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• WPF: How to connect to a sql ce 3.5 database with ADO.NET?

  - by EV

  Hi, I'm trying to write an application that has two DataGrids - the first one displays customers and the second one selected customer's records. I have generated the ADO.NET Entity Model and the connection property are set in App.config file. Now I want to populate the datagrids with the data from sql ce 3.5 database which does not support LINQ-TO-SQL. I used this code for the first datagrid in code behind: CompanyDBEntities db; private void Window_Loaded(object sender, RoutedEventArgs e) { db = new CompanyDBEntities(); ObjectQuery<Employees> departmentQuery = db.Employees; try { // lpgrid is the name of the first datagrid this.lpgrid.ItemsSource = departmentQuery; } catch (Exception ex) { MessageBox.Show(ex.Message); } However, the datagrid is empty although there are records in a database. It would also be better to use it in MVVM pattern but I'm not sure how does the ado.net and MVVM work together and if it is even possible to use them like that. Could anyone help? Thanks in advance.

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• How much of STL is too much?

  - by Darius Kucinskas

  I am using a lot of STL code with std::for_each, bind, and so on, but I noticed that sometimes STL usage is not good idea. For example if you have a std::vector and want to do one action on each item of the vector, your first idea is to use this: std::for_each(vec.begin(), vec.end(), Foo()) and it is elegant and ok, for a while. But then comes the first set of bug reports and you have to modify code. Now you should add parameter to call Foo(), so now it becomes: std::for_each(vec.begin(), vec.end(), std::bind2nd(Foo(), X)) but that is only temporary solution. Now the project is maturing and you understand business logic much better and you want to add new modifications to code. It is at this point that you realize that you should use old good: for(std::vector::iterator it = vec.begin(); it != vec.end(); ++it) Is this happening only to me? Do you recognise this kind of pattern in your code? Have you experience similar anti-patterns using STL?

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• Is it immoral to write crappy code even if readability and correctness is not a requirement?

  - by mafutrct

  There are cases when crappy (i.e. unreadable and buggy) code is not much of a problem. For instance, imagine you need to generate a big text file that mostly follows a simple pattern with a few very complex exceptions. What do you do? You quickly write a simple algorithm and insert the exceptional bits in the output manually to save 4 hours. The code is unreadable, and the output is flawed, but it's still the correct way since it is way faster. But let's get this straight: I hate bad code. I've had to read and work with code that caused my stomach to hurt. I care a lot about good code. And actually, I caught myself thinking that it is immoral to write bad code even though the dirty approach is sometimes superior. I was surprised by myself and found my idea to be very irrational. Did you ever experience this? Should I just get rid of this stupid idea and use the most efficient approach to coding?

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• SHGetFolderPath returns path with question marks in it

  - by Colen

  Hi, Our application calls ShGetFolderPath when it runs, to get the My Documents folder. This normally works great. However, for three users - ???????, Jörg and Jörgen (see if you can spot the pattern!) - the call returns some very strange results. For example, for ???????, the call returns: c:\Users\???????\Documents I assume there's some sort of character encoding shenanigan going on here, possibly related to Unicode, but I don't have any experience with that sort of thing. How can I get a useful path to the folder (and other related folders) out of windows, without grovelling through registry keys for the information? In an email to me, ??????? ("Dmitry"), told me his "my documents" folder was actually located here: C:\Users\43D6~1\Documents So I know there's a way to get a "normal" version of the path out of Windows, I just don't know what it is. Background: Our application is not unicode-aware, and uses standard "char *" strings. How can we get the "normal" path? I'm not opposed to calling the "unicode" version of the function, then converting it to "normal" text, if that's possible. Converting the application entirely to use unicode is not an option here (we don't have the time). Thanks.

