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  • WinForm-style Invoke() in unmanaged C++

    - by Matt Green
    I've been playing with a DataBus-type design for a hobby project, and I ran into an issue. Back-end components need to notify the UI that something has happened. My implementation of the bus delivers the messages synchronously with respect to the sender. In other words, when you call Send(), the method blocks until all the handlers have called. (This allows callers to use stack memory management for event objects.) However, consider the case where an event handler updates the GUI in response to an event. If the handler is called, and the message sender lives on another thread, then the handler cannot update the GUI due to Win32's GUI elements having thread affinity. More dynamic platforms such as .NET allow you to handle this by calling a special Invoke() method to move the method call (and the arguments) to the UI thread. I'm guessing they use the .NET parking window or the like for these sorts of things. A morbid curiosity was born: can we do this in C++, even if we limit the scope of the problem? Can we make it nicer than existing solutions? I know Qt does something similar with the moveToThread() function. By nicer, I'll mention that I'm specifically trying to avoid code of the following form: if(! this->IsUIThread()) { Invoke(MainWindowPresenter::OnTracksAdded, e); return; } being at the top of every UI method. This dance was common in WinForms when dealing with this issue. I think this sort of concern should be isolated from the domain-specific code and a wrapper object made to deal with it. My implementation consists of: DeferredFunction - functor that stores the target method in a FastDelegate, and deep copies the single event argument. This is the object that is sent across thread boundaries. UIEventHandler - responsible for dispatching a single event from the bus. When the Execute() method is called, it checks the thread ID. If it does not match the UI thread ID (set at construction time), a DeferredFunction is allocated on the heap with the instance, method, and event argument. A pointer to it is sent to the UI thread via PostThreadMessage(). Finally, a hook function for the thread's message pump is used to call the DeferredFunction and de-allocate it. Alternatively, I can use a message loop filter, since my UI framework (WTL) supports them. Ultimately, is this a good idea? The whole message hooking thing makes me leery. The intent is certainly noble, but are there are any pitfalls I should know about? Or is there an easier way to do this?

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  • Java: Preventing array going out of bounds.

    - by Troy
    I'm working on a game of checkers, if you want to read more about you can view it here; http://minnie.tuhs.org/I2P/Assessment/assig2.html When I am doing my test to see if the player is able to get to a certain square on the grid (i.e. +1 +1, +1 -1 .etc) from it's current location, I get an java.lang.ArrayIndexOutOfBoundsException error. This is the code I am using to make the move; public static String makeMove(String move, int playerNumber) { // variables to contain the starting and destination coordinates, subtracting 1 to match array size int colStart = move.charAt(1) - FIRSTCOLREF - 1; int rowStart = move.charAt(0) - FIRSTROWREF - 1; int colEnd = move.charAt(4) - FIRSTCOLREF - 1; int rowEnd = move.charAt(3) - FIRSTROWREF - 1; // variable to contain which player is which char player, enemy; if (playerNumber==1) { player= WHITEPIECE; enemy= BLACKPIECE; } else { player= BLACKPIECE; enemy= WHITEPIECE; } // check that the starting square contains a player piece if (grid [ colStart ] [ rowStart ] == player) { // check that the player is making a diagonal move if (grid [ colEnd ] [ rowEnd ] == grid [ (colStart++) ] [ (rowEnd++) ] && grid [ colEnd ] [ rowEnd ] == grid [ (colStart--) ] [ (rowEnd++) ] && grid [ colEnd ] [ rowEnd ] == grid [ (colStart++) ] [ (rowEnd--) ] && grid [ colEnd ] [ rowEnd ] == grid [ (colStart--) ] [ (rowEnd--) ]) { // check that the destination square is free if (grid [ colEnd ] [ rowEnd ] == BLANK) { grid [ colStart ] [ rowStart ] = BLANK; grid [ colEnd ] [ rowEnd ] = player; } } // check if player is jumping over a piece else if (grid [ colEnd ] [ rowEnd ] == grid [ (colStart+2) ] [ (rowEnd+2) ] && grid [ colEnd ] [ rowEnd ] == grid [ (colStart-2) ] [ (rowEnd+2) ] && grid [ colEnd ] [ rowEnd ] == grid [ (colStart+2) ] [ (rowEnd-2) ] && grid [ colEnd ] [ rowEnd ] == grid [ (colStart-2) ] [ (rowEnd-2) ]) { // check that the piece in between contains an enemy if ((grid [ (colStart++) ] [ (rowEnd++) ] == enemy ) && (grid [ (colStart--) ] [ (rowEnd++) ] == enemy ) && (grid [ (colStart++) ] [ (rowEnd--) ] == enemy ) && (grid [ (colStart--) ] [ (rowEnd--) ] == enemy )) { // check that the destination is free if (grid [ colEnd ] [ rowEnd ] == BLANK) { grid [ colStart ] [ rowStart ] = BLANK; grid [ colEnd ] [ rowEnd ] = player; } } } } I'm not sure how I can prevent the error from happening, what do you recommend?

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  • jQuery fadeIn is not working in Internet Explorer

    - by Nazaf
    I have the following HTML DIV which does not work using FadeIn in IE: $(".tip").fadeIn("slow"); /* Is not working in IE. */ $(".tip").show(); /* Works well in IE, that's weird. */ <div class="tip" style="width: 220px; display: none;"> <div class="tip-header"> <span><b>Title</b></span> <div class="right close"><a href="javascript:void(0);">close</a> <img alt="" src="/Images/close-normal.png"/></div> </div> <div class="tip-content">EBody comes here.</div> </div> .tip { display: block; z-index: 99999; position: fixed; background-color: #ffffff; -moz-box-shadow: 2px 2px 10px 2px rgba(0, 0, 0, 0.6); -webkit-box-shadow: 2px 2px 10px 2px rgba(0, 0, 0, 0.6); border:solid 1px #82C2FA; -moz-border-radius: 8px; -webkit-border-radius: 8px; } .tip-header { padding: 8px; min-height: 10px; -moz-border-radius-topleft: 8px; -moz-border-radius-topright: 8px; -webkit-border-radius-topright: 8px; -webkit-border-radius-topleft: 8px; background-color: #CFE6FD; border-bottom: 1px solid #82C2FA; } .tip-header span { font-size: 14px; color: #666666; } .tip-content { padding: 8px; text-align: left; font-size: 12px; } .close, .whats-this { cursor: pointer; } .close a { color: #085FBC; text-decoration: none; } .close img { vertical-align: bottom; }

