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  • Routing in Php and decorator pattern

    - by Joey Salac Hipolito
    I do not know if I am using the term 'routing' correctly, but here is the situation: I created an .htaccess file to 'process' (dunno if my term is right) the url of my application, like this : RewriteEngine On RewriteCond %{REQUEST_FILENAME} !-d RewriteCond %{REQUEST_FILENAME} !-f RewriteRule ^(.+)$ index.php?url=$1 [QSA,L] Now I have this : http://appname/controller/method/parameter http://appname/$url[0]/$url[1]/$url[2] What I did is: setup a default controller, in case it is not specified in the url setup a Controller wrapper I did it like this $target = new $url[0]() $controller = new Controller($target) The problem with that one is that I can't use the methods in the object I passed in the constructor of the Controller: I resolved it like this : class Controller { protected $target; protected $view; public function __construct($target, $view) { $this->target = $target; $this->view = $view; } public function __call($method, $arguments) { if (method_exists($this->target, $method)) { return call_user_func_array(array($this->target, $method), $arguments); } } } This is working fine, the problem occurs in the index where I did the routing, here it is if(isset($url[2])){ if(method_exists($controller, $url[1])){ $controller->$url[1]($url[2]) } } else { if(method_exists($controller, $url[1])){ $controller->$url[1]() } } where $controller = new Controller($target) The problem is that the method doesn't exist, although I can use it directly without checking if method exist, how can I resolve this?

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  • Is it safe to use random Unicode for complex delimiter sequences in strings?

    - by ccomet
    Question: In terms of program stability and ensuring that the system will actually operate, how safe is it to use chars like ¦, § or ‡ for complex delimiter sequences in strings? Can I reliable believe that I won't run into any issues in a program reading these incorrectly? I am working in a system, using C# code, in which I have to store a fairly complex set of information within a single string. The readability of this string is only necessary on the computer side, end-users should only ever see the information after it has been parsed by the appropriate methods. Because some of the data in these strings will be collections of variable size, I use different delimiters to identify what parts of the string correspond to a certain tier of organization. There are enough cases that the standard sets of ;, |, and similar ilk have been exhausted. I considered two-char delimiters, like ;# or ;|, but I felt that it would be very inefficient. There probably isn't that large of a performance difference in storing with one char versus two chars, but when I have the option of picking the smaller option, it just feels wrong to pick the larger one. So finally, I considered using the set of characters like the double dagger and section. They only take up one char, and they are definitely not going to show up in the actual text that I'll be storing, so they won't be confused for anything. But character encoding is finicky. While the visibility to the end user is meaningless (since they, in fact, won't see it), I became recently concerned about how the programs in the system will read it. The string is stored in one database, while a separate program is responsible for both encoding and decoding the string into different object types for the rest of the application to work with. And if something is expected to be written one way, is possibly written another, then maybe the whole system will fail and I can't really let that happen. So is it safe to use these kind of chars for background delimiters?

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  • Pass Parameter to Subroutine in Codebehind