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• What is the best software design to use in this scenario

  - by domdefelice

  I need to generate HTML snippets using jQuery. The creation of those snippets depends on some data. The data is stored server-side, in session (where PHP is used). At the moment I achieved this - retrieving the data from the server via AJAX in form of JSON - and building the snippets via specific javascript functions that read those data The problem is that the complexity of the data is getting bigger and hence the serialization into JSON is getting even more difficult since I can't do it automatically. I can't do it automatically because some information are sensible so I generate a "stripped" version to send to the client. I know it is difficult to understand without any code to read, but I am hoping this is a common scenario and would be glad for any tip, suggestion or even design-pattern you can give me. Should I store both a complete and a stripped data on the server and then use some library to automatically generate the JSON from the stripped data? But this also means I have to get the two data synchronized. Or maybe I could move the logic server-side, this way avoiding sending the data. But this means sending javascript code (since I rely on jQuery). Maybe not a good idea. Feel free to ask me more details if this is not clear. Thank you for any help

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• Tableview not updating correctly after adding person

  - by tazboy

  I have to be missing something simple here but it escapes me. After the user enters a new person to a mutable array I want to update the table. The mutable array is the datasource. I believe my issue lies within cellForRowAtIndexPath. - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { TextFieldCell *customCell = (TextFieldCell *)[tableView dequeueReusableCellWithIdentifier:@"TextCellID"]; UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"cell"]; if (indexPath.row == 0) { if (customCell == nil) { NSArray *nibObjects = [[NSBundle mainBundle] loadNibNamed:@"TextFieldCell" owner:nil options:nil]; for (id currentObject in nibObjects) { if ([currentObject isKindOfClass:[TextFieldCell class]]) customCell = (TextFieldCell *)currentObject; } } customCell.nameTextField.delegate = self; cell = customCell; } else { if (cell == nil) { cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:@"cell"]; cell.textLabel.text = [[self.peopleArray objectAtIndex:indexPath.row-1] name]; NSLog(@"PERSON AT ROW %d = %@", indexPath.row-1, [[self.peopleArray objectAtIndex:indexPath.row-1] name]); NSLog(@"peopleArray's Size = %d", [self.peopleArray count]); } } return cell; } When I first load the view everything is great. This is what prints: PERSON AT ROW 0 = Melissa peopleArray's Size = 2 PERSON AT ROW 1 = Dave peopleArray's Size = 2 After I add someone to that array I get this: PERSON AT ROW 1 = Dave peopleArray's Size = 3 PERSON AT ROW 2 = Tom peopleArray's Size = 3 When I add a second person I get: PERSON AT ROW 2 = Tom peopleArray's Size = 4 PERSON AT ROW 3 = Ralph peopleArray's Size = 4 Why is not printing everyone in the array? This pattern continues and it only ever prints two people, and it's always the last two people. What the heck am I missing?

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• Java: Match tokens between two strings and return the number of matched tokens

  - by Cryssie

  Need some help to find the number of matched tokens between two strings. I have a list of string stored in ArrayList (example given below): Line 0 : WRB VBD NN VB IN CC RB VBP NNP Line 1 : WDT NNS VBD DT NN NNP NNP Line 2 : WRB MD PRP VB DT NN IN NNS POS JJ NNS Line 3 : WDT NN VBZ DT NN IN DT JJ NN IN DT NNP Line 4 : WP VBZ DT JJ NN IN NN Here, you can see each string consists of a bunch of tokens separated by spaces. So, there's three things I need to work with.. Compare the first token (WRB) in Line 0 to the tokens in Line 1 to see if they match. Move on to the next tokens in Line 0 until a match is found. If there's a match, mark the matched tokens in Line 1 so that it will not be matched again. Return the number of matched tokens between Line 0 and Line 1. Return the distance of the matched tokens. Example: token NN is found on position 3 on line 0 and position 5 on Line 1. Distance = |3-5| = 2 I've tried using split string and store it to String[] but String[] is fixed and doesn't allow shrinking or adding of new elements. Tried Pattern Matcher but with disasterous results. Tried a few other methods but there's some problems with my nested for loops..(will post part of my coding if it will help). Any advice or pointers on how to solve this problem this would be very much appreciated. Thank you very much.

