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• Alternative to singleton for unique resources

  - by user1320881

  I keep reading over and over again that one should avoid using singletons for various reasons. I'm wondering how to correctly handle a situation where a class represents a unique system resource. For example, a AudioOutput class using SDL. Since SDL_OpenAudio can only be open once at a time it makes no sense having more then one object of this type and it seems to me preventing accidentally making more then one object would actually be good. Just wondering what experienced programmers think about this, am i missing another option ?

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• When designing an event, is it a good idea to prevent listeners from being added twice?

  - by Matt

  I am creating an event-based API where a user can subscribe to an event by adding listener objects (as is common in Java or C#). When the event is raised, all subscribed listeners are invoked with the event information. I initially decided to prevent adding an event listener more than once. If a listener is added that already exists in the listener collection, it is not added again. However, after thinking about it some more, it doesn't seem that most event-based structures actually prevent this. Was my initial instinct wrong? I'm not sure which way to go here. I guess I thought that preventing addition of an existing listener would help to avoid a common programming error. Then again, it could also hide a bug that would lead to code being run multiple times when it shouldn't.

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• Perl array and hash manipulation using map

  - by somebody

  I have the following test code use Data::Dumper; my $hash = { foo => 'bar', os => 'linux' }; my @keys = qw (foo os); my $extra = 'test'; my @final_array = (map {$hash->{$_}} @keys,$extra); print Dumper \@final_array; The output is $VAR1 = [ 'bar', 'linux', undef ]; Shouldn't the elements be "bar, linux, test"? Why is the last element undefined and how do I insert an element into @final_array? I know I can use the push function but is there a way to insert it on the same line as using the map command? Basically the manipulated array is meant to be used in an SQL command in the actual script and I want to avoid using extra variables before that and instead do something like: $sql->execute(map {$hash->{$_}} @keys,$extra);

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• How to handle added input data colums without having to maintain multiple versions of SSIS packages?

  - by GLFelger

  I’m writing to solicit ideas for a solution to an upcoming problem. The product that provides data to our ETL process currently has multiple versions. Our clients are all using some version of the product, but not all use the same version and they will not all be upgraded at the same time. As new versions of the product are rolled out, the most common change is to add new data columns. Columns being dropped or renamed may happen occasionally, but our main focus right now is how to handle new columns being added. The problem that we want to address is how to handle the data for clients who use an older version of the product. If we don’t account for the new columns in our SSIS packages, then the data in those columns for clients using an older product version will not be processed. What we want to avoid is having to maintain a separate version of the SSIS packages for each version of the product. Has anyone successfully implemented a solution for this situation?

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• Replace the content of a tag with a certain class

  - by fire

  I am looking for suitable replacement code that allows me replace the content inside of any HTML tag that has a certain class e.g. $class = "blah"; $content = "new content"; $html = '<div class="blah">hello world</div>'; // code to replace, $html now looks like: // <div class="blah">new content</div> Bare in mind that: It wont necessarily be a div, it could be <h2 class="blah"> The class can have more than one class and still needs to be replaced e.g. <div class="foo blah green">hello world</div> I am thinking regular expressions should be able to do this, if not I am open to other suggestions such as using the DOM class (although I would rather avoid this if possible because it has to be PHP4 compatible).

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• Select n+1 problem

  - by Arnis L.

  Foo has Title. Bar references Foo. I have a collection with Bars. I need a collection with Foo.Title. If i have 10 bars in collection, i'll call db 10 times. bars.Select(x=x.Foo.Title) At the moment this (using NHibernate Linq and i don't want to drop it) retrieves Bar collection. var q = from b in Session.Linq<Bar>() where ... select b; I read what Ayende says about this. Another related question. A bit of documentation. And another related blog post. Maybe this can help? What about this? Maybe MultiQuery is what i need? :/ But i still can't 'compile' this in proper solution. How to avoid select n+1?