    - by Sanjubaba
    I'm trying to pass an ID of an activity (RefNum) to a Sub in my codebehind. I know I'm supposed to use parentheses when passing parameters to subroutines and methods, and I've tried a number of ways and keep receiving the following error: BC30203: Identifier expected. I'm hard-coding it on the front-end just to try to get it to pass [ OnDataBound="FillSectorCBList("""WK.002""")" ], but it's obviously wrong. :( Front-end: <asp:DetailsView ID="dvEditActivity" AutoGenerateRows="False" DataKeyNames="RefNum" OnDataBound="dvSectorID_DataBound" OnItemUpdated="dvEditActivity_ItemUpdated" DataSourceID="dsEditActivity" > <Fields> <asp:TemplateField> <ItemTemplate> <br /><span style="color:#0e85c1;font-weight:bold">Sector</span><br /><br /> <asp:CheckBoxList ID="cblistSector" runat="server" DataSourceID="dsGetSectorNames" DataTextField="SectorName" DataValueField="SectorID" OnDataBound="FillSectorCBList("""WK.002""")" ></asp:CheckBoxList> <%-- Datasource to populate cblistSector --%> <asp:SqlDataSource ID="dsGetSectorNames" runat="server" ConnectionString="<%$ ConnectionStrings:dbConn %>" ProviderName="<%$ ConnectionStrings:dbConn.ProviderName %>" SelectCommand="SELECT SectorID, SectorName from Sector ORDER BY SectorID"></asp:SqlDataSource> </ItemTemplate> </asp:TemplateField> </Fields> </asp:DetailsView> Code-behind: Sub FillSectorCBList(ByVal RefNum As String, ByVal sender As Object, ByVal e As System.EventArgs) Dim SectorIDs As New ListItem Dim myConnection As String = ConfigurationManager.ConnectionStrings("dbConn").ConnectionString() Dim objConn As New SqlConnection(myConnection) Dim strSQL As String = "SELECT DISTINCT A.RefNum, AS1.SectorID, S.SectorName FROM Activity A LEFT OUTER JOIN Activity_Sector AS1 ON AS1.RefNum = A.RefNum LEFT OUTER JOIN Sector S ON AS1.SectorID = S.SectorID WHERE A.RefNum = @RefNum ORDER BY A.RefNum" Dim objCommand As New SqlCommand(strSQL, objConn) objCommand.Parameters.AddWithValue("RefNum", RefNum) Dim ad As New SqlDataAdapter(objCommand) Try [Code] Finally [Code] End Try objCommand.Connection.Close() objCommand.Dispose() objConn.Close() End Sub Any advice would be great. I'm not sure if I even have the right approach. Thank you!

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  • Why isn't componentHidden called for my JPopupMenu?

    - by heycam
    I want to be notified when my JPopupMenu is hidden — whether because an item was selected, the menu was dismissed, or setVisible(false) was called on it. Here is my test code: import javax.swing.*; import java.awt.*; import java.awt.event.*; public class A extends ComponentAdapter implements Runnable, ActionListener { private JButton b; public static void main(String[] args) { EventQueue.invokeLater(new A()); } public void run() { JFrame f = new JFrame("Test"); b = new JButton("Click me"); b.addActionListener(this); f.add(b); f.pack(); f.setVisible(true); } public void actionPerformed(ActionEvent e) { JPopupMenu pm = new JPopupMenu(); pm.addComponentListener(this); pm.add("Popup..."); pm.add("...menu!"); pm.show(b, 10, 10); } public void componentShown(ComponentEvent e) { System.out.println("componentShown"); } public void componentHidden(ComponentEvent e) { System.out.println("componentHidden"); } } Regardless of how I interact with the menu, neither of the two ComponentListener methods are being called. Why is that? Is there different/better/correct way of finding out when my JPopupMenu is hidden? Thanks, Cameron

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  • Accessing jQuery objects in the module pattern

    - by Stewart
    Hello, Really getting in to javascript and looking around at some patterns. One I have come accross is the module pattern. Its seems like a nice way to think of chucks of functionality so I went ahead and tried to implement it with jQuery. I ran in to a snag though. Consider the following code <!DOCTYPE html> <html> <head> <meta http-equiv="Content-type" content="text/html; charset=utf-8"> <title>index</title> <script type="text/javascript" charset="utf-8" src="https://ajax.googleapis.com/ajax/libs/jquery/1.4.4/jquery.min.js"></script> <script type="text/javascript" charset="utf-8"> $(document).ready(function(){ var TestClass2 = (function(){ var someDiv; return { thisTest: function () { someDiv = document.createElement("div"); $(someDiv).append("#index"); $(someDiv).html("hello"); $(someDiv).addClass("test_class"); } } })(); TestClass2.thisTest(); }); </script> </head> <body id="index" onload=""> <div id="name"> this is content </div> </body> </html> The above code alerts the html content of the div and then adds a class. These both use jQuery methods. The problem is that the .html() method works fine however i can not add the class. No errors result and the class does not get added. What is happening here? Why is the class not getting added to the div?

