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• MERGE gives better OUTPUT options

  - by Rob Farley

  MERGE is very cool. There are a ton of useful things about it – mostly around the fact that you can implement a ton of change against a table all at once. This is great for data warehousing, handling changes made to relational databases by applications, all kinds of things. One of the more subtle things about MERGE is the power of the OUTPUT clause. Useful for logging.   If you’re not familiar with the OUTPUT clause, you really should be – it basically makes your DML (INSERT/DELETE/UPDATE/MERGE) statement return data back to you. This is a great way of returning identity values from INSERT commands (so much better than SCOPE_IDENTITY() or the older (and worse) @@IDENTITY, because you can get lots of rows back). You can even use it to grab default values that are set using non-deterministic functions like NEWID() – things you couldn’t normally get back without running another query (or with a trigger, I guess, but that’s not pretty). That inserted table I referenced – that’s part of the ‘behind-the-scenes’ work that goes on with all DML changes. When you insert data, this internal table called inserted gets populated with rows, and then used to inflict the appropriate inserts on the various structures that store data (HoBTs – the Heaps or B-Trees used to store data as tables and indexes). When deleting, the deleted table gets populated. Updates get a matching row in both tables (although this doesn’t mean that an update is a delete followed by an inserted, it’s just the way it’s handled with these tables). These tables can be referenced by the OUTPUT clause, which can show you the before and after for any DML statement. Useful stuff. MERGE is slightly different though. With MERGE, you get a mix of entries. Your MERGE statement might be doing some INSERTs, some UPDATEs and some DELETEs. One of the most common examples of MERGE is to perform an UPSERT command, where data is updated if it already exists, or inserted if it’s new. And in a single operation too. Here, you can see the usefulness of the deleted and inserted tables, which clearly reflect the type of operation (but then again, MERGE lets you use an extra column called $action to show this). (Don’t worry about the fact that I turned on IDENTITY_INSERT, that’s just so that I could insert the values) One of the things I love about MERGE is that it feels almost cursor-like – the UPDATE bit feels like “WHERE CURRENT OF …”, and the INSERT bit feels like a single-row insert. And it is – but into the inserted and deleted tables. The operations to maintain the HoBTs are still done using the whole set of changes, which is very cool. And $action – very convenient. But as cool as $action is, that’s not the point of my post. If it were, I hope you’d all be disappointed, as you can’t really go near the MERGE statement without learning about it. The subtle thing that I love about MERGE with OUTPUT is that you can hook into more than just inserted and deleted. Did you notice in my earlier query that my source table had a ‘src’ field, that wasn’t used in the insert? Normally, this would be somewhat pointless to include in my source query. But with MERGE, I can put that in the OUTPUT clause. This is useful stuff, particularly when you’re needing to audit the changes. Suppose your query involved consolidating data from a number of sources, but you didn’t need to insert that into the actual table, just into a table for audit. This is now very doable, either using the INTO clause of OUTPUT, or surrounding the whole MERGE statement in brackets (parentheses if you’re American) and using a regular INSERT statement. This is also doable if you’re using MERGE to just do INSERTs. In case you hadn’t realised, you can use MERGE in place of an INSERT statement. It’s just like the UPSERT-style statement we’ve just seen, except that we want nothing to match. That’s easy to do, we just use ON 1=2. This is obviously more convoluted than a straight INSERT. And it’s slightly more effort for the database engine too. But, if you want the extra audit capabilities, the ability to hook into the other source columns is definitely useful. Oh, and before people ask if you can also hook into the target table’s columns... Yes, of course. That’s what deleted and inserted give you.

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• play sound from different applications on different output devices (speakers, headphones)

  - by Mike

  I want music (played e.g. via Audacious) to be played on speaker system, and all other sounds produced by other applications (including ubuntu sound effects) to be played on headphones. My computer has sound connectors at its back, and also connectors on its front panel. When I connect both headphones and speakers, only headphones work (I take it, the front connectors take precedence?). Should I purchase another sound card (in addition to the motherboard-integrated sound I have)? When I go to Audacious output settings, I see only the ouput plugin selection list, with PulseAudio selected and options like ALSA, OSS4 etc. But there's no facility to select particular output device (and I guess it wouldn't magically appear even if I had the second soundcard). Is this at all possible to bind specific application to particular output device?