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  • c++ i need help with this program. everytime i try to run it, i got a problem

    - by FOXMULDERIZE
    1-the program must read numeric data from a file. 2-only one line per number 3-half way between those numbers is a negative number. 4-the program must sum those who are above the negative number in a acumulator an those below the negative number in another acumulator. 5-the black screen shall print both results and determined who is grater or equal. include include using namespace std; void showvalues(int,int,int[]); void showvalues2(int,int); void sumtotal(int,int); int main() { int total1=0; int total2=0; const int SIZE_A= 9; int arreglo[SIZE_A]; int suma,total,a,b,c,d,e,f; ifstream archivo_de_entrada; archivo_de_entrada.open("numeros.txt"); //lee/// for(int count =0 ;count < SIZE_A;count++) archivo_de_entrada>>arreglo[count] ; archivo_de_entrada.close(); showvalues(0,3,arreglo); showvalues2(5,8); sumtotal(total1,total2); system("pause"); return 0; } void showvalues(int a,int b,int arreglos) { int total1=0; //muestra//////////////////////// cout<< "los num son "; for(int count = a ;count <= b;count++) total1 += arreglos[count]; cout < } void showvalues2(int c,int d) { ////////////////////////////// int total2=0; cout<< "los num 2 son "; for(count =5 ;count <=8;count++) total2 = total2 + arreglo[count]; cout < void sumtotal(int e,int f) { ///////////////////////////////// cout<<"la suma de t1 y t2 es "; total= total1 + total2; cout< }

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  • bad file descriptor with close() socket (c++)

    - by user321246
    hi everybody! I'm running out of file descriptors when my program can't connect another host. The close() system call doesn't work, the number of open sockets increases. I can se it with cat /proc/sys/fs/file-nr Print from console: connect: No route to host close: Bad file descriptor connect: No route to host close: Bad file descriptor .. Code: #include <stdio.h> #include <stdlib.h> #include <sys/socket.h> #include <netinet/in.h> #include <netdb.h> #include <string.h> #include <iostream> using namespace std; #define PORT 1238 #define MESSAGE "Yow!!! Are we having fun yet?!?" #define SERVERHOST "192.168.9.101" void write_to_server (int filedes) { int nbytes; nbytes = write (filedes, MESSAGE, strlen (MESSAGE) + 1); if (nbytes < 0) { perror ("write"); } } void init_sockaddr (struct sockaddr_in *name, const char *hostname, uint16_t port) { struct hostent *hostinfo; name->sin_family = AF_INET; name->sin_port = htons (port); hostinfo = gethostbyname (hostname); if (hostinfo == NULL) { fprintf (stderr, "Unknown host %s.\n", hostname); } name->sin_addr = *(struct in_addr *) hostinfo->h_addr; } int main() { for (;;) { sleep(1); int sock; struct sockaddr_in servername; /* Create the socket. */ sock = socket (PF_INET, SOCK_STREAM, 0); if (sock < 0) { perror ("socket (client)"); } /* Connect to the server. */ init_sockaddr (&servername, SERVERHOST, PORT); if (0 > connect (sock, (struct sockaddr *) &servername, sizeof (servername))) { perror ("connect"); sock = -1; } /* Send data to the server. */ if (sock > -1) write_to_server (sock); if (close (sock) != 0) perror("close"); } return 0; }

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  • Running out of memory.. How?

    - by maxdj
    I'm attempting to write a solver for a particular puzzle. It tries to find a solution by trying every possible move one at a time until it finds a solution. The first version tried to solve it depth-first by continually trying moves until it failed, then backtracking, but this turned out to be too slow. I have rewritten it to be breadth-first using a queue structure, but I'm having problems with memory management. Here are the relevant parts: int main(int argc, char *argv[]) { ... int solved = 0; do { solved = solver(queue); } while (!solved && !pblListIsEmpty(queue)); ... } int solver(PblList *queue) { state_t *state = (state_t *) pblListPoll(queue); if (is_solution(state->pucks)) { print_solution(state); return 1; } state_t *state_cp; puck new_location; for (int p = 0; p < puck_count; p++) { for (dir i = NORTH; i <= WEST; i++) { if (!rules(state->pucks, p, i)) continue; new_location = in_dir(state->pucks, p, i); if (new_location.x != -1) { state_cp = (state_t *) malloc(sizeof(state_t)); state_cp->move.from = state->pucks[p]; state_cp->move.direction = i; state_cp->prev = state; state_cp->pucks = (puck *) malloc (puck_count * sizeof(puck)); memcpy(state_cp->pucks, state->pucks, puck_count * sizeof(puck)); /*CRASH*/ state_cp->pucks[p] = new_location; pblListPush(queue, state_cp); } } } return 0; } When I run it I get the error: ice(90175) malloc: *** mmap(size=2097152) failed (error code=12) *** error: can't allocate region *** set a breakpoint in malloc_error_break to debug Bus error The error happens around iteration 93,000. From what I can tell, the error message is from malloc failing, and the bus error is from the memcpy after it. I have a hard time believing that I'm running out of memory, since each game state is only ~400 bytes. Yet that does seem to be what's happening, seeing as the activity monitor reports that it is using 3.99GB before it crashes. I'm using http://www.mission-base.com/peter/source/ for the queue structure (it's a linked list). Clearly I'm doing something dumb. Any suggestions?

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  • How to prevent google chrome from caching my inputs, esp hidden ones when user click back?