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• Reporting tool for OLAP, *not* OLTP!

  - by Stefan Moser

  I'm looking for a control that I can put on top of an already existing OLAP star schema to allow the user to define their own "queries" and generate reports. Right now I have some predefined reports built on top of the cubes, but I'd like to allow the user to define their own criteria based on the cubes that I've created. I've found lots of products that will allow you to treat a transactional table like an OLAP cube, but nothing specifically for pre-existing cubes. EDIT: Let me be clear, I know there are countless reporting tools out there that claim to report on OLAP cubes. The problem is they all assume they are looking at transactional data and try to create their own cubes. I have tables that contain tens, if not hundreds of millions of records. Most tools crash when handling this much data, the others just run incredible slowly. I don't want a tool that is targeting the business people. I want a tool that understands what a star and snowflake schema is. I want to be able to tell it what the fact tables are and what the dimension tables are, and then creates a UI on top of them. This is an easier problem to solve for the tool vendor because I am spoon feeding them the cubes. I want to rely on the fact that cubes are a standardized pattern and I want a tool that takes advantage of this fact. I want a tool that targets developers and starts with the assumption that I actually know how to manage my data, it just needs to build pretty reports for me and not crumble under the weight of my data.

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• At what line in the following code should I be commiting my UnitOfWork ?

  - by Pure.Krome

  Hi folks, I have the following code which is in a transaction. I'm not sure where/when i should be commiting my unit of work. If someone knows where, can they please explain WHY they have said, where? (i'm trying to understand the pattern through example(s), as opposed to just getting my code to work). Here's what i've got :- using (TransactionScope transactionScope = new TransactionScope(TransactionScopeOption.RequiresNew, new TransactionOptions { IsolationLevel = IsolationLevel.ReadUncommitted })) { _logEntryRepository.InsertOrUpdate(logEntry); //_unitOfWork.Commit(); // Here, commit #1 ? // Now, if this log entry was a NewConnection or an LostConnection, then we need to make sure we update the ConnectedClients. if (logEntry.EventType == EventType.NewConnection) { _connectedClientRepository.Insert(new ConnectedClient { LogEntryId = logEntry.LogEntryId }); //_unitOfWork.Commit(); // Here, commit #2 ? } // A (PB) BanKick does _NOT_ register a lost connection .. so we need to make sure we handle those scenario's as a LostConnection. if (logEntry.EventType == EventType.LostConnection || logEntry.EventType == EventType.BanKick) { _connectedClientRepository.Delete(logEntry.ClientName, logEntry.ClientIpAndPort); //_unitOfWork.Commit(); // Here, commit #3 ? } _unitOfWork.Commit(); // Here, commit #4 ? transactionScope.Complete(); } Cheers :)

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• Why put a DAO layer over a persistence layer (like JDO or Hibernate)

  - by Todd Owen

  Data Access Objects (DAOs) are a common design pattern, and recommended by Sun. But the earliest examples of Java DAOs interacted directly with relational databases -- they were, in essence, doing object-relational mapping (ORM). Nowadays, I see DAOs on top of mature ORM frameworks like JDO and Hibernate, and I wonder if that is really a good idea. I am developing a web service using JDO as the persistence layer, and am considering whether or not to introduce DAOs. I foresee a problem when dealing with a particular class which contains a map of other objects: public class Book { // Book description in various languages, indexed by ISO language codes private Map<String,BookDescription> descriptions; } JDO is clever enough to map this to a foreign key constraint between the "BOOKS" and "BOOKDESCRIPTIONS" tables. It transparently loads the BookDescription objects (using lazy loading, I believe), and persists them when the Book object is persisted. If I was to introduce a "data access layer" and write a class like BookDao, and encapsulate all the JDO code within this, then wouldn't this JDO's transparent loading of the child objects be circumventing the data access layer? For consistency, shouldn't all the BookDescription objects be loaded and persisted via some BookDescriptionDao object (or BookDao.loadDescription method)? Yet refactoring in that way would make manipulating the model needlessly complicated. So my question is, what's wrong with calling JDO (or Hibernate, or whatever ORM you fancy) directly in the business layer? Its syntax is already quite concise, and it is datastore-agnostic. What is the advantage, if any, of encapsulating it in Data Access Objects?