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• ASP.NET GridView - how to enable validation declaratively

  - by Joe

  It it possible to enable validation in an ASP.NET GridView purely declaratively? What I've tried: A GridView bound to an ObjectDataSource with SelectMethod and UpdateMethod defined The GridView contains some ReadOnly BoundField columns and a TemplateField whose EditTemplate contains a TextBox and a RegularExpressionValidator that only allows numeric input in the TextBox. The GridView also contains a CommandField with ShowEditButton=true and CausesValidation=true. If I click on Edit, enter an invalid value, then click on Save, there is a PostBack, and an exception is thrown in the server (Input string was not in a correct format). I can of course avoid this by adding validation code to the RowUpdating event handler on the server (see below), but is there any declarative way to force the validation to be done without adding this code? protected void MyGridView_RowUpdating(object sender, GridViewUpdateEventArgs e) { Page.Validate("MyValidationGroup"); if (!Page.IsValid) { e.Cancel = true; } }

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• "Automatic" class proxy in C++

  - by PierreBdR

  I need to allow the user to change members of two data structures of the same type at the same time. For example: struct Foo { int a, b; } Foo a1 = {1,2}, a2 = {3,4}; dual(a1,a2)->a = 5; // Now a1 = {5,2} and a2 = {5,2} I have a class that works and that change first a1 and then copy a1 into a2. This is fine as long as: the class copied is small the user doesn't mind about everything being copied, not only the part modified. Is there a way to obtain this behavior: dual(a1,a2)->a = 5; // Now a1 = {5,2} and a2 = {5,4} I am opened to alternative syntax, but they should stay simple, and I would like to avoid things like: set_members(a1, a2, &Foo::a, 5); members(a1, a2, &Foo::a) = 5; or anything involving specifying explictely &Foo::

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• Scheduling a visual studio load test using powershell giving me BSOD

  - by user952342

  I have a visual studio load test which I want to run every hour so that I can start to collect some data. To do this, I thought it would be best to make a little powershell script and put a command like this inside: Invoke-Expression -command "& '$env:VS100COMNTOOLS..\IDE\mstest.exe' /testcontainer:"C:\Users\benb\Documents\Visual Studio 2010\Projects\BBPerformanceTest\bin\Debug\HomePageOnly.loadtest"" That command works fine, but sometimes when its run I get a blue screen of death. However, when I run my load test through the visual studio GUI, I never get a BSOD. two questions: is it possible to avoid this BSOD? Is there another way I can schedule my load test? Thanks

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• Sharepoint 2010 web application development suitability evaluation/assessment

  - by Robert Koritnik

  I would like to know what kind of applications are suitable to be developed on top of Sharepoint 2010 and which should not be built on to of it. So when to embrace/avoid Sharepoint 2010 as a development platform for new web applications. Addendum Would you as a sharepoint development specialist choose it as a platform for your next enterprise application with these characteristics: processor intensive lots of various screens for entering and managing data many complex business processes no need to change the UI (ie. reposition parts) ERP integration etc. I'm an Asp.net MVC (former web forms) developer and would like to know if usual multi-page semi complex web applications (intra/extra-net) should be built on top of Sharepoint 2010 and why (if yes or if no).

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• Best practices to test protected methods with PHPUnit

  - by GrGr

  Hello, I found the discussion on Do you test private method informative. I have decided, that in some classes, I want to have protected methods, but test them. Some of these methods are static and short. Because most of the public methods make use of them, I will probably be able to safely remove the tests later. But for starting with a TDD approach and avoid debugging, I really want to test them. I thought of the following: Method Object as adviced in an answer seems to be overkill for this. Start with public methods and when code coverage is given by higher level tests, turn them protected and remove the tests. Inherit a class with a testable interface making protected methods public Which is best practice? Is there anything else? It seems, that JUnit automatically changes protected methods to be public, but I did not have a deeper look at it. PHP does not allow this via reflection.

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• jQuery: Quick question. How to select string variable?

