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Mixing .NET versions between website and virtual directories and the "server application unavailable" error Message

- by Doug Chamberlain

Backstory Last month our development team created a new asp.net 3.5 application to place out on our production website. Once we had the work completed, we requested from the group that manages are server to copy the app out to our production site, and configure the virtual directory as a new application. On 12/27/2010, two public 'Gineau Pigs' were selected to use the app, and it worked great. On 12/30/2010, We received notification by internal staff, that when that staff member tried to access the application (this was the Business Process Owner) they recieved the 'Server Application Unavailable' message. When I called the group that does our server support, I was told that it probably failed, because I didn't close the connections in my code. However, the same group went in and then created a separate app pool for this Extension Request application. It has had no issues since. I did a little googling, since I do not like being blamed for things. I found that the 'Server Application Unavailable' message will also appear when you have multiple applications using different frameworks and you do not put them in different application pools. Technical Details - Tree of our website structure Main Website <-- ASP Classic +-Virtual Directory(ExtensionRequest) <-- ASP 3.5 From our server support group: 'Reviewed server logs and website setup in IIS. Had to reset the application pool as it was not working properly. This corrected the website and it is now back online. We went ahead and created a application pool for the extension web so it is isolated from the main site pool. In the past we have seen other application do this when there is a connection being left open and the pool fills up. Would recommend reviewing site code to make sure no connections are being left open.' The Real Question: What really caused the failure? Isn't the connection being left open issue an ASP Classic issue? Wouldn't the ExtensionRequest application have to be used (more than twice) in the first place to have the connections left open? Is it more likely the failure is caused by them not bothering to setup the new Application in it's own App Pool in the first place? Sorry for the long windedness

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XML and XSD - use element name as replacement of xsi:type for polymorphism

- by disown

Taking the W3C vehicle XSD as an example: <schema xmlns="http://www.w3.org/2001/XMLSchema" targetNamespace="http://cars.example.com/schema" xmlns:target="http://cars.example.com/schema"> <complexType name="Vehicle" abstract="true"/> <complexType name="Car"> <complexContent> <extension base="target:Vehicle"/> ... </complexContent> </complexType> <complexType name="Plane"> <complexContent> <extension base="target:Vehicle"/> <sequence> <element name="wingspan" type="integer"/> </sequence> </complexContent> </complexType> </schema> , and the following definition of 'meansOfTravel': <complexType name="MeansOfTravel"> <complexContent> <sequence> <element name="transport" type="target:Vehicle"/> </sequence> </complexContent> </complexType> <element name="meansOfTravel" type="target:MeansOfTravel"/> With this definition you need to specify the type of your instance using xsi:type, like this: <meansOfTravel> <transport xsi:type="Plane"> <wingspan>3</wingspan> </transport> </meansOfTravel> I would just like to acheive a 'name of type' - 'name of element' mapping so that this could be replaced with just <meansOfTravel> <plane> <wingspan>3</wingspan> </plane> </meansOfTravel> The only way I could do this until now is by making it explicit: <complexType name="MeansOfTravel"> <sequence> <choice> <element name="plane" type="target:Plane"/> <element name="car" type="target:Car"/> </choice> </sequence> </complexType> <element name="meansOfTravel" type="target:MeansOfTravel"/> But this means that I have to list all possible sub-types in the 'MeansOfTravel' complex type. Is there no way of making the XML parser assume that you mean a 'Plane' if you call the element 'plane'? Or do I have to make the choice explicit? I would just like to keep my design DRY - if you have any other suggestions (like groups or so) - i would love to hear them.

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Primary language - C++/Qt, C#, Java?

- by Airjoe

I'm looking for some input, but let me start with a bit of background (for tl;dr skip to end). I'm an IT major with a concentration in networking. While I'm not a CS major nor do I want to program as a vocation, I do consider myself a programmer and do pretty well with the concepts involved. I've been programming since about 6th grade, started out with a proprietary game creation language that made my transition into C++ at college pretty easy. I like to make programs for myself and friends, and have been paid to program for local businesses. A bit about that- I wrote some programs for a couple local businesses in my senior year in high school. I wrote management systems for local shops (inventory, phone/pos orders, timeclock, customer info, and more stuff I can't remember). It definitely turned out to be over my head, as I had never had any formal programming education. It was a great learning experience, but damn was it crappy code. Oh yeah, by the way, it was all vb6. So, I've used vb6 pretty extensively, I've used c++ in my classes (intro to programming up to algorithms), used Java a little bit in another class (had to write a ping client program, pretty easy) and used Java for some simple Project Euler problems to help learn syntax and such when writing the program for the class. I've also used C# a bit for my own simple personal projects (simple programs, one which would just generate an HTTP request on a list of websites and notify if one responded unexpectedly or not at all, and another which just held a list of things to do and periodically reminded me to do them), things I would've written in vb6 a year or two ago. I've just started using Qt C++ for some undergrad research I'm working on. Now I've had some formal education, I [think I] understand organization in programming a lot better (I didn't even use classes in my vb6 programs where I really should have), how it's important to structure code, split into functions where appropriate, document properly, efficiency both in memory and speed, dynamic and modular programming etc. I was looking for some input on which language to pick up as my "primary". As I'm not a "real programmer", it will be mostly hobby projects, but will include some 'real' projects I'm sure. From my perspective: QtC++ and Java are cross platform, which is cool. Java and C# run in a virtual machine, but I'm not sure if that's a big deal (something extra to distribute, possibly a bit slower? I think Qt would require additional distributables too, right?). I don't really know too much more than this, so I appreciate any help, thanks! TL;DR Am an avocational programmer looking for a language, want quick and straight forward development, liked vb6, will be working with database driven GUI apps- should I go with QtC++, Java, C#, or perhaps something else?

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Java DriverManager Always Assigns My Driver

- by JGB146

I am writing a driver to act as a wrapper around two separate MySQL connections (to distributed databases). Basically, the goal is to enable interaction with my driver for all applications instead of requiring the application to sort out which database holds the desired data. Most of the code for this is in place, but I'm having a problem in that when I attempt to create connections via the MySQL Driver, the DriverManager is returning an instance of my driver instead of the MySQL Driver. I'd appreciate any tips on what could be causing this and what could be done to fix it! Below is a few relevant snippets of code. I can provide more, but there's a lot, so I'd need to know what else you want to see. First, from MyDriver.java: public MyDriver() throws SQLException { DriverManager.registerDriver(this); } public Connection connect(String url, Properties info) throws SQLException { try { return new MyConnection(info); } catch (Exception e) { return null; } } public boolean acceptsURL(String url) throws SQLException { if (url.contains("jdbc:jgb://")) { return true; } return false; } It is my understanding that this acceptsURL function will dictate whether or not the DriverManager deems my driver a suitable fit for a given URL. Hence it should only be passing connections from my driver if the URL contains "jdbc:jgb://" right? Here's code from MyConnection.java: Connection c1 = null; Connection c2 = null; /** *Constructors */ public DDBSConnection (Properties info) throws SQLException, Exception { info.list(System.out); //included for testing Class.forName("com.mysql.jdbc.Driver").newInstance(); String url1 = "jdbc:mysql://server1.com/jgb"; String url2 = "jdbc:mysql://server2.com/jgb"; this.c1 = DriverManager.getConnection( url1, info.getProperty("username"), info.getProperty("password")); this.c2 = DriverManager.getConnection( url2, info.getProperty("username"), info.getProperty("password")); } And this tells me two things. First, the info.list() call confirms that the correct user and password are being sent. Second, because we enter an infinite loop, we see that the DriverManager is providing new instances of my connection as matches for the mysql URLs instead of the desired mysql driver/connection. FWIW, I have separately tested implementations that go straight to the mysql driver using this exact syntax (al beit only one at a time), and was able to successfully interact with each database individually from a test application outside of my driver.

