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• GWT vs. Cappuccino

  - by James

  Hi, I'm in the planning stage of a web application and I'm trying to choose between GWT and Cappuccino. I have an idea of which one I think is better, but my partner is sold on the other choice. I was hoping to get some feedback on pros and cons for each from people who have used one or the other or both. Thanks in advance for any insight you might have.

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• detecting pauses in a spoken word audio file using pymad, pcm, vad, etc

  - by james

  First I am going to broadly state what I'm trying to do and ask for advice. Then I will explain my current approach and ask for answers to my current problems. Problem I have an MP3 file of a person speaking. I'd like to split it up into segments roughly corresponding to a sentence or phrase. (I'd do it manually, but we are talking hours of data.) If you have advice on how to do this programatically or for some existing utilities, I'd love to hear it. (I'm aware of voice activity detection and I've looked into it a bit, but I didn't see any freely available utilities.) Current Approach I thought the simplest thing would be to scan the MP3 at certain intervals and identify places where the average volume was below some threshold. Then I would use some existing utility to cut up the mp3 at those locations. I've been playing around with pymad and I believe that I've successfully extracted the PCM (pulse code modulation) data for each frame of the mp3. Now I am stuck because I can't really seem to wrap my head around how the PCM data translates to relative volume. I'm also aware of other complicating factors like multiple channels, big endian vs little, etc. Advice on how to map a group of pcm samples to relative volume would be key. Thanks!

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• .Net System.Net.HttpWebRequest & Authentication Cookies

  - by James

  I would like to know if the following is possible: As part of the PageLoad of an ASP.Net page request: Use HttpWebRequest (POST) to make a request to a forms authentication webpage of a different web application Examine the response to see if the authentication succeeded (identifiable if an authentication cookie has been set) If it fails, then finish the ASP.Net page request, which will display a message saying "couldn't auto-login" or some such thing If success, then instead of completing the ASP.Net page lifecycle, use "Response.Write" to send the response from the HttpWebRequest back to the browser (thus essentially displaying the webpage from the HttpWebRequest) If the above is possible, then, is there also a way to transfer the authentication cookie from the HttpWebResponse to the requesting browser? My gut feeling is probably not - but if this is the case, then how do proxy servers handle such things? Is that not essentially what they are doing? Thanks for any help

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• How to speed up marching cubes?

  - by Dan Vinton

  I'm using this marching cube algorithm to draw 3D isosurfaces (ported into C#, outputting MeshGeomtry3Ds, but otherwise the same). The resulting surfaces look great, but are taking a long time to calculate. Are there any ways to speed up marching cubes? The most obvious one is to simply reduce the spatial sampling rate, but this reduces the quality of the resulting mesh. I'd like to avoid this. I'm considering a two-pass system, where the first pass samples space much more coarsely, eliminating volumes where the field strength is well below my isolevel. Is this wise? What are the pitfalls? Edit: the code has been profiled, and the bulk of CPU time is split between the marching cubes routine itself and the field strength calculation for each grid cell corner. The field calculations are beyond my control, so speeding up the cubes routine is my only option... I'm still drawn to the idea of trying to eliminate dead space, since this would reduce the number of calls to both systems considerably.

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• Can't import obj in Python on OS X 10.6.3 Snow Leopard - libiconv.2.dylib?

  - by James

  on OS X 10.6.3 Snow Leopard % python Python 2.6.1 (r261:67515, Feb 11 2010, 00:51:29) [GCC 4.2.1 (Apple Inc. build 5646)] on darwin Type "help", "copyright", "credits" or "license" for more information. import objc Traceback (most recent call last): File "", line 1, in File "/Library/Python/2.6/site-packages/pyobjc_core-2.2-py2.6-macosx-10.6-universal.egg/objc/__init__.py", line 22, in _update() File "/Library/Python/2.6/site-packages/pyobjc_core-2.2-py2.6-macosx-10.6-universal.egg/objc/__init__.py", line 19, in _update import _objc ImportError: dlopen(/Library/Python/2.6/site-packages/pyobjc_core-2.2-py2.6-macosx-10.6-universal.egg/objc/_objc.so, 2): Library not loaded: /opt/local/lib/libiconv.2.dylib Referenced from: /Library/Python/2.6/site-packages/pyobjc_core-2.2-py2.6-macosx-10.6-universal.egg/objc/_objc.so Reason: Incompatible library version: _objc.so requires version 8.0.0 or later, but libiconv.2.dylib provides version 7.0.0 -- what do I need to do?

