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• Does it make a difference in performance if I use self.fooBar instead of fooBar?

  - by mystify

  Note: I know exactly what a property is. This question is about performance. Using self.fooBar for READ access seems a waste of time for me. Unnecessary Objective-C messaging is going on. The getters typically simply pass along the ivar, so as long as it's pretty sure there will be no reasonable getter method written, I think it's perfectly fine to bypass this heavy guy. Objective-C messaging is about 20 times slower than direct calls. So if there is some high-performance-high-frequency code with hundreds of properties in use, maybe it does help a lot to avoid unnessessary objective-c messaging? Or am I wasting my time thinking about this?

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• ContextSwitchDeadlock Was Detected error in C#

  - by assassin

  Hi, I am running a C# application, and during run-time I get the following error: The CLR has been unable to transition from COM context 0x20e480 to COM context 0x20e5f0 for 60 seconds. The thread that owns the destination context/apartment is most likely either doing a non pumping wait or processing a very long running operation without pumping Windows messages. This situation generally has a negative performance impact and may even lead to the application becoming non responsive or memory usage accumulating continually over time. To avoid this problem, all single threaded apartment (STA) threads should use pumping wait primitives (such as CoWaitForMultipleHandles) and routinely pump messages during long running operations. Can anyone please help me out with the problem here? Thanks a lot.

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

  - 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 should 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 its 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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• C++ Forward declaration for virtual function

  - by Gokul

  Hi, I have a class hierarchy and i am writing a virtual function in it. Say there are three classes class A { virtual A* test(); }; ( File A.h ) class B : public A { virtual C* test(); }; ( File B.h ) class C : public A {}; ( File C.h ) Now is it possible for me to avoid including C.h in B.h, by doing some kind of forward declaration saying that C is a sub-class of A? Thanks, Gokul.

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• ASP.NET single quotes are converted to &#39;

  - by Monty

  Note: Most probably this will be a double question, but since I haven't found a clear answer, I'm asking it anyway. In ASP.NET I'd like to add some JavaScript to the onclick event of a CheckBox. I've simplified the case to this: <asp:CheckBox ID="TestCheckBox" runat="server" onclick="alert('test');" Text="Test" /> The resulting HTML is as follows: <input id="MainContainer_TestCheckBox" type="checkbox" name="ctl00$MainContainer$TestCheckBox" onclick="alert(&#39;test&#39;);" /><label for="MainContainer_TestCheckBox">Test</label> What particularly bothers me is that a single quote 'automatically' gets converted into '&#39;'. If I omit the onclick in the markup and assign it in Page_Load, the exact same results show in the HTML. protected void Page_Load(object sender, EventArgs e) { this.TestCheckBox.Attributes["onclick"] = "alert('test');"; } Anyone got a clue about what's happening? Or how to fix/ avoid it?

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• Show friendly message on ASP.NET Ajax error

  - by balexandre

  You all know how annoying is this: I do have a log system and the correct error is well explicit there, but I want to give a better message to the user. I keep trying several ways but I'm using Telerik components and well jQuery and I ended up using both ASP.NET Ajax methods and jQuery, so I use function pageLoad() { try { var manager = Sys.WebForms.PageRequestManager.getInstance(); manager.add_endRequest(endRequest); manager.add_beginRequest(OnBeginRequest); manager } catch (err) { alert(err); } } as well $(document).ready(function() { ... } that alert(err) is never fired even upon OnClick events what's the best approach to avoid this message errors and provide a cleaner way? all this happens in <asp:UpdatePanel> as I use that when I didn't know better (3 years ago!) and I really don't want to mess up and build all again from scratch :( Any help is greatly appreciated Updated with more error windows after volpav solution

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• Planning a competition

  - by Jérôme

  I need to produce the schedule of a sport-event. There are 30 teams. Each team has to play 8 matches. This means that it is not possible for each team to compete again all other teams, but I need to avoid that two team compete more than once against each other. My idea was to generate all possible matches (for 30 teams: (30*29)/2 = 435 matches) and select from this list 120 matches (8 match for each team: 8 * 30 / 2 = 120 matches). This is where I'm having a hard time: how can I select these 120 matches? I tried some simple solutions (take first match of the list, then the last, and so on) but they don't seem to work with 30 teams. I also tried to generate all possible match combination and find which one is working but with 30 team, this is too much calculation time. Is there an existing algorithm that I could implement?

