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  • Odd performance with C# Asynchronous server socket

    - by The.Anti.9
    I'm working on a web server in C# and I have it running on Asynchronous socket calls. The weird thing is that for some reason, when you start loading pages, the 3rd request is where the browser won't connect. It just keeps saying "Connecting..." and doesn't ever stop. If I hit stop. and then refresh, it will load again, but if I try another time after that it does the thing where it doesn't load again. And it continues in that cycle. I'm not really sure what is making it do that. The code is kind of hacked together from a couple of examples and some old code I had. Any miscellaneous tips would be helpful as well. Heres my little Listener class that handles everything (pastied here. thought it might be easier to read this way) using System; using System.Collections.Generic; using System.Net; using System.Net.Sockets; using System.Text; using System.Threading; namespace irek.Server { public class Listener { private int port; private Socket server; private Byte[] data = new Byte[2048]; static ManualResetEvent allDone = new ManualResetEvent(false); public Listener(int _port) { port = _port; } public void Run() { server = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp); IPEndPoint iep = new IPEndPoint(IPAddress.Any, port); server.Bind(iep); Console.WriteLine("Server Initialized."); server.Listen(5); Console.WriteLine("Listening..."); while (true) { allDone.Reset(); server.BeginAccept(new AsyncCallback(AcceptCon), server); allDone.WaitOne(); } } private void AcceptCon(IAsyncResult iar) { allDone.Set(); Socket s = (Socket)iar.AsyncState; Socket s2 = s.EndAccept(iar); SocketStateObject state = new SocketStateObject(); state.workSocket = s2; s2.BeginReceive(state.buffer, 0, SocketStateObject.BUFFER_SIZE, 0, new AsyncCallback(Read), state); } private void Read(IAsyncResult iar) { try { SocketStateObject state = (SocketStateObject)iar.AsyncState; Socket s = state.workSocket; int read = s.EndReceive(iar); if (read > 0) { state.sb.Append(Encoding.ASCII.GetString(state.buffer, 0, read)); if (s.Available > 0) { s.BeginReceive(state.buffer, 0, SocketStateObject.BUFFER_SIZE, 0, new AsyncCallback(Read), state); return; } } if (state.sb.Length > 1) { string requestString = state.sb.ToString(); // HANDLE REQUEST HERE // Temporary response string resp = "<h1>It Works!</h1>"; string head = "HTTP/1.1 200 OK\r\nContent-Type: text/html;\r\nServer: irek\r\nContent-Length:"+resp.Length+"\r\n\r\n"; byte[] answer = Encoding.ASCII.GetBytes(head+resp); // end temp. state.workSocket.BeginSend(answer, 0, answer.Length, SocketFlags.None, new AsyncCallback(Send), state.workSocket); } } catch (Exception) { return; } } private void Send(IAsyncResult iar) { try { SocketStateObject state = (SocketStateObject)iar.AsyncState; int sent = state.workSocket.EndSend(iar); state.workSocket.Shutdown(SocketShutdown.Both); state.workSocket.Close(); } catch (Exception) { } return; } } } And my SocketStateObject: public class SocketStateObject { public Socket workSocket = null; public const int BUFFER_SIZE = 1024; public byte[] buffer = new byte[BUFFER_SIZE]; public StringBuilder sb = new StringBuilder(); }

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  • What's the right way to do mutable data structures (e.g., skip lists, splay trees) in F#?

    - by dan
    What's a good way to implement mutable data structures in F#? The reason I’m asking is because I want to go back and implement the data structures I learned about in the algorithms class I took this semester (skip lists, splay trees, fusion trees, y-fast tries, van Emde Boas trees, etc.), which was a pure theory course with no coding whatsoever, and I figure I might as well try to learn F# while I’m doing it. I know that I “should” use finger trees to get splay tree functionality in a functional language, and that I should do something with laziness to get skip-list functionality, etc. , but I want to get the basics nailed down before I try playing with purely functional implementations. There are lots of examples of how to do functional data structures in F#, but there isn’t much on how to do mutable data structures, so I started by fixing up the doubly linked list here into something that allows inserts and deletes anywhere. My plan is to turn this into a skip list, and then use a similar structure (discriminated union of a record) for the tree structures I want to implement. Before I start on something more substantial, is there a better way to do mutable structures like this in F#? Should I just use records and not bother with the discriminated union? Should I use a class instead? Is this question "not even wrong"? Should I be doing the mutable structures in C#, and not dip into F# until I want to compare them to their purely functional counterparts? And, if a DU of records is what I want, could I have written the code below better or more idiomatically? It seems like there's a lot of redundancy here, but I'm not sure how to get rid of it. module DoublyLinkedList = type 'a ll = | None | Node of 'a ll_node and 'a ll_node = { mutable Prev: 'a ll; Element : 'a ; mutable Next: 'a ll; } let insert x l = match l with | None -> Node({ Prev=None; Element=x; Next=None }) | Node(node) -> match node.Prev with | None -> let new_node = { Prev=None; Element=x; Next=Node(node)} node.Prev <- Node(new_node) Node(new_node) | Node(prev_node) -> let new_node = { Prev=node.Prev; Element=x; Next=Node(node)} node.Prev <- Node(new_node) prev_node.Next <- Node(new_node) Node(prev_node) let rec nth n l = match n, l with | _,None -> None | _,Node(node) when n > 0 -> nth (n-1) node.Next | _,Node(node) when n < 0 -> nth (n+1) node.Prev | _,Node(node) -> Node(node) //hopefully only when n = 0 :-) let rec printLinkedList head = match head with | None -> () | Node(x) -> let prev = match x.Prev with | None -> "-" | Node(y) -> y.Element.ToString() let cur = x.Element.ToString() let next = match x.Next with | None -> "-" | Node(y) -> y.Element.ToString() printfn "%s, <- %s -> %s" prev cur next printLinkedList x.Next

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  • how to do android image animation

    - by user270811
    hi, i am trying to get a simple image animation going. i want to make it looks as if the helicopter's propeller blades are turning. i have 3 images for the helicopter, and i am showing one of these images depending on the animation progress. the problem is that all three images end up overlapping each other as opposed to just one image showing up at one time, thereby creating the animation. this is what i did so far, i even tried to clear canvas by doing this canvas.drawColor(Color.BLACK), but that would clear out the whole canvas, which is not what i want. this is what i have: 1) in the View class: static class Helicopter { private long mLastUpdate; private long mProgress = 0; private final float mX; private final float mY; private final Bitmap mHelicopter1; private final Bitmap mHelicopter2; private final Bitmap mHelicopter3; private final float mRadius; Helicopter(long mLastUpdate, float mX, float mY, Bitmap helicopter1, Bitmap helicopter2, Bitmap helicopter3) { this.mLastUpdate = mLastUpdate; this.mX = mX; this.mY = mY; this.mHelicopter1 = helicopter1; this.mHelicopter2 = helicopter2; this.mHelicopter3 = helicopter3; mRadius = ((float) mHelicopter1.getWidth()) / 2f; } public void update(long now) { mProgress += (now - mLastUpdate); if(mProgress >= 400L) { mProgress = 0; } mLastUpdate = now; } public void setNow(long now) { mLastUpdate = now; } public void draw(Canvas canvas, Paint paint) { if (mProgress < 150L) { canvas.drawBitmap(mHelicopter1, mX - mRadius, mY - mRadius, paint); } else if (mProgress < 300L) { canvas.drawBitmap(mHelicopter2, mX - mRadius, mY - mRadius, paint); } else if(mProgress < 400L) { canvas.drawBitmap(mHelicopter3, mX - mRadius, mY - mRadius, paint); } } public boolean done() { return mProgress > 700L; } } private ArrayList<Helicopter> mHelicopters = new ArrayList<Helicopter>(); 2) this is being called in the run() of a thread: private void doDraw(Canvas canvas) { final long now = SystemClock.elapsedRealtime(); canvas.save(); for (int i = 0; i < mHelicopters.size(); i++) { final Helicopter explosion = mHelicopters.get(i); explosion.update(now); } for (int i = 0; i < mHelicopters.size(); i++) { final Helicopter explosion = mHelicopters.get(i); explosion.draw(canvas, mPaint); } canvas.restore(); } can someone help me? i have looked at a lot of the examples on the web on animation, they seem to always involve text, but not images. thanks.

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  • Javascript Closures - What are the negatives?