    - by melaos
    hi there, i have an asp.net mvc app which have quite a few hidden inputs to keep values around and formatting their names so that i can use the Model binding later when i submit the form. i stumble into a weird bug with chrome which i don't have with IE or Firefox when the user submits the form and click on the back button, i find that chrome will keep my hidden input values as well. this whole chunk is generated via javascript hence i believe chrome is caching this. function addProductRow(productId, productName) { if (productName != "") { //use guid to ensure that the row never repeats var guid = $.Guid.New(); var temp = parseFloat($(".tboProductCount").val()); //need the span to workaround for chrome var szHTML = "<tr valign=\"top\" id=\"productRow\"><td class=\"productIdCol\"><input type=\"hidden\" id=productRegsID" + temp + "\" name=\"productRegs[" + temp + "].productId\" value=\"" + productId + "\"/>" + "<span id=\"spanProdID" + temp + "\" name=\"spanProdID" + temp + "\" >" + productId + "</span>" + "</td>" //+ "<td><input type=\"text\" id=\"productRegName\" name=\"productRegs[" + temp + "].productName\" value=\"" + productName + "\" class=\"productRegName\" size=\"50\" readonly=\"readonly\"/></td>" + "<td><span id=\"productRegName\" name=\"productRegs[" + temp + "].productName\" class=\"productRegName\">"+ productName + "<\span></td>" + "<td id=\"" + guid + "\" class=\"productrowguid\" \>" + "<input type=\"text\" size=\"20\" id=\"productSerialNo" + temp + "\" name=\"productRegs[" + temp + "].serialNo\" value=\"" + "\" class=\"productSerialNo\" maxlength=\"18\" />" + "<a class=\"fancybox\" id=\"btnImgSerialNo" + temp + "\" href=\"#divSerialNo" + temp + "\"><img class=\"btnImgSerialNo\" src=\"Images/landing_14.gif\" /></a>" + "<span id=\"snFlag" + temp + "\" class=\"redWarning\"></span></td>" + "<td><input type=\"text\" id=\"productRegDate" + temp + "\" name=\"productRegs[" + temp + "].PurchaseDate\" readonly=\"readonly\" />" + "<span id=\"snRegDate" + temp + "\" class=\"redWarning\"></span></td>" + "<td align=\"center\"><img style=\"cursor:pointer\" id=\"btnImgDelete\" src=\"Images/btn_remove.gif\" onclick=\"javascript:removeProductRow('" + guid + "')\" /><div style=\"display:none;\"><div id=\"divSerialNo" + temp + "\" style=\"font-family:verdana;font-size:11px;width:600px\">" + serialnumbergeneral + "<br /><br />" + getSNImageByCategory(productId) + "</div></div></td>" + "</tr>"; $(".ProductRegistrationTable").append(szHTML); $("a.fancybox").fancybox(); //initialization $("#productRegDate" + temp).datepicker({ minDate: new Date(1996, 1 - 1, 1), maxDate: 0 }); //sanity check //s7test alert('1 '+$("#spanProdID" + temp)); alert('2 '+$("#productRegsID" + temp)); } //end function addNewProductRow i need the id to be refreshed when the user select a new product, but putting another span tag beside it shows that the span will have the new id will the hidden input will still have the previous id. is there an elegant way to workaround this issue? thanks

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  • How to set background in OpenGL captured image from OpenCV

    - by user325487
    Hey All, i'm relatively new to Artoolkitplus and openGL i'm having a tough time getting the image i capture through openCV to be set as the background image in OpenGL ... I also cannot convert the image i take through the camera using opencv to be scaled to 320x280 from 640x480 .. i also have to save my image and load if for things to work... here's my code //////////// int findMarker() { IplImage* image = cvQueryFrame( capture ); if( !capture ) { fprintf( stderr, "ERROR: capture is NULL \n" ); getchar(); return -1; } if( !image ) { fprintf( stderr, "ERROR: frame is null...\n" ); getchar(); } //cvShowImage( "Capture", frame ); //image = cvCloneImage( frame ); try{ if(!cvSaveImage("immagineTmp.jpg",image)) printf("Could not save\n"); } catch(void*) {} image = cvLoadImage("immagineTmp.jpg", 1); cvShowImage( "Image", image ); glLoadIdentity(); ////////////// glDisable(GL_DEPTH_TEST); glOrtho(0,640,0,480,-1,1); glGenTextures(1, &bgid); glBindTexture(GL_TEXTURE_2D, bgid); // Create Linear Filtered Texture glBindTexture(GL_TEXTURE_2D, bgid); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR); glTexImage2D(GL_TEXTURE_2D, 0, 3, image-width, image-height, 0, GL_RGB, GL_UNSIGNED_BYTE, image-imageData); glBindTexture(GL_TEXTURE_2D, bgid); glBegin(GL_QUADS); glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.2f, -1.0f, -2.0f); glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.2f, -1.0f, -2.0f); glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.2f, 1.0f, -2.0f); glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.2f, 1.0f, -2.0f); glEnd(); glEnable(GL_DEPTH_TEST); glLoadIdentity(); //////////// // do the OpenGL camera setup glMatrixMode(GL_PROJECTION); glLoadMatrixf(tracker-getProjectionMatrix()); int markerId = tracker-calc((unsigned char *)(image-imageData)); float conf = tracker-getConfidence(); // use the result of calc() to setup the OpenGL transformation glMatrixMode(GL_MODELVIEW); glLoadMatrixf(tracker-getModelViewMatrix()); if(markerId!=-1) { printf("\n\nFound marker %d (confidence %d%%)\n\nPose-Matrix:\n ", markerId, (int(conf*100.0f))); for(int i=0; i<16; i++) printf("%.2f %s", tracker-getModelViewMatrix()[i], (i%4==3)?"\n " : ""); } cvReleaseImage(&image); return 0; }

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  • How to download file into string with progress callback?

    - by Kaminari
    I would like to use the WebClient (or there is another better option?) but there is a problem. I understand that opening up the stream takes some time and this can not be avoided. However, reading it takes a strangely much more amount of time compared to read it entirely immediately. Is there a best way to do this? I mean two ways, to string and to file. Progress is my own delegate and it's working good. FIFTH UPDATE: Finally, I managed to do it. In the meantime I checked out some solutions what made me realize that the problem lies elsewhere. I've tested custom WebResponse and WebRequest objects, library libCURL.NET and even Sockets. The difference in time was gzip compression. Compressed stream lenght was simply half the normal stream lenght and thus download time was less than 3 seconds with the browser. I put some code if someone will want to know how i solved this: (some headers are not needed) public static string DownloadString(string URL) { WebClient client = new WebClient(); client.Headers["User-Agent"] = "Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US) AppleWebKit/532.5 (KHTML, like Gecko) Chrome/4.1.249.1045 Safari/532.5"; client.Headers["Accept"] = "application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5"; client.Headers["Accept-Encoding"] = "gzip,deflate,sdch"; client.Headers["Accept-Charset"] = "ISO-8859-2,utf-8;q=0.7,*;q=0.3"; Stream inputStream = client.OpenRead(new Uri(URL)); MemoryStream memoryStream = new MemoryStream(); const int size = 32 * 4096; byte[] buffer = new byte[size]; if (client.ResponseHeaders["Content-Encoding"] == "gzip") { inputStream = new GZipStream(inputStream, CompressionMode.Decompress); } int count = 0; do { count = inputStream.Read(buffer, 0, size); if (count > 0) { memoryStream.Write(buffer, 0, count); } } while (count > 0); string result = Encoding.Default.GetString(memoryStream.ToArray()); memoryStream.Close(); inputStream.Close(); return result; } I think that asyncro functions will be almost the same. But i will simply use another thread to fire this function. I dont need percise progress indication.