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• How to write a jUnit test for this class?

  - by flash

  Hi, I would like to know what's the best approach to test the method "pushEvent()" in the following class with a jUnit test. My problem is, that the private method "callWebsite()" always requires a connection to the network. How can I avoid this requirement or refactor my class that I can test it without a connection to the network? class MyClass { public String pushEvent (Event event) { //do something here String url = constructURL (event); //construct the website url String response = callWebsite (url); return response; } private String callWebsite (String url) { try { URL requestURL = new URL (url); HttpURLConnection connection = null; connection = (HttpURLConnection) requestURL.openConnection (); String responseMessage = responseParser.getResponseMessage (connection); return responseMessage; } catch (MalformedURLException e) { e.printStackTrace (); return e.getMessage (); } catch (IOException e) { e.printStackTrace (); return e.getMessage (); } } }

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• Is there a consolidated way of writing several prototype functions for a single object?

  - by Christopher Altman

  I have about eight prototype functions for the Date object. I would like to avoid repeating Date.prototype. Is there a consolidated way of writing several prototype functions for a single object? I tried this to no avail: Date.prototype = { getMonthText: function(date){ var month = this.getMonth(); if(month==12) month = 0; return ['JAN','FEB','MAR','APR','MAY','JUN','JUL','AUG','SEP','OCT','NOV','DEC'][month]; }, getDaysInMonth: function(date){ return 32 - new Date(this.getFullYear(), this.getMonth(), 32).getDate(); } };

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• Heavy use of templates for mobile platforms

  - by Chris P. Bacon

  I've been flicking through the book Modern C++ Design by Andrei Alexandrescu and it seems interesting stuff. However it makes very extensive use of templates and I would like to find out if this should be avoided if using C++ for mobile platform development (Brew MP, WebOS, iOS etc.) due to size considerations. In Symbian OS C++ the standard use of templates is discouraged, the Symbian OS itself uses them but using an idiom known as thin templates where the underlying implementation is done in a C style using void* pointers with a thin template layered on top of this to achieve type safety. The reason they use this idiom as opposed to regular use of templates is specifically to avoid code bloating. So what are opinions (or facts) on the use of templates when developing applications for mobile platforms.

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• SQL query not taking values more than 2100

  - by user175084

  SELECT MachineID, MachineName, count(ID) as Total, sum(Size) as TotalSize FROM Files join Machines on Files.MachineID = Machines.MachineID Where Files.MachineID In(sql.Append(string.Format("@MachineId{0}", i)); group by Files.MachineID,MachineName now when the machinId count is less than 2100 the query is performed and if it machines go above 2100 an error is thrown Error: The incoming tabular data stream (TDS) remote procedure call (RPC) protocol stream is incorrect. Too many parameters were provided in this RPC request. The maximum is 2100. how do i make increase the limit or just avoid getting this error.. and put values in gridview thanks..

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• Pure virtual destructor in interface

  - by ALOR

  Hello all. Here is my problem. I'm making C++ dll, which extensively relies on instance object exports. So i return my actual instances as a pointers to interface through some exported factory method. Interfaces i use are purely virtual, to avoid linking problame. So i need a pure virtual destructor too, and i implemented one (with empty body, as i googled it). All compiles perfectly well, except... I can't see, if the actual destructors are called or not - because when i added some std::cout << "hello destructor"; i never get to see it. I have some explicit "delete obj", that's not the problem. Am i missing something? Is there another way to delete my object through interface?

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• Is it possible to dynamically set a static string during *class* Initialisation?

  - by LonnieBest

  I'm trying to dynamically create a connection string during compile time: public static string ConnectionString { get { string connectionString = @"Data Source=" + myLibrary.common.GetExeDir() + @"\Database\db.sdf;"; return connectionString; } } I keep running into type initialisation errors. I was trying to avoid having to set the connection string for all applications that user my code library. The location of the database is different for each project that uses the library. I have code that can determine the correction string, but was wanting run it during compile time. Is this even possible?

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• How to sanely read and dump structs to disk when some fields are pointers?