    - by vol7ron
    Question: There seem to be many benefits to Closures, but what are the negatives (memory leakage? obfuscation problems? bandwidth increasage?)? Additionally, is my understanding of Closures correct? Finally, once closures are created, can they be destroyed? I've been reading a little bit about Javascript Closures. I hope someone a little more knowledgeable will guide my assertions, correcting me where wrong. Benefits of Closures: Encapsulate the variables to a local scope, by using an internal function. The anonymity of the function is insignificant. What I've found helpful is to do some basic testing, regarding local/global scope: <script type="text/javascript"> var global_text = ""; var global_count = 0; var global_num1 = 10; var global_num2 = 20; var global_num3 = 30; function outerFunc() { var local_count = local_count || 0; alert("global_num1: " + global_num1); // global_num1: undefined var global_num1 = global_num1 || 0; alert("global_num1: " + global_num1); // global_num1: 0 alert("global_num2: " + global_num2); // global_num2: 20 global_num2 = global_num2 || 0; // (notice) no definition with 'var' alert("global_num2: " + global_num2); // global_num2: 20 global_num2 = 0; alert("local_count: " + local_count); // local_count: 0 function output() { global_num3++; alert("local_count: " + local_count + "\n" + "global_count: " + global_count + "\n" + "global_text: " + global_text ); local_count++; } local_count++; global_count++; return output; } var myFunc = outerFunc(); myFunc(); /* Outputs: ********************** * local_count: 1 * global_count: 1 * global_text: **********************/ global_text = "global"; myFunc(); /* Outputs: ********************** * local_count: 2 * global_count: 1 * global_text: global **********************/ var local_count = 100; myFunc(); /* Outputs: ********************** * local_count: 3 * global_count: 1 * global_text: global **********************/ alert("global_num1: " + global_num1); // global_num1: 10 alert("global_num2: " + global_num2); // global_num2: 0 alert("global_num3: " + global_num3); // global_num3: 33 </script> Interesting things I took out of it: The alerts in outerFunc are only called once, which is when the outerFunc call is assigned to myFunc (myFunc = outerFunc()). This assignment seems to keep the outerFunc open, in what I would like to call a persistent state. Everytime myFunc is called, the return is executed. In this case, the return is the internal function. Something really interesting is the localization that occurs when defining local variables. Notice the difference in the first alert between global_num1 and global_num2, even before the variable is trying to be created, global_num1 is considered undefined because the 'var' was used to signify a local variable to that function. -- This has been talked about before, in the order of operation for the Javascript engine, it's just nice to see this put to work. Globals can still be used, but local variables will override them. Notice before the third myFunc call, a global variable called local_count is created, but it as no effect on the internal function, which has a variable that goes by the same name. Conversely, each function call has the ability to modify global variables, as noticed by global_var3. Post Thoughts: Even though the code is straightforward, it is cluttered by alerts for you guys, so you can plug and play. I know there are other examples of closures, many of which use anonymous functions in combination with looping structures, but I think this is good for a 101-starter course to see the effects. The one thing I'm concerned with is the negative impact closures will have on memory. Because it keeps the function environment open, it is also keeping those variables stored in memory, which may/may not have performance implications, especially regarding DOM traversals and garbage collection. I'm also not sure what kind of role this will play in terms of memory leakage and I'm not sure if the closure can be removed from memory by a simple "delete myFunc;." Hope this helps someone, vol7ron

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  • MIME "Content-Type" folding and parameter question regarding RFCs?

    - by BastiBense
    Hello, I'm trying to implement a basic MIME parser for the multipart/related in C++/Qt. So far I've been writing some basic parser code for headers, and I'm reading the RFCs to get an idea how to do everything as close to the specification as possible. Unfortunately there is a part in the RFC that confuses me a bit: From RFC882 Section 3.1.1: Each header field can be viewed as a single, logical line of ASCII characters, comprising a field-name and a field-body. For convenience, the field-body portion of this conceptual entity can be split into a multiple-line representation; this is called "folding". The general rule is that wherever there may be linear-white-space (NOT simply LWSP-chars), a CRLF immediately followed by AT LEAST one LWSP-char may instead be inserted. Thus, the single line Alright, so I simply parse a header field and if a CRLF follows with linear whitespace, I simply concat those in a useful manner to result in a single header line. Let's proceed... From RFC2045 Section 5.1: In the Augmented BNF notation of RFC 822, a Content-Type header field value is defined as follows: content := "Content-Type" ":" type "/" subtype *(";" parameter) ; Matching of media type and subtype ; is ALWAYS case-insensitive. [...] parameter := attribute "=" value attribute := token ; Matching of attributes ; is ALWAYS case-insensitive. value := token / quoted-string token := 1*<any (US-ASCII) CHAR except SPACE, CTLs, or tspecials> Okay. So it seems if you want to specify a Content-Type header with parameters, simple do it like this: Content-Type: multipart/related; foo=bar; something=else ... and a folded version of the same header would look like this: Content-Type: multipart/related; foo=bar; something=else Correct? Good. As I kept reading the RFCs, I came across the following in RFC2387 Section 5.1 (Examples): Content-Type: Multipart/Related; boundary=example-1 start="<[email protected]>"; type="Application/X-FixedRecord" start-info="-o ps" --example-1 Content-Type: Application/X-FixedRecord Content-ID: <[email protected]> [data] --example-1 Content-Type: Application/octet-stream Content-Description: The fixed length records Content-Transfer-Encoding: base64 Content-ID: <[email protected]> [data] --example-1-- Hmm, this is odd. Do you see the Content-Type header? It has a number of parameters, but not all have a ";" as parameter delimiter. Maybe I just didn't read the RFCs correctly, but if my parser works strictly like the specification defines, the type and start-info parameters would result in a single string or worse, a parser error. Guys, what's your thought on this? Just a typo in the RFCs? Or did I miss something? Thanks!

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  • Exception thrown while accessing HTML DataTable in backing bean

    - by Denzil
    Hi folks, I am building a simple application in JSF with the CrUD functionality. I am trying to implement edit functionality using the tomahawk component .I am unable to retrieve the selected row in my backing bean. Here's my JSP file snip: <t:dataTable id="data" binding="#{selectOneRowList.dataTable}" styleClass="scrollerTable" headerClass="standardTable_Header" footerClass="standardTable_Header" rowClasses="standardTable_Row1,standardTable_Row2" columnClasses="standardTable_Column,standardTable_ColumnCentered,standardTable_Column" var="car" value="#{selectOneRowList.list}" sortColumn="#{selectOneRowList.sortColumn}" sortAscending="#{selectOneRowList.sortAscending}" preserveDataModel="false" preserveSort="true" preserveRowStates="true" rows="10" > <h:column> <f:facet name="header"> <h:outputText value="Select"/> </f:facet> <t:selectOneRow groupName="selection" id="hugo" value="#{selectOneRowList.selectedRowIndex}" onchange="submit();" immediate="true" valueChangeListener="#{selectOneRowList.processRowSelection}"/> </h:column> <h:column> <f:facet name="header"> </f:facet> <h:outputText value="#{car.id}" /> </h:column> <h:column> <f:facet name="header"> <h:outputText value="Cars" /> </f:facet> <h:outputText value="#{car.type}" /> </h:column> <t:column sortable="true"> <f:facet name="header"> <h:outputText value="Color" /> </f:facet> <h:outputText value="#{car.color}" /> </t:column> </t:dataTable> Here's my backing bean SelectOneRowList.java : public void editCar(ActionEvent event) { System.out.println("Row number ## " + _selectedRowIndex.toString() + " selected!"); System.out.println("Datatable ::"+ dataTable); System.out.println("Row Count ::" + dataTable.getRowCount()); dataItem = (SimpleCar) getDataTable().getRowData(); //selectedCar = (SimpleCar) _list.get(Integer.parseInt(_selectedRowIndex.toString())); selectedCar = (SimpleCar) dataTable.getRowData(); System.out.println(dataTable.getRowData()); } My DTO{Data Transfer Object} which is SimpleCar.java contains the variables ID, type, color and their respective setters/getters. The dataItem variable is of type "SimpleCar". The dataTable is of type HTMLDataTable. I am able to get the the first 3 SOP's but the 4th SOP isn't printed. I receive the following exception on the server : javax.faces.el.EvaluationException: Exception while invoking expression #{selectOneRowList.editCar} org.apache.myfaces.el.MethodBindingImpl.invoke(MethodBindingImpl.java:156) javax.faces.component.UICommand.broadcast(UICommand.java:89) javax.faces.component.UIViewRoot._broadcastForPhase(UIViewRoot.java:97) javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:171) org.apache.myfaces.lifecycle.InvokeApplicationExecutor.execute(InvokeApplicationExecutor.java:32) org.apache.myfaces.lifecycle.LifecycleImpl.executePhase(LifecycleImpl.java:95) org.apache.myfaces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:70) javax.faces.webapp.FacesServlet.service(FacesServlet.java:139) org.apache.myfaces.webapp.filter.ExtensionsFilter.doFilter(ExtensionsFilter.java:341) On click of the edit button the editCar method in my backing bean is invoked. I need to get the data of the selected row in my backing bean. Why is the exception occurring ? The above example is taken from the tomawhawk examples WAR distributed on the website. I have gone through many links including the ones on BalusC but none of them have helped. Regards,