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  • actionscript-3: refactor interface inheritance to get rid of ambiguous reference error

    - by maxmc
    hi! imagine there are two interfaces arranged via composite pattern, one of them has a dispose method among other methods: interface IComponent extends ILeaf { ... function dispose() : void; } interface ILeaf { ... } some implementations have some more things in common (say an id) so there are two more interfaces: interface ICommonLeaf extends ILeaf { function get id() : String; } interface ICommonComponent extends ICommonLeaf, IComponent { } so far so good. but there is another interface which also has a dispose method: interface ISomething { ... function dispose() : void; } and ISomething is inherited by ICommonLeaf: interface ICommonLeaf extends ILeaf, ISomething { function get id() : String; } As soon as the dispose method is invoked on an instance which implements the ICommonComponent interface, the compiler fails with an ambiguous reference error because ISomething has a method called dispose and ILeaf also has a dispose method, both living in different interfaces (IComponent, ISomething) within the inheritace tree of ICommonComponent. I wonder how to deal with the situation if the IComponent, the ILeaf and the ISomething can't change. the composite structure must also work for for the ICommonLeaf & ICommonComponent implementations and the ICommonLeaf & ICommonComponent must conform to the ISomething type. this might be an actionscript-3 specific issue. i haven't tested how other languages (for instance java) handle stuff like this.

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  • NoClassDefFoundError: HttpClient 4 (APACHE)

    - by Pujan Srivastava
    Hello All, I am using HC APACHE. I have added both httpcore-4.0.1.jar and httpclient-4.0.1.jar in the classpath of netbeans. I am getting error: java.lang.NoClassDefFoundError: org/apache/http/impl/client/DefaultHttpClient My Code is as follows. Please help. import org.apache.http.client.HttpClient; import org.apache.http.client.ResponseHandler; import org.apache.http.client.methods.HttpGet; import org.apache.http.impl.client.BasicResponseHandler; import org.apache.http.impl.client.DefaultHttpClient; public class HttpClientManager { public HttpClient httpclient; public HttpClientManager() { this.init(); } public void init() { try { httpclient = new DefaultHttpClient(); } catch (Exception e) { e.printStackTrace(); } } public void getCourseList() { String url = "http://exnet.in.th/api.php?username=demoinst&ha=2b62560&type=instructor"; HttpGet httpget = new HttpGet(url); ResponseHandler<String> responseHandler = new BasicResponseHandler(); try { String responseBody = httpclient.execute(httpget, responseHandler); System.out.println(responseBody); } catch (Exception e) { } } }

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  • PHP: MVC and Model

    - by Pirkka
    Hello I`ve been wondering this one thing about creating models. If I make for example Page model. Is it the both: It can retrieve one row from the table or all the rows. Somehow Im mixing the objects and the database. I have thought it like this: I would have to make a Page-class that would represent one row in the table. It also would have all the basic CRUD-methods. Then I would have to do a Pages-class (somekind of collection) that would retrieve rows from the table and instantiate a Page object from each row. Is this kind of weird? If someone could explain to me the idea of model throughout.. Im again confused. Maybe Im thinking the whole OOP too difficult.. And by the way this forum is great. Hopefully people will just understand my problems. Heh. I was a long time procedural style programmer and now in 3 months I have dived into OOP and MVC and PHP frameworks and I just get more excited day by day when I explore this stuff!

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  • Baffled by differences between WPF BitmapEncoders