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• CUDA: When to use shared memory and when to rely on L1 caching?

  - by Roger Dahl

  After Compute Capability 2.0 (Fermi) was released, I've wondered if there are any use cases left for shared memory. That is, when is it better to use shared memory than just let L1 perform its magic in the background? Is shared memory simply there to let algorithms designed for CC < 2.0 run efficiently without modifications? To collaborate via shared memory, threads in a block write to shared memory and synchronize with __syncthreads(). Why not simply write to global memory (through L1), and synchronize with __threadfence_block()? The latter option should be easier to implement since it doesn't have to relate to two different locations of values, and it should be faster because there is no explicit copying from global to shared memory. Since the data gets cached in L1, threads don't have to wait for data to actually make it all the way out to global memory. With shared memory, one is guaranteed that a value that was put there remains there throughout the duration of the block. This is as opposed to values in L1, which get evicted if they are not used often enough. Are there any cases where it's better too cache such rarely used data in shared memory than to let the L1 manage them based on the usage pattern that the algorithm actually has?

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• Best practices for managing updating a database with a complex set of changes

  - by Sarge

  I am writing an application where I have some publicly available information in a database which I want the users to be able to edit. The information is not textual like a wiki but is similar in concept because the edits bring the public information increasingly closer to the truth. The changes will affect multiple tables and the update needs to be automatically checked before affecting the public tables. I'm working on the design and I'm wondering if there are any best practices that might help with some particular issues. I want to provide undo capability. I want to show the user the combined result of all their changes. When the user says they're done, I need to check the underlying public data to make sure it hasn't been changed by somebody else. My current plan is to have the user work in a set of tables setup to be a private working area. Once they're ready they can kick off a process to check everything and update the public tables. Undo can be recorded using Command pattern saving to a table. Are there any techniques I might have missed or useful papers or patterns? Thanks in advance!

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• How to disable mod_security2 rule (false positive) for one domain on centos 5

  - by nicholas.alipaz

  Hi I have mod_security enabled on a centos5 server and one of the rules is keeping a user from posting some text on a form. The text is legitimate but it has the words 'create' and an html <table> tag later in it so it is causing a false positive. The error I am receiving is below: [Sun Apr 25 20:36:53 2010] [error] [client 76.171.171.xxx] ModSecurity: Access denied with code 500 (phase 2). Pattern match "((alter|create|drop)[[:space:]]+(column|database|procedure|table)|delete[[:space:]]+from|update.+set.+=)" at ARGS:body. [file "/usr/local/apache/conf/modsec2.user.conf"] [line "352"] [id "300015"] [rev "1"] [msg "Generic SQL injection protection"] [severity "CRITICAL"] [hostname "www.mysite.com"] [uri "/node/181/edit"] [unique_id "@TaVDEWnlusAABQv9@oAAAAD"] and here is /usr/local/apache/conf/modsec2.user.conf (line 352) #Generic SQL sigs SecRule ARGS "((alter|create|drop)[[:space:]]+(column|database|procedure|table)|delete[[:space:]]+from|update.+set.+=)" "id:1,rev:1,severity:2,msg:'Generic SQL injection protection'" The questions I have are: What should I do to "whitelist" or allow this rule to get through? What file do I create and where? How should I alter this rule? Can I set it to only be allowed for the one domain, since it is the only one having the issue on this dedicated server or is there a better way to exclude table tags perhaps? Thanks guys

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• I like the way they Design/Architecture it but how do I implement this