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  • Hardware/Software inventory open source projects

    - by Dick dastardly
    Dear Stackoverflowers I would like to develop a Network Inventory application that works on any operating system. Reports on every possible resource attacehd to a network. Reports all pertinent details of hardware and software. Thats (and i hate to use the phrase) my "End Game". However I am running before i can crawl here. I have no experience of this type of development, e.g. discovering a computers hardware and software settings. I've spent almost two weeks googling and come up short! :-(. So I am turning to you to ask these questions:- My first step is to find an existing open source project i can incorporate into my own code that extracts the fine grained details i am after, e.g. EVERYTHING there is to know about the hardaware and software on a single machine. Does this project exist? or do i have to develop that first? Have i got to write all this in C? I am guessing getting this information about a computer is going to be easier than for printers, scanners, routers etc... e.g. everything else you would find attached to a network. Once i have access to a single computers details i then need to investigate how i can traverse an entire newtork of printers, scanners, routers, load balancers, switches, firewalls, workstations, servers, storeage devices, laptops, monitors, the list goes on and on One problem i have is i dont have a 1000 machine newtork to play on! Is there any such resource available on theinternet? (is that a silly question?) Anywho, if you dont ask you wont find out! One aspect iam really looking forward to finding out how to travers the entire network, should i be using TCP/IP for this? Whats a good site, blog, usergorup, book for TCP/IP development? How do i go about getting through firewalls? How many questions can i ask in one go? :-) My previous question on this topic ended up with PYTHON being championed as the language/script to go with to develop this application in. Having looked at a few PYTHON examples they all seemed to be related to WINDOWS networks and interrogating Windows Management Instrumentation (WMI). I had the feeling you cant rely on whats in WMI, and even if you can that s no good for UNIX netwrks. Surely there exist common code for extracting hardware and software details from a computer? Why cant i find it on the internet? Pease help? Theres no prizes though :-( Thanks in advance I would like to appologise if i have broken forum rules or not tried hard enough on my own before asking for assistance. I just would like to start moving forward with this as its one of the best projects i have been involved with. I am inspired by the many differnt number of challenges involved and that if i manage to produce a useful application at the end of it it would hopefully be extremely helpful to many people. That sit Thanks in advance DD

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  • Covariance and Contravariance in C#

    - by edalorzo
    I will start by saying that I am Java developer learning to program in C#. As such I do comparisons of what I know with what I am learning. I have been playing with C# generics for a few hours now, and I have been able to reproduce the same things I know in Java in C#, with the exception of a couple of examples using covariance and contravariance. The book I am reading is not very good in the subject. I will certainly seek more info on the web, but while I do that, perhaps you can help me find a C# implementation for the following Java code. An example is worth a thousand words, and I was hoping that by looking a good code sample I will be able to assimilate this more rapidly. Covariance In Java I can do something like this: public static double sum(List<? extends Number> numbers) { double summation = 0.0; for(Number number : numbers){ summation += number.doubleValue(); } return summation; } I can use this code as follows: List<Integer> myInts = asList(1,2,3,4,5); List<Double> myDoubles = asList(3.14, 5.5, 78.9); List<Long> myLongs = asList(1L, 2L, 3L); double result = 0.0; result = sum(myInts); result = sum(myDoubles) result = sum(myLongs); Now I did discover that C# supports covariance/contravariance only on interfaces and as long as they have been explicitly declared to do so (out). I think I was not able to reproduce this case, because I could not find a common ancestor of all numbers, but I believe that I could have used IEnumerable to implement such thing if a common ancestor exists. Since IEnumerable is a covariant type. Right? Any thoughts on how to implement the list above? Just point me into the right direction. Is there any common ancestor of all numeric types? Contravariance The contravariance example I tried was the following. In Java I can do this to copy one list into another. public static void copy(List<? extends Number> source, List<? super Number> destiny){ for(Number number : source) { destiny.add(number); } } Then I could use it with contravariant types as follows: List<Object> anything = new ArrayList<Object>(); List<Integer> myInts = asList(1,2,3,4,5); copy(myInts, anything); My basic problem, trying to implement this in C# is that I could not find an interface that was both covariant and contravariant at the same time, as it is case of List in my example above. Maybe it can be done with two different interface in C#. Any thoughts on how to implement this? Thank you very much to everyone for any answers you can contribute. I am pretty sure I will learn a lot from any example you can provide.

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  • jQuery .live fireing multiple times!

    - by cstrzelc
    Greetings Guru's, This is a little hard to explain, but I'll give it a shot. I have a quick question regarding to the .live() function in JQuery. I'm going to simplify the example here. I have a page "index.php" that has a container "#display_files_container" which is populated with anchor links that are generated dynamically by a different page "process.php". The links are loaded into that same <div> when those links are selected based on the attributes of that link. See Examples: INDEX.PHP <html> <head><title>index.php</title> <!-- this function below loads process.php and passes it the dirid variable via post. I then use this post variable inside of process.php to pull other links from the database --> <script language="text/javascript"> $('.directory').live("click", function() { $('#display_files_container').load('plugins/project_files/process.php', {dirid: $(this).attr('dirid')}); }); </script> </head> <?php /*This code initial populates the link array so we have the first links populated before the users clicks for the first time*/ some code to fetch the $current_directory_list array from the database initially.... >? <body> <div id='display_files_container'> <?php /*Cycle through the array and echo out all the links which have been pulled from DB*/ for($i=0;$i<$current_directory_count;$i++) { echo "<a href='#' class='directory' dirid='".$current_directory_list[$i]['id']." '>".$current_directory_list[$i]['directory_name']. "</a> "; } ?> </div> </body> </html> PROCESS.PHP this file includes code to populate the $current_directory_list[] array from the database based on the post variable "$_POST['dirid']" that was sent from the .click() method in index.php. It then echo's the results out and we display them in the #display_files_container container. When you click on those links the process repeats. This works..... you can click though the directory tree and it loads the new links every time. However, it seems to want to .load() the process.php file many times over for one click. The number of times process.php is loaded seems to increase the more the links are clicked. So for example you can click on a link and firebug reports that process.php was loaded 23 times..... Eventually I would imagine I would record a stackoverflow. Please let me know if you have any ideas. Are there any ways that I can assure that .live() loads the process.php file only once? Thanks, -cs

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  • overloaded stream insetion operator with a vector

    - by julz666
    hi, i'm trying to write an overloaded stream insertion operator for a class who's only member is a vector. i dont really know what i'm doing. (lets make that clear) it's a vector of "Points" which is a struct containing two doubles. i figure what i want is to insert user input (a bunch of doubles) into a stream that i then send to a modifier method? i keep working off other stream insertion examples such as... std::ostream& operator<< (std::ostream& o, Fred const& fred) { return o << fred.i_; } but when i try a similar..... istream & operator >> (istream &inStream, Polygon &vertStr) { inStream >> ws; inStream >> vertStr.vertices; return inStream; } i get an error "no match for operator etc etc. if i leave off the .vertices it compiles but i figure it's not right? (vertices is the name of my vector ) and even if it is right, i dont actually know what syntax to use in my driver to use it? also not %100 on what my modifier method needs to look like. here's my Polygon class //header #ifndef POLYGON_H #define POLYGON_H #include "Segment.h" #include <vector> class Polygon { friend std::istream & operator >> (std::istream &inStream, Polygon &vertStr); public: //Constructor Polygon(const Point &theVerts); //Default Constructor Polygon(); //Copy Constructor Polygon(const Polygon &polyCopy); //Accessor/Modifier methods inline std::vector<Point> getVector() const {return vertices;} //Return number of Vector elements inline int sizeOfVect() const {return (int) vertices.capacity();} //add Point elements to vector inline void setVertices(const Point &theVerts){vertices.push_back (theVerts);} private: std::vector<Point> vertices; }; #endif //Body using namespace std; #include "Polygon.h" // Constructor Polygon::Polygon(const Point &theVerts) { vertices.push_back (theVerts); } //Copy Constructor Polygon::Polygon(const Polygon &polyCopy) { vertices = polyCopy.vertices; } //Default Constructor Polygon::Polygon(){} istream & operator >> (istream &inStream, Polygon &vertStr) { inStream >> ws; inStream >> vertStr; return inStream; } any help greatly appreciated, sorry to be so vague, a lecturer has just kind of given us a brief example of stream insertion then left us on our own thanks. oh i realise there are probably many other problems that need fixing

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  • Looking for a function that will split profits/loss equally between 2 business partners.