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  • how SendMailMAPI is adjusted to support multiple file attachments

    - by Tom
    I have this code that sends just one attachment by time, how can I adjust this code to send 1-2 attachments? function SendMailMAPI(const Subject, Body, FileName, SenderName, SenderEMail, RecepientName, RecepientEMail: String) : Integer; var message: TMapiMessage; lpSender, lpRecepient: TMapiRecipDesc; FileAttach: TMapiFileDesc; SM: TFNMapiSendMail; MAPIModule: HModule; begin FillChar(message, SizeOf(message), 0); with message do begin if (Subject<>'') then begin lpszSubject := PChar(Subject) end; if (Body<>'') then begin lpszNoteText := PChar(Body) end; if (SenderEMail<>'') then begin lpSender.ulRecipClass := MAPI_ORIG; if (SenderName='') then begin lpSender.lpszName := PChar(SenderEMail) end else begin lpSender.lpszName := PChar(SenderName) end; lpSender.lpszAddress := PChar('SMTP:'+SenderEMail); lpSender.ulReserved := 0; lpSender.ulEIDSize := 0; lpSender.lpEntryID := nil; lpOriginator := @lpSender; end; if (RecepientEMail<>'') then begin lpRecepient.ulRecipClass := MAPI_TO; if (RecepientName='') then begin lpRecepient.lpszName := PChar(RecepientEMail) end else begin lpRecepient.lpszName := PChar(RecepientName) end; lpRecepient.lpszAddress := PChar('SMTP:'+RecepientEMail); lpRecepient.ulReserved := 0; lpRecepient.ulEIDSize := 0; lpRecepient.lpEntryID := nil; nRecipCount := 1; lpRecips := @lpRecepient; end else begin lpRecips := nil end; if (FileName='') then begin nFileCount := 0; lpFiles := nil; end else begin FillChar(FileAttach, SizeOf(FileAttach), 0); FileAttach.nPosition := Cardinal($FFFFFFFF); FileAttach.lpszPathName := PChar(FileName); nFileCount := 1; lpFiles := @FileAttach; end; end; MAPIModule := LoadLibrary(PChar(MAPIDLL)); if MAPIModule=0 then begin Result := -1 end else begin try @SM := GetProcAddress(MAPIModule, 'MAPISendMail'); if @SM<>nil then begin Result := SM(0, Application.Handle, message, MAPI_DIALOG or MAPI_LOGON_UI, 0); end else begin Result := 1 end; finally FreeLibrary(MAPIModule); end; end; if Result<>0 then begin MessageDlg('Error sending mail ('+IntToStr(Result)+').', mtError, [mbOk], 0) end; end;

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  • Accordion nonfunctional in Opera

    - by nona
    While working as expected in all other browsers, opera refuses to tween the height of content. oddly enough, as i sat annoyed rapidly clicking it over and over again, if it's closed, and you select some text, and keep clicking the same spot long enough, sometimes it pops open. lol. seriously. ahh, it seems to sometimes open the first time clicked after the page is loaded. wth? the javascript: window.addEvent('domready', function(){ var content_height = [];i=0; $$( '.bio_accordion' ).each(function(item){ i++; content_height.push(item.getElement('.moreInfo').offsetHeight); var thisSlider = new Fx.Slide( item.getElement( '.moreInfo' ), { mode: 'horizontal' } ); thisSlider.hide(); item.getElement('.moreInfo').set('tween').tween('height', '0px'); var morph = new Fx.Morph(item.getElement( '.divToggle' )); var selected = 0; item.getElement( '.divToggle' ).addEvents({ 'mouseenter': function(){ if(!selected) this.morph('.div_highlight'); }, 'mouseleave': function(){ if(!selected) { this.morph('.divToggle'); } }, 'click': function(){ if (!selected){ if (this.getElement('.symbol').innerHTML == '+') this.getElement('.symbol').innerHTML = '-'; else this.getElement('.symbol').innerHTML = '+'; item.getElement('.moreInfo').set('tween', { duration: 1500, transition: Fx.Transitions.Bounce.easeOut }).tween('height', content_height[i]); selected = 1; thisSlider.slideIn(); } else{ if (this.getElement('.symbol').innerHTML == '+') this.getElement('.symbol').innerHTML = '-'; else this.getElement('.symbol').innerHTML = '+'; thisSlider.slideOut(); item.getElement('.moreInfo').set('tween', { duration: 1000, transition: Fx.Transitions.Bounce.easeOut }).tween('height', '0px'); selected = 0; } } }); } ); }); the html: <div class="bio_accordion"> <div class="divToggle">test<span class="symbol">-</span></div> <div class="moreInfo" style="margin-left:10px;"> aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa asdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdf aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa asdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdf aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa asdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdf </div> </div> the css: .bio_accordion { padding:0px; margin:0px; } .divToggle { cursor: pointer; color: #ffffff; background-color:#1089b5; padding: 8px; } .div_highlight { padding-left:30px; padding-right:30px; background-color:#096687; } .moreInfo { padding: 2px; padding-top:15px; padding-bottom:15px; overflow: hidden; } .symbol { float:right; }

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  • Why I get a segmentation fault?

    - by frx08
    Why I get a segmentation fault? int main() { int height, width, step, step_mono, channels; int y, x; char str[15]; uchar *data, *data_mono; CvMemStorage* storage = cvCreateMemStorage(0); CvSeq* contour = 0; CvPoint* p; CvFont font; CvCapture *capture; IplImage *frame = 0, *mono_thres = 0; capture = cvCaptureFromAVI("source.avi"); //capture video if(!cvGrabFrame(capture)) exit(0); frame = cvRetrieveFrame(capture); //capture the first frame from video source cvNamedWindow("Result", 1); while(1){ mono_thres = cvCreateImage(cvGetSize(frame), 8, 1); height = frame -> height; width = frame -> width; step = frame -> widthStep; step_mono = mono_thres -> widthStep; channels = frame -> nChannels; data = (uchar *)frame -> imageData; data_mono = (uchar *)mono_thres -> imageData; //converts the image to a binary highlighting the lightest zone for(y=0;y < height;y++) for(x=0;x < width;x++) data_mono[y*step_mono+x*1+0] = data[y*step+x*channels+0]; cvThreshold(mono_thres, mono_thres, 230, 255, CV_THRESH_BINARY); cvFindContours(mono_thres, storage, &contour, sizeof(CvContour), CV_RETR_CCOMP, CV_CHAIN_APPROX_SIMPLE); //gets the coordinates of the contours and draws a circle and the coordinates in that point p = CV_GET_SEQ_ELEM(CvPoint, contour, 1); cvCircle(frame, *p, 1, CV_RGB(0,0,0), 2); cvInitFont(&font, CV_FONT_HERSHEY_PLAIN, 1.1, 1.1, 0, 1); sprintf(str, "(%d ,%d)", p->x, p->y); cvPutText(frame, str, cvPoint(p->x+5,p->y-5), &font, CV_RGB(0,0,0)); cvShowImage("Result", mono_thres); //next frame if(!cvGrabFrame(capture)) break; frame = cvRetrieveFrame(capture); if((cvWaitKey(10) & 255) == 27) break; } cvReleaseCapture(&capture); cvDestroyWindow("Result"); return 0; }