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Programmatically created GridView cells don't scale to fit screen

- by ChrisAshton84

I've read a ton of other responses about GridView already but almost all deal with the XML format (which I had working). I wanted to learn the programmatic way of designing Android, though, so I'm trying to build most of this app without XML. All I define in XML are the GridView and the first TextView. After that I add the other LinearLayouts in onCreate(). I would like to have a 2 column GridView containing a title and several (4 for now) LinearLayouts. I realize from documentation that the GridView won't scale cells unless they have a gravity set, but no matter how I try to do this I can't get it to work. After adding two cells, my GridView tree would look like: GridView -> TextView (colspan 2) -> LinearLayout (Vertical) -> TextView -> LinearLayout (Horizontal) -> TextView -> TextView -> LinearLayout (Horizontal) -> TextView -> TextView -> LinearLayout (Vertical) -> TextView -> LinearLayout (Horizontal) -> TextView -> TextView -> LinearLayout (Horizontal) -> TextView -> TextView I've tried about every combination of FILL and FILL_HORIZONTAL I could think of on either the outermost LinearLayouts, or also trying on the TextViews and inner LinearLayouts. No matter what I do, the LinearLayouts I add are always sized as small as possible and pushed to the left of the screen. Meanwhile, the first TextView (the colspan 2 one) with only CENTER_HORIZONTAL set is correctly centered in the screen. Its as if that TextView gets one idea of the column widths and the LinearLayouts get another! (If I add the FILL Gravity for it, it also moves all the way left.) I believe I had this working accidentally with 100% XML, but I would prefer not to switch back unless this is known to not work programatically. Any ideas what I can try to get this working?

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MediaElement not showing in custom 3D class

- by user3271180

I'm trying to display a videostream in a Viewport3d. When I add the MediaElement via xaml, the video plays without a problem; even when I add the video as ModelVisual3D in the code-behind, the video works. When I abstract the video into a class, however, the video stops appearing. This happens with both web and local video files. I tried compiling with both x86 and 64 bit. Any way to fix this behaviour? Why is this happening? I have the following viewport: <Viewport3D>  <Viewport3D.Camera> <PerspectiveCamera Position="0,0,100" LookDirection="0,0,-1" UpDirection="0,1,0" /> </Viewport3D.Camera>  <ModelVisual3D> <ModelVisual3D.Content> <AmbientLight Color="White" /> </ModelVisual3D.Content> </ModelVisual3D>  <mediaElementTest:VideoControl />   </Viewport3D> VideoControl.xaml <UIElement3D x:Class="MediaElementTest.VideoControl" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"/> VideoControl.xaml.cs public partial class VideoControl { public VideoControl() { InitializeComponent(); Visual3DModel = CreateModel(); } private GeometryModel3D CreateModel() { return new GeometryModel3D { Geometry = new MeshGeometry3D { Positions = new Point3DCollection { new Point3D(-100, -100, 0), new Point3D(100, -100, 0), new Point3D(100, 100, 0), new Point3D(-100, 100, 0) }, TextureCoordinates = new PointCollection { new Point(0, 1), new Point(1, 1), new Point(1, 0), new Point(0, 0) }, TriangleIndices = new Int32Collection { 0, 1, 2, 0, 2, 3 } }, Material = new DiffuseMaterial(new VisualBrush(new MediaElement { Source = new Uri("http://www.quirksmode.org/html5/videos/big_buck_bunny.mp4", UriKind.RelativeOrAbsolute) })) }; } }

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When saving a model with has_one or has_many associations, which side of the association is saved fi

- by SeeBees

I have three simplified models: class Team < ActiveRecord::Base has_many :players has_one :coach end class Player < ActiveRecord::Base belongs_to :team validates_presence_of :team_id end class Coach < ActiveRecord::Base belongs_to :team validates_presence_of :team_id end I use the following code to test these models: t = Team.new team.coach = Coach.new team.save! team.save! returns true. But in another test: t = Team.new team.players << Player.new team.save! team.save! gives the following error: > ActiveRecord::RecordInvalid: > Validation failed: Players is invalid > from > /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/validations.rb:1090:in > `save_without_dirty!' from > /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/dirty.rb:87:in `save_without_transactions!' from > /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/transactions.rb:200:in > `save!' from > /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/connection_adapters/abstract/database_statements.rb:136:in > `transaction' from > /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/transactions.rb:182:in > `transaction' from > /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/transactions.rb:200:in > `save!' from > /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/transactions.rb:208:in > `rollback_active_record_state!' from > /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/transactions.rb:200:in > `save!' from (irb):14 I figured out that when team.save! is called, it first calls player.save!. player needs to validate the presence of the id of the associated team. But at the time player.save! is called, team hasn't been saved yet, and therefore, team_id doesn't yet exist for player. This fails the player's validation, so the error occurs. But on the other hand, team is saved before coach.save!, otherwise the first example will get the same error as the second one. So I've concluded that when a has_many bs, a.save! will save bs prior to a. When a has_one b, a.save! will save a prior to b. If I am right, why is this the case? It doesn't seem logical to me. Why do has_one and has_many association have different order in saving? Any ideas? And is there any way I can change the order? Say I want to have the same saving order for both has_one and has_many. Thanks.