    - by Hamish Grubijan
    This is not homework, for I am not a student. This is for my general curiosity. I apologize if I am reinventing the wheel here.The function I seek can be defined as follows (language agnostic): int getPercentageOfA(double moneyA, double workA, double moneyB, double workB) { // Perhaps you may assume that workA == 0 // Compute result return result; } Suppose Alice and Bob want to do business together ... such as ... selling used books. Alice is only interested in investing money in it and nothing else. Bob might invest some money, but he might have no $ available to invest. He will, however, put in the effort in finding a seller, a buyer, and doing maintenance. There are no tools, education, health insurance costs, or other expenses to consider. Both Alice and Bob wish to split the profits "equally" (A different weight like 40/60 for advanced users). Both are entrepreneurs, so they deal with low ROI/wage, and high income alike. There is no fixed wage, minimum wage, fixed ROI, or minimum ROI. They try to find the best deal possible, assume risks and go for it. Now, let's stick with the 50/50 model. If Alice invests $100, Bob invests work, and they will end up with a profit (or loss) of $60, they will split it equally - either both get $30 for their efforts/investments, or Bob ends up owing $30 to Alice. A second possibility: Both Alice and Bob invest 100, then Bob does all the work, and they end up splitting $60 profit. It looks like Alice should get only $15, because $30 of that profit came from Bob's investment and Bob's effort, so Alice shall have none of it, and the other $30 is to be split 50/50. Both of the examples above are trivial even when A and B want to split it 35/65 or what have you. Now it gets more complicated: What if Alice invests $70, and Bob invests $30 + does all of the work. It appears simple: (70,30) = (30,30) + (40,0) ... but, if only we knew how to weigh the two parts relative to each other. Another complicated (I think) example: what if Alice and Bob invest $70 and $30 respectively, and also put in an equal amount of work? I have a few data points: When A and B put in the same amount of work and the same $ - 50/50. When A puts in 100% of the money, and B does 100% of the work - 50/50. When A does all of the work and puts in all of the money - 100 for A / 0 for B (and vice-versa). When A puts in 50% of the money, and B puts in 50% of the money as well as does all of the work - 25 for A, and 75 for B (and vice-versa). If I fix things such that always workA = 0%, workB = 100% of the total work, then getPercentageOfA becomes a function: height z given x and y. The question is - how do you extrapolate this function between these several points? What is this function? If you can cover the cases when workA does not have to be 0% of the total work, and when investment vs work is split as 85/15 or using some other model, then what would the new function be?

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  • Why only one video shows up in ASP.NET Video panel ?

    - by user284523
    It is possible to have multiple videos with Flowplayer http://flowplayer.org/demos/installation/multiple-players.html To do so in ASP.NET DYNAMICALLY, one has to use a Panel (see http://idevwebs.com/Default.aspx?id=25): <%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <!-- A minimal Flowplayer setup to get you started --> <!-- include flowplayer JavaScript file that does Flash embedding and provides the Flowplayer API. --> <script type="text/javascript" src="flowplayer-3.1.4.min.js"></script> <!-- page title --> <title>Minimal Flowplayer setup</title> </head><body> <form id="form1" runat="server"> <div id="page"> <h1>Minimal Flowplayer setup</h1> <p>View commented source code to get familiar with Flowplayer installation.</p> <!-- this A tag is where your Flowplayer will be placed. it can be anywhere --> <!-- player #1 --> <asp:Panel ID="panelVideo" runat="server"> </asp:Panel> <!-- this will install flowplayer inside previous A- tag. --> <script type="text/javascript"> flowplayer("player", "flowplayer-3.1.5.swf"); </script> <!-- after this line is purely informational stuff. does not affect on Flowplayer functionality --> <p> If you are running these examples <strong>locally</strong> and not on some webserver you must edit your <a href="http://www.macromedia.com/support/documentation/en/flashplayer/help/settings_manager04.html"> Flash security settings</a>. </p> <p class="less"> Select "Edit locations" &gt; "Add location" &gt; "Browse for files" and select flowplayer-x.x.x.swf you just downloaded. </p> <h2>Documentation</h2> <p> <a href="http://flowplayer.org/documentation/installation/index.html">Flowplayer installation</a> </p> <p> <a href="http://flowplayer.org/documentation/configuration/index.html">Flowplayer configuration</a> </p> <p> See this identical page on <a href="http://flowplayer.org/demos/example/index.htm">Flowplayer website</a> </p> </div> </form> </body></html> and then add video anchor dynamically public partial class _Default : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { this.panelVideo.Controls.Add(new LiteralControl("<a href=\"" + "http://blip.tv/file/get/" + "KimAronson-TwentySeconds58192" + ".flv\" style=\"display:block;width:388px;height:230px\" id=\"player\"></a>")); this.panelVideo.Controls.Add(new LiteralControl("<a href=\"" + "http://blip.tv/file/get/" + "KimAronson-TwentySeconds67463" + ".flv\" style=\"display:block;width:388px;height:230px\" id=\"player\"></a>")); } } But it works only partially as the first video shows up not both. And all html below doesn't show up either.

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  • C++ MySQL++ Delete query statement brain killer question

    - by shauny
    Hello all, I'm relatively new to the MySQL++ connector in C++, and have an really annoying issue with it already! I've managed to get stored procedures working, however i'm having issues with the delete statements. I've looked high and low and have found no documentation with examples. First I thought maybe the code needs to free the query/connection results after calling the stored procedure, but of course MySQL++ doesn't have a free_result method... or does it? Anyways, here's what I've got: #include <iostream> #include <stdio.h> #include <queue> #include <deque> #include <sys/stat.h> #include <mysql++/mysql++.h> #include <boost/thread/thread.hpp> #include "RepositoryQueue.h" using namespace boost; using namespace mysqlpp; class RepositoryChecker { private: bool _isRunning; Connection _con; public: RepositoryChecker() { try { this->_con = Connection(false); this->_con.set_option(new MultiStatementsOption(true)); this->_con.set_option(new ReconnectOption(true)); this->_con.connect("**", "***", "***", "***"); this->ChangeRunningState(true); } catch(const Exception& e) { this->ChangeRunningState(false); } } /** * Thread method which runs and creates the repositories */ void CheckRepositoryQueues() { //while(this->IsRunning()) //{ std::queue<RepositoryQueue> queues = this->GetQueue(); if(queues.size() > 0) { while(!queues.empty()) { RepositoryQueue &q = queues.front(); char cmd[256]; sprintf(cmd, "svnadmin create /home/svn/%s/%s/%s", q.GetPublicStatus().c_str(), q.GetUsername().c_str(), q.GetRepositoryName().c_str()); if(this->DeleteQueuedRepository(q.GetQueueId())) { printf("query deleted?\n"); } printf("Repository created!\n"); queues.pop(); } } boost::this_thread::sleep(boost::posix_time::milliseconds(500)); //} } protected: /** * Gets the latest queue of repositories from the database * and returns them inside a cool queue defined with the * RepositoryQueue class. */ std::queue<RepositoryQueue> GetQueue() { std::queue<RepositoryQueue> queues; Query query = this->_con.query("CALL sp_GetRepositoryQueue();"); StoreQueryResult result = query.store(); RepositoryQueue rQ; if(result.num_rows() > 0) { for(unsigned int i = 0;i < result.num_rows(); ++i) { rQ = RepositoryQueue((unsigned int)result[i][0], (unsigned int)result[i][1], (String)result[i][2], (String)result[i][3], (String)result[i][4], (bool)result[i][5]); queues.push(rQ); } } return queues; } /** * Allows the thread to be shut off. */ void ChangeRunningState(bool isRunning) { this->_isRunning = isRunning; } /** * Returns the running value of the active thread. */ bool IsRunning() { return this->_isRunning; } /** * Deletes the repository from the mysql queue table. This is * only called once it has been created. */ bool DeleteQueuedRepository(unsigned int id) { char cmd[256]; sprintf(cmd, "DELETE FROM RepositoryQueue WHERE Id = %d LIMIT 1;", id); Query query = this->_con.query(cmd); return (query.exec()); } }; I've removed all the other methods as they're not needed... Basically it's the DeleteQueuedRepository method which isn't working, the GetQueue works fine. PS: This is on a Linux OS (Ubuntu server) Many thanks, Shaun