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  • Saving JQuery Draggable Sitemap Values Correctly

    - by mdolon
    I am trying to implement Boagworld's Sitemap tutorial, however I am running into difficulty trying to correctly save the child/parent relationships. The HTML is as follows, however populated with other items as well: <input type="hidden" name="sitemap-order" id="sitemap-order" value="" /> <ul id=”sitemap”> <li id="1"> <dl> <dt><a href=”#”>expand/collapse</a> <a href=”#”>Page Title</a></dt> <dd>Text Page</dd> <dd>Published</dd> <dd><a href=”#”>delete</a></dd> </dl> <ul><!–child pages–></ul> </li> </ul> And here is the JQuery code: $('#sitemap li').prepend('<div class="dropzone"></div>'); $('#sitemap li').draggable({ handle: ' > dl', opacity: .8, addClasses: false, helper: 'clone', zIndex: 100 }); var order = ""; $('#sitemap dl, #sitemap .dropzone').droppable({ accept: '#sitemap li', tolerance: 'pointer', drop: function(e, ui) { var li = $(this).parent(); var child = !$(this).hasClass('dropzone'); //If this is our first child, we'll need a ul to drop into. if (child && li.children('ul').length == 0) { li.append('<ul/>'); } //ui.draggable is our reference to the item that's been dragged. if (child) { li.children('ul').append(ui.draggable); }else { li.before(ui.draggable); } //reset our background colours. li.find('dl,.dropzone').css({ backgroundColor: '', backgroundColor: '' }); li.find('.dropzone').css({ height: '8px', margin: '0' }); // THE PROBLEM: var parentid = $(this).parent().attr('id'); menuorder += ui.draggable.attr('id')+'=>'+parentid+','; $("#sitemap-order").val(order); }, over: function() { $(this).filter('dl').css({ backgroundColor: '#ccc' }); $(this).filter('.dropzone').css({ backgroundColor: '#aaa', height: '30px', margin: '5px 0'}); }, out: function() { $(this).filter('dl').css({ backgroundColor: '' }); $(this).filter('.dropzone').css({ backgroundColor: '', height: '8px', margin: '0' }); } }); When moving items into the top-level (without parents), the parentid value I get is of the first list item (the parent container), so I can never remove the parent value and have a top-level item. Is there a no-brainer answer that I'm just not seeing right now? Any help is appreciated.

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  • Learning... anything really

    - by WebDevHobo
    I'm particularly interested in Windows PowerShell, but here's a somewhat more general complaint: When asking for help on learning something new, be it a small subject on PHP or understanding a class in Java, what usually happens is that people direct me towards the documentation pages. What I'm looking for is somewhat of a course. A deep explanation of why something works the way it does. I know my basic programming, like Java and C#. I've never seen C or C++, though I have seen a bit of assembler. I know what the Stack and Heap are, how boxing and unboxing works, why you have to deep-copy an array instead of copying the pointer and some other things. Windows PowerShell on the other hand, I know nothing about. And I notice that when reading the small document or some code, I usually forget what it does or why it works. What I am looking for is preferably, a nice tutorial that explains the beginnings, the concepts, and goes to more difficult things at a steady pace. The only thing documentation can do is explain what a function does. That's no good to me since I don't know what I want to do yet. I could read about a thousand functions, and forget about most of them, because I don't need to implement them right after it. Randomly wandering through the documentation doesn't do me any good. So conclude, what is a good tutorial on Windows Powershell? One which explains in clear language what is happening, one which builds on previous things learned. I don't think googling this is a good idea. Doing a Google search on this would turn up numerous tutorials. And experience tells me that you have to look long and hard to find the gem you're looking for. That's why I'm asking here. Because this is the place where you can find more experienced people. Many of the PowerShell guys among you will know the good ones already, and by asking you, I avoid wasting time that could be spent learning. So to summarize: I will not google this!

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  • Javascript - Canvas image never appears on first function run

    - by Matt
    I'm getting a bit of a weird issue, the image never shows the first time you run the game in your browser, after that you see it every time. If you close your browser and re open it and run the game again, the same issue occurs - you don't see the image the first time you run it. Here's the issue in action, just hit a wall and there's no image the first time on the end game screen. Any help would be appreciated. Regards, Matt function showGameOver() { ctx.clearRect(0, 0, canvas.width, canvas.height); ctx.fillStyle = "black"; ctx.font = "16px sans-serif"; ctx.fillText("Game Over!", ((canvas.width / 2) - (ctx.measureText("Game Over!").width / 2)), 50); ctx.font = "12px sans-serif"; ctx.fillText("Your Score Was: " + score, ((canvas.width / 2) - (ctx.measureText("Your Score Was: " + score).width / 2)), 70); myimage = new Image(); myimage.src = "xcLDp.gif"; var size = [119, 26], //set up size coord = [443, 200]; ctx.font = "12px sans-serif"; ctx.fillText("Restart", ((canvas.width / 2) - (ctx.measureText("Restart").width / 2)), 197); ctx.drawImage( //draw it on canvas myimage, coord[0], coord[1], size[0], size[1] ); $("canvas").click(function(e) { //when click.. if ( testIfOver(this, e, size, coord) ) { startGame(); //reload } }); $("canvas").mousemove(function(e) { //when mouse moving if ( testIfOver(this, e, size, coord) ) { $(this).css("cursor", "pointer"); //change the cursor } else { $(this).css("cursor", "default"); //change it back } }); function testIfOver(ele,ev,size,coord){ if ( ev.pageX > coord[0] + ele.offsetLeft && ev.pageX < coord[0] + size[0] + ele.offsetLeft && ev.pageY > coord[1] + ele.offsetTop && ev.pageY < coord[1] + size[1] + ele.offsetTop ) { return true; } return false; } }