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PHP Parse Error unexpected '{'

- by Laxmidi

Hi, I'm getting a "Parse error: syntax error, unexpected '{' in line 2". And I don't see the problem. <?php class pointLocation { var $pointOnVertex = true; // Check if the point sits exactly on one of the vertices function pointLocation() { } function pointInPolygon($point, $polygon, $pointOnVertex = true) { $this->pointOnVertex = $pointOnVertex; // Transform string coordinates into arrays with x and y values $point = $this->pointStringToCoordinates($point); $vertices = array(); foreach ($polygon as $vertex) { $vertices[] = $this->pointStringToCoordinates($vertex); } // Check if the point sits exactly on a vertex if ($this->pointOnVertex == true and $this->pointOnVertex($point, $vertices) == true) { return "vertex"; } // Check if the point is inside the polygon or on the boundary $intersections = 0; $vertices_count = count($vertices); for ($i=1; $i < $vertices_count; $i++) { $vertex1 = $vertices[$i-1]; $vertex2 = $vertices[$i]; if ($vertex1['y'] == $vertex2['y'] and $vertex1['y'] == $point['y'] and $point['x'] > min($vertex1['x'], $vertex2['x']) and $point['x'] < max($vertex1['x'], $vertex2['x'])) { // Check if point is on an horizontal polygon boundary return "boundary"; } if ($point['y'] > min($vertex1['y'], $vertex2['y']) and $point['y'] <= max($vertex1['y'], $vertex2['y']) and $point['x'] <= max($vertex1['x'], $vertex2['x']) and $vertex1['y'] != $vertex2['y']) { $xinters = ($point['y'] - $vertex1['y']) * ($vertex2['x'] - $vertex1['x']) / ($vertex2['y'] - $vertex1['y']) + $vertex1['x']; if ($xinters == $point['x']) { // Check if point is on the polygon boundary (other than horizontal) return "boundary"; } if ($vertex1['x'] == $vertex2['x'] || $point['x'] <= $xinters) { $intersections++; } } } // If the number of edges we passed through is even, then it's in the polygon. if ($intersections % 2 != 0) { return "inside"; } else { return "outside"; } } function pointOnVertex($point, $vertices) { foreach($vertices as $vertex) { if ($point == $vertex) { return true; } } } function pointStringToCoordinates($pointString) { $coordinates = explode(" ", $pointString); return array("x" => $coordinates[0], "y" => $coordinates[1]); } } $pointLocation = new pointLocation(); $points = array("30 19", "0 0", "10 0", "30 20", "11 0", "0 11", "0 10", "30 22", "20 20"); $polygon = array("10 0", "20 0", "30 10", "30 20", "20 30", "10 30", "0 20", "0 10", "10 0"); foreach($points as $key => $point) { echo "$key ($point) is " . $pointLocation->pointInPolygon($point, $polygon) . "<br>"; } ?> Does anyone see the problem? Thanks, -Laxmidi

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how to use window.onload?

- by Patrick

I'm refactoring a website using MVC. What was a set of huge pages with javascript, php, html etc etc is becoming a series of controllers and views. I'm trying to do it in a modular way so views are split in 'modules' that I can reuse in other pages when needed eg. "view/searchform displays only one div with the searchform "view/display_events displays a list of events and so on. One of the old pages was supposed to load a google map with a marker on it. Amongst the rest of the code, I can identify the relevant bits as follows <head> <script src="http://maps.google.com/maps?file=api&v=2&key=blablabla" type="text/javascript"></script> <script type="text/javascript"> //<![CDATA[ function load() { if (GBrowserIsCompatible()) { var map = new GMap2(document.getElementById("map")); var point = new GLatLng(<?php echo ($info->lat && $info->lng) ? $info->lat .",". $info->lng : "51.502759,-0.126171"; ?>); map.setCenter(new GLatLng(<?php echo ($info->lat && $info->lng) ? $info->lat .",". $info->lng : "51.502759,-0.126171"; ?>), 15); map.addControl(new GLargeMapControl()); map.addControl(new GScaleControl()); map.addOverlay(new GMarker(point)); var marker = createMarker(point,GIcon(),"CIAO"); map.addOverlay(marker); } } //]]> </script> </head> ...then <body onload="load()" onunload="GUnload()"> ...and finally this div where the map should be displayed <div id="map" style="width: 440px; height: 300px"> </div> Don't know much about js, but my understanding is that a) I have to include the scripts in the view module I'm writing (directly in the HTML? I would prefer to load a separate script) b) I have to trigger that function using the equivalent of body onload... (obviously there's no body tag in my view. In my ignorance I've tried div onload=.... but didn't seem to be working :) What do you suggest I do? I've read about window.onload but don't know what's the correct syntax for that. please keep in mind that other parts of the page include other js functions (eg, google adsense) that are called after the footer.

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How to unit test synchronized code

- by gillJ

Hi, I am new to Java and junit. I have the following peice of code that I want to test. Would appreciate if you could send your ideas about what's the best way to go about testing it. Basically, the following code is about electing a leader form a Cluster. The leader holds a lock on the shared cache and services of the leader get resumed and disposed if it somehow looses the lock on the cache. How can i make sure that a leader/thread still holds the lock on the cache and that another thread cannot get its services resumed while the first is in execution? public interface ContinuousService { public void resume(); public void pause(); } public abstract class ClusterServiceManager { private volatile boolean leader = false; private volatile boolean electable = true; private List<ContinuousService> services; protected synchronized void onElected() { if (!leader) { for (ContinuousService service : services) { service.resume(); } leader = true; } } protected synchronized void onDeposed() { if (leader) { for (ContinuousService service : services) { service.pause(); } leader = false; } } public void setServices(List<ContinuousService> services) { this.services = services; } @ManagedAttribute public boolean isElectable() { return electable; } @ManagedAttribute public boolean isLeader() { return leader; } public class TangosolLeaderElector extends ClusterServiceManager implements Runnable { private static final Logger log = LoggerFactory.getLogger(TangosolLeaderElector.class); private String election; private long electionWaitTime= 5000L; private NamedCache cache; public void start() { log.info("Starting LeaderElector ({})",election); Thread t = new Thread(this, "LeaderElector ("+election+")"); t.setDaemon(true); t.start(); } public void run() { // Give the connection a chance to start itself up try { Thread.sleep(1000); } catch (InterruptedException e) {} boolean wasElectable = !isElectable(); while (true) { if (isElectable()) { if (!wasElectable) { log.info("Leadership requested on election: {}",election); wasElectable = isElectable(); } boolean elected = false; try { // Try and get the lock on the LeaderElectorCache for the current election if (!cache.lock(election, electionWaitTime)) { // We didn't get the lock. cycle round again. // This code to ensure we check the electable flag every now & then continue; } elected = true; log.info("Leadership taken on election: {}",election); onElected(); // Wait here until the services fail in some way. while (true) { try { Thread.sleep(electionWaitTime); } catch (InterruptedException e) {} if (!cache.lock(election, 0)) { log.warn("Cache lock no longer held for election: {}", election); break; } else if (!isElectable()) { log.warn("Node is no longer electable for election: {}", election); break; } // We're fine - loop round and go back to sleep. } } catch (Exception e) { if (log.isErrorEnabled()) { log.error("Leadership election " + election + " failed (try bfmq logs for details)", e); } } finally { if (elected) { cache.unlock(election); log.info("Leadership resigned on election: {}",election); onDeposed(); } // On deposition, do not try and get re-elected for at least the standard wait time. try { Thread.sleep(electionWaitTime); } catch (InterruptedException e) {} } } else { // Not electable - wait a bit and check again. if (wasElectable) { log.info("Leadership NOT requested on election ({}) - node not electable",election); wasElectable = isElectable(); } try { Thread.sleep(electionWaitTime); } catch (InterruptedException e) {} } } } public void setElection(String election) { this.election = election; } @ManagedAttribute public String getElection() { return election; } public void setNamedCache(NamedCache nc) { this.cache = nc; }

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How can I create a Searchstring for a Google AJAX Search API?