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  • surfaceDestroyed called out of turn

    - by Avasulthiris
    I'm currently developing on minimum sdk version 3 (Android 1.5 - cupcake) and I'm having a strange unexplained issue that I have not been able to solve on my own. It is now becoming a rather urgent issue as I've already missed 1 deadline... I'm writing a high-level library to make long term android development easier and quicker. The one specific module has to capture images for a application... I've gotten everything right so far over the last couple months, except this one little thing and I don't know what to do any more: When I use the Camera object and implement a SurfaceHolder.Callback, the methods surfaceCreated() and surfaceChanged() are called one after the other. Then when the activity finishes, surfaceDestroyed() is called. This is how it should be, but when I stick the exact same code in my library (plain Java library that references the Android API - not in an activity), surfaceDestroyed() is called directly after created and changed. As a result - the camera object is closed before I can use it and the application force closes. What a pain. I can't do anything! This method call is controlled by the device.. Why does the surface close for no reason? Even when I post it to run on the activity thread through my own invokeAndWait(Runnable) method, like I do for many other things. I have 5 different working examples of different ways and implementations of capturing images in android but I still get the same issue when I plug it into my library. I don't understand what the difference is. The code is pretty much the same - and I post all the related code to the UI thread so its not a thread handling issue or anything like that. I've rewritten it about 20 times in different ways - same issue every time.. The only other way to approach it that I know of is creating a new Camera and setting it to the VideoView. The android source (c++ native code) however provides no Camera constructor, only an open() method which automatically forwards the camera's state to 'prepared' but I can only set the camera to the VideoView from the 'initialized' state. Pretty silly, I know, but there is no way around it unless I modify the Android library source code haha. not an option! The API does not allow for this method - you are expected to use it like my first example. So essentially - i just need to understand exactly why surfaceDestroyed() is called out of turn and if there is anything I can do to avoid it closing? If i can just understand the exact logic behind it and how it works! The documentation isn't much help! Secondly, if someone knows of any alternative ways to do it, as my second example, but hopefully one which the API actually allows for? haha Thanks guys. I would post code, but its fairly complicated, a couple thousand lines for this specific class and it would probably take a couple days to explain with all the threading and event listeners and what not. I just need help with this 1 single thing. Please let me know if you have any questions.

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  • Better, simpler example of 'semantic conflict'?

    - by rhubbarb
    I like to distinguish three different types of conflict from a version control system (VCS): textual syntactic semantic A textual conflict is one that is detected by the merge or update process. This is flagged by the system. A commit of the result is not permitted by the VCS until the conflict is resolved. A syntactic conflict is not flagged by the VCS, but the result will not compile. Therefore this should also be picked up by even a slightly careful programmer. (A simple example might be a variable rename by Left and some added lines using that variable by Right. The merge will probably have an unresolved symbol. Alternatively, this might introduce a semantic conflict by variable hiding.) Finally, a semantic conflict is not flagged by the VCS, the result compiles, but the code may have problems running. In mild cases, incorrect results are produced. In severe cases, a crash could be introduced. Even these should be detected before commit by a very careful programmer, through either code review or unit testing. My example of a semantic conflict uses SVN (Subversion) and C++, but those choices are not really relevant to the essence of the question. The base code is: int i = 0; int odds = 0; while (i < 10) { if ((i & 1) != 0) { odds *= 10; odds += i; } // next ++ i; } assert (odds == 13579) The Left (L) and Right (R) changes are as follows. Left's 'optimisation' (changing the values the loop variable takes): int i = 1; // L int odds = 0; while (i < 10) { if ((i & 1) != 0) { odds *= 10; odds += i; } // next i += 2; // L } assert (odds == 13579) Right's 'optimisation' (changing how the loop variable is used): int i = 0; int odds = 0; while (i < 5) // R { odds *= 10; odds += 2 * i + 1; // R // next ++ i; } assert (odds == 13579) This is the result of a merge or update, and is not detected by SVN (which is correct behaviour for the VCS). int i = 1; // L int odds = 0; while (i < 5) // R { odds *= 10; odds += 2 * i + 1; // R // next i += 2; // L } assert (odds == 13579) The assert fails because odds is 37. So my question is as follows. Is there a simpler example than this? Is there a simple example where the compiled executable has a new crash? As a secondary question, are there cases of this that you have encountered in real code? Again, simple examples are especially welcome.

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  • Create attribute in XML

    - by user560411
    Hello. I have the following php code that adds data into XML and works correctly. However, in my second step I will create a form that deletes some of the elements. The problem is that I want to add an ID number and then the PHP file will search for it and delete entire node. My question is how can i add an ID into CD for this to work ? For example ( <cd id="xxxx"> ) Also, any ideas or examples of a code that deletes CD having the ID would be appreciate. insert.php ( my index file with the form ) <h1>Playlist</h1> <form action="insert2.php" method="post"> <fieldset> <label for="TITLE">TITLE:</label><input type="text" id="title" name="title" /><br /> <label for="title">BAND:</label> <input type="text" id="band" name="band"/><br /> <label for="path">YEAR:</label> <input type="text" id="year" name="year" /> <br /> <input type="submit" /> </fieldset> </form> <h2>Current entries:</h2> <p>TITLE - BAND - YEAR</p> <?php $doc = new DOMDocument(); $doc->load( 'insert.xml' ); $CATEGORIES = $doc->getElementsByTagName( "CD" ); foreach( $CATEGORIES as $CD ) { $TITLES = $CD->getElementsByTagName( "TITLE" ); $TITLE = $TITLES->item(0)->nodeValue; $BANDS= $CD->getElementsByTagName( "BAND" ); $BAND= $BANDS->item(0)->nodeValue; $YEARS = $CD->getElementsByTagName( "YEAR" ); $YEAR = $YEARS->item(0)->nodeValue; echo "<b>$TITLE - $BAND - $YEAR\n</b><br>"; } ?> inser2.php ( the main code ) <?php $CD = array( 'TITLE' => $_POST['title'], 'BAND' => $_POST['band'], 'YEAR' => $_POST['year'], ); $doc = new DOMDocument(); $doc->load( 'insert.xml' ); $doc->formatOutput = true; $r = $doc->getElementsByTagName("CATEGORIES")->item(0); $b = $doc->createElement("CD"); $TITLE = $doc->createElement("TITLE"); $TITLE->appendChild( $doc->createTextNode( $CD["TITLE"] ) ); $b->appendChild( $TITLE ); $BAND = $doc->createElement("BAND"); $BAND->appendChild( $doc->createTextNode( $CD["BAND"] ) ); $b->appendChild( $BAND ); $YEAR = $doc->createElement("YEAR"); $YEAR->appendChild( $doc->createTextNode( $CD["YEAR"] ) ); $b->appendChild( $YEAR ); $r->appendChild( $b ); $doc->save("insert.xml"); ?> the XML file <?xml version="1.0" encoding="utf-8"?> <MY_CD> <CATEGORIES> <CD> <TITLE>NEVER MIND THE BOLLOCKS</TITLE> <BAND>SEX PISTOLS</BAND> <YEAR>1977</YEAR> </CD> <CD> <TITLE>NEVERMIND</TITLE> <BAND>NIRVANA</BAND> <YEAR>1991</YEAR> </CD> </CATEGORIES> </MY_CD>

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  • Rendering a Long Document on iPad