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• Double buffering with C# has negative effect

  - by Roland Illig

  I have written the following simple program, which draws lines on the screen every 100 milliseconds (triggered by timer1). I noticed that the drawing flickers a bit (that is, the window is not always completely blue, but some gray shines through). So my idea was to use double-buffering. But when I did that, it made things even worse. Now the screen was almost always gray, and only occasionally did the blue color come through (demonstrated by timer2, switching the DoubleBuffered property every 2000 milliseconds). What could be an explanation for this? using System; using System.Drawing; using System.Windows.Forms; namespace WindowsFormsApplication1 { public partial class Form1 : Form { public Form1() { InitializeComponent(); } private void Form1_Paint(object sender, PaintEventArgs e) { Graphics g = CreateGraphics(); Pen pen = new Pen(Color.Blue, 1.0f); Random rnd = new Random(); for (int i = 0; i < Height; i++) g.DrawLine(pen, 0, i, Width, i); } // every 100 ms private void timer1_Tick(object sender, EventArgs e) { Invalidate(); } // every 2000 ms private void timer2_Tick(object sender, EventArgs e) { DoubleBuffered = !DoubleBuffered; this.Text = DoubleBuffered ? "yes" : "no"; } } }

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• Indy Write Buffering / Efficient TCP communication

  - by Smasher

  I know, I'm asking a lot of questions...but as a new delphi developer I keep falling over all these questions :) This one deals with TCP communication using indy 10. To make communication efficient, I code a client operation request as a single byte (in most scenarios followed by other data bytes of course, but in this case only one single byte). Problem is that var Bytes : TBytes; ... SetLength (Bytes, 1); Bytes [0] := OpCode; FConnection.IOHandler.Write (Bytes, 1); ErrorCode := Connection.IOHandler.ReadByte; does not send that byte immediately (at least the servers execute handler is not invoked). If I change the '1' to a '9' for example everything works fine. I assumed that Indy buffers the outgoing bytes and tried to disable write buffering with FConnection.IOHandler.WriteBufferClose; but it did not help. How can I send a single byte and make sure that it is immediatly sent? And - I add another little question here - what is the best way to send an integer using indy? Unfortunately I can't find function like WriteInteger in the IOHandler of TIdTCPServer...and WriteLn (IntToStr (SomeIntVal)) seems not very efficient to me. Does it make a difference whether I use multiple write commands in a row or pack things together in a byte array and send that once? Thanks for any answers! EDIT: I added a hint that I'm using Indy 10 since there seem to be major changes concerning the read and write procedures.

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• Getting input and output from a jar file run from java class?

  - by Jack L.

  Hi, I have a jar file that runs this code: public class InputOutput { /** * @param args * @throws IOException */ public static void main(String[] args) throws IOException { boolean cont = true; BufferedReader in = new BufferedReader(new InputStreamReader(System.in)); while (cont) { System.out.print("Input something: "); String temp = in.readLine(); if (temp.equals("end")) { cont = false; System.out.println("Terminated."); } else System.out.println(temp); } } } I want to program another java class that executes this jar file and can get the input and send output to it. Is it possible? The current code I have is this but it is not working: public class JarTest { /** * Test input and output of jar files * @author Jack */ public static void main(String[] args) { try { Process io = Runtime.getRuntime().exec("java -jar InputOutput.jar"); BufferedReader in = new BufferedReader(new InputStreamReader(io.getInputStream())); OutputStreamWriter out = new OutputStreamWriter(io.getOutputStream()); boolean cont = true; BufferedReader consolein = new BufferedReader(new InputStreamReader(System.in)); while (cont) { String temp = consolein.readLine(); out.write(temp); System.out.println(in.readLine()); } } catch (IOException e) { e.printStackTrace(); } } } Thanks for your help

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• CGI Buffering issue

  - by Punit

  I have a server side C based CGI code as: cgiFormFileSize("UPDATEFILE", &size); //UPDATEFILE = file being uploaded cgiFormFileName("UPDATEFILE", file_name, 1024); cgiFormFileContentType("UPDATEFILE", mime_type, 1024); buffer = malloc(sizeof(char) * size); if (cgiFormFileOpen("UPDATEFILE", &file) != cgiFormSuccess) { exit(1); } output = fopen("/tmp/cgi.tar.gz", "w+"); printf("The size of file is: %d bytes", size); inc = size/(1024*100); while (cgiFormFileRead(file, b, sizeof(b), &got_count) == cgiFormSuccess) { fwrite(b,sizeof(char),got_count,output); i++; if(i == inc && j<=100) { ***inc_pb*** = j; i = 0; j++; // j is the progress bar increment value } } cgiFormFileClose(file); retval = system("mkdir /tmp/update-tmp;\ cd /tmp/update-tmp;\ tar -xzf ../cgi.tar.gz;\ bash -c /tmp/update-tmp/update.sh"); However, this doesn't work the way as is seen above. Instead of printing 1,2,...100 to progress_bar.txt one by one it prints at ONE GO, seems it buffers and then writes to the file. fflush() also didn't work. Any clue/suggestion would be really appreciated.