  - by Rachel

  Summary: I have different components on homepage and each components shows some promotion to the user. I have Cart as one Component and depending upon content of the cart promotion are show. I have to track user online activities and send that information to Omniture for Report Generation. Now my components are loaded asynchronously basically are loaded when AjaxRequest is fired up and so there is not fix pattern or rather information on when components will appear on the webpages. Now in order to pass information to Omniture I need to call track function on $(document).(ready) and append information for each components(7 parameters are required by Omniture for each component). So in the init:config function of each component am calling Omniture and passing paramters but now no. of Omniture calls is directly proportional to no. of Components on the webpage but this is not acceptable as each call to Omniture is very expensive. Now I am looking for a way where in I can club the information about 7 parameters and than make one Call to Omniture wherein I pass those information. Points to note is that I do not know when the components are loaded and so there is no pre-defined time or no. of components that would be loaded. The thing is am calling track function when document is ready but components are loaded after call to Omniture has been made and so my question is Q: How can I collect the information for all the components and than just make one call to Omniture to send those information ? As mentioned, I do not know when the components are loaded as they are done on the Ajax Request. Hope I am able to explain my challenge and would appreciate if some one can provide from Design/Architect Solutions for the Challenge.

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• Better way to call superclass method in ExtJS

  - by Rene Saarsoo

  All the ExtJS documentation and examples I have read suggest calling superclass methods like this: MyApp.MyPanel = Ext.extend(Ext.Panel, { initComponent: function() { // do something MyPanel specific here... MyApp.MyPanel.superclass.initComponent.call(this); } }); I have been using this pattern for quite some time and the main problem is, that when you rename your class then you also have to change all the calls to superclass methods. That's quite inconvenient, often I will forget and then I have to track down strange errors. But reading the source of Ext.extend() I discovered, that instead I could use the superclass() or super() methods that Ext.extend() adds to the prototype: MyApp.MyPanel = Ext.extend(Ext.Panel, { initComponent: function() { // do something MyPanel specific here... this.superclass().initComponent.call(this); } }); In this code renaming MyPanel to something else is simple - I just have to change the one line. But I have doubts... I haven't seen this documented anywhere and the old wisdom says, I shouldn't rely on undocumented behaviour. I didn't found a single use of these superclass() and supr() methods in ExtJS source code. Why create them when you aren't going to use them? Maybe these methods were used in some older version of ExtJS but are deprecated now? But it seems such a useful feature, why would you deprecate it? So, should I use these methods or not?

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• How can I exclude pages created from a specific template from the CQ5 dispatcher cache?

  - by Shawn

  I have a specific Adobe CQ5 (5.5) content template that authors will use to create pages. I want to exclude any page that is created from this template from the dispatcher cache. As I understand it currently, the only way I know to prevent caching is to configure dispatcher.any to not cache a particular URL. But in this case, the URL isn't known until a web author uses the template to create a page. I don't want to have to go back and modify dispatcher.any every time a page is created--or at least I want to automate this if there is no other way. I am using IIS for the dispatcher. The reason I don't want to cache the pages is because the underlying JSPs that render the content for these pages produce dynamic content, and the pages don't use querystrings and won't carry authentication headers. The pages will be created in unpredictable directories, so I don't know the URL pattern ahead of time. How can I configure things so that any page that is created from a certain template will be automatically excluded from the dispatcher cache? It seems like CQ ought to have some mechanism to respect HTTP response/caching headers. If the HTTP response headers specify that the response shouldn't be cached, it seems like the dispatcher shouldn't cache it--regardless of what dispatcher.any says. This is the CQ5 documentation I have been referencing.