    - by DanM
    I wrote a little utility class that saves BitmapSource objects to image files. The image files can be either bmp, jpeg, or png. Here is the code: public class BitmapProcessor { public void SaveAsBmp(BitmapSource bitmapSource, string path) { Save(bitmapSource, path, new BmpBitmapEncoder()); } public void SaveAsJpg(BitmapSource bitmapSource, string path) { Save(bitmapSource, path, new JpegBitmapEncoder()); } public void SaveAsPng(BitmapSource bitmapSource, string path) { Save(bitmapSource, path, new PngBitmapEncoder()); } private void Save(BitmapSource bitmapSource, string path, BitmapEncoder encoder) { using (var stream = new FileStream(path, FileMode.Create)) { encoder.Frames.Add(BitmapFrame.Create(bitmapSource)); encoder.Save(stream); } } } Each of the three Save methods work, but I get unexpected results with bmp and jpeg. Png is the only format that produces an exact reproduction of what I see if I show the BitmapSource on screen using a WPF Image control. Here are the results: BMP - too dark JPEG - too saturated PNG - correct Why am I getting completely different results for different file types? I should note that the BitmapSource in my example uses an alpha value of 0.1 (which is why it appears very desaturated), but it should be possible to show the resulting colors in any image format. I know if I take a screen capture using something like HyperSnap, it will look correct regardless of what file type I save to. Here's a HyperSnap screen capture saved as a bmp: As you can see, this isn't a problem, so there's definitely something strange about WPF's image encoders. Do I have a setting wrong? Am I missing something?

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  • Advice on Method overloads.

    - by Muhammad Kashif Nadeem
    Please see following methods. public static ProductsCollection GetDummyData(int? customerId, int? supplierId) { try { if (customerId != null && customerId > 0) { Filter.Add(Customres.CustomerId == customerId); } if (supplierId != null && supplierId > 0) { Filter.Add(Suppliers.SupplierId == supplierId); } ProductsCollection products = new ProductsCollection(); products.FetchData(Filter); return products; } catch { throw; } } public static ProductsCollection GetDummyData(int? customerId) { return ProductsCollection GetDummyData(customerId, (int?)null); } public static ProductsCollection GetDummyData() { return ProductsCollection GetDummyData((int?)null); } 1- Please advice how can I make overloads for both CustomerId and SupplierId because only one overload can be created with GetDummyData(int? ). Should I add another argument to mention that first argument is CustomerId or SupplierId for example GetDummyData(int?, string). OR should I use enum as 2nd argument and mention that first argument is CustoemId or SupplierId. 2- Is this condition is correct or just checking 0 is sufficient - if (customerId != null && customerId 0) 3- Using Try/catch like this is correct? 4- Passing (int?)null is correct or any other better approach. Edit: I have found some other posts like this and because I have no knowledge of Generics that is why I am facing this problem. Am I right? Following is the post. http://stackoverflow.com/questions/422625/overloaded-method-calling-overloaded-method

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  • PHP: tips/resources/patterns for learning to implement a basic ORM

    - by BoltClock
    I've seen various MVC frameworks as well as standalone ORM frameworks for PHP, as well as other ORM questions here; however, most of the questions ask for existing frameworks to get started with, which is not what I'm looking for. (I have also read this SO question but I'm not sure what to make of it, and the answers are vague.) Instead, I figured I'd learn best by getting my hands dirty and actually writing my own ORM, even a simple one. Except I don't really know how to get started, especially since the code I see in other ORMs is so complicated. With my PHP 5.2.x (this is important) MVC framework I have a basic custom database abstraction layer, that has: Very simple methods like connect($host, $user, $pass, $base), query($sql, $binds), etc Subclasses for each DBMS that it supports A class (and respective subclasses) to represent SQL result sets But does not have: Active Record functionality, which I assume is an ORM thing (correct me if I'm wrong) I've read up a little about ORM, and from my understanding they provide a means to further abstract data models from the database itself by representing data as nothing more than PHP-based classes/objects; again, correct me if I am wrong or have missed out in any way. Still, I'd like some simple tips from anyone else who's dabbled more or less with ORM frameworks. Is there anything else I need to take note of, simple example code for me to refer to, or resources I can read? Thanks a lot in advance!

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  • Open a new browser window from embeded Internet Explorer

    - by Buddy
    I am working on a Windows desktop app (C++) that has an embedded Internet Explorer page. I'm working on the html page that is displayed in the There is not a back button control, so one of the requests is that links clicked on in the page should open the link in a browser window. It can open the link in the users default browser or in IE. Is this possible? I realize that this is not possible because javascript is in a sandbox and cannot touch outside applications. I'm thinking there might be a way because it is using the IE. I have tried the two methods that have worked for me in the past. Using jquery, I've tried these two approaches, but neither work in the app. They both work fine in normal browsers. Using target="_blank" $( "a" ).attr( "target", "_blank" ); The other is using window.open: $( "a" ).click( function() { window.open( $( this ).attr( "href" ) ); } ); I'm afraid that writing windows desktop applications is outside my area of expertise, so I cannot give more information regarding that side of the issue.