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• RPX API Call auth_info is returning "missing parameter" error

  - by James Lawruk

  I cannot get the RPX auth_info API call to work. It keeps returning the error: "Missing parameter: apiKey" I am using the C# RPX Helper Class provided on their Wiki:RPX Helper Class Below is my code in my Page_Load method. The RPX service works by sending a POST to a Url that I specify. My code gets the token from the post data shown below. Then I call the AuthInfo API method. string token = Request.Params["token"]; string apiKey = "xxxxxxxxxxxxxxx"; //my API key Rpx rpx = new Rpx(apiKey, "http://rpxnow.com"); XmlElement xmlElement = rpx.AuthInfo(token); Everything looks good. The token is populated. Within their code, the "apiKey" value pair is added to the post data written to the Request stream. Has anyone had luck with this? Any ideas why this is not working? Thanks.

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• Using statement question

  - by Dan

  I have two questions. 1) Should you always use a using statement on a connection? So, I would use it on the connection and then another one on a reader within the connection? So I would be using two using statements. 2) Lets say you use the using statement on the connection and also a reader being returned on the connection. So you have two using statements. Does it create two Try{}Finally{} blocks or just one? Thanks!

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• iTunes Visualizer Plugin in C# - Energy Function

  - by James D

  Hi, iTunes Visualizer plugin in C#. Easiest way to compute the "energy level" for a particular sample? I looked at this writeup on beat detection over at GameDev and have had some success with it (I'm not doing beat detection per se, but it's relevant). But ultimately I'm looking for a stupid-as-possible, quick-and-dirty approach for demo purposes. For those who aren't familiar with how iTunes structures visualization data, basically you're given this: struct VisualPluginData { /* SNIP */ RenderVisualData renderData; UInt32 renderTimeStampID; UInt8 minLevel[kVisualMaxDataChannels]; // 0-128 UInt8 maxLevel[kVisualMaxDataChannels]; // 0-128 }; struct RenderVisualData { UInt8 numWaveformChannels; UInt8 waveformData[kVisualMaxDataChannels][kVisualNumWaveformEntries]; // 512-point FFT UInt8 numSpectrumChannels; UInt8 spectrumData[kVisualMaxDataChannels][kVisualNumSpectrumEntries]; }; Ideally, I'd like an approach that a beginning programmer with little to no DSP experience could grasp and improve on. Any ideas? Thanks!

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• Zend Framework: Zend_translate and routing related issue

  - by Dan

  I have implemented Zend_Navigation, Zend_Translate in my application. The routing is setup in Bootstrap.php like below. $fc = Zend_Controller_Front::getInstance(); $zl=new Zend_Locale(); Zend_Registry::set('Zend_Locale',$zl); $lang=$zl->getLanguage().'_'.$zl->getRegion(); $router = $fc->getRouter(); $route = new Zend_Controller_Router_Route(':lang/:module/:controller/:action/*', array( 'lang'=>$lang, 'module'=>'default', 'controller'=>'index', 'action'=>'index' )); $router->addRoute('default', $route); $fc->setRouter($router); $fc->registerPlugin( new Plugin_LanguageSetup()); in LaunguageSetup Plugin i have defined the dispatchLoopStartup method to do the checking of the language param public function dispatchLoopStartup(Zend_Controller_Request_Abstract $request) { $this->createLangUrl($request); $this->_language = $request->getParam('lang'); if ((!isset($this->_language)) || !in_array($this->_language, $this->_languagesArray)) { $this->_language = 'en_US'; $request->setParam('lang', 'en_US'); } $file = APPLICATION_PATH.$this->_directory.$this->_language.'.csv'; $translate = new Zend_Translate('csv', $file, $this->_language); Zend_Registry::set('Zend_Translate', $translate); $zl = Zend_Registry::get('Zend_Locale'); $zl->setLocale($this->_language); Zend_Registry::set('Zend_Locale', $zl); // $fc = Zend_Controller_Front::getInstance(); // $router = $fc->getRouter(); // $route = new Zend_Controller_Router_Route(':lang/:module/:controller/:action/*', array( // 'lang'=>$this->_language, 'module'=>'default', 'controller'=>'index', 'action'=>'index' // )); // $router->addRoute('default', $route); // $fc->setRouter($router); } What happen is the language always have the default value, the 'lang' param never default lang value in route, even if i type it in the address bar manually i.e /en_US/module/controller/action/ It always get revert back to the default Zend_locale(); Only way i can fix it is to setup the route again in the plugin and inject a correct language value as default. Any Idea why?