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• NHibernate Session DI from StructureMap in components

  - by Corey Coogan

  I know this is somewhat of a dead horse, but I'm not finding a satisfactory answer. First let me say, I am NOT dealing with a web app, otherwise managing NH Session is quite simple. I have a bunch of enterprise components. Those components have their own service layer that will act on multiple repositories. For example: Claim Component Claim Processing Service Claim Repository Billing Component Billing Service Billing REpository Policy Component PolicyLockService Policy Repository Now I may have a console, or windows application that needs to coordinate an operation that involves each of the services. I want to write the services to be injected with (DI) their required repositories. The Repositories should have an ISession, or similar, injected into them so that I can have this operation performed under one ISession/ITransaction. I'm aware of the Unit Of Work pattern and the many samples out there, but none of them showed DI. I'm also leery of [ThreadStatic] because this stuff can also be used from WCF and I have found enough posts describing how to do that. I've read about Business Conversations, but need something simple that each windows/console app can easily bootstrap since we have alot of these apps and some pretty inexperienced developers. So how can I configure StructureMap to inject the same ISession into each of the dependent repositories from an application? Here's a totally contrived and totally made up example without using SM (for clarification only - please don't spend energy critisizing): ConsoleApplication Main { using(ISession session = GetSession()) using(ITransaction trans = session.BeginTransaction()) { var policyRepo = new PolicyRepo(session); var policyService = new PolicyService(policyRepo); var billingRepo = new BillingRepo(session) var billingService = new BillingService(billingRepo); var claimRepo = new ClaimsRepo(session); var claimService = new ClaimService(claimRepo, policyService, billingService); claimService.FileCLaim(); trans.Commit(); } }

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• Automatic .NET code, nhibernate session, and LINQ datacontext clean-up?

  - by AverageJoe719

  Hi all, in my goal to adopt better coding practices I have a few questions in general about automatic handling of code. I have heard different answers both from online and talking with other developers/programmers at my work. I am not sure if I should have split them into 3 questions, but they all seem sort of related: 1) How does .NET handle instances of classes and other code things that take up memory? I recently found out about using the factory pattern for certain things like service classes so that they are only instantiated once in the entire application, but then I was told that '.NET handles a lot of that stuff automatically when mentioning it.' 2) How does Nhibernate's session handle automatic clean-up of un-used things? I've seen some say that it is great at handling things automatically and you should just use a session factory and that's it, no need to close it. But I have also read and seem many examples where people close the hibernate session. 3) How does LINQ's datacontext handle this? Most of the time I never .disposed my datacontext's and the app didn't see to take a performance hit (though I am not running anything super intensively), but it seems like most people recommend disposing of your datacontext after you are done with it. However, I have seen many many code examples where the dispose method is never called. Also in general I found it kind of annoying that you couldn't access even one-deep child related objects after disposing of the datacontext unless you explicity also grabbed them in the query. Thanks all. I am loving this site so far, I kind of get lost and spend hours just reading things on here. =)

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• Vim + OmniCppComplete and completing members of class members

  - by Robert S. Barnes

  I've noticed that I can't seem to complete members of class members using OmniCppComplete. For example, given the following files: // foo.h #include <string> class foo { public: void set_str(const std::string &); std::string get_str_reverse( void ); private: std::string str; }; // foo.cpp #include "foo.h" using std::string; string foo::get_str_reverse ( void ) { string temp; temp.assign(str); reverse(temp.begin(), temp.end()); return temp; } /* ----- end of method foo::get_str ----- */ void foo::set_str ( const string &s ) { str.assign(s); } /* ----- end of method foo::set_str ----- */ I've set up tags for stdlibc++ and generated the tags for these two files using: ctags -R --c++-kinds=+pl --fields=+iaS --extra=+q . When I type temp. in the cpp I get a list of string member functions as expected. But if I type str. omnicomplete spits out "Pattern Not Found". I've noticed that the temp. completion only works if I have the using std::string; declaration. How do I get completion to work on my class members?