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  • iPhone Development - Location Accuracy

    - by Mustafa
    I'm using following conditions in-order to make sure that the location i get has adequate accuracy, In my case kCLLocationAccuracyBest. But the problem is that i still get inaccurate location. // Filter out nil locations if(!newLocation) return; // Make sure that the location returned has the desired accuracy if(newLocation.horizontalAccuracy < manager.desiredAccuracy) return; // Filter out points that are out of order if([newLocation.timestamp timeIntervalSinceDate:oldLocation.timestamp] < 0) return; // Filter out points created before the manager was initialized NSTimeInterval secondsSinceManagerStarted = [newLocation.timestamp timeIntervalSinceDate:locationManagerStartDate]; if(secondsSinceManagerStarted < 0) return; // Also, make sure that the cached location was not returned by the CLLocationManager (it's current) - Check for 5 seconds difference if([newLocation.timestamp timeIntervalSinceReferenceDate] < [[NSDate date] timeIntervalSinceReferenceDate] - 5) return; When i activate the GPS, i get inaccurate results before i actually get an accurate result. What methods do you use to get accurate/precise location information?

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  • Scrolling to the bottom of a div on page load: issue with syntaxhighlighter

    - by Rayne
    I've been using this code: var objDiv = document.getElementById("code"); objDiv.scrollTop = objDiv.scrollHeight; to scroll to the very bottom of the div. It worked perfectly in FF and Chrome (I asked a question about it not working in Chrome a few days ago, but it appears the guy who was testing it on Chrome was incorrect, so I tested it myself) until I started syntax highlighting the code that I put in the div with SyntaxHighlighter. Before, I was putting the code in a <p> and breaking lines with <br />, but the <br /> stuff doesn't fly with SyntaxHighlighter, so I replaced all of those with newlines (not entirely certain if this is important, but it's worth mentioning). Now, when the page loads, it does scroll, but not all the way down. It scrolls nearly to the bottom. I've tried all the methods listed in the other question I mentioned but they all do the same thing, or nothing at all. Is there anything else I can try? Here is the relevant piece of the generated HTML. Forgive the poor formatting, I'm not writing the HTML by hand, but rather using Hiccup with Clojure, and it doesn't bother with formatting. <div class="scroll" id="code"><pre class="brush: clojure">=> (doseq [x (range 1 100)] (println x)) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 nil </pre></div><script type="text/javascript">var objDiv = document.getElementById("code"); objDiv.scrollTop = objDiv.scrollHeight;</script>

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  • Perl+Image::Magick usage: how to assemble several areas in one image into a new image?

    - by Jin
    Hi Everybody, I'm new to ImageMagick and haven't figured out how to assemble several areas into a new image. E.g., I know the "geometry" of words "hello" and "world" respectively in an image, what I need to do is to retrieve the word images and put then into one line image while keep their relative positions. Question1: Suppose I use the perl API, how should I use Composite() or other correct methods to do this? my $geom = sprintf('%dx%x+%d+%d', $word->{width}, $word->{height}, $offsetx, $offsety); $x = $lineimg->Composite($wordimg, $geom); warn "$x" if "$x"; Suppose $lineimg's size is big enough to hold all word images and the geometry has been computed. This code gives out a complain by ImageMagick: Exception 410: composite image required `Image::Magick' @ Magick.xs/XS_Image__Magick_Mogrify/7790 ... Question2: currently I only know how to crop a word image out of the original one and then Clone() method to restore the original image. Is there a way to copy instead of crop a specific area from a image? This way can save the time to copy back and forth the whole image several times. Does anybody know how to write this kind of processing? I appreciate all your help and suggestions! -Jin

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  • CSS3 transition on table row using height property