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• How can I undo my last git add/commit ?

  - by dan

  I edited a file and did: git add file.py git commit -m 'fixed bug' I then edited another file and performed a minor bug fix. I don't want two commits, one after the other, showing 'bug fix'. I want one commit with 'bug fixes'. How can I undo the last add/commit and change the first commit message? I was looking at the git reset, git revert, git undo commands but I don't want to screw up my repo with a guess EDIT: Found out how to do it: http://www.gitready.com/advanced/2009/02/10/squashing-commits-with-rebase.html

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• Sending a JSON array to be received as a Dictionary<string,string>

  - by James Bond

  I have a method with the following signature: public ActionResult RenderFamilyTree(string name, Dictionary<string, string> children) I'm trying to call it from javascript using jQuery like this: $('#div_render').load( "<%= Url.Action("RenderFamilyTree") %>", { 'name': 'Raul', [ {'key':'key1','value':'value1'}, {'key':'key2','value':'value2'} ] }, function() { alert('Loaded'); } ); Am I missing something to get this to work?

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• Synchronized IEnumerator<T>

  - by Dan Bryant

  I'm putting together a custom SynchronizedCollection<T> class so that I can have a synchronized Observable collection for my WPF application. The synchronization is provided via a ReaderWriterLockSlim, which, for the most part, has been easy to apply. The case I'm having trouble with is how to provide thread-safe enumeration of the collection. I've created a custom IEnumerator<T> nested class that looks like this: private class SynchronizedEnumerator : IEnumerator<T> { private SynchronizedCollection<T> _collection; private int _currentIndex; internal SynchronizedEnumerator(SynchronizedCollection<T> collection) { _collection = collection; _collection._lock.EnterReadLock(); _currentIndex = -1; } #region IEnumerator<T> Members public T Current { get; private set;} #endregion #region IDisposable Members public void Dispose() { var collection = _collection; if (collection != null) collection._lock.ExitReadLock(); _collection = null; } #endregion #region IEnumerator Members object System.Collections.IEnumerator.Current { get { return Current; } } public bool MoveNext() { var collection = _collection; if (collection == null) throw new ObjectDisposedException("SynchronizedEnumerator"); _currentIndex++; if (_currentIndex >= collection.Count) { Current = default(T); return false; } Current = collection[_currentIndex]; return true; } public void Reset() { if (_collection == null) throw new ObjectDisposedException("SynchronizedEnumerator"); _currentIndex = -1; Current = default(T); } #endregion } My concern, however, is that if the Enumerator is not Disposed, the lock will never be released. In most use cases, this is not a problem, as foreach should properly call Dispose. It could be a problem, however, if a consumer retrieves an explicit Enumerator instance. Is my only option to document the class with a caveat implementer reminding the consumer to call Dispose if using the Enumerator explicitly or is there a way to safely release the lock during finalization? I'm thinking not, since the finalizer doesn't even run on the same thread, but I was curious if there other ways to improve this. EDIT After thinking about this a bit and reading the responses (particular thanks to Hans), I've decided this is definitely a bad idea. The biggest issue actually isn't forgetting to Dispose, but rather a leisurely consumer creating deadlock while enumerating. I now only read-lock long enough to get a copy and return the enumerator for the copy.