  - by bp

  Hello, I'm writing a FUSE plugin in C. I'm keeping track of data structures in the filesystem through structs like: typedef struct { block_number_t inode; filename_t filename; //char[SOME_SIZE] some_other_field_t other_field; } fs_directory_table_item_t; Obviously, I have to read (write) these structs from (to) disk at some point. I could treat the struct as a sequence of bytes and do something like this: read(disk_fd, directory_table_item, sizeof(fs_directory_table_item_t)); ...except that cannot possibly work as filename is actually a pointer to the char array. I'd really like to avoid having to write code like: read(disk_df, *directory_table_item.inode, sizeof(block_number_t)); read(disk_df, directory_table_item.filename, sizeof(filename_t)); read(disk_df, *directory_table_item.other_field, sizeof(some_other_field_t)); ...for each struct in the code, because I'd have to replicate code and changes in no less than three different places (definition, reading, writing). Any DRYer but still maintainable ideas?

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• AS3: creating a class with multiple and optional parameters?

  - by redconservatory

  I'm creating a slideshow where each slide can have: - a video or a still - 1 audio track or many (up to 3) - 1 button or many (up to 3) I was thinking that each slide can be it's own object, and then I would pass the video, audio, buttons, etc., into it as parameters: package { import flash.media.Video; public class Section { public function Section (video:Video, still:myPhotoClass, audiotrack:Sound, button:myButtonClass) { // can have video OR a still // can have 1 audio track or several // can have 1 button or more } } I'm not sure how to go about approaching this since there can be multiples of certain items (audio, buttons) and also two items are sort-of-optional in the sense that there can be ONE or the OTHER (video/still). For example, is this something that I should just avoid passing as parameters altogether, using a different approach (getters/setters, maybe)?

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• Most efficient way for a lookup/search in a huge list (python)

  - by user229269

  Hey guys, -- I just parsed a big file and I created a list containing 42.000 strings/words. I want to query [against this list] to check if a given word/string belongs to it. So my question is: What is the most efficient way for such a lookup? A first approach is to sort the list [list.sort()] and then just use the if word in list: print 'word' -- which is really trivial and I am sure there is a better way to do it. My goal is to apply a fast lookup that finds whether a given string is in this list or not. If you have any ideas of another data structure, they are welcome. Yet, I want to avoid for now more sophisticated data-structures like Tries etc. I am interested in hearing ideas (or tricks) about fast lookups or any other python library methods that might do the search faster than the simple 'in'. Thanks in advance!

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• Is it OK to mixed NumberLong and normal integers in the same field in MongoDB?

  - by Nicholas Tolley Cottrell

  I have been using Morphia to persistent objects from Java. I have also been running some batch processes from the console. I just realised that some values are now stored as NumberLong and number as plain Javascript numbers. I have an index on this field. Everything seems to be ok, but if I query: {f: 100} from the console it still returns the object even if it actually contains {f: NumberLong(100)} Is this true of all the drivers? It is best practice to avoid NumberLong is I can fit the value inside 32-bit? Will I save a lot of data and index space if I convert all NumberLongs to basic numbers?

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• Stop IE6 overwriting Button text when setting value.

  - by RoToRa

  I've got a button which contains a span I need for styling: <button id="example" name="example" value="Example"><span>Example</span></button> IE6 has a bug that it submits the contents of the button instead of it's value, but I've already worked around that. Now I need to change the value of the button and the text in the span in JavaScript/jQuery: jQuery("#example").val("Changed").children("span").text("Changed"); However IE6 also changes the contents of the button when setting the value per JavaScript/jQuery, so that the span is lost. Does any one know of a way other that identifying IE6 with jQuery.browser that I could use to avoid that?

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• ASP.NET - DropDown DataBinding (Rebind?)

  - by Bob Fincheimer

  I have a drop down which has a method which binds data to it: dropDown.Items.Clear() dropDown.AppendDataBoundItems = True Select Case selType Case SelectionTypes.Empty dropDown.Items.Insert(0, New ListItem("", "")) Case SelectionTypes.Any dropDown.Items.Insert(0, New ListItem("ANY", "")) Case SelectionTypes.Select dropDown.Items.Insert(0, New ListItem("Select One", "")) End Select BindDropDown(val) The BindDropDown method simply sets the datasource, datakeyname, datavaluename, and then databinds the data. For a reason which I cannot avoid, I MUST call this method twice sometimes. When it is called twice, All of the databound items show up two times, but the top item (the one I manually insert) is there only once. Is ASP doing something wierd when i databind twice even though i clear the list between? Or does it have to do something with the viewstate/controlstate? EDIT__ The entire page, and this control has EnableViewState="false" EDIT___ The dropdown is inside a form view. After the selected value is set I have to rebind the dropdown just in case the selected value is not there [because it is an inactive user]. After this, the formview duplicates the databound items.