    - by Alexis Leclerc
    I have an HTML table displaying some information with a few rows. On each row, the user can click to reveal some additional rows that contains information related to the clicked row. Something like this: While the additional rows are being created with an AJAX request, a loading row is inserted right after the clicked row : Currently, everything works perfectly (drill down style), but I would like to add some animation to the loading row. I found a question ( this one ) that has a JSFiddle showing kind of what I want ( this fiddle ). I tried to implement something similar with CSS3 transitions, but I can't get it to work. Here's my simulated attempt ( fiddle only for deployment of the loading row ) using these transitions : -webkit-transition: height 0.1s ease-in-out; -moz-transition: height 0.1s ease-in-out; -ms-transition: height 0.1s ease-in-out; -o-transition: height 0.1s ease-in-out; transition: height 0.1s ease-in-out; Any thought on why my fiddle doesn't do any animation? Any other methods you would propose? Thanks!

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  • Need help coming up with a better HtmlHelper Extension method.

    - by zSysop
    Hi all, I've inherited the following code and i was wondering if i could pick at your brains to see if there's a nicer way to do duplicate this. Heres the html for most of our partial input views <% if (Html.IsInputReadOnly()) { %> <td> Id </td> <td> <%= Html.TextBox( "Id" , (Model == null ? null : Model.Id) , new { @readonly = "readonly", @disabled="disabled" } )%> <% } elseif (Html.IsInputDisplayable() == false) { %> <td></td> <td></td> <% } else { %> <td>Id</td> <td><%= Html.TextBox("Id")%> <%= Html.ValidationMessage("Id", "*")%> </td> <%} %> Here are my entension methods public static bool IsInputReadOnly(this HtmlHelper helper) { string actionName = ActionName(helper); // The Textbox should be read only on all pages except for the lookup page if (actionName.ToUpper().CompareTo("EDIT") == 0) return true; return false; } public static bool IsInputDisplayable(this HtmlHelper helper) { string actionName = ActionName(helper); // The Textbox should be read only on all pages except for the lookup page if (actionName.ToUpper().CompareTo("CREATE") == 0) return true; return false; } Thanks in advance

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  • What are the use cases for this static reflection code?

    - by Maslow
    This is Oliver Hanappi's static reflection code he posted on stackoverflow private static string GetMemberName(Expression expression) { switch (expression.NodeType) { case ExpressionType.MemberAccess: var memberExpression = (MemberExpression)expression; var supername = GetMemberName(memberExpression.Expression); if (String.IsNullOrEmpty(supername)) return memberExpression.Member.Name; return String.Concat(supername, '.', memberExpression.Member.Name); case ExpressionType.Call: var callExpression = (MethodCallExpression)expression; return callExpression.Method.Name; case ExpressionType.Convert: var unaryExpression = (UnaryExpression)expression; return GetMemberName(unaryExpression.Operand); case ExpressionType.Parameter: return String.Empty; default: throw new ArgumentException("The expression is not a member access or method call expression"); } } I have the public wrapper methods: public static string Name<T>(Expression<Action<T>> expression) { return GetMemberName(expression.Body); } public static string Name<T>(Expression<Func<T, object>> expression) { return GetMemberName(expression.Body); } then added my own method shortcuts public static string ClassMemberName<T>(this T sourceType,Expression<Func<T,object>> expression) { return GetMemberName(expression.Body); } public static string TMemberName<T>(this IEnumerable<T> sourceList, Expression<Func<T,object>> expression) { return GetMemberName(expression.Body); } What are examples of code that would necessitate or take advantage of the different branches in the GetMemberName(Expression expression) switch? what all is this code capable of making strongly typed?