    - by benjismith
    I'm implementing a document viewer with highlighting/annotation capabilities for a custom document format on iPad. The documents are kind of long (100 to 200 pages, if printed on paper) and I've had a hard time finding the right approach. Here are the requirments: 1) Basic rich-text styling: control of left/right margins. Control of font name, size, foreground/background color, and line spacing. Bold, italics, underline, etc. 2) Selection and highlighting of arbitrary text regions (not limited to paragraph boundaries, like in Safari/UIWebView). 3) Customization of the Cut/Copy/Paste popup (what is that thing called anyhow? UIActionBar?) This is one of the essential requirements of the app. My first implementation was based on UIWebView. I just rendered the document as HTML with CSS for text styling. But I couldn't get the kind of text selection behavior I wanted (across paragraph boundaries) and the UIActionBar can't be customized from within UIWebView. So I started working on a javascript approach, faking the device text-selection behavior using JQuery to trap touch events and dynamically modifying the DOM to change the background color of selected regions of text. I built a fake UIActionBar control as a hidden DIV, positioning it and unhiding it whenever there was an active selection region. Not too shabby. The main problem is that it's SLOOOOOOOW. Scrolling through the document is nice and quick, but dynamically changing the DOM is not very snappy. Plus, I couldn't figure out how to recreate the magnifier loupe, so my fake text-selection GUI doesn't look quite the same as the native implementation. Also, I haven't yet implemented the communication bridge between the javascript layer and the objective-c layer (where the rest of the app lives), but it was shaping up to be a huge hassle. So I've been looking at CoreText, but there are precious few examples on the web. I spent a little time with this simple little demo: http://github.com/jonasschnelli/I7CoreTextExample/ It shows how to use CoreText to draw an NSAttributedText string into a UIView. But it has its own problems: It doesn't implement text-selection behavior, and it doesn't present a UIActionBar, so I don't have any idea how to make that happen. And, more importantly, it tries to draw the entire document all at once, with significant performance degradations for long documents. My documents can have thousands of paragraphs, and less than 1% of the document is ever on screen at a time. On the plus side, these documents already contain precise formatting information. I know the exact page-position of every line of text, so I don't need a layout engine. Does anyone know how to implement this sort of view using CoreText? I understand that a full-fledged implementation is overkill for a question like this, but I'm looking for a good CoreText example with a few basic requirements: 1) Precise layout & formatting control (using the formatting metrics and text styles I've already calculated). 2) Arbitrary selection of text. 3) Customization of the UIActionBar. 4) Efficient recycling of resources for off-screen objects. I'd be happy to implement my own recycling when text elements scroll off-screen, but wouldn't that require re-implementing UIScrollView? I'm brand-new to iPhone development, and still getting used to Objective-C, but I've been working in other languages (Java, C#, flex/actionscript, etc) for more than ten years, so I feel confident in my ability to get the work done, if only I had a better feel for the iPhone SDK and the common coding patterns for stuff like this. Is it just me, or does the SDK documentation really suck? Anyhow, thanks for your help!

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  • How to write a bison grammer for WDI?

    - by Rizo
    I need some help in bison grammar construction. From my another question: I'm trying to make a meta-language for writing markup code (such as xml and html) wich can be directly embedded into C/C++ code. Here is a simple sample written in this language, I call it WDI (Web Development Interface): /* * Simple wdi/html sample source code */ #include <mySite> string name = "myName"; string toCapital(string str); html { head { title { mySiteTitle; } link(rel="stylesheet", href="style.css"); } body(id="default") { // Page content wrapper div(id="wrapper", class="some_class") { h1 { "Hello, " + toCapital(name) + "!"; } // Lists post ul(id="post_list") { for(post in posts) { li { a(href=post.getID()) { post.tilte; } } } } } } } Basically it is a C source with a user-friendly interface for html. As you can see the traditional tag-based style is substituted by C-like, with blocks delimited by curly braces. I need to build an interpreter to translate this code to html and posteriorly insert it into C, so that it can be compiled. The C part stays intact. Inside the wdi source it is not necessary to use prints, every return statement will be used for output (in printf function). The program's output will be clean html code. So, for example a heading 1 tag would be transformed like this: h1 { "Hello, " + toCapital(name) + "!"; } // would become: printf("<h1>Hello, %s!</h1>", toCapital(name)); My main goal is to create an interpreter to translate wdi source to html like this: tag(attributes) {content} = <tag attributes>content</tag> Secondly, html code returned by the interpreter has to be inserted into C code with printfs. Variables and functions that occur inside wdi should also be sorted in order to use them as printf parameters (the case of toCapital(name) in sample source). Here are my flex/bison files: id [a-zA-Z_]([a-zA-Z0-9_])* number [0-9]+ string \".*\" %% {id} { yylval.string = strdup(yytext); return(ID); } {number} { yylval.number = atoi(yytext); return(NUMBER); } {string} { yylval.string = strdup(yytext); return(STRING); } "(" { return(LPAREN); } ")" { return(RPAREN); } "{" { return(LBRACE); } "}" { return(RBRACE); } "=" { return(ASSIGN); } "," { return(COMMA); } ";" { return(SEMICOLON); } \n|\r|\f { /* ignore EOL */ } [ \t]+ { /* ignore whitespace */ } . { /* return(CCODE); Find C source */ } %% %start wdi %token LPAREN RPAREN LBRACE RBRACE ASSIGN COMMA SEMICOLON CCODE QUOTE %union { int number; char *string; } %token <string> ID STRING %token <number> NUMBER %% wdi : /* empty */ | blocks ; blocks : block | blocks block ; block : head SEMICOLON | head body ; head : ID | ID attributes ; attributes : LPAREN RPAREN | LPAREN attribute_list RPAREN ; attribute_list : attribute | attribute COMMA attribute_list ; attribute : key ASSIGN value ; key : ID {$$=$1} ; value : STRING {$$=$1} /*| NUMBER*/ /*| CCODE*/ ; body : LBRACE content RBRACE ; content : /* */ | blocks | STRING SEMICOLON | NUMBER SEMICOLON | CCODE ; %% I am having difficulties on defining a proper grammar for the language, specially in splitting WDI and C code . I just started learning language processing techniques so I need some orientation. Could someone correct my code or give some examples of what is the right way to solve this problem?

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  • Efficient representation of Hierarchies in Hibernate.

    - by Alison G
    I'm having some trouble representing an object hierarchy in Hibernate. I've searched around, and haven't managed to find any examples doing this or similar - you have my apologies if this is a common question. I have two types which I'd like to persist using Hibernate: Groups and Items. * Groups are identified uniquely by a combination of their name and their parent. * The groups are arranged in a number of trees, such that every Group has zero or one parent Group. * Each Item can be a member of zero or more Groups. Ideally, I'd like a bi-directional relationship allowing me to get: * all Groups that an Item is a member of * all Items that are a member of a particular Group or its descendants. I also need to be able to traverse the Group tree from the top in order to display it on the UI. The basic object structure would ideally look like this: class Group { ... /** @return all items in this group and its descendants */ Set<Item> getAllItems() { ... } /** @return all direct children of this group */ Set<Group> getChildren() { ... } ... } class Item { ... /** @return all groups that this Item is a direct member of */ Set<Group> getGroups() { ... } ... } Originally, I had just made a simple bi-directional many-to-many relationship between Items and Groups, such that fetching all items in a group hierarchy required recursion down the tree, and fetching groups for an Item was a simple getter, i.e.: class Group { ... private Set<Item> items; private Set<Group> children; ... /** @return all items in this group and its descendants */ Set<Item> getAllItems() { Set<Item> allItems = new HashSet<Item>(); allItems.addAll(this.items); for(Group child : this.getChildren()) { allItems.addAll(child.getAllItems()); } return allItems; } /** @return all direct children of this group */ Set<Group> getChildren() { return this.children; } ... } class Item { ... private Set<Group> groups; /** @return all groups that this Item is a direct member of */ Set<Group> getGroups() { return this.groups; } ... } However, this resulted in multiple database requests to fetch the Items in a Group with many descendants, or for retrieving the entire Group tree to display in the UI. This seems very inefficient, especially with deeper, larger group trees. Is there a better or standard way of representing this relationship in Hibernate? Am I doing anything obviously wrong or stupid? My only other thought so far was this: Replace the group's id, parent and name fields with a unique "path" String which specifies the whole ancestry of a group, e.g.: /rootGroup /rootGroup/aChild /rootGroup/aChild/aGrandChild The join table between Groups and Items would then contain group_path and item_id. This immediately solves the two issues I was suffering previously: 1. The entire group hierarchy can be fetched from the database in a single query and reconstructed in-memory. 2. To retrieve all Items in a group or its descendants, we can select from group_item where group_path='N' or group_path like 'N/%' However, this seems to defeat the point of using Hibernate. All thoughts welcome!

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  • Editing a Gridview row with drop-down lists gets too wide - how can I use popup panels instead?