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• CodeDom : compile partial class

  - by James

  I'm attempting to compile code in a text file to change a value in a TextBox on the main form of a WinForms application. Ie. add another partial class with method to the calling form. The form has one button (button1) and one TextBox (textBox1). The code in the text file is: this.textBox1.Text = "Hello World!!"; And the code: namespace WinFormCodeCompile { public partial class Form1 : Form { public Form1() { InitializeComponent(); } private void button1_Click(object sender, EventArgs e) { // Load code from file StreamReader sReader = new StreamReader(@"Code.txt"); string input = sReader.ReadToEnd(); sReader.Close(); // Code literal string code = @"using System; using System.Windows.Forms; namespace WinFormCodeCompile { public partial class Form1 : Form { public void UpdateText() {" + input + @" } } }"; // Compile code CSharpCodeProvider cProv = new CSharpCodeProvider(); CompilerParameters cParams = new CompilerParameters(); cParams.ReferencedAssemblies.Add("mscorlib.dll"); cParams.ReferencedAssemblies.Add("System.dll"); cParams.ReferencedAssemblies.Add("System.Windows.Forms.dll"); cParams.GenerateExecutable = false; cParams.GenerateInMemory = true; CompilerResults cResults = cProv.CompileAssemblyFromSource(cParams, code); // Check for errors if (cResults.Errors.Count != 0) { foreach (var er in cResults.Errors) { MessageBox.Show(er.ToString()); } } else { // Attempt to execute method. object obj = cResults.CompiledAssembly.CreateInstance("WinFormCodeCompile.Form1"); Type t = obj.GetType(); t.InvokeMember("UpdateText", BindingFlags.InvokeMethod, null, obj, null); } } } } When I compile the code, the CompilerResults returns an error that says WinFormCodeCompile.Form1 does not contain a definition for textBox1. Is there a way to dynamically create another partial class file to the calling assembly and execute that code? I assume I'm missing something really simple here.

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• How to manually add a legend to a ggplot object

  - by Dan

  I have this data frame: structure(list(month_num = 1:24, founded_month = c(4L, 5L, 6L, 7L, 8L, 9L, 10L, 11L, 12L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 10L, 11L, 12L, 1L, 2L, 3L), founded_year = c(2008L, 2008L, 2008L, 2008L, 2008L, 2008L, 2008L, 2008L, 2008L, 2009L, 2009L, 2009L, 2009L, 2009L, 2009L, 2009L, 2009L, 2009L, 2009L, 2009L, 2009L, 2010L, 2010L, 2010L), count = c(270L, 222L, 256L, 250L, 277L, 268L, 246L, 214L, 167L, 408L, 201L, 225L, 203L, 220L, 230L, 225L, 177L, 207L, 166L, 135L, 116L, 122L, 69L, 42L), month_abb = c("Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec", "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec", "Jan", "Feb", "Mar"), short_year = c("08", "08", "08", "08", "08", "08", "08", "08", "08", "09", "09", "09", "09", "09", "09", "09", "09", "09", "09", "09", "09", "10", "10", "10" ), proj = c(282, 246, 292, 298, 337, 340, 330, 310, 275, 528, 333, 369, 359, 388, 410, 417, 381, 423, 394, 375, 368, 386, 345, 330), label = c("Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec", "Jan\n09", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec", "Jan\n10", "Feb", "Mar")), .Names = c("month_num", "founded_month", "founded_year", "count", "month_abb", "short_year", "proj", "label"), row.names = c(NA, -24L), class = "data.frame") and i've got all of this done (I know the code's a bit ugly looking, pointers appreciated): p <- ggplot(m_summary2, aes(x = month_num, y = count)) p + geom_line(colour = rgb(0/255, 172/255, 0/255)) + geom_point(colour = rgb(0/255, 172/255, 0/255)) + geom_line(aes(x = m_summary2$month_num, y = m_summary2$proj), colour = rgb(18/255, 111/255, 150/255)) + geom_point(aes(x = m_summary2$month_num, y = m_summary2$proj), colour = rgb(18/255, 111/255, 150/255)) + scale_x_continuous("Month", breaks = m_summary2$month_num, labels = m_summary2$label) + scale_y_continuous("# Startups Founded") + opts(title = paste("# Startups Founded:", m_summary2$month_abb[1], m_summary2$short_year[1], "-", m_summary2$month_abb[nrow(m_summary2)], m_summary2$short_year[nrow(m_summary2)])) Now I would like to add a legend to clarify that the blue line is a projection and the green line is the current data. Thanks in advance!