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  • Java Polynomial Multiplication with ArrayList

    - by user1506919
    I am having a problem with one of my methods in my program. The method is designed to take 2 arraylists and the perform multiplication between the two like a polynomial. For example, if I was to say list1={3,2,1} and list2={5,6,7}; I am trying to get a return value of 15,28,38,20,7. However, all I can get is an error message that says: Exception in thread "main" java.lang.IndexOutOfBoundsException: Index: 0, Size: 0. I have provided the method below: private static ArrayList<Integer> multiply(ArrayList<Integer> list1,ArrayList<Integer> list2) { ArrayList<Integer> array =new ArrayList<Integer>(list1.size()+list2.size()); for (int i=0;i<array.size();i++) array.add(i, 0); for (int i = 0; i < list1.size(); i++) for (int j = 0; j < list2.size(); j++) array.set(i+j, ((list1.get(i) * list2.get(j))+array.get(i+j))); return array; } Any help with solving this problem is greatly appreciated.

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  • How would you code a washing machine?

    - by Dan
    Imagine I have a class that represents a simple washing machine. It can perform following operations in the following order: turn on - wash - centrifuge - turn off. I see two basic alternatives: A) I can have a class WashingMachine with methods turnOn(), wash(int minutes), centrifuge(int revs), turnOff(). The problem with this is that the interface says nothing about the correct order of operations. I can at best throw InvalidOprationException if the client tries to centrifuge before machine was turned on. B) I can let the class itself take care of correct transitions and have the single method nextOperation(). The problem with this on the other hand, is that the semantics is poor. Client will not know what will happen when he calls the nextOperation(). Imagine you implement the centrifuge button’s click event so it calls nextOperation(). User presses the centrifuge button after machine was turned on and ups! machine starts to wash. I will probably need a few properties on my class to parameterize operations, or maybe a separate Program class with washLength and centrifugeRevs fields, but that is not really the problem. Which alternative is better? Or maybe there are some other, better alternatives that I missed to describe?

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  • How to build a sequence in the method calls of a fluent interface

    - by silverfighter
    Hi I would like to build a fluent interface for creating am object some sort of factory or builder. I understand that I have to "return this" in order to make the methods chainable. public class CarBuilder { public CarBuilder() { car = new Car(); } private Car car; public CarBuilder AddEngine(IEngineBuilder engine) { car.Engine = engine.Engine(); return this; } public CarBuilder AddWheels(IWheelsBuilder wheels) { car.Wheels = wheels.Wheels(); return this; } public CarBuilder AddFrame(IFrameBuilder frame) { car.Frame = frame.Frame(); return this; } public Car BuildCar() { return car; } } with this I could build a car like that: Car c = builder.AddFrame(fBuilder).AddWheels(wBuilder).AddEngine(eBuilder).BuildCar(); But what I need is a special sequence or workflow: I can only build the wheels on top of the frame and when the wheels exist then I'll be able to build up the engine. So instead of offering every method of the car builder I want to be able to add only the frame to the builder and then only the wheels to the frame and then the engine on top of that... And how would it be or what would be a good implementation if the EngineBuilder itself has a fluent api like eBuilder.Cylinders(12).WithPistons().... Would it be possible to have something like this Car c = builder.AddFrame(fBuilder).AddWheels(wBuilder).AddEngine(x=>x.WithCylinders(12).WithPistons()).BuildCar(); So in sum how to structure the flow of the fluent interface and how to nest fluent Interfaces?

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  • Python C API from C++ app - know when to lock

    - by Alex
    Hi Everyone, I am trying to write a C++ class that calls Python methods of a class that does some I/O operations (file, stdout) at once. The problem I have ran into is that my class is called from different threads: sometimes main thread, sometimes different others. Obviously I tried to apply the approach for Python calls in multi-threaded native applications. Basically everything starts from PyEval_AcquireLock and PyEval_ReleaseLock or just global locks. According to the documentation here when a thread is already locked a deadlock ensues. When my class is called from the main thread or other one that blocks Python execution I have a deadlock. Python Cfunc1() - C++ func that creates threads internally which lead to calls in "my class", It stuck on PyEval_AcquireLock, obviously the Python is already locked, i.e. waiting for C++ Cfunc1 call to complete... It completes fine if I omit those locks. Also it completes fine when Python interpreter is ready for the next user command, i.e. when thread is calling funcs in the background - not inside of a native call I am looking for a workaround. I need to distinguish whether or not the global lock is allowed, i.e. Python is not locked and ready to receive the next command... I tried PyGIL_Ensure, unfortunately I see hang. Any known API or solution for this ? (Python 2.4)

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  • Wait on multiple condition variables on Linux without unnecessary sleeps?