    - by David
    I have a series of GridViews in a Tab Panel - databound to a generic List of Business Objects. The columns in the Gridview are all similar to the following: <asp:TemplateField HeaderText="Company" SortExpression="Company.ShortName"> <ItemTemplate> <asp:Label ID="lblCompany" runat="server" Text='<%# Bind("Company.ShortName") %>'></asp:Label> </ItemTemplate> <EditItemTemplate> <asp:DropDownList ID="ddlCompany" runat="server"></asp:DropDownList> </EditItemTemplate> </asp:TemplateField> The GridView generates the "Edit" link at the beginning of the row, all the events fire ok. The problem is that the data is getting long. When in 'display mode', it's fine because the GridView control is smart enough to break some text into multiple lines (in particular Project, Title and Worker names can get pretty long). The problem come in editing mode. Drop-down lists DON'T break entries into multiple lines (for obvious reasons). Going into Edit ode on a row in the Gridview can make the Griview expand horizontally to twice the screen size (blowing through the width limits in the Master page and CSS but that's only a related problem). What I need is something like the ModalPopup - but trying to tie it to an ID in an EditItemTemplate gives me errors when the page renders (because the 'ddlXXXX' doesn't exist at the time). In addition I don't know how to dynamically populate the panel so that I can get a response from it (like the ID of the Company they selected). I'm also trying to avoid javascript and would like this to be a 'pure' aspx/code-behind solution (for simplicity's sake among others). All the examples I find are of Modal Popups with the panels pre-defined. Even if it (the popup panel) were something like a list of checkboxes, it could be databound to the SortedList I have ready to go and an OK/Cancel button combination to accept or ignore things. I'm just not sure of what goes where. I'm open to suggestions. Thanks in advance. EDIT: Final solution looks as follows: <asp:TemplateField HeaderText="Company" SortExpression="Company.ShortName"> <ItemTemplate> <asp:Label ID="lblCompany" runat="server" Text='<%# Bind("Company.ShortName") %>'></asp:Label> </ItemTemplate> <EditItemTemplate> <asp:LinkButton ID="lnkCompany" runat="server" Text='<%# Bind("Company.ShortName") %>'></asp:LinkButton> <asp:Panel ID="pnlCompany" runat="server" style="display:none"> <div> <asp:DropDownList ID="ddlCompany" runat="server" ></asp:DropDownList> <br/> <asp:ImageButton ID="btnOKCo" runat="server" ImageUrl="~/Images/greencheck.gif" OnCommand="PopupButton_Command" CommandName="SelectCO" /> <asp:ImageButton ID="btnCxlCo" runat="server" ImageUrl="~/Images/RedX.gif" /> </div> </asp:Panel> <cc1:ModalPopupExtender ID="mpeCompany" runat="server" TargetControlID="lnkCompany" PopupControlID="pnlCompany" BackgroundCssClass="modalBackground" CancelControlID="btnCxlCo" DropShadow="true" PopupDragHandleControlID="pnlCompany" /> </EditItemTemplate> </asp:TemplateField> And in the code-behind, lstIDLabor is the generic List of data lines (of which Company is one of the properties that is also a business object) that is bound to the GridView: Sub PopupButton_Command(ByVal sender As Object, ByVal e As CommandEventArgs) Dim intRow As Integer Dim intVal As Integer RestoreFromSessionVariables() Select Case e.CommandName Case "SelectCO" intRow = grdIDCostLabor.EditIndex Dim ddlCo As DropDownList = CType(grdIDCost.Rows(intRow).FindControl("ddlCompany"), DropDownList) intVal = ddlCo.SelectedValue lstIDLabor(intRow).CompanyID = intVal lstIDLabor(intRow).Company = Company.Read(intVal) Case Else ' End Select MakeSessionVariables() BindGrids() End Sub

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  • evaluating cost/benefits of using extension methods in C# => 3.0

    - by BillW
    Hi, In what circumstances (usage scenarios) would you choose to write an extension rather than sub-classing an object ? < full disclosure : I am not an MS employee; I do not know Mitsu Furota personally; I do know the author of the open-source Componax library mentioned here, but I have no business dealings with him whatsoever; I am not creating, or planning to create any commercial product using extensions : in sum : this post is from pure intellectal curiousity related to my trying to (continually) become aware of "best practices" I find the idea of extension methods "cool," and obviously you can do "far-out" things with them as in the many examples you can in Mitsu Furota's (MS) blog postslink text. A personal friend wrote the open-source Componax librarylink text, and there's some remarkable facilities in there; but he is in complete command of his small company with total control over code guidelines, and every line of code "passes through his hands." While this is speculation on my part : I think/guess other issues might come into play in a medium-to-large software team situation re use of Extensions. Looking at MS's guidelines at link text, you find : In general, you will probably be calling extension methods far more often than implementing your own. ... In general, we recommend that you implement extension methods sparingly and only when you have to. Whenever possible, client code that must extend an existing type should do so by creating a new type derived from the existing type. For more information, see Inheritance (C# Programming Guide). ... When the compiler encounters a method invocation, it first looks for a match in the type's instance methods. If no match is found, it will search for any extension methods that are defined for the type, and bind to the first extension method that it finds. And at Ms's link text : Extension methods present no specific security vulnerabilities. They can never be used to impersonate existing methods on a type, because all name collisions are resolved in favor of the instance or static method defined by the type itself. Extension methods cannot access any private data in the extended class. Factors that seem obvious to me would include : I assume you would not write an extension unless you expected it be used very generally and very frequently. On the other hand : couldn't you say the same thing about sub-classing ? Knowing we can compile them into a seperate dll, and add the compiled dll, and reference it, and then use the extensions : is "cool," but does that "balance out" the cost inherent in the compiler first having to check to see if instance methods are defined as described above. Or the cost, in case of a "name clash," of using the Static invocation methods to make sure your extension is invoked rather than the instance definition ? How frequent use of Extensions would affect run-time performance or memory use : I have no idea. So, I'd appreciate your thoughts, or knowing about how/when you do, or don't do, use Extensions, compared to sub-classing. thanks, Bill

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  • Why is this XMLHttpRequest sample from Mozilla is not working in Firefox 3?

    - by j0rd4n
    I'm trying to get the sample code from Mozilla that consumes a REST web service to work under Firefox 3.0.10. The following code does NOT work in Firefox but does in IE 8! Why is this not working? Does IE 8 have support for XMLHttpRequest? Most examples I've seen use the ActiveX allocation. What should I be doing? XMLHttpRequest seems more standardized. Sample: var req = new XMLHttpRequest(); req.open('GET', 'http://localhost/myRESTfulService/resource', false); // throws 'undefined' exception req.send(null); if(req.status == 0) dump(req.responseText); The open statement is throwing an exception with the description 'undefined'. This is strange as I allocate the req object, am running it in Firefox, and checked to make sure it is defined before calling open (which it says it is of type 'object'). I've also tried the asynchronous version of this with no luck. EDIT 2: Below is my most recent code: function createRequestObject() { if( window.XMLHttpRequest ) { return new XMLHttpRequest(); } else if( window.ActiveXObject ) { return new ActiveXObject( "Microsoft.XMLHTTP" ); } return null; } function handleResponse( req ) { document.writeln( "Handling response..." ); // NEVER GETS CALLED if( req.readyState == 0 ) { document.writeln( "UNITIALIZED" ); } else if( req.readyState == 1 ) { document.writeln( "LOADING" ); } else if( req.readyState == 2 ) { document.writeln( "LOADED" ); } else if( req.readyState == 3 ) { document.writeln( "INTERACTIVE" ); } else if( req.readyState == 4 ) { document.writeln( "COMPLETE" ); if( req.status == 200 ) { document.writeln( "SUCCESS" ); } } } document.writeln( "" ); var req = createRequestObject(); try { document.writeln( "Opening service..." ); req.onreadystatechange = function() { handleResponse( req ); }; req.open('POST', 'http://localhost/test/test2.txt', true); // WORKS IN IE8 & NOT FIREFOX document.writeln( "Sending service request..." ); req.send(''); document.writeln( "Done" ); } catch( err ) { document.writeln( "ERROR: " + err.description ); } EDIT 3: Alright, I reworked this in jQuery. jQuery works great in IE but it throws 'Undefined' when running from Firefox. I double checked and 'Enable JavaScript' is turned on in Firefox - seems to work fine in all other web pages. Below is the jQuery code: function handleResponse( resp ) { alert( "Name: " + resp.Name ); alert( "URL: " + resp.URL ); } $(document).ready( function() { $("a").click( function(event) { try { $.get( "http://localhost/services/ezekielservices/configservice/ezekielservices.svc/test", "{}", function(data) { handleResponse( data ); }, "json" ); } catch( err ) { alert("'$.get' threw an exception: " + err.description); } event.preventDefault(); }); } ); // End 'ready' check Summary of Solution: Alright, web lesson 101. My problem was indeed cross-domain. I was viewing my site unpublished (just on the file system) which was hitting a published service. When I published my site under the same domain it worked. Which also brings up an important distinction between IE and Firefox. When IE experiences this scenario, it prompts the user whether or not they accept the cross-domain call. Firefox throws an exception. While I'm fine with an exception, a more descriptive one would have been helpful. Thanks for all those who helped me.