- by elmaso

Hello, i have this code to get the search resutls from the api: querygoogle.php: <?php session_start(); // Here's the Google AJAX Search API url for curl. It uses Google Search's site:www.yourdomain.com syntax to search in a specific site. I used $_SERVER['HTTP_HOST'] to find my domain automatically. Change $_POST['searchquery'] to your posted search query $url = 'http://ajax.googleapis.com/ajax/services/search/web?rsz=large&v=1.0&start=20&q=' . urlencode('' . $_POST['searchquery']); // use fopen and fread to pull Google's search results $handle = fopen($url, 'rb'); $body = ''; while (!feof($handle)) { $body .= fread($handle, 8192); } fclose($handle); // now $body is the JSON encoded results. We need to decode them. $json = json_decode($body); // now $json is an object of Google's search results and we need to iterate through it. foreach($json->responseData->results as $searchresult) { if($searchresult->GsearchResultClass == 'GwebSearch') { $formattedresults .= ' <div class="searchresult"> <h3><a href="' . $searchresult->unescapedUrl . '">' . $searchresult->titleNoFormatting . '</a></h3> <p class="resultdesc">' . $searchresult->content . '</p> <p class="resulturl">' . $searchresult->visibleUrl . '</p> </div>'; } } $_SESSION['googleresults'] = $formattedresults; header('Location: ' . $_SERVER['HTTP_REFERER']); exit; ?> search.php <?php session_start(); ?> <form method="post" action="querygoogle.php"> <label for="searchquery"><span class="caption">Search this site</span> <input type="text" size="20" maxlength="255" title="Enter your keywords and click the search button" name="searchquery" /></label> <input type="submit" value="Search" /> </form> <?php if(!empty($_SESSION['googleresults'])) { echo $_SESSION['googleresults']; unset($_SESSION['googleresults']); } ?> but with this code, I cant add a searchstring.. how can i add a search string like search.php?search=keyword ? thanks

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Urgent help needed on How to update NSMutableDictionary. My code doesn't work.

- by dawatson833

I've populated an array using. arrSettings = [[NSMutableArray alloc] initWithContentsOfFile:[self settingsPath]]; The file is a plist with the root as an array and then a dictionary with three three keys defined as number. I've also tried setting the keys to string. I display the values in the plist file on a view using. diaper = [[arrSettings objectAtIndex:0] objectForKey:@"Diaper Expenses"]; oil = [[arrSettings objectAtIndex:0] objectForKey:@"Oil Used"]; tree = [[arrSettings objectAtIndex:0] objectForKey:@"Wood Used"]; This code works fine, the values in the dictionary are assigned to the variables and they are displayed. The user can make changes and then press a save button. I use this code to extract the dictionary part of the array so I can update it. The assignment to editDictionary works. I've double checked the key names including case and that is correct. editDictionary = [[NSMutableDictionary alloc] init]; editDictionary = [arrSettings objectAtIndex:0]; NSNumber *myNumber = [NSNumber numberWithFloat:diaperAmount]; [editDictionary setValue:myNumber forKey:@"Diaper Expenses"]; myNumber = [NSNumber numberWithFloat:oilAmount]; [editDictionary setValue:myNumber forKey:@"Oil Used"]; myNumber = [NSNumber numberWithFloat:treeAmount]; [editDictionary setValue:myNumber forKey:@"Wood Used"]; In this example I've used a nsnumber. But I've also tried the xxxAmount field as part of SetValue instead of creating a NSNumber. Neither implementation works. Several strange things happen. Sometimes the first two setvalue statements work, but the last setvalue fails with a EXC_BAD_ACCESS failure. Other times the first setValue fails with the same error. I have no idea why the first two sometimes work. I'm at a loss of what to do next. I've tried several implentations and none of them work. Also, in the debugger how can I display the editDictionary elements. I can see editDictionary, but I don't know how to display the individual elements.

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Generating Unordered List with PHP + CodeIgniter from a MySQL Database

- by Tim

Hello Everyone, I am trying to build a dynamically generated unordered list in the following format using PHP. I am using CodeIgniter but it can just be normal php. This is the end output I need to achieve. <ul id="categories" class="menu"> <li rel="1"> Arts & Humanities <ul> <li rel="2"> Photography <ul> <li rel="3"> 3D </li> <li rel="4"> Digital </li> </ul> </li> <li rel="5"> History </li> <li rel="6"> Literature </li> </ul> </li> <li rel="7"> Business & Economy </li> <li rel="8"> Computers & Internet </li> <li rel="9"> Education </li> <li rel="11"> Entertainment <ul> <li rel="12"> Movies </li> <li rel="13"> TV Shows </li> <li rel="14"> Music </li> <li rel="15"> Humor </li> </ul> </li> <li rel="10"> Health </li> And here is my SQL that I have to work with. -- -- Table structure for table `categories` -- CREATE TABLE IF NOT EXISTS `categories` ( `id` mediumint(8) NOT NULL auto_increment, `dd_id` mediumint(8) NOT NULL, `parent_id` mediumint(8) NOT NULL, `cat_name` varchar(256) NOT NULL, `cat_order` smallint(4) NOT NULL, PRIMARY KEY (`id`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=1 ; So I know that I am going to need at least 1 foreach loop to generate the first level of categories. What I don't know is how to iterate inside each loop and check for parents and do that in a dynamic way so that there could be an endless tree of children. Thanks for any help you can offer. Tim

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How do I get around this lambda expression outer variable issue?

- by panamack

I'm playing with PropertyDescriptor and ICustomTypeDescriptor (still) trying to bind a WPF DataGrid to an object, for which the data is stored in a Dictionary. Since if you pass WPF DataGrid a list of Dictionary objects it will auto generate columns based on the public properties of a dictionary (Comparer, Count, Keys and Values) my Person subclasses Dictionary and implements ICustomTypeDescriptor. ICustomTypeDescriptor defines a GetProperties method which returns a PropertyDescriptorCollection. PropertyDescriptor is abstract so you have to subclass it, I figured I'd have a constructor that took Func and an Action parameters that delegate the getting and setting of the values in the dictionary. I then create a PersonPropertyDescriptor for each Key in the dictionary like this: foreach (string s in this.Keys) { var descriptor = new PersonPropertyDescriptor( s, new Func<object>(() => { return this[s]; }), new Action<object>(o => { this[s] = o; })); propList.Add(descriptor); } The problem is that each property get's its own Func and Action but they all share the outer variable s so although the DataGrid autogenerates columns for "ID","FirstName","LastName", "Age", "Gender" they all get and set against "Gender" which is the final resting value of s in the foreach loop. How can I ensure that each delegate uses the desired dictionary Key, i.e. the value of s at the time the Func/Action is instantiated? Much obliged. Here's the rest of my idea, I'm just experimenting here these are not 'real' classes... // DataGrid binds to a People instance public class People : List<Person> { public People() { this.Add(new Person()); } } public class Person : Dictionary<string, object>, ICustomTypeDescriptor { private static PropertyDescriptorCollection descriptors; public Person() { this["ID"] = "201203"; this["FirstName"] = "Bud"; this["LastName"] = "Tree"; this["Age"] = 99; this["Gender"] = "M"; } //... other ICustomTypeDescriptor members... public PropertyDescriptorCollection GetProperties() { if (descriptors == null) { var propList = new List<PropertyDescriptor>(); foreach (string s in this.Keys) { var descriptor = new PersonPropertyDescriptor( s, new Func<object>(() => { return this[s]; }), new Action<object>(o => { this[s] = o; })); propList.Add(descriptor); } descriptors = new PropertyDescriptorCollection(propList.ToArray()); } return descriptors; } //... other other ICustomTypeDescriptor members... } public class PersonPropertyDescriptor : PropertyDescriptor { private Func<object> getFunc; private Action<object> setAction; public PersonPropertyDescriptor(string name, Func<object> getFunc, Action<object> setAction) : base(name, null) { this.getFunc = getFunc; this.setAction = setAction; } // other ... PropertyDescriptor members... public override object GetValue(object component) { return getFunc(); } public override void SetValue(object component, object value) { setAction(value); } }