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  • Can't Show image in gridview using templates

    - by n10i
    i am trying to load images from the northwind database (categories table, images that are stored in the database) into grid view control. But it dosenot seems to work. Plz! have a look... Default.aspx <asp:GridView ID="GridView1" runat="server" AllowSorting="True" AutoGenerateColumns="False" DataKeyNames="CategoryID" DataSourceID="NorthWindSQLExpressConnectionString" EnableModelValidation="True"> <Columns> <asp:BoundField DataField="CategoryID" HeaderText="CategoryID" InsertVisible="False" ReadOnly="True" SortExpression="CategoryID" /> <asp:BoundField DataField="CategoryName" HeaderText="CategoryName" SortExpression="CategoryName" /> <asp:BoundField DataField="Description" HeaderText="Description" SortExpression="Description" /> <asp:TemplateField HeaderText="Picture" SortExpression="Picture"> <EditItemTemplate> <asp:TextBox ID="TextBox1" runat="server" Text='<%# Bind("Picture") %>'></asp:TextBox> </EditItemTemplate> <ItemTemplate> <asp:Image ID="Image1" runat="server" ImageUrl='<%# RetriveImage(Eval("CategoryID")) %>' /> </ItemTemplate> </asp:TemplateField> </Columns> </asp:GridView> <asp:SqlDataSource ID="NorthWindSQLExpressConnectionString" runat="server" ConnectionString="<%$ ConnectionStrings:NorthwindSQLExpressConnectionString %>" SelectCommand="SELECT [CategoryID], [CategoryName], [Description], [Picture] FROM [Categories]"> </asp:SqlDataSource> </div> </form> [Partial] Default.aspx.cs protected string RetriveImage(object eval) { return ("ImageHandler.ashx?CategoryID=" + eval.ToString()); } [Partial] ImageHandler.ashx public void ProcessRequest(HttpContext context) { if (context.Request.QueryString == null) { } else { try { using (var sqlCon = new SqlConnection(conString)) { const string cmdString = "Select picture from Categories where CategoryID=@CategoryID"; using (var sqlCmd = new SqlCommand(cmdString, sqlCon)) { sqlCmd.Parameters.AddWithValue("@CategoryID", context.Request.QueryString["CategoryID"]); string trmp = sqlCmd.ToString(); sqlCon.Open(); using (var sqlDr = sqlCmd.ExecuteReader()) { sqlDr.Read(); context.Response.BinaryWrite((byte[])sqlDr["Picture"]); } } } } catch (Exception ex) { context.Response.Write(ex.Message); } } }

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  • Function returning MYSQL_ROW

    - by Gabe
    I'm working on a system using lots of MySQL queries and I'm running into some memory problems I'm pretty sure have to do with me not handling pointers right... Basically, I've got something like this: MYSQL_ROW function1() { string query="SELECT * FROM table limit 1;"; MYSQL_ROW return_row; mysql_init(&connection); // "connection" is a global variable if (mysql_real_connect(&connection,HOST,USER,PASS,DB,0,NULL,0)){ if (mysql_query(&connection,query.c_str())) cout << "Error: " << mysql_error(&connection); else{ resp = mysql_store_result(&connection); //"resp" is also global if (resp) return_row = mysql_fetch_row(resp); mysql_free_result(resp); } mysql_close(&connection); }else{ cout << "connection failed\n"; if (mysql_errno(&connection)) cout << "Error: " << mysql_errno(&connection) << " " << mysql_error(&connection); } return return_row; } And function2(): MYSQL_ROW function2(MYSQL_ROW row) { string query = "select * from table2 where code = '" + string(row[2]) + "'"; MYSQL_ROW retorno; mysql_init(&connection); if (mysql_real_connect(&connection,HOST,USER,PASS,DB,0,NULL,0)){ if (mysql_query(&connection,query.c_str())) cout << "Error: " << mysql_error(&conexao); else{ // My "debugging" shows me at this point `row[2]` is already fubar resp = mysql_store_result(&connection); if (resp) return_row = mysql_fetch_row(resp); mysql_free_result(resp); } mysql_close(&connection); }else{ cout << "connection failed\n"; if (mysql_errno(&connection)) cout << "Error : " << mysql_errno(&connection) << " " << mysql_error(&connection); } return return_row; } And main() is an infinite loop basically like this: int main( int argc, char* args[] ){ MYSQL_ROW row = NULL; while (1) { row = function1(); if(row != NULL) function2(row); } } (variable and function names have been generalized to protect the innocent) But after the 3rd or 4th call to function2, that only uses row for reading, row starts losing its value coming to a segfault error... Anyone's got any ideas why? I'm not sure the amount of global variables in this code is any good, but I didn't design it and only got until tomorrow to fix and finish it, so workarounds are welcome! Thanks!

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  • Running daemon through rsh

    - by Max
    I want to run program as daemon in remote machine in Unix. I have rsh connection and I want the program to be running after disconnection. Suppose I have two programs: util.cpp and forker.cpp. util.cpp is some utility, for our purpose let it be just infinite root. util.cpp int main() { while (true) {}; return 0; } forker.cpp takes some program and run it in separe process through fork() and execve(): forker.cpp #include <stdio.h> #include <errno.h> #include <stdlib.h> #include <unistd.h> int main(int argc, char** argv) { if (argc != 2) { printf("./a.out <program_to_fork>\n"); exit(1); } pid_t pid; if ((pid = fork()) < 0) { perror("fork error."); exit(1); } else if (!pid) { // Child. if (execve(argv[1], &(argv[1]), NULL) == -1) { perror("execve error."); exit(1); } } else { // Parent: do nothing. } return 0; } If I run: ./forker util forker is finished very quickly, and bash 'is not paused', and util is running as daemon. But if I run: scp forker remote_server://some_path/ scp program remote_server://some_path/ rsh remote_server 'cd /some_path; ./forker program' then it is all the same (i.e. at the remote_sever forker is finishing quickly, util is running) but my bash in local machine is paused. It is waiting for util stopping (I checked it. If util.cpp is returning than it is ok.), but I don't understand why?! There are two questions: 1) Why is it paused when I run it through rsh? I am sure that I chose some stupid way to run daemon. So 2) How to run some program as daemon in C/C++ in unix-like platforms. Tnx!