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  • Languages and VMs: Features that are hard to optimize and why

    - by mrjoltcola
    I'm doing a survey of features in preparation for a research project. Name a mainstream language or language feature that is hard to optimize, and why the feature is or isn't worth the price paid, or instead, just debunk my theories below with anecdotal evidence. Before anyone flags this as subjective, I am asking for specific examples of languages or features, and ideas for optimization of these features, or important features that I haven't considered. Also, any references to implementations that prove my theories right or wrong. Top on my list of hard to optimize features and my theories (some of my theories are untested and are based on thought experiments): 1) Runtime method overloading (aka multi-method dispatch or signature based dispatch). Is it hard to optimize when combined with features that allow runtime recompilation or method addition. Or is it just hard, anyway? Call site caching is a common optimization for many runtime systems, but multi-methods add additional complexity as well as making it less practical to inline methods. 2) Type morphing / variants (aka value based typing as opposed to variable based) Traditional optimizations simply cannot be applied when you don't know if the type of someting can change in a basic block. Combined with multi-methods, inlining must be done carefully if at all, and probably only for a given threshold of size of the callee. ie. it is easy to consider inlining simple property fetches (getters / setters) but inlining complex methods may result in code bloat. The other issue is I cannot just assign a variant to a register and JIT it to the native instructions because I have to carry around the type info, or every variable needs 2 registers instead of 1. On IA-32 this is inconvenient, even if improved with x64's extra registers. This is probably my favorite feature of dynamic languages, as it simplifies so many things from the programmer's perspective. 3) First class continuations - There are multiple ways to implement them, and I have done so in both of the most common approaches, one being stack copying and the other as implementing the runtime to use continuation passing style, cactus stacks, copy-on-write stack frames, and garbage collection. First class continuations have resource management issues, ie. we must save everything, in case the continuation is resumed, and I'm not aware if any languages support leaving a continuation with "intent" (ie. "I am not coming back here, so you may discard this copy of the world"). Having programmed in the threading model and the contination model, I know both can accomplish the same thing, but continuations' elegance imposes considerable complexity on the runtime and also may affect cache efficienty (locality of stack changes more with use of continuations and co-routines). The other issue is they just don't map to hardware. Optimizing continuations is optimizing for the less-common case, and as we know, the common case should be fast, and the less-common cases should be correct. 4) Pointer arithmetic and ability to mask pointers (storing in integers, etc.) Had to throw this in, but I could actually live without this quite easily. My feelings are that many of the high-level features, particularly in dynamic languages just don't map to hardware. Microprocessor implementations have billions of dollars of research behind the optimizations on the chip, yet the choice of language feature(s) may marginalize many of these features (features like caching, aliasing top of stack to register, instruction parallelism, return address buffers, loop buffers and branch prediction). Macro-applications of micro-features don't necessarily pan out like some developers like to think, and implementing many languages in a VM ends up mapping native ops into function calls (ie. the more dynamic a language is the more we must lookup/cache at runtime, nothing can be assumed, so our instruction mix is made up of a higher percentage of non-local branching than traditional, statically compiled code) and the only thing we can really JIT well is expression evaluation of non-dynamic types and operations on constant or immediate types. It is my gut feeling that bytecode virtual machines and JIT cores are perhaps not always justified for certain languages because of this. I welcome your answers.

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  • Why is the this-pointer needed to access inherited attributes?

    - by Shadow
    Hi, assume the following class is given: class Base{ public: Base() {} Base( const Base& b) : base_attr(b.base_attr) {} void someBaseFunction() { .... } protected: SomeType base_attr; }; When I want a class to inherit from this one and include a new attribute for the derived class, I would write: class Derived: public Base { public: Derived() {} Derived( const Derived& d ) : derived_attr(d.derived_attr) { this->base_attr = d.base_attr; } void SomeDerivedFunction() { .... } private: SomeOtherType derived_attr; }; This works for me (let's ignore eventually missing semicolons or such please). However, when I remove the "this-" in the copy constructor of the derived class, the compiler complains that "'base_attr' was not declared in this scope". I thought that, when inheriting from a class, the protected attributes would then also be accessible directly. I did not know that the "this-" pointer was needed. I am now confused if it is actually correct what I am doing there, especially the copy-constructor of the Derived-class. Because each Derived object is supposed to have a base_attr and a derived_attr and they obviously need to be initialized/set correctly. And because Derived is inheriting from Base, I don't want to explicitly include an attribute named "base_attr" in the Derived-class. IMHO doing so would generally destroy the idea behind inheritance, as everything would have to be defined again. EDIT Thank you all for the quick answers. I completely forgot the fact that the classes actually are templates. Please, see the new examples below, which are actually compiling when including "this-" and are failing when omiting "this-" in the copy-constructor of the Derived-class: Base-class: #include <iostream> template<class T> class Base{ public: Base() : base_attr(0) {} Base( const Base& b) : base_attr(b.base_attr) {} void baseIncrement() { ++base_attr; } void printAttr() { std::cout << "Base Attribute: " << base_attr << std::endl; } protected: T base_attr; }; Derived-class: #include "base.hpp" template< class T > class Derived: public Base<T>{ public: Derived() : derived_attr(1) {} Derived( const Derived& d) : derived_attr(d.derived_attr) { this->base_attr = d.base_attr; } void derivedIncrement() { ++derived_attr; } protected: T derived_attr; }; and for completeness also the main function: #include "derived.hpp" int main() { Derived<int> d; d.printAttr(); d.baseIncrement(); d.printAttr(); Derived<int> d2(d); d2.printAttr(); return 0; }; I am using g++-4.3.4. Although I understood now that it seems to come from the fact that I use template-class definitions, I did not quite understand what is causing the problem when using templates and why it works when not using templates. Could someone please further clarify this?

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  • Formatting Telerik Chart and Legend Labels in Silverlight

    - by Bryan
    I am trying to format a column called 'Month' using the 3-character month abbreviation in my data grid which is bound to a bar chart. My grid and chart are based on this demo example: http://demos.telerik.com/silverlight/#Chart/Aggregates. Basically, the grid compiles data and summarizes by Year, Quarter, Month, and then some other categories as well. For the Month column, I tried two different methods (for sorting purposes, I have to use an integer or some date value for the month). First, I just made Month an integer field and then used a converter mapped in the xaml for the 'Month' field to display 'JAN', 'FEB', etc. This worked fine for the grid, but the chart would display 1, 2, etc. instead of the month abbreviation. I researched this and was not able to come up with a solution to map the converter to the chart. So, I tried making the Month field a datetime and then set the value to 1/1/1900, 2/1/1900, etc. and specified the format of the field to 'MMM' in the xaml for the grid. I then used the following statement to set the the format in the chart when the user grouped by month: SalesAnalysisChart.DefaultView.ChartArea.AxisX.DefaultLabelFormat = "MMM"; This partially worked in that when the months were displayed across the x-axis they were labeled properly, but not when they appeared in the legend (the user, of course, can group by any of the columns which may or may not include month). I've tried setting LegendItemLabelFormat, ItemLabelFormat, etc. but without success. I'm not sure of the element on which to set the property. I only need to change the default format for just the Month column - all other columns should display normally when grouped. I also came across a class called 'LegendItemFormatConverter' which looks promising but I can't find any examples as to how to implement it. I would actually prefer the converter method because the converter I wrote displays the month abbreviation in all caps, whereas the 'MMM' format displays in upper/lower case. Here is the converter code that I originally used for the grid: using System; using System.Net; using System.Windows; using System.Windows.Controls; using System.Windows.Documents; using System.Windows.Ink; using System.Windows.Input; using System.Windows.Media; using System.Windows.Media.Animation; using System.Windows.Shapes; using System.Windows.Data; namespace ApolloSL { public class MonthConverter : IValueConverter { public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture) { if (value != null) { DateTime date = new DateTime(1900, (Int32)value, 1); return date.ToString("MMM").ToUpper(); } else { return ""; } } public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture) { return value.ToString(); } } } Please help... Thanks in advance for your assistance, Bryan

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