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Why oh why doesn't my asp.net treeview update?

- by Brendan

I'm using an ASP.net treeview on a page with a custom XmlDataSource. When the user clicks on a node of the tree, a detailsview pops up and edits a bunch of things about the underlying object. All this works properly, and the underlying object gets updated in my background object-management classes. Yay! However, my treeview just isn't updating the display. Either immediately (which i would like it to), or on full page re-load (which is the minimal useful level i need it to be at). Am i subclassing XmlDataSource poorly? I really don't know. Can anyone point me in a good direction? Thanks! The markup looks about like this (chaff removed): <data:DefinitionDataSource runat="server" ID="DefinitionTreeSource" RootDefinitionID="uri:1"></data:DefinitionDataSource> <asp:TreeView ID="TreeView" runat="server" DataSourceID="DefinitionTreeSource"> <DataBindings> <asp:TreeNodeBinding DataMember="definition" TextField="name" ValueField="id" /> </DataBindings> </asp:TreeView> <asp:DetailsView ID="DetailsView1" runat="server" AutoGenerateRows="False" DataKeyNames="Id" DataSourceID="DefinitionSource" DefaultMode="Edit"> <Fields> <asp:BoundField DataField="Name" HeaderText="Name" HeaderStyle-Wrap="false" SortExpression="Name" /> <asp:CommandField ShowCancelButton="False" ShowInsertButton="True" ShowEditButton="True" ButtonType="Button" /> </Fields> </asp:DetailsView> And the DefinitionTreeSource code looks like this: public class DefinitionDataSource : XmlDataSource { public string RootDefinitionID { get { if (ViewState["RootDefinitionID"] != null) return ViewState["RootDefinitionID"] as String; return null; } set { if (!Object.Equals(ViewState["RootDefinitionID"], value)) { ViewState["RootDefinitionID"] = value; DataBind(); } } } public DefinitionDataSource() { } public override void DataBind() { base.DataBind(); setData(); } private void setData() { String defXML = "<?xml version=\"1.0\" ?>"; Test.Management.TestManager.Definition root = Test.Management.TestManager.Definition.GetDefinitionById(RootDefinitionID); if (root != null) this.Data = defXML + root.ToXMLString(); else this.Data = defXML + "<definition id=\"null\" name=\"Set Root Node\" />"; } } }

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General workflow to allow multiple OpenIDs to be associated with one app account

- by BobTodd

I have a (typical?) scenario: that my app's users can use multiple openids mapped to one app account (like stackoverflow). For me the unique thing on the account is the email address, so this binds openids to the profile. Question is, how to allow a user to start using a second openid once one is setup. I am asking as I have read that it is a security hole to allow automatic account openid syncing simply based on the provider-supplied email address as someone could easily spoof someone's email address to create a spoof openid and falsely access the account (how I am not sure) - although this seems to be exactly how stack operates. See options a. and b. below. Problem for me with a. is what happens if the original openid no longer works for whatever reason - how would you set-up a new openid? Would b. be more acceptable if we used email verification? Does anyone have an article detailing a "standard" way (set of user stories) for this - it seems to be an increasingly popular way to authenticate. I have tried to detail this in a rough decision tree... 1. My Site > authentication landing page - user chooses an openid (facebook, google, myopenid etc), redirection > 2. Provider site returns with token (includes user registering a new openid, logging in or is already logged in to Provider site) 3. My Site > use token id to lookup user 3.1 Profile exists? Yes > authenticate. ends. No > 3.1.1 was email address supplied by provider? Yes > lookup user by email address 3.1.1.1 Profile exists? Yes > a. error message - please login with existing openid and associate this openid (from special page) Yes > b. or associate this openid with existing profile automatically. authenticate. ends. No > Register profile. With registration email address follow 3.1.1, except this time where email is unique, we will associate openid. ends

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C++ templated factory constructor/de-serialization

- by KRao

Hi, I was looking at the boost serialization library, and the intrusive way to provide support for serialization is to define a member function with signature (simplifying): class ToBeSerialized { public: //Define this to support serialization //Notice not virtual function! template<class Archive> void serialize(Archive & ar) {.....} }; Moreover, one way to support serilization of derived class trough base pointers is to use a macro of the type: //No mention to the base class(es) from which Derived_class inherits BOOST_CLASS_EXPORT_GUID(Derived_class, "derived_class") where Derived_class is some class which is inheriting from a base class, say Base_class. Thanks to this macro, it is possible to serialize classes of type Derived_class through pointers to Base_class correctly. The question is: I am used in C++ to write abstract factories implemented through a map from std::string to (pointer to) functions which return objects of the desired type (and eveything is fine thanks to covariant types). Hover I fail to see how I could use the above non-virtual serialize template member function to properly de-serialize (i.e. construct) an object without knowing its type (but assuming that the type information has been stored by the serializer, say in a string). What I would like to do (keeping the same nomenclature as above) is something like the following: XmlArchive xmlArchive; //A type or archive xmlArchive.open("C:/ser.txt"); //Contains type information for the serialized class Base_class* basePtr = Factory<Base_class>::create("derived_class",xmlArchive); with the function on the righ-hand side creating an object on the heap of type Derived_class (via default constructor, this is the part I know how to solve) and calling the serialize function of xmlArchive (here I am stuck!), i.e. do something like: Base_class* Factory<Base_class>::create("derived_class",xmlArchive) { Base_class* basePtr = new Base_class; //OK, doable, usual map string to pointer to function static_cast<Derived_class*>( basePtr )->serialize( xmlArchive ); //De-serialization, how????? return basePtr; } I am sure this can be done (boost serialize does it but its code is impenetrable! :P), but I fail to figure out how. The key problem is that the serialize function is a template function. So I cannot have a pointer to a generic templated function. As the point in writing the templated serialize function is to make the code generic (i.e. not having to re-write the serialize function for different Archivers), it does not make sense then to have to register all the derived classes for all possible archive types, like: MY_CLASS_REGISTER(Derived_class, XmlArchive); MY_CLASS_REGISTER(Derived_class, TxtArchive); ... In fact in my code I relies on overloading to get the correct behaviour: void serialize( XmlArchive& archive, Derived_class& derived ); void serialize( TxtArchive& archive, Derived_class& derived ); ... The key point to keep in mind is that the archive type is always known, i.e. I am never using runtime polymorphism for the archive class...(again I am using overloading on the archive type). Any suggestion to help me out? Thank you very much in advance! Cheers