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  • How to pass operators as parameters

    - by Rodion Ingles
    I have to load an array of doubles from a file, multiply each element by a value in a table (different values for different elements), do some work on it, invert the multiplication (that is, divide) and then save the data back to file. Currently I implement the multiplication and division process in two separate methods. Now there is some extra work behind the scenes but apart from the specific statements where the multiplication/division occurs, the rest of the code is identical. As you can imagine, with this approach you have to be very careful making any changes. The surrounding code is not trivial, so its either a case of manually editing each method or copying changes from one method to the other and remembering to change the * and / operators. After too many close calls I am fed up of this and would like to make a common function which implements the common logic and two wrapper functions which pass which operator to use as a parameter. My initial approach was to use function pointers: MultiplyData(double data) { TransformData(data, &(operator *)); } DivideData(double data) { TransformData(data, &(operator /)); } TransformData(double data, double (*func)(double op1, double op2)) { /* Do stuff here... */ } However, I can't pass the operators as pointers (is this because it is an operator on a native type?), so I tried to use function objects. Initially I thought that multiplies and divides functors in <functional> would be ideal: MultiplyData(double data) { std::multiplies<double> multFunct; TransformData(data, &multFunct); } DivideData(double data) { std::divides<double> divFunct; TransformData(data, &divFunct); } TransformData(double data, std::binary_function<double, double, double> *funct) { /* Do stuff here... */ } As you can see I was trying to use a base class pointer to pass the functor polymorphically. The problem is that std::binary_function does not declare an operator() member for the child classes to implement. Is there something I am missing, or is the solution to implement my own functor heirarchy (which really seems more trouble than it is worth)?

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  • casting doubles to integers in order to gain speed

    - by antirez
    Hello all, in Redis (http://code.google.com/p/redis) there are scores associated to elements, in order to take this elements sorted. This scores are doubles, even if many users actually sort by integers (for instance unix times). When the database is saved we need to write this doubles ok disk. This is what is used currently: snprintf((char*)buf+1,sizeof(buf)-1,"%.17g",val); Additionally infinity and not-a-number conditions are checked in order to also represent this in the final database file. Unfortunately converting a double into the string representation is pretty slow. While we have a function in Redis that converts an integer into a string representation in a much faster way. So my idea was to check if a double could be casted into an integer without lost of data, and then using the function to turn the integer into a string if this is true. For this to provide a good speedup of course the test for integer "equivalence" must be fast. So I used a trick that is probably undefined behavior but that worked very well in practice. Something like that: double x = ... some value ... if (x == (double)((long long)x)) use_the_fast_integer_function((long long)x); else use_the_slow_snprintf(x); In my reasoning the double casting above converts the double into a long, and then back into an integer. If the range fits, and there is no decimal part, the number will survive the conversion and will be exactly the same as the initial number. As I wanted to make sure this will not break things in some system, I joined #c on freenode and I got a lot of insults ;) So I'm now trying here. Is there a standard way to do what I'm trying to do without going outside ANSI C? Otherwise, is the above code supposed to work in all the Posix systems that currently Redis targets? That is, archs where Linux / Mac OS X / *BSD / Solaris are running nowaday? What I can add in order to make the code saner is an explicit check for the range of the double before trying the cast at all. Thank you for any help.

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  • unable to trigger event in IE during clonning

    - by Abhimanyu
    Following is the code which will clone a set of div with their events(onclick) which is working fine for FF but in case of IE it is not firing events associated with each div. <html> <head> <style type='text/css'> .firstdiv{ border:1px solid red; } </style> <script language="JavaScript"> function show_tooltip(idx,condition,ev) { alert(idx +"=="+condition+"=="+ev); } function createCloneNode () { var cloneObj = document.getElementById("firstdiv").cloneNode(true); document.getElementById("maindiv").appendChild(cloneObj); } function init(){ var mainDiv = document.createElement("div"); mainDiv.id = 'maindiv'; var firstDiv = document.createElement("div"); firstDiv.id ='firstdiv'; firstDiv.className ='firstdiv'; for(var j=0;j<4;j++) { var summaryDiv = document.createElement("div"); summaryDiv.id = "sDiv"+j summaryDiv.className ='summaryDiv'; summaryDiv.onmouseover = function() {this.setAttribute("style","text-decoration:underline;cursor:pointer;");} summaryDiv.onmouseout = function() {this.setAttribute("style","text-decoration:none;");} summaryDiv.setAttribute("onclick", "show_tooltip("+j+",'view_month',event)"); summaryDiv.innerHTML = 'Div'+j; firstDiv.appendChild(summaryDiv); } mainDiv.appendChild(firstDiv); var secondDiv = document.createElement("div"); var linkDiv = document.createElement("div"); linkDiv.innerHTML ='create clone of above element'; linkDiv.onclick = function() { createCloneNode(); } secondDiv.appendChild(linkDiv); mainDiv.appendChild(secondDiv); document.body.appendChild(mainDiv); } </script> </head> <body> <script language="JavaScript"> init() </script> </body> </html> can anybody tell me whats the problem in above code please correct me..

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  • urgent..haskell mini interpreter

    - by mohamed elshikh
    i'm asked to implement this project and i have problems in part b which is the eval function this is the full describtion of the project You are required to implement an interpreter for mini-Haskell language. An interpreter is dened in Wikipedia as a computer program that executes, i.e. performs, instructions written in a programming language. The interpreter should be able to evaluate functions written in a special notation, which you will dene. A function is dened by: Function name Input Parameters : dened as a list of variables. The body of the function. The body of the function can be any of the following statements: a) Variable: The function may return any of the input variables. b) Arithmetic Expressions: The arithmetic expressions include input variables and addition, sub- traction, multiplication, division and modulus operations on arithmetic expressions. c) Boolean Expressions: The Boolean expressions include the ordering of arithmetic expressions (applying the relationships: <, =<, , = or =) and the anding, oring and negation of Boolean expressions. d) If-then-else statements: where the if keyword is followed by a Boolean expression. The then and else parts may be followed by any of the statements described here. e) Guarded expressions: where each case consists of a boolean expression and any of the statements described here. The expression consists of any number of cases. The rst case whose condition is true, its body should be evaluated. The guarded expression has to terminate with an otherwise case. f) Function calls: the body of the function may have a call to another function. Note that all inputs passed to the function will be of type Int. The output of the function can be of type Int or Bool. To implement the interpreter, you are required to implement the following: a) Dene a datatype for the following expressions: Variables Arithmetic expressions Boolean expressions If-then-else statements Guarded expressions Functions b) Implement the function eval which evaluates a function. It takes 3 inputs: The name of a function to be evaluated represented as a string. A list of inputs to that function. The arguments will always be of datatype Int. A list of functions. Each function is represented as instance of the datatype that you have created for functions. c) Implement the function get_type that returns the type of the function (as a string). The input to this function is the same as in part b. here is what i've done data Variable = v(char) data Arth= va Variable | Add Arth Arth | Sub Arth Arth | Times Arth Arth | Divide Arth Arth data Bol= Great Arth Arth | Small Arth Arth | Geq Arth Arth | Seq Arth Arth | And Bol Bol | Or Bol Bol | Neg Bol data Cond = data Guard = data Fun =cons String [Variable] Body data Body= bodycons(String) |Bol |Cond |Guard |Arth

