so far: 1) http://www.codeproject.com/KB/cs/pluginsincsharp.aspx - simple concept that seems like it should work nicely. Since plugins are used in my game for every round I would suffice to add the Restart() method and if a plugin is no longer needed Unload() method + GC should take care of that. 2) http://mef.codeplex.com/Wikipage - Managed Extensibility Framework - my program should work on .NET 3.5 and I don't want to add any other framework separately I want to write my plugin system myself. Therefore this solution is out of question. 3) Microsoft provides: http://msdn.microsoft.com/en-us/library/system.addin.aspx but according to a few articles I've read it is very complex. 4) Different AppDomains for plugins. According to Marc Gravell ( http://stackoverflow.com/questions/665668/usage-of-appdomain-in-c ) different AppDomains allow isolation. Unloading of plugins would be easy. What would the performance load be? I need to call methods of plugins very often (to draw objects for example). Using Application Domains - http://msdn.microsoft.com/en-us/library/yb506139.aspx A few tutorials on java2s.com Could you please comment on my findings? New approaches are also welcomed! Thanks!

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