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Returning JSON in CFFunction and appending it to layer is causing an error

- by Mel

I'm using the qTip jQuery plugin to generate a dynamic tooltip. I'm getting an error in my JS, and I'm unsure if its source is the JSON or the JS. The tooltip calls the following function: (sorry about all this code, but it's necessary) <cffunction name="fGameDetails" access="remote" returnType="any" returnformat="JSON" output="false" hint="This grabs game details for the games.cfm page">  <cfargument name="gameID" type="numeric" required="true" hint="CFC will look for GameID and retrieve its details">  <cfset var qGameDetails = "">  <cfquery name="qGameDetails" datasource="#REQUEST.datasource#"> SELECT titles.titleName AS tName, titles.titleBrief AS tBrief, games.gameID, games.titleID, games.releaseDate AS rDate, genres.genreName AS gName, platforms.platformAbbr AS pAbbr, platforms.platformName AS pName, creviews.cReviewScore AS rScore, ratings.ratingName AS rName FROM games Inner Join platforms ON platforms.platformID = games.platformID Inner Join titles ON titles.titleID = games.titleID Inner Join genres ON genres.genreID = games.genreID Inner Join creviews ON games.gameID = creviews.gameID Inner Join ratings ON ratings.ratingID = games.ratingID WHERE (games.gameID = #ARGUMENTS.gameID#); </cfquery> <cfreturn qGameDetails> </cffunction> This function returns the following JSON: { "COLUMNS": [ "TNAME", "TBRIEF", "GAMEID", "TITLEID", "RDATE", "GNAME", "PABBR", "PNAME", "RSCORE", "RNAME" ], "DATA": [ [ "Dark Void", "Ancient gods known as 'The Watchers,' once banished from our world by superhuman Adepts, have returned with a vengeance.", 154, 54, "January, 19 2010 00:00:00", "Action & Adventure", "PS3", "Playstation 3", 3.3, "14 Anos" ] ] } The problem I'm having is every time I try to append the JSON to the layer #catalog, I get a syntax error that says "missing parenthetical." This is the JavaScript I'm using: $(document).ready(function() { $('#catalog a[href]').each(function() { $(this).qtip( { content: { url: '/gamezilla/resources/components/viewgames.cfc?method=fGameDetails', data: { gameID: $(this).attr('href').match(/gameID=([0-9]+)$/)[1] }, method: 'get' }, api: { beforeContentUpdate: function(content) { var json = eval('(' + content + ')'); content = $('<div />').append( $('<h1 />', { html: json.TNAME })); return content; } }, style: { width: 300, height: 300, padding: 0, name: 'light', tip: { corner: 'leftMiddle', size: { x: 40, y : 40 } } }, position: { corner: { target: 'rightMiddle', tooltip: 'leftMiddle' } } }); }); }); Any ideas where I'm going wrong? I tried many things for several days and I can't find the issue. Many thanks!

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How to give the First image in a gallery a different class than the rest of the images - Carrierwave

- by ChrisBedoya

I have a model called "Photo" that belongs to a model called "Shoe". I using Carrierwave to upload multiple images. index.html.erb <% shoes.each do |shoe| %> <div class="shoe"> <div class="gallery"> <% shoe.photos.each do |photo| %> <%= link_to image_tag(photo.photo_file.url(:thumb).to_s), photo.photo_file.url.to_s, :class => 'fancybox', :rel => 'gallery' %> <% end %> </div> </div> <% end %> Outputs this: <div class="shoe"> <div class="gallery"> <a class="fancybox" href="../nike-kd-6-meteorology-2.jpg" rel="gallery"> <img src="../thumb_nike-kd-6-meteorology-2.jpg"> </a> <a class="fancybox" href="../nike-kd-6-meteorology-2.jpg" rel="gallery"> <img src="../thumb_nike-kd-6-meteorology-2.jpg"> </a> <a class="fancybox" href="../nike-kd-6-meteorology-2.jpg" rel="gallery"> <img src="../thumb_nike-kd-6-meteorology-2.jpg"> </a> </div> </div> But I want the first image of each gallery to be able to have its own class and the rest of the images to have their own class. Something like this: <a class="firstclass" href="../nike-kd-6-meteorology-2.jpg" rel="gallery"> <img src="../thumb_nike-kd-6-meteorology-2.jpg"> </a> <a class="fancybox" href="../nike-kd-6-meteorology-2.jpg" rel="gallery"> <img src="../thumb_nike-kd-6-meteorology-2.jpg"> </a> <a class="fancybox" href="../nike-kd-6-meteorology-2.jpg" rel="gallery"> <img src="../thumb_nike-kd-6-meteorology-2.jpg"> </a> How can I do this? Also I want each gallery to have its own unique id but when I try to add this: :rel => 'gallery<%= shoe.id %>' I get a Syntax error. Thanks.

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Why do we have reinterpret_cast in C++ when two chained static_cast can do it's job?

- by Nawaz

Say I want to cast A* to char* and vice-versa, we have two choices (I mean, many of us think we've two choices, because both seems to work! Hence the confusion!): struct A { int age; char name[128]; }; A a; char *buffer = static_cast<char*>(static_cast<void*>(&a)); //choice 1 char *buffer = reinterpret_cast<char*>(&a); //choice 2 Both work fine. //convert back A *pA = static_cast<A*>(static_cast<void*>(buffer)); //choice 1 A *pA = reinterpret_cast<A*>(buffer); //choice 2 Even this works fine! So why do we have reinterpret_cast in C++ when two chained static_cast can do it's job? Some of you might think this topic is a duplicate of the previous topics such as listed at the bottom of this post, but it's not. Those topics discuss only theoretically, but none of them gives even a single example demonstrating why reintepret_cast is really needed, and two static_cast would surely fail. I agree, one static_cast would fail. But how about two? If the syntax of two chained static_cast looks cumbersome, then we can write a function template to make it more programmer-friendly: template<class To, class From> To any_cast(From v) { return static_cast<To>(static_cast<void*>(v)); } And then we can use this, as: char *buffer = any_cast<char*>(&a); //choice 1 char *buffer = reinterpret_cast<char*>(&a); //choice 2 //convert back A *pA = any_cast<A*>(buffer); //choice 1 A *pA = reinterpret_cast<A*>(buffer); //choice 2 Also, see this situation where any_cast can be useful: Proper casting for fstream read and write member functions. So my question basically is, Why do we have reinterpret_cast in C++? Please show me even a single example where two chained static_cast would surely fail to do the same job? Which cast to use; static_cast or reinterpret_cast? Cast from Void* to TYPE* : static_cast or reinterpret_cast

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How can I pipe two Perl CORE::system commands in a cross-platform way?