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  • Marshalling non-Blittable Structs from C# to C++

    - by Greggo
    I'm in the process of rewriting an overengineered and unmaintainable chunk of my company's library code that interfaces between C# and C++. I've started looking into P/Invoke, but it seems like there's not much in the way of accessible help. We're passing a struct that contains various parameters and settings down to unmanaged codes, so we're defining identical structs. We don't need to change any of those parameters on the C++ side, but we do need to access them after the P/Invoked function has returned. My questions are: What is the best way to pass strings? Some are short (device id's which can be set by us), and some are file paths (which may contain Asian characters) Should I pass an IntPtr to the C# struct or should I just let the Marshaller take care of it by putting the struct type in the function signature? Should I be worried about any non-pointer datatypes like bools or enums (in other, related structs)? We have the treat warnings as errors flag set in C++ so we can't use the Microsoft extension for enums to force a datatype. Is P/Invoke actually the way to go? There was some Microsoft documentation about Implicit P/Invoke that said it was more type-safe and performant. For reference, here is one of the pairs of structs I've written so far: C++ /** Struct used for marshalling Scan parameters from managed to unmanaged code. */ struct ScanParameters { LPSTR deviceID; LPSTR spdClock; LPSTR spdStartTrigger; double spinRpm; double startRadius; double endRadius; double trackSpacing; UINT64 numTracks; UINT32 nominalSampleCount; double gainLimit; double sampleRate; double scanHeight; LPWSTR qmoPath; //includes filename LPWSTR qzpPath; //includes filename }; C# /// <summary> /// Struct used for marshalling scan parameters between managed and unmanaged code. /// </summary> [StructLayout(LayoutKind.Sequential)] public struct ScanParameters { [MarshalAs(UnmanagedType.LPStr)] public string deviceID; [MarshalAs(UnmanagedType.LPStr)] public string spdClock; [MarshalAs(UnmanagedType.LPStr)] public string spdStartTrigger; public Double spinRpm; public Double startRadius; public Double endRadius; public Double trackSpacing; public UInt64 numTracks; public UInt32 nominalSampleCount; public Double gainLimit; public Double sampleRate; public Double scanHeight; [MarshalAs(UnmanagedType.LPWStr)] public string qmoPath; [MarshalAs(UnmanagedType.LPWStr)] public string qzpPath; }

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  • Can I write a test that succeeds if and only if a statement does not compile?

    - by Billy ONeal
    I'd like to prevent clients of my class from doing something stupid. To that end, I have used the type system, and made my class only accept specific types as input. Consider the following example (Not real code, I've left off things like virtual destructors for the sake of example): class MyDataChunk { //Look Ma! Implementation! }; class Sink; class Source { virtual void Run() = 0; Sink *next_; void SetNext(Sink *next) { next_ = next; } }; class Sink { virtual void GiveMeAChunk(const MyDataChunk& data) { //Impl }; }; class In { virtual void Run { //Impl } }; class Out { }; //Note how filter and sorter have the same declaration. Concrete classes //will inherit from them. The seperate names are there to ensure only //that some idiot doesn't go in and put in a filter where someone expects //a sorter, etc. class Filter : public Source, public Sink { //Drop objects from the chain-of-command pattern that don't match a particular //criterion. }; class Sorter : public Source, public Sink { //Sorts inputs to outputs. There are different sorters because someone might //want to sort by filename, size, date, etc... }; class MyClass { In i; Out o; Filter f; Sorter s; public: //Functions to set i, o, f, and s void Execute() { i.SetNext(f); f.SetNext(s); s.SetNext(o); i.Run(); } }; What I don't want is for somebody to come back later and go, "Hey, look! Sorter and Filter have the same signature. I can make a common one that does both!", thus breaking the semantic difference MyClass requires. Is this a common kind of requirement, and if so, how might I implement a test for it?

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  • Are Objective-C initializers allowed to share the same name?

    - by NattKatt
    I'm running into an odd issue in Objective-C when I have two classes using initializers of the same name, but differently-typed arguments. For example, let's say I create classes A and B: A.h: #import <Cocoa/Cocoa.h> @interface A : NSObject { } - (id)initWithNum:(float)theNum; @end A.m: #import "A.h" @implementation A - (id)initWithNum:(float)theNum { self = [super init]; if (self != nil) { NSLog(@"A: %f", theNum); } return self; } @end B.h: #import <Cocoa/Cocoa.h> @interface B : NSObject { } - (id)initWithNum:(int)theNum; @end B.m: #import "B.h" @implementation B - (id)initWithNum:(int)theNum { self = [super init]; if (self != nil) { NSLog(@"B: %d", theNum); } return self; } @end main.m: #import <Foundation/Foundation.h> #import "A.h" #import "B.h" int main (int argc, const char * argv[]) { NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init]; A *a = [[A alloc] initWithNum:20.0f]; B *b = [[B alloc] initWithNum:10]; [a release]; [b release]; [pool drain]; return 0; } When I run this, I get the following output: 2010-04-26 20:44:06.820 FnTest[14617:a0f] A: 20.000000 2010-04-26 20:44:06.823 FnTest[14617:a0f] B: 1 If I reverse the order of the imports so it imports B.h first, I get: 2010-04-26 20:45:03.034 FnTest[14635:a0f] A: 0.000000 2010-04-26 20:45:03.038 FnTest[14635:a0f] B: 10 For some reason, it seems like it's using the data type defined in whichever @interface gets included first for both classes. I did some stepping through the debugger and found that the isa pointer for both a and b objects ends up the same. I also found out that if I no longer make the alloc and init calls inline, both initializations seem to work properly, e.g.: A *a = [A alloc]; [a initWithNum:20.0f]; If I use this convention when I create both a and b, I get the right output and the isa pointers seem to be different for each object. Am I doing something wrong? I would have thought multiple classes could have the same initializer names, but perhaps that is not the case.

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