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• I am getting an error when trying to use melt() on a dataframe containing Dates

  - by Dan

  I'd like to melt the dataframe so that in one column i have dates in a second i have username as the variable and finally the value. I'm getting this error: Error in as.Date.numeric(value) : 'origin' must be supplied and while I understand the error I'm not exactly sure how to get around it. A small sample of the data is: structure(list(created_at = structure(c(14007, 14008, 14009, 14010, 14011, 14012), class = "Date"), benjamin = c(16, 0, 0, 0, 0, 0), byron = c(0, 0, 0, 0, 0, 0), cameronc = c(0, 0, 0, 0, 0, 0), daniel = c(0, 0, 0, 0, 0, 0), djdiaz = c(0, 0, 0, 0, 0, 0), gene = c(16, 77, 64, 38, 72, 36), joel = c(0, 0, 0, 0, 0, 2), kerem = c(0, 0, 0, 0, 0, 0), sophia = c(0, 0, 0, 0, 0, 0), SuperMoonMan = c(0, 0, 0, 0, 0, 0)), .Names = c("created_at", "benjamin", "byron", "cameronc", "daniel", "djdiaz", "gene", "joel", "kerem", "sophia", "SuperMoonMan"), row.names = c(NA, 6L), class = c("cast_df", "data.frame")) Thanks for your help.

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• Getting Cabal to work with GHC 6.12.1

  - by Dan Dyer

  I've installed the latest GHC package (6.12.1) on OS X, but I can't get Cabal to work. I've removed the version I had previously that worked with GHC 6.10 and tried to re-install from scratch. The latest Cabal version available for download is 1.6.0.2. However, when I try to build this I get the following error: Configuring Cabal-1.6.0.2... Setup: failed to parse output of 'ghc-pkg dump' From what I've found searching, this seems to suggest that the version of Cabal is too old for the version of GHC. Is there any way to get Cabal to work with GHC 6.12.1 yet? EDIT: To be clear, I'm trying to set-up cabal-install.

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• stack.ToList() in .NET - order of elements?

  - by James M.

  When using the .ToList() extension method on a Stack<T>, is the result the same as popping each element and adding to a new list (reverse of what was pushed)? If so, is this because it really is iterating over each element, or does it store the elements in reverse internally and slip the array into a new List<T>?

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• Limit search results based on publication dates in the Google AJAX Search API

  - by James

  Is it possible to limit the search results in a news or blog search using the Google AJAX Search API by the publication date of the story or post? I'm aware it's possible to sort the results by date but is it possible to limit the date to a period in time, say between the 10th and 15th of Jan 09?

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• The quick hack you are most proud of

  - by James Newton-King

  What crazily awesome (or crazily bad) stuff have you hacked together to meet a tight deadline? What are you most proud of?

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• JVM segmentation faults due to "Invalid memory access of location"

  - by Dan

  I have a small project written in Scala 2.9.2 with unit tests written using ScalaTest. I use SBT for compiling and running my tests. Running sbt test on my project makes the JVM segfault regularly, but just compiling and running my project from SBT works fine. Here is the exact error message: Invalid memory access of location 0x8 rip=0x10959f3c9 [1] 11925 segmentation fault sbt I cannot locate a core dump anywhere, but would be happy to provide it if it can be obtained. Running java -version results in this: java version "1.6.0_37" Java(TM) SE Runtime Environment (build 1.6.0_37-b06-434-11M3909) Java HotSpot(TM) 64-Bit Server VM (build 20.12-b01-434, mixed mode) But I've also got Java 7 installed (though I was never able to actually run a Java program with it, afaik). Another issue that may be related: some of my test cases contain titles including parentheses like ( and ). SBT or ScalaTest (not sure) will consequently insert square parens in the middle of the output. For example, a test case with the name (..)..(..) might suddenly look like (..[)..](..). Any help resolving these issues is much appreciated :-) EDIT: I installed the Java 7 JDK, so now java -version shows the right thing: java version "1.7.0_07" Java(TM) SE Runtime Environment (build 1.7.0_07-b10) Java HotSpot(TM) 64-Bit Server VM (build 23.3-b01, mixed mode) This also means that I now get a more detailed segfault error and a core dump: # # A fatal error has been detected by the Java Runtime Environment: # # SIGSEGV (0xb) at pc=0x000000010a71a3e3, pid=16830, tid=19459 # # JRE version: 7.0_07-b10 # Java VM: Java HotSpot(TM) 64-Bit Server VM (23.3-b01 mixed mode bsd-amd64 compressed oops) # Problematic frame: # V [libjvm.dylib+0x3cd3e3] And the dump.