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• Abstracting boxed array structures in J

  - by estanford

  I've been working on a J function for a while, that's supposed to scan a list and put consecutive copies of an element into separate, concatenated boxes. My efforts have taken me as far as the function (<;. 2) ((2&(~:/\)),1:) which tests successive list entries for inequality, returns a list of boolean values, and cuts the list into boxes that end each time the number 1 appears. Here's an example application: (<;. 2) ((2&(~:/\)),1:) 1 2 3 3 3 4 1 1 1 +-+-+-----+-+-----+ |1|1|0 0 1|1|0 0 1| +-+-+-----+-+-----+ The task would be finished if I could then replace all those booleans with their corresponding values in the input argument. I've been looking for some kind of mystery function that would let me do something like final =: mysteryfunction @ (<;. 2) ((2&(~:/\)),1:) final 1 2 3 3 3 4 1 1 1 +-+-+-----+-+-----+ |1|2|3 3 3|4|1 1 1| +-+-+-----+-+-----+ In an ideal situation, there would be some way to abstractly represent the nesting pattern generated by (<;. 2) ((2&(~:/\)),1:) to the original input list. (i.e. "This boxed array over here has the first element boxed at depth one, the second element boxed at depth one, the third, fourth, and fifth elements boxed together at depth one,..., so take that unboxed list over there and box it up the same way.") I tried fooling around with ;. , S: , L:, L. and &. to produce that behavior, but I haven't had much luck. Is there some kind of operator or principle I'm missing that could make this happen? It wouldn't surprise me if I were overthinking the whole issue, but I'm running out of ideas.

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• Unable to access Java-created file -- sometimes

  - by BlairHippo

  In Java, I'm working with code running under WinXP that creates a file like this: public synchronized void store(Properties props, byte[] data) { try { File file = filenameBasedOnProperties(props); if ( file.exists() ) { return; } File temp = File.createTempFile("tempfile", null); FileOutputStream out = new FileOutputStream(temp); out.write(data); out.flush(); out.close(); file.getParentFile().mkdirs(); temp.renameTo(file); } catch (IOException ex) { // Complain and whine and stuff } } Sometimes, when a file is created this way, it's just about totally inaccessible from outside the code (though the code responsible for opening and reading the file has no problem), even when the application isn't running. When accessed via Windows Explorer, I can't move, rename, delete, or even open the file. Under Cygwin, I get the following when I ls -l the directory: ls: cannot access [big-honkin-filename] total 0 ?????????? ? ? ? ? ? [big-honkin-filename] As implied, the filenames are big, but under the 260-character max for XP (though they are slightly over 200 characters). To further add to the sense the my computer just wants me to feel stupid, sometimes the files created by this code are perfectly normal. The only pattern I've spotted is that once one file in the directory "locks", the rest are screwed. Anybody ever run into something like this before, or have any insights into what's going on here?

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• Java method keyword "final" and its use

  - by Lukas Eder

  When I create complex type hierarchies (several levels, several types per level), I like to use the final keyword on methods implementing some interface declaration. An example: interface Garble { int zork(); } interface Gnarf extends Garble { /** * This is the same as calling {@link #zblah(0)} */ int zblah(); int zblah(int defaultZblah); } And then abstract class AbstractGarble implements Garble { @Override public final int zork() { ... } } abstract class AbstractGnarf extends AbstractGarble implements Gnarf { // Here I absolutely want to fix the default behaviour of zblah // No Gnarf shouldn't be allowed to set 1 as the default, for instance @Override public final int zblah() { return zblah(0); } // This method is not implemented here, but in a subclass @Override public abstract int zblah(int defaultZblah); } I do this for several reasons: It helps me develop the type hierarchy. When I add a class to the hierarchy, it is very clear, what methods I have to implement, and what methods I may not override (in case I forgot the details about the hierarchy) I think overriding concrete stuff is bad according to design principles and patterns, such as the template method pattern. I don't want other developers or my users do it. So the final keyword works perfectly for me. My question is: Why is it used so rarely in the wild? Can you show me some examples / reasons where final (in a similar case to mine) would be very bad?