- by Pedro Silva

I'm writing a System::Wrapper module to abstract away from CORE::system and the qx operator. I have a serial method that attempts to connect command1's output to command2's input. I've made some progress using named pipes, but POSIX::mkfifo is not cross-platform. Here's part of what I have so far (the run method at the bottom basically calls system): package main; my $obj1 = System::Wrapper->new( interpreter => 'perl', arguments => [-pe => q{''}], input => ['input.txt'], description => 'Concatenate input.txt to STDOUT', ); my $obj2 = System::Wrapper->new( interpreter => 'perl', arguments => [-pe => q{'$_ = reverse $_}'}], description => 'Reverse lines of input input', output => { '>' => 'output' }, ); $obj1->serial( $obj2 ); package System::Wrapper; #... sub serial { my ($self, @commands) = @_; eval { require POSIX; POSIX->import(); require threads; }; my $tmp_dir = File::Spec->tmpdir(); my $last = $self; my @threads; push @commands, $self; for my $command (@commands) { croak sprintf "%s::serial: type of args to serial must be '%s', not '%s'", ref $self, ref $self, ref $command || $command unless ref $command eq ref $self; my $named_pipe = File::Spec->catfile( $tmp_dir, int \$command ); POSIX::mkfifo( $named_pipe, 0777 ) or croak sprintf "%s::serial: couldn't create named pipe %s: %s", ref $self, $named_pipe, $!; $last->output( { '>' => $named_pipe } ); $command->input( $named_pipe ); push @threads, threads->new( sub{ $last->run } ); $last = $command; } $_->join for @threads; } #... My specific questions: Is there an alternative to POSIX::mkfifo that is cross-platform? Win32 named pipes don't work, as you can't open those as regular files, neither do sockets, for the same reasons. 2. The above doesn't quite work; the two threads get spawned correctly, but nothing flows across the pipe. I suppose that might have something to do with pipe deadlocking or output buffering. What throws me off is that when I run those two commands in the actual shell, everything works as expected. Point 2 is solved; a -p fifo file test was not testing the correct file.

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Help with ejb 3, weblogic and spring.

- by berserkpi

So,hi there. I've created a simple EJB3 test project, the code is simple: @Stateless @Remote( { ISumaSimple.class }) public class SumaSimpleBean implements ISumaSimple { /** * Default constructor. */ public SumaSimpleBean() { // TODO Auto-generated constructor stub } @Override public int sumar(int a, int b) { // TODO Auto-generated method stub return a + b; } } public interface ISumaSimple { public int sumar(int a, int b); } Ok, my client is a stand alone spring aplication which configuration is: <bean id="sumaSimpleServicio" class="org.springframework.jndi.JndiObjectFactoryBean"> <property name="jndiEnvironment"> <props> <prop key="java.naming.factory.initial"> org.apache.openejb.client.RemoteInitialContextFactory </prop> <prop key="java.naming.provider.url"> ejbd://localhost:4201 </prop> </props> </property> <property name="jndiName" value="SumaSimpleBeanRemote" /> </bean> <bean id="clienteService" class="qtx.cliente.simple.ClienteService"> <property name="sumaSimpleServicio" ref="sumaSimpleServicio"></property> </bean> All worked smoothly, but then I tried deploying using weblogic 10.3, I just changed these values: weblogic.jndi.WLInitialContextFactory t3://localhost:7010 In weblogic jndi tree my ejb is under: SimpleEJB3SimpleEJB_jarSumaSimple3_ISumaSimple Of course I added wlclient.jar to my spring client classpath. I think I am missing something in weblogic case, but dunno. My spring client is throwing this exception: Caused by: org.springframework.beans.TypeMismatchException: Failed to convert property value of type [qtx.ejb.simple._SumaSimple3_gwze0z_ISumaSimpleIntf_Stub] to required type [qtx.servicio.simple.ISumaSimple] for property 'sumaSimpleServicio'; nested exception is java.lang.IllegalArgumentException: Cannot convert value of type [qtx.ejb.simple._SumaSimple3_gwze0z_ISumaSimpleIntf_Stub] to required type [qtx.servicio.simple.ISumaSimple] for property 'sumaSimpleServicio': no matching editors or conversion strategy found at org.springframework.beans.BeanWrapperImpl.convertForProperty(BeanWrapperImpl.java:391) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.convertForProperty(AbstractAutowireCapableBeanFactory.java:1288) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyPropertyValues(AbstractAutowireCapableBeanFactory.java:1249) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1010) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:472) ... 14 more Caused by: java.lang.IllegalArgumentException: Cannot convert value of type [qtx.ejb.simple._SumaSimple3_gwze0z_ISumaSimpleIntf_Stub] to required type [qtx.servicio.simple.ISumaSimple] for property 'sumaSimpleServicio': no matching editors or conversion strategy found at org.springframework.beans.TypeConverterDelegate.convertIfNecessary(TypeConverterDelegate.java:219) at org.springframework.beans.TypeConverterDelegate.convertIfNecessary(TypeConverterDelegate.java:138) at org.springframework.beans.BeanWrapperImpl.convertForProperty(BeanWrapperImpl.java:386) ... 18 more Any help would be appreciated.

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Step by Step / Deep explain: The Power of (Co)Yoneda (preferably in scala) through Coroutines