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• Decoding a compressed short string; uncertain on compression used - Updated

  - by James

  Hi, I have a program that is compressing a string in an unknown way. I know a few inputs and the output produced, but I am not sure what is being used to compress the string. Here are my examples. (just 38 x a, no spaces or anything else) In: "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa" Out: "026900211AA63000026900"   (just 32 x a) In: "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa" Out: "0209001c1aa7a000020900" (31 x a, then 1 b) In: "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaab" Out: "0209000177c553c000020900" (31 x b, then 1 a) In: "bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbba" Out: "0209001e7754f38000020900" In: "Hey wot u doing 2day u wanna do something" Out: "02990011C7C62E78CE6B8E3ACD83E81B37C5C5A6B9D1E1B06963DB5E71155C1000029900" (same as previous string, but with a space at the end) In: "Hey wot u doing 2day u wanna do something " Out: "02A90012C7718B9E339AE2EB360FA02CDF17177A674786DF4B1EDAF388AAE08000000002A90000" The only definite thing I can see so far is digit 2 and 3 are the amount of characters (hex value), ie first one is 26 = 38 Also the first 6 digits are repeated at the end Any help / advice would be great, thanks!

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• How do you redirect in ColdFusion and control the status code (i.e. 301 instead of a 302)

  - by James Lawruk

  This code does a redirect, but uses a 302 status code: <cflocation url="http://stackoverflow.com" addToken="no" /> I found this on the Internet, but I think it only works in ColdFusion8. I am using ColdFusion7. <cflocation url="http://stackoverflow.com" addToken="no" statuscode="301" /> Hoe do you control the status code in ColdFusion7?

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• How do I resize a Google Map with JavaScript after it has loaded?

  - by Matthew James Taylor

  I have a 'mapwrap' div set to 400px x 400px and inside that I have a Google 'map' set to 100% x 100%. So the map loads at 400 x 400px, then with JavaScript I resize the 'mapwrap' to 100% x 100% of the screen - the google map resizes to the whole screen as I expected but tiles start disappearing before the right hand edge of the page. Is there a simple function I can call to cause the Google map to re-adjust to the larger size 'mapwrap' div?

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• What is CDbl doing?

  - by Dan Tao

  I had until recently been under the impression that the CDbl(x) operation in VB.NET was essentially a cast (i.e., the VB equivalent of (double)x in C#); but a recent discovery has revealed that this is not the case. If I have this string: Dim s As String = "12345.12345-" And I do this: Dim d As Double = CDbl(s) d will be set to the value -12345.12345! Now, don't get me wrong, this is kind of convenient in my particular scenario; but I have to admit I'm confused as to why this works. In particular, I'm confused because: Double.Parse does not work with the above input. Double.TryParse does not work. Convert.ToDouble does not work. How is CDbl so clever?

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• F# passing an operator with arguments to a function

  - by dan

  Can you pass in an operation like "divide by 2" or "subtract 1" using just a partially applied operator, where "add 1" looks like this: List.map ((+) 1) [1..5];; //equals [2..6] // instead of having to write: List.map (fun x-> x+1) [1..5] What's happening is 1 is being applied to (+) as it's first argument, and the list item is being applied as the second argument. For addition and multiplication, this argument ordering doesn't matter. Suppose I want to subtract 1 from every element (this will probably be a common beginners mistake): List.map ((-) 1) [1..5];; //equals [0 .. -4], the opposite of what we wanted 1 is applied to the (-) as its first argument, so instead of (list_item - 1), I get (1 - list_item). I can rewrite it as adding negative one instead of subtracting positive one: List.map ((+) -1) [1..5];; List.map (fun x -> x-1) [1..5];; // this works too I'm looking for a more expressive way to write it, something like ((-) _ 1), where _ denotes a placeholder, like in the Arc language. This would cause 1 to be the second argument to -, so in List.map, it would evaluate to list_item - 1. So if you wanted to map divide by 2 to the list, you could write: List.map ((/) _ 2) [2;4;6] //not real syntax, but would equal [1;2;3] List.map (fun x -> x/2) [2;4;6] //real syntax equivalent of the above Can this be done or do I have to use (fun x -> x/2)? It seems that the closest we can get to the placeholder syntax is to use a lambda with a named argument.

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