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• Using Sub-Types And Return Types in Scala to Process a Generic Object Into a Specific One

  - by pr1001

  I think this is about covariance but I'm weak on the topic... I have a generic Event class used for things like database persistance, let's say like this: class Event( subject: Long, verb: String, directobject: Option[Long], indirectobject: Option[Long], timestamp: Long) { def getSubject = subject def getVerb = verb def getDirectObject = directobject def getIndirectObject = indirectobject def getTimestamp = timestamp } However, I have lots of different event verbs and I want to use pattern matching and such with these different event types, so I will create some corresponding case classes: trait EventCC case class Login(user: Long, timestamp: Long) extends EventCC case class Follow( follower: Long, followee: Long, timestamp: Long ) extends EventCC Now, the question is, how can I easily convert generic Events to the specific case classes. This is my first stab at it: def event2CC[T <: EventCC](event: Event): T = event.getVerb match { case "login" => Login(event.getSubject, event.getTimestamp) case "follow" => Follow( event.getSubject, event.getDirectObject.getOrElse(0), event.getTimestamp ) // ... } Unfortunately, this is wrong. <console>:11: error: type mismatch; found : Login required: T case "login" => Login(event.getSubject, event.getTimestamp) ^ <console>:12: error: type mismatch; found : Follow required: T case "follow" => Follow(event.getSubject, event.getDirectObject.getOrElse(0), event.getTimestamp) Could someone with greater type-fu than me explain if, 1) if what I want to do is possible (or reasonable, for that matter), and 2) if so, how to fix event2CC. Thanks!

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• SQL Concurrent test update question

  - by ptoinson

  Howdy Folks, I have a SQLServer 2008 database in which I have a table for Tags. A tag is just an id and a name. The definition of the tags table looks like: CREATE TABLE [dbo].[Tag]( [ID] [int] IDENTITY(1,1) NOT NULL, [Name] [varchar](255) NOT NULL CONSTRAINT [PK_Tag] PRIMARY KEY CLUSTERED ( [ID] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ) Name is also a unique index. further I have several processes adding data to this table at a pretty rapid rate. These processes use a stored proc that looks like: ALTER PROC [dbo].[lg_Tag_Insert] @Name varchar(255) AS DECLARE @ID int SET @ID = (select ID from Tag where Name=@Name ) if @ID is null begin INSERT Tag(Name) VALUES (@Name) RETURN SCOPE_IDENTITY() end else begin return @ID end My issues is that, other than being a novice at concurrent database design, there seems to be a race condition that is causing me to occasionally get an error that I'm trying to enter duplicate keys (Name) into the DB. The error is: Cannot insert duplicate key row in object 'dbo.Tag' with unique index 'IX_Tag_Name'. This makes sense, I'm just not sure how to fix this. If it where code I would know how to lock the right areas. SQLServer is quite a different beast. First question is what is the proper way to code this 'check, then update pattern'? It seems I need to get an exclusive lock on the row during the check, rather than a shared lock, but it's not clear to me the best way to do that. Any help in the right direction will be greatly appreciated. Thanks in advance.

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• Can I use the auto-generated Linq-to-SQL entity classes in 'disconnected' mode?

  - by Gary McGill

  Suppose I have an automatically-generated Employee class based on the Employees table in my database. Now suppose that I want to pass employee data to a ShowAges method that will print out name & age for a list of employees. I'll retrieve the data for a given set of employees via a linq query, which will return me a set of Employee instances. I can then pass the Employee instances to the ShowAges method, which can access the Name & Age fields to get the data it needs. However, because my Employees table has relationships with various other tables in my database, my Employee class also has a Department field, a Manager field, etc. that provide access to related records in those other tables. If the ShowAges method were to invoke any of those methods, this would cause lots more data to be fetched from the database, on-demand. I want to be sure that the ShowAges method only uses the data I have already fetched for it, but I really don't want to have to go to the trouble of defining a new class which replicates the Employee class but has fewer methods. (In my real-world scenario, the class would have to be considerably more complex than the Employee class described here; it would have several 'joined' classes that do need to be populated, and others that don't). Is there a way to 'switch off' or 'disconnect' the Employees instances so that an attempt to access any property or related object that's not already populated will raise an exception? If not, then I assume that since this must be a common requirement, there might be an already-established pattern for doing this sort of thing?

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