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• Accessing both stored procedure output parameters AND the result set in Entity Framework?

  - by MS.

  Is there any way of accessing both a result set and output parameters from a stored procedure added in as a function import in an Entity Framework model? I am finding that if I set the return type to "None" such that the designer generated code ends up calling base.ExecuteFunction(...) that I can access the output parameters fine after calling the function (but of course not the result set). Conversely if I set the return type in the designer to a collection of complex types then the designer generated code calls base.ExecuteFunction<T>(...) and the result set is returned as ObjectResult<T> but then the value property for the ObjectParameter instances is NULL rather than containing the proper value that I can see being passed back in Profiler. I speculate the second method is perhaps calling a DataReader and not closing it. Is this a known issue? Any work arounds or alternative approaches? Edit My code currently looks like public IEnumerable<FooBar> GetFooBars( int? param1, string param2, DateTime from, DateTime to, out DateTime? createdDate, out DateTime? deletedDate) { var createdDateParam = new ObjectParameter("CreatedDate", typeof(DateTime)); var deletedDateParam = new ObjectParameter("DeletedDate", typeof(DateTime)); var fooBars = MyContext.GetFooBars(param1, param2, from, to, createdDateParam, deletedDateParam); createdDate = (DateTime?)(createdDateParam.Value == DBNull.Value ? null : createdDateParam.Value); deletedDate = (DateTime?)(deletedDateParam.Value == DBNull.Value ? null : deletedDateParam.Value); return fooBars; }

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• Measuring ASP.NET and SharePoint output cache

  - by DigiMortal

  During ASP.NET output caching week in my local blog I wrote about how to measure ASP.NET output cache. As my posting was based on real work and real-life results then I thought that this posting is maybe interesting to you too. So here you can read what I did, how I did and what was the result. Introduction Caching is not effective without measuring it. As MVP Henn Sarv said in one of his sessions then you will get what you measure. And right he is. Lately I measured caching on local Microsoft community portal to make sure that our caching strategy is good enough in environment where this system lives. In this posting I will show you how to start measuring the cache of your web applications. Although the application measured is built on SharePoint Server publishing infrastructure, all those counters have same meaning as similar counters under pure ASP.NET applications. Measured counters I used Performance Monitor and the following performance counters (their names are similar on ASP.NET and SharePoint WCMS): Total number of objects added – how much objects were added to output cache. Total object discards – how much objects were deleted from output cache. Cache hit count – how many times requests were served by cache. Cache hit ratio – percent of requests served from cache. The first three counters are cumulative while last one is coefficient. You can use also other counters to measure the full effect of caching (memory, processor, disk I/O, network load etc before and after caching). Measuring process The measuring I describe here started from freshly restarted web server. I measured application during 12 hours that covered also time ranges when users are most active. The time range does not include late evening hours and night because there is nothing to measure during these hours. During measuring we performed no maintenance or administrative tasks on server. All tasks performed were related to usual daily content management and content monitoring. Also we had no advertisement campaigns or other promotions running at same time. The results You can see the results on following graphic.   Total number of objects added   Total object discards   Cache hit count   Cache hit ratio You can see that adds and discards are growing in same tempo. It is good because cache expires and not so popular items are not kept in memory. If there are more popular content then the these lines may have bigger distance between them. Cache hit count grows faster and this shows that more and more content is served from cache. In current case it shows that cache is filled optimally and we can do even better if we tune caches more. The site contains also pages that are discarded when some subsite changes (page was added/modified/deleted) and one modification may affect about four or five pages. This may also decrease cache hit count because during day the site gets about 5-10 new pages. Cache hit ratio is currently extremely good. The suggested minimum is about 85% but after some tuning and measuring I achieved 98.7% as a result. This is due to the fact that new pages are most often requested and after new pages are added the older ones are requested only sometimes. So they get discarded from cache and only some of these will return sometimes back to cache. Although this may also indicate the need for additional SEO work the result is very well in technical means. Conclusion Measuring ASP.NET output cache is not complex thing to do and you can start by measuring performance of cache as a start. Later you can move on and measure caching effect to other counters such as disk I/O, network, processors etc. What you have to achieve is optimal cache that is not full of items asked only couple of times per day (you can avoid this by not using too long cache durations). After some tuning you should be able to boost cache hit ratio up to at least 85%.