    - by Joseph Garvin
    I'm writing a latency sensitive app that in effect wants to wait on multiple condition variables at once. I've read before of several ways to get this functionality on Linux (apparently this is builtin on Windows), but none of them seem suitable for my app. The methods I know of are: Have one thread wait on each of the condition variables you want to wait on, which when woken will signal a single condition variable which you wait on instead. Cycling through multiple condition variables with a timed wait. Writing dummy bytes to files or pipes instead, and polling on those. #1 & #2 are unsuitable because they cause unnecessary sleeping. With #1, you have to wait for the dummy thread to wake up, then signal the real thread, then for the real thread to wake up, instead of the real thread just waking up to begin with -- the extra scheduler quantum spent on this actually matters for my app, and I'd prefer not to have to use a full fledged RTOS. #2 is even worse, you potentially spend N * timeout time asleep, or your timeout will be 0 in which case you never sleep (endlessly burning CPU and starving other threads is also bad). For #3, pipes are problematic because if the thread being 'signaled' is busy or even crashes (I'm in fact dealing with separate process rather than threads -- the mutexes and conditions would be stored in shared memory), then the writing thread will be stuck because the pipe's buffer will be full, as will any other clients. Files are problematic because you'd be growing it endlessly the longer the app ran. Is there a better way to do this? Curious for answers appropriate for Solaris as well.

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  • How to specify a parameter as part of every web service call?

    - by LES2
    Currently, each web service for our application has a user parameter that is added for every method. For example: @WebService public interface FooWebService { @WebMethod public Foo getFoo(@WebParam(name="alwaysHere",header=true,partName="alwaysHere") String user, @WebParam(name="fooId") Long fooId); @WebMethod public Result deletetFoo(@WebParam(name="alwaysHere",header=true,partName="alwaysHere") String user, @WebParam(name="fooId") Long fooId); // ... } There could be twenty methods in a service, each with the first parameter as user. And there could be twenty web services. We don't actually use the 'user' argument in the implementations - in fact, I don't know why it's there - but I wasn't involved in the design, and the person that put it there had a reason (I hope). Anyway, I'm trying to straighten out this Big Ball of Mud. I have already come a long way by wrapping the web services by a Spring proxy, which allows me to do some before-and-after processing in an interceptor (before there were at least 20 lines of copy-pasted boiler plate per method). I'm wondering if there's some kind of "message header" I can apply to the method or package and that can be accessed by some type of handler or something outside of each web service method. Thanks in advance for the advice, LES

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  • How to increase the performance of a loop which runs for every 'n' minutes.

    - by GustlyWind
    Hi Giving small background to my requirement and what i had accomplished so far: There are 18 Scheduler tasks run at regular intervals (least being 30 mins) takes input of nearly 5000 eligible employees run into a static method for iteration and generates a mail content for that employee and mails. An average task takes about 9 min multiplied by 18 will be roughly 162 mins meanwhile there would be next tasks which will be in queue (I assume). So my plan is something like the below loop try { // Handle Arraylist of alerts eligible employees Iterator employee = empIDs.iterator(); while (employee.hasNext()) { ScheduledImplementation.getInstance().sendAlertInfoToEmpForGivenAlertType((Long)employee.next(), configType,schedType); } } catch (Exception vEx) { _log.error("Exception Caught During sending " + configType + " messages:" + configType, vEx); } Since I know how many employees would come to my method I will divide the while loop into two and perform simultaneous operations on two or three employees at a time. Is this possible. Or is there any other ways I can improve the performance. Some of the things I had implemented so far 1.Wherever possible made methods static and variables too Didn't bother to catch exceptions and send back because these are background tasks. (And I assume this improves performance) Get the DB values in one query instead of multiple hits. If am successful in optimizing the while loop I think i can save couple of mins. Thanks

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