  - by user317563

  Hello world, EDIT: I would like to avoid doing something like this: var str = 'Hello'; if ( str == 'Hello') { alert(str); } I would rather do: var str = 'Hello'; $(str).filter(':contains("Hello")').each(function(){ alert(this) }); I've tried a lot of things: $(str).text().method1().method2().method3(); $(str).val().method1().method2().method3(); $(str).contents().method1().method2().method3(); Nothing worked. Is it possible to do this? Thank you for your time. Kind regards, Marius

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• Long key press handling in android 1.5

  - by Kaillash

  Hi, I want to handle key press and long key press for the key code KEYCODE_BACK(back button). can any one suggest me how to do this in android 1.5(API level 3). Here is the code. public boolean onKeyDown(int keyCode, KeyEvent event) { if (keyCode == KeyEvent.KEYCODE_BACK) { if(event.getRepeatCount()==0) { // normal key press // But problem is, this code is hitting for long press also, how to avoid this } else { // Long key press //Do something here } // Always consume back key event by returning true //so that default behavior of back is overrided return true; } return super.onKeyDown(keyCode, event); }

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• Why does C++ linking use virtually no CPU? (updated)

  - by John

  On a native C++ project, linking right now can take a minute or two, yet during this time CPU drops from 100% during compilation to virtually zero. Does this mean linking is primarily a disk activity? If so, is this the main area an SSD would make big changes? But, why aren't all my OBJ files (or as many as possible) kept in RAM after compilation to avoid this? With 4Gb of RAM I should be able to save a lot of disk access and make it CPU-bound again, no? update: so the obvious follow-up is, can VC++ compiler and linker talk together better to streamline things and keep OBJ files in memory, similar to how Delphi does?

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• oracle call stored procedure inside select

  - by CC

  Hi everybody. I'm working on a query (a SELECT) and I need to insert the result of this one in a table. Before doing the insert I have some checking to do, and if all columns are valid, I will do the insert. The checking is done in a stored procedure. The same procedure is used somewhere else too. So I'm thinking using the same procedure to do my checks. The procedure does the checkings and insert the values is all OK. I tryied to call the procedure inside my SELECT but it does not works. SELECT field1, field2, myproc(field1, field2) from MYTABLE. This kind of code does not works. I think it can be done using a cursor, but I would like to avoid the cursors. I'm looking for the easiest solution. Anybody, any idea ? Thanks alot. C.C.

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• Do I have to hash twice in C#?

  - by Joe H

  I have code like the following: class MyClass { string Name; int NewInfo; } List<MyClass> newInfo = .... // initialize list with some values Dictionary<string, int> myDict = .... // initialize dictionary with some values foreach(var item in newInfo) { if(myDict.ContainsKey(item.Name)) // 'A' I hash the first time here myDict[item.Name] += item.NewInfo // 'B' I hash the second (and third?) time here else myDict.Add(item.Name, item.NewInfo); } Is there any way to avoid doing two lookups in the Dictionary -- the first time to see if contains an entry, and the second time to update the value? There may even be two hash lookups on line 'B' -- one to get the int value and another to update it.

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• Are C++ Templates just Macros in disguise?

  - by Roddy

  I've been programming in C++ for a few years, and I've used STL quite a bit and have created my own template classes a few times to see how it's done. Now I'm trying to integrate templates deeper into my OO design, and a nagging thought keeps coming back to me: They're just a macros, really... You could implement (rather UGLY) auto_ptrs using #defines, if you really wanted to. This way of thinking about templates helps me understand how my code will actually work, but I feel that I must be missing the point somehow. Macros are meant evil incarnate, yet "template metaprogramming" is all the rage. So, what ARE the real distinctions? and how can templates avoid the dangers that #define leads you into, like Inscrutable compiler errors in places where you don't expect them? Code bloat? Difficulty in tracing code? Setting Debugger Breakpoints?