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• java double buffering problem

  - by russell

  Whats wrong with my applet code which does not render double buffering correctly.I am trying and trying.But failed to get a solution.Plz Plz someone tell me whats wrong with my code. import java.applet.* ; import java.awt.* ; import java.awt.event.* ; public class Ball extends Applet implements Runnable { // Initialisierung der Variablen int x_pos = 10; // x - Position des Balles int y_pos = 100; // y - Position des Balles int radius = 20; // Radius des Balles Image buffer=null; //Graphics graphic=null; int w,h; public void init() { Dimension d=getSize(); w=d.width; h=d.height; buffer=createImage(w,h); //graphic=buffer.getGraphics(); setBackground (Color.black); } public void start () { // Schaffen eines neuen Threads, in dem das Spiel l?uft Thread th = new Thread (this); // Starten des Threads th.start (); } public void stop() { } public void destroy() { } public void run () { // Erniedrigen der ThreadPriority um zeichnen zu erleichtern Thread.currentThread().setPriority(Thread.MIN_PRIORITY); // Solange true ist l?uft der Thread weiter while (true) { // Ver?ndern der x- Koordinate repaint(); x_pos++; y_pos++; //x2--; //y2--; // Neuzeichnen des Applets if(x_pos>410) x_pos=20; if(y_pos>410) y_pos=20; try { Thread.sleep (30); } catch (InterruptedException ex) { // do nothing } Thread.currentThread().setPriority(Thread.MAX_PRIORITY); } } public void paint (Graphics g) { Graphics screen=null; screen=g; g=buffer.getGraphics(); g.setColor(Color.red); g.fillOval(x_pos - radius, y_pos - radius, 2 * radius, 2 * radius); g.setColor(Color.green); screen.drawImage(buffer,0,0,this); } public void update(Graphics g) { paint(g); } } what change should i make.When offscreen image is drawn the previous image also remain in screen.How to erase the previous image from the screen??

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• How can I capture the output and exit value of a subprocess in Perl? [closed]

  - by Ryan Thompson

  Possible Duplicate: How do you capture stderr, stdout, and the exit code all at once, in Perl? I'm writing a Perl script that needs to call a subprocess and capture both the output and the exit value. Is there a way to get both?

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• How to line-wrap console output in NetBeans 6.8?

  - by JRL

  Is there a way to make the console output text wrap based on the actual width of the window? I have limited screen height real estate on my laptop, and so want to have the console window docked on the right rather than the bottom of the window. An option or a plugin is fine, I'm using NetBeans 6.8. If this exists in a newer version of NetBeans, please say so, but I can't install a dev build.

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• How to redirect output of PHP script DURING execution?

  - by George Edison

  Is there a way to redirect output of an executing PHP script? Of course this is trivial when launching the script via the command line. But how is this accomplished after the script is started?

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• How to run sql from a .net application against sqlserver and get output like with SQL Management Stu

  - by Rory

  I'd like my app to run sql files and receive the results output as if the sql was run from SQL Management Studio with results to text. i.e. nicely formatted recordsets, printed messages, rows affected, errors, running multiple batches separated by GO statements, etc. Any suggestions how to do this without building it from scratch on top of a normal SQL connection?

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• Capture output and exit value of subprocess in perl?

  - by Ryan Thompson

  I'm writing a per script that needs to call a subprocess and capture both the output and the exit value. Is there a way to get both?

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• How to have one PHP script launch another and capture its output?

  - by George Edison

  This is a little tricky so bear with me: I have a PHP script a.php that is launched from the command line and data is provided to it via STDIN I have another PHP script b.php I want to have a.php launch b.php and capture its output. Also, a.php has to forward the STDIN to b.php Is there an easy way to do this?

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• How can you store JSP buffered output from an include/import to a variable?

  - by codeninja

  I don't want to use any JAVA, I just want to use <jsp:include> or <c:import> or something to that effect.. so that I can use <c:set var="myPage" value="bufferedPageOutput" /> to output the generated html later How can I do this with JSP/JSTL/Struts ?