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• MySQL foreign key constraints, cascade delete

  - by Cudos

  Hello. I want to use foreign keys to keep the integrity and avoid orphans (I already use innoDB). How do I make a SQL statment that DELETE ON CASCADE? Secondly, that using DELETE ON CASCADE. E.g. if I delete a category then it would delete products related to that category even though there are other categories related to those products. The pivot table "categories_products" creates a many-to-many relationship between the two other tables. categories - id (INT) - name (VARCHAR 255) products - id - name - price categories_products - categories_id - products_id

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• Best way to identify and dispose locked thread in java.

  - by Bala R

  I have to call a function 3rd party module on a new thread. From what I've seen, the call either completes quickly if everything went well or it just hangs for ever locking up the thread. What's a good way to start the thread and make the call and wait for a few secs and if the thread is still alive, then assuming it's locked up, kill (or stop or abandon) the thread without using any deprecated methods. I have something like this for now, but I'm not sure if this is the best way to do it and I want to avoid calling Thread.stop() as it's deprecated. Thanks. private void foo() throws Exception { Runnable runnable = new Runnable() { @Override public void run() { // stuff that could potentially lock up the thread. } }; Thread thread; thread = new Thread(runnable); thread.start(); thread.join(3500); if (thread.isAlive()) { thread.stop(); throw new Exception(); } }

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• Designing template for Ruby on Rails view. What and where to learn?

  - by Victor

  Hi. I have a project going on, and I am in charge of the front-end design, whereas my developers will work on the back-end with Ruby on Rails. I do not know Ruby on Rails, and am designing front-end using XHTML, CSS, jQuery, 960.gs CSS Framework. My developer is supposed to take my design and connect the elements of back-end to it, with Ajax too. What are the things that I should know while designing the template/view so that I won't kick my developers' asses with my design? How to help the connecting of elements painless? I understand I must avoid . Some Ruby on Rails developers also prefer Blueprint CSS Framework over 960.gs. Any guidance? Thanks.

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• Have parameters in Dao methods to get entities the most efficient way for read-only access

  - by Blankman

  Allot of my use of hibernate, at least for that data that is presented on many parts of the web application, is for read-only purposes. I want to add some parameters to my Dao methods so I can modify the way hibernate pulls the data and how it handles transactions etc. Example usage: Data on the front page of my website is displayed to the users, it is read-only, so I want to avoid any session/entity tracking that hibernate usually does. This is data that is read-only, will not be changed in this transaction, etc. What would be the most performant way to pull the data? (the code below is c#/nhibernate, I'm implementing this in java as I learn it) public IList<Article> GetArticles() { return Session.CreateCriteria(typeof(Article)) // some where cluase }

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• How to suppress error messages in rpy2

  - by Björn

  Hello! The following code does not work. It seems that the R warning message raises a python error. # enable use of python objects in rpy2 import rpy2.robjects.numpy2ri import numpy as np from rpy2.robjects import r # create an example array a = np.array([[5,2,5],[3,7,8]]) # this line leads to a warning message, which in turn raises an # error message if run within a script. result = r['chisq.test'](a) Running that code example in ipython works, however, running it inside a script raises the errorTypeError: 'module' object is unsubscriptable. I assume this is due to the warning message. What is the best way to avoid this problem? Thanks in advance!

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• Side effects of reordering columns in PostgreSQL

  - by Summer

  I sometimes re-order the columns in my Postgres DB. Since Postgres can only add columns at the end of tables, I end up re-ordering by adding new columns at the end of the table, setting them equal to existing columns, and then dropping the original columns. My question is: what does PostgreSQL do with the memory that's freed by dropped columns? Does it automatically re-use the memory, so a single record consumes the same amount of space as it did beforehand? But that would require a re-write of the whole table, so to avoid that, does it just keep a bunch of blank space around in each record? Thanks! ~S

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