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• dates when saving to mysql database

  - by Patrick

  in my php code I was asking the user to choose day, month and year from some dropdown fields where values where 1, 2, 3 etc instead of 01, 02, 03. these were then combined to form a string like "YYYY-MM-DD" for the insertion in a db (in a date field). Having missed the initial 0, I thought I was sending strings in the wrong format, eg "YYYY-M-D" or YYYY-MM-D", but then I've noticed they appear in the right format in the database anyway: even if I submitted YYYY-M-D, it appeared as YYYY-MM-DD. is this the normal behaviour of mysql? if so, can i just avoid worrying about changing the code in my application?

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• How can you check if a file exists before including/importing it in JSP?

  - by codeninja

  Assuming that requestScope.importMe is expecting a path to a jsp file <c:choose> <c:when test="${!empty requestScope.importMe && fileExists(requestScope.importMe) }"> <c:import url="${requestScope.importMe}" /> ... How can I check if the file exists before trying to include it so that an error is not thrown? I'd like to avoid using inline Java. Something using one of the JSTL tags is the preferred approach.

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

  - by Jon Cage

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

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• UITableViewController executes delate functions before network request finishes

  - by user1543132

  I'm having trouble trying to populate a UITableView with the results of a network request. It seems that my code is alright as it works perfectly when my network is speedy, however, when it's not, the function - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath- still executes, which results in a bad access error. I presume that this is because the array that the aforesaid function attempts to utilize has not been populated. This brings me to my question: Is there anyway that I can have the UITableView delegate methods delayed to avoid this? - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { static NSString *CellIdentifier = @"AlbumsCell"; //UITableViewCell *basicCell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath]; AlbumsCell *cell = (AlbumsCell *)[tableView dequeueReusableCellWithIdentifier:CellIdentifier]; if (!cell) { **// Here is where the Thread 1: EXC_BAD_ACCESS (code=2 address=0x8)** cell = [[[AlbumsCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease]; } Album *album = [_albums objectAtIndex:[indexPath row]]; [cell setAlbum:album]; return cell; }

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• is vim able to detect in which language a file is written, and then load the correct dictionnary ?

  - by Niels

  I am using several languages, and by now I am obliged to indicate vim with which of these the spell check must be done. Is there a way to set up vim so that he automatically detects the correct one ? I remember vaguely that in a previous version of vim, when the spell check was not integrated, this was possible, using the vimspell script. It would be even better if this could apply not only to a file but also to a portion of a file, since I frequently mix several languages in a single file. Of course, I would like to avoid to load several dictionaries simultaneously.

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• How to access device settings on a S60 symbian based mobile phone?

  - by TheRHCP

  Hello everyone, I recently bought a Sony Ericsson mobile phone which embeds Symbian S60 and I would like to add a missing feature myself. In fact I cannot actually disable Internet connection in an easy way when roaming, which cost me a lot of money last time I moved away ... So I would like to develop a little application that would just replace the actual Internet configuration with a fake configuration to avoid auto-connections. So what I would like to know is how can I access programmatically to my phone settings? I believe that this is possible but I do not really have a clue where to start. I know that Sony Ericsson provides a SDK to run Java applications on its customised JVM but Symbian is also providing a SDK to develop applications for S60 devices in many languages. The real questions is which SDK will provide an API able to access phone settings. This is not well documented so I am asking this question with the hope that someone here already had experience with development for Sony Ericsson/Symbian devices. Thanks.

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• In few words, what can be said about Func<>

  - by Richard77

  Hello, I've been seing Func< for sometime now, and I've manage to avoid it (for now). But, now it looks like I can't dodge it forever. For instance, I tried Dynamic Linq, but almost everything was in terms of Func<. I've tried one of my book (C# 2008/Deitel&Deitel) and also MSDN but I'm not getting it yet. They all jump straight in the subject. What can be said (in few words) about Func< Can I get some links on the web that can get me started on that matter? Thanks for helping

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• div Height: 0 problem in IE

  - by meo

  to clear: both my content i use this: CSS: .clr { clear: both; height: 0; /* i have tried 0.001em to */ line-height: .001em; overflow: hidden; } HTML: <div class="clr">&nbsp;</div> it works perfectly in every navigator. But in IE 7 & 8 the div still have a height of a few pixels. How can i avoid this?

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