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• How to merge your referenced assemblies into the output assembly for improved usability

  - by Daniel Cazzulino

  Something we've been doing in moq since the very beginning is to have a single assembly as output: Moq.dll. This reduces the clutter for users and lets them focus on what they need from our library, rather than getting the noise of whatever third-party (or internal) libraries we use to implement it. This is good from the deployment point of view too, and if all your libraries are actually internal infrastructure assemblies, you can even make them all internal types of your output assembly....Read full article

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• Automatically change Sound Input Output device

  - by Senthil Kumaran

  I have to plugin my USB Audio adapter ( 4300054 Gigawire USB Audio Adapter) for audio input because has a combo-input-output port for voice. After I do this, I have go open Sound Settings and manually select the USB Audio adapter for Input and Output, if I do not, the system default remains selected. Is there anyway, I can make Ubuntu to automatically select the USB Audio Adapter as the default as soon as I plug-in?

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• Making diff output more readable

  - by mgunes

  I'm looking for a tool that will take diff / debdiff output (and more specifically, the output of this script) and display the result of the comparison in a highly readable, graphical way. Any pointers would be appreciated. Ideally, it would be the GTK+, FOSS equivalent of MDR. Meld, Diffuse and similar software are not fit for this purpose, since they're intended to work standalone, and don't take input from stdin.

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• How to remove the xmlns:XSI and xmlns:XSD namespaces from the xml output of a webservice in .net fra

  - by Chetan

  HI, This is an old question, i have seen some solutions on this forum itself, but am trying to use webservices for the first time so please bear with me on this one. I have a webservice that returns XML in the following format <subs xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" msisdn="965xxxxxx"> <shortcode label="XXXX"> <channels> <channel> <id>442</id> <name>News</name> <billingperiod>7</billingperiod> <billingamount>3</billingamount> <lastbilling>4/14/2010 1:41:11 PM</lastbilling> </channel> <channel> <id>443</id> <name>News2</name> <billingperiod>7</billingperiod> <billingamount>3</billingamount> <lastbilling>4/14/2010 1:41:19 PM</lastbilling> </channel> </channels> </shortcode> </subs> I want the same XMl output without the xmlns:xsd and xmlns:xsi tags. I have tried the following solution that was suggested: Public Function GetSubscription(....) As String Dim namespaces As New XmlSerializerNamespaces namespaces.Add(String.Empty, String.Empty) Dim serializer As New XmlSerializer(SubsDetail.GetType) Dim sw As New System.IO.StringWriter Dim writer As New System.Xml.XmlTextWriter(sw) writer.Formatting = Formatting.None serializer.Serialize(writer, SubsDetail, namespaces) writer.Close() Return sw.toString() The result was that I got an xml in the following format: <string> <?xml version="1.0" encoding="utf-16"?><subs msisdn="965xxxx"> <shortcode label="XXXX"> <channels> <channel> <id>442</id> <name>News</name> <billingperiod>7</billingperiod> <billingamount>3</billingamount> <lastbilling>4/14/2010 1:41:11 PM</lastbilling> </channel> <channel> <id>443</id> <name>News2</name> <billingperiod>7</billingperiod> <billingamount>3</billingamount> <lastbilling>4/14/2010 1:41:19 PM</lastbilling> </channel> </channels> </shortcode> </subs> </string> Though the format of the xml is correct it is coming as string within the <string> tags. This is really driving me nuts. Can I get the output as xml without the outer string tags?

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• Force line-buffering of stdout when piping to tee

  - by houbysoft

  Usually, stdout is line-buffered. In other words, as long as your printf argument ends with a newline, you can expect the line to be printed instantly. This does not appear to hold when using a pipe to redirect to tee. I have a C++ program, a, that outputs strings, always \n-terminated, to stdout. When it is run by itself (./a), everything prints correctly and at the right time, as expected. However, if I pipe it to tee (./a | tee output.txt), it doesn't print anything until it quits, which defeats the purpose of using tee. I know that I could fix it by adding a fflush(stdout) after each printing operation in the C++ program. But is there a cleaner, easier way? Is there a command I can run, for example, that would force stdout to be line-buffered, even when using a pipe?