- by Mzk

some background code /** FunctorStr: ? F[-]. (? A B. (A -> B) -> F[A] -> F[B]) */ trait FunctorStr[F[_]] { self => def map[A, B](f: A => B): F[A] => F[B] } trait Yoneda[F[_], A] { yo => def apply[B](f: A => B): F[B] def run: F[A] = yo(x => x) def map[B](f: A => B): Yoneda[F, B] = new Yoneda[F, B] { def apply[X](g: B => X) = yo(f andThen g) } } object Yoneda { implicit def yonedafunctor[F[_]]: FunctorStr[({ type l[x] = Yoneda[F, x] })#l] = new FunctorStr[({ type l[x] = Yoneda[F, x] })#l] { def map[A, B](f: A => B): Yoneda[F, A] => Yoneda[F, B] = _ map f } def apply[F[_]: FunctorStr, X](x: F[X]): Yoneda[F, X] = new Yoneda[F, X] { def apply[Y](f: X => Y) = Functor[F].map(f) apply x } } trait Coyoneda[F[_], A] { co => type I def fi: F[I] def k: I => A final def map[B](f: A => B): Coyoneda.Aux[F, B, I] = Coyoneda(fi)(f compose k) } object Coyoneda { type Aux[F[_], A, B] = Coyoneda[F, A] { type I = B } def apply[F[_], B, A](x: F[B])(f: B => A): Aux[F, A, B] = new Coyoneda[F, A] { type I = B val fi = x val k = f } implicit def coyonedaFunctor[F[_]]: FunctorStr[({ type l[x] = Coyoneda[F, x] })#l] = new CoyonedaFunctor[F] {} trait CoyonedaFunctor[F[_]] extends FunctorStr[({type l[x] = Coyoneda[F, x]})#l] { override def map[A, B](f: A => B): Coyoneda[F, A] => Coyoneda[F, B] = x => apply(x.fi)(f compose x.k) } def liftCoyoneda[T[_], A](x: T[A]): Coyoneda[T, A] = apply(x)(a => a) } Now I thought I understood yoneda and coyoneda a bit just from the types – i.e. that they quantify / abstract over map fixed in some type constructor F and some type a, to any type B returning F[B] or (Co)Yoneda[F, B]. Thus providing map fusion for free (? is this kind of like a cut rule for map ?). But I see that Coyoneda is a functor for any type constructor F regardless of F being a Functor, and that I don't fully grasp. Now I'm in a situation where I'm trying to define a Coroutine type, (I'm looking at https://www.fpcomplete.com/school/to-infinity-and-beyond/pick-of-the-week/coroutines-for-streaming/part-2-coroutines for the types to get started with) case class Coroutine[S[_], M[_], R](resume: M[CoroutineState[S, M, R]]) sealed trait CoroutineState[S[_], M[_], R] object CoroutineState { case class Run[S[_], M[_], R](x: S[Coroutine[S, M, R]]) extends CoroutineState[S, M, R] case class Done[R](x: R) extends CoroutineState[Nothing, Nothing, R] class CoroutineStateFunctor[S[_], M[_]](F: FunctorStr[S]) extends FunctorStr[({ type l[x] = CoroutineState[S, M, x]})#l] { override def map[A, B](f : A => B) : CoroutineState[S, M, A] => CoroutineState[S, M, B] = { ??? } } } and I think that if I understood Coyoneda better I could leverage it to make S & M type constructors functors way easy, plus I see Coyoneda potentially playing a role in defining recursion schemes as the functor requirement is pervasive. So how could I use coyoneda to make type constructors functors like for example coroutine state? or something like a Pause functor ?

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Translate parse_git_branch function to zsh from bash (for prompt)

- by yar

I am using this function in Bash function parse_git_branch { git_status="$(git status 2> /dev/null)" pattern="^# On branch ([^${IFS}]*)" if [[ ! ${git_status}} =~ "working directory clean" ]]; then state="*" fi # add an else if or two here if you want to get more specific if [[ ${git_status} =~ ${pattern} ]]; then branch=${BASH_REMATCH[1]} echo "(${branch}${state})" fi } but I'm determined to use zsh. While I can use this perfectly as a shell script (even without a shebang) in my .zshrc the error is a parse error on this line if [[ ! ${git_status}}... What do I need to do to get it ready for zshell? Edit: The "actual error" I'm getting is " parse error near } and it refers to the line with the strange double }}, which works on Bash. Edit: Here's the final code, just for fun: parse_git_branch() { git_status="$(git status 2> /dev/null)" pattern="^# On branch ([^[:space:]]*)" if [[ ! ${git_status} =~ "working directory clean" ]]; then state="*" fi if [[ ${git_status} =~ ${pattern} ]]; then branch=${match[1]} echo "(${branch}${state})" fi } setopt PROMPT_SUBST PROMPT='$PR_GREEN%n@$PR_GREEN%m%u$PR_NO_COLOR:$PR_BLUE%2c$PR_NO_COLOR%(!.#.$)' RPROMPT='$PR_GREEN$(parse_git_branch)$PR_NO_COLOR' Thanks to everybody for your patience and help. Edit: The best answer has schooled us all: git status is porcelain (UI). Good scripting goes against GIT plumbing. Here's the final function: parse_git_branch() { in_wd="$(git rev-parse --is-inside-work-tree 2>/dev/null)" || return test "$in_wd" = true || return state='' git diff-index HEAD --quiet 2>/dev/null || state='*' branch="$(git symbolic-ref HEAD 2>/dev/null)" test -z "$branch" && branch='<detached-HEAD>' echo "(${branch#refs/heads/}${state})" } PROMPT='$PR_GREEN%n@$PR_GREEN%m%u$PR_NO_COLOR:$PR_BLUE%2c$PR_NO_COLOR%(!.#.$)' RPROMPT='$PR_GREEN$(parse_git_branch)$PR_NO_COLOR' Note that only the prompt is zsh-specific. In Bash it would be your prompt plus "\$(parse_git_branch)". This might be slower (more calls to GIT, but that's an empirical question) but it won't be broken by changes in GIT (they don't change the plumbing). And that is very important for a good script moving forward. Days Later: Ugh, it turns out that diff-index HEAD is NOT the same as checking status against working directory clean. So will this mean another plumbing call? I surely don't have time/expertise to write my own porcelain....

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Is there a way to make PHP's SplHeap recalculate? (aka: add up-heap to SplHeap?)

- by md2k7

I am using an SplHeap to hold graph nodes of a tree with directed edges that will be traversed from the leaves to the root. For this, I precalculate the "fan-in" of nodes and put them into the heap so that I can always retrieve the node with the smallest fan-in (0) from it. After visiting a node, I reduce the fan-in of its successor by 1. Then obviously, the heap needs to be recalculated because the successor is now in the wrong place there. I have tried recoverFromCorruption(), but it doesn't do anything and keeps the heap in the wrong order (node with larger fanIn stays in front of smaller fanIn). As a workaround, I'm now creating a new heap after each visit, amounting to a full O(N*log(N)) sort each time. It should be possible, however, to make up-heap operations on the changed heap entry until it's in the right position in O(log(N)). The API for SplHeap doesn't mention an up-heap (or deletion of an arbitrary element - it could then be re-added). Can I somehow derive a class from SplHeap to do this or do I have to create a pure PHP heap from scratch? EDIT: Code example: class VoteGraph { private $nodes = array(); private function calculateFanIn() { /* ... */ } // ... private function calculateWeights() { $this->calculateFanIn(); $fnodes = new GraphNodeHeap(); // heap by fan-in ascending (leaves are first) foreach($this->nodes as $n) { // omitted: filter loops $fnodes->insert($n); } // traversal from leaves to root while($fnodes->valid()) { $node = $fnodes->extract(); // fetch a leaf from the heap $successor = $this->nodes[$node->successor]; // omitted: actual job of traversal $successor->fanIn--; // will need to fix heap (sift up successor) because of this //$fnodes->recoverFromCorruption(); // doesn't work for what I want // workaround: rebuild $fnodes from scratch $fixedHeap = new GraphNodeHeap(); foreach($fnodes as $e) $fixedHeap->insert($e); $fnodes = $fixedHeap; } } } class GraphNodeHeap extends SplHeap { public function compare($a, $b) { if($a->fanIn === $b->fanIn) return 0; else return $a->fanIn < $b->fanIn ? 1 : -1; } }

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