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• Cannot use apt-get/dpkg -- Input/output error

  - by mecho

  I have bumped into an issue that doesn't allow me to do anything related to apt-get: install, remove, etc. Whenever I try to do something (e.g. sudo apt-get install firefox -f) it gives me the same error message: Reading database ... dpkg: unrecoverable fatal error, aborting: unable to open files list file for package `fontconfig-config': Input/output error E: Sub-process /usr/bin/dpkg returned an error code (2) I have tried to deal with the package `fontconfig-config' without success. I have found that the "Input/output error" is usually linked with physical problems of the hd, but I do not think that's the case I am using that hd without any other problem. I have tried removing the mention to the package in /var/lib/dpkg/status as mentioned here. I have tried deleting all files related to the package in /var/lib/dpkg/info as I found somewhere. But I still cannot do anything. The funny bit comes when I look for the file that is giving me troubles: mecho@Ansible-MS-7680:/var/lib/dpkg/info$ ls fontconfig* ls: cannot access fontconfig-config.list: Input/output error fontconfig.list fontconfig.postinst fontconfig.preinst fontconfig.triggers fontconfig.md5sums fontconfig.postrm fontconfig.prerm This is done after I deleted all files ... it looks like fontconfig-config.list still exists but it doesn't show up! Any idea about how to solve the problem? I am on kubuntu precise, fontconfig-config_2.8.0-3ubuntu9.1

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• How can I unit test rendering output?

  - by stephelton

  I've been embracing Test-Driven Development (TDD) recently and it's had wonderful impacts on my development output and the resiliency of my codebase. I would like to extend this approach to some of the rendering work that I do in OpenGL, but I've been unable to find any good approaches to this. I'll start with a concrete example so we know what kinds of things I want to test; lets say I want to create a unit cube that rotates about some axis, and that I want to ensure that, for some number of frames, each frame is rendered correctly. How can I create an automated test case for this? Preferably, I'd even be able to write a test case before writing any code to render the cube (per usual TDD practices.) Among many other things, I'd want to make sure that the cube's size, location, and orientation are correct in each rendered frame. I may even want to make sure that the lighting equations in my shaders are correct in each frame. The only remotely useful approach to this that I've come across involves comparing rendered output to a reference output, which generally precludes TDD practice, and is very cumbersome. I could go on about other desired requirements, but I'm afraid the ones I've listed already are out of reach.

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• Named output parameters vs return values

  - by Abyx

  Which code is better: // C++ void handle_message(...some input parameters..., bool& wasHandled) void set_some_value(int newValue, int* oldValue = nullptr) // C# void handle_message(...some input parameters..., out bool wasHandled) void set_some_value(int newValue, out int oldValue) or bool handle_message(...some input parameters...) ///< Returns -1 if message was handled //(sorry, this documentation was broken a year ago and we're too busy to fix it) int set_some_value(T newValue) // (well, it's obvious what this function returns, so I didn't write any documentation for it) The first one doesn't have and need any documentation. It's a self-documenting code. Output value clearly says what it means, and it's really hard to make a change like this: - void handle_message(Message msg, bool& wasHandled) { - wasHandled = false; - if (...) { wasHandled = true; ... + void handle_message(Message msg, int& wasHandled) { + wasHandled = -1; + if (...) { wasHandled = ...; With return values such change could be done easily /// Return true if message was handled - bool handle_message(Message msg) { + int handle_message(Message msg) { ... - return true; + return -1; Most of compilers don't (and can't) check documentation written in comments. Programmers also tend to ignore comments while editing code. So, again, the question is: if subroutine has single output value, should it be a procedure with well-named self-documenting output parameter, or should it be a function which returns an unnamed value and have a comment describing it?

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• optimize output value using a class and public member

  - by wiso

  Suppose you have a function, and you call it a lot of times, every time the function return a big object. I've optimized the problem using a functor that return void, and store the returning value in a public member: #include <vector> const int N = 100; std::vector<double> fun(const std::vector<double> & v, const int n) { std::vector<double> output = v; output[n] *= output[n]; return output; } class F { public: F() : output(N) {}; std::vector<double> output; void operator()(const std::vector<double> & v, const int n) { output = v; output[n] *= n; } }; int main() { std::vector<double> start(N,10.); std::vector<double> end(N); double a; // first solution for (unsigned long int i = 0; i != 10000000; ++i) a = fun(start, 2)[3]; // second solution F f; for (unsigned long int i = 0; i != 10000000; ++i) { f(start, 2); a = f.output[3]; } } Yes, I can use inline or optimize in an other way this problem, but here I want to stress on this problem: with the functor I declare and construct the output variable output only one time, using the function I do that every time it is called. The second solution is two time faster than the first with g++ -O1 or g++ -O2. What do you think about it, is it an ugly optimization?

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