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• DataSets to POCOs - an inquiry regarding DAL architecture

  - by alexsome

  Hello all, I have to develop a fairly large ASP.NET MVC project very quickly and I would like to get some opinions on my DAL design to make sure nothing will come back to bite me since the BL is likely to get pretty complex. A bit of background: I am working with an Oracle backend so the built-in LINQ to SQL is out; I also need to use production-level libraries so the Oracle EF provider project is out; finally, I am unable to use any GPL or LGPL code (Apache, MS-PL, BSD are okay) so NHibernate/Castle Project are out. I would prefer - if at all possible - to avoid dishing out money but I am more concerned about implementing the right solution. To summarize, there are my requirements: Oracle backend Rapid development (L)GPL-free Free I'm reasonably happy with DataSets but I would benefit from using POCOs as an intermediary between DataSets and views. Who knows, maybe at some point another DAL solution will show up and I will get the time to switch it out (yeah, right). So, while I could use LINQ to convert my DataSets to IQueryable, I would like to have a generic solution so I don't have to write a custom query for each class. I'm tinkering with reflection right now, but in the meantime I have two questions: Are there any problems I overlooked with this solution? Are there any other approaches you would recommend to convert DataSets to POCOs? Thanks in advance.

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• x86_64 assembler: only one call per subroutine?

  - by zneak

  Hello everyone, I decided yesterday to start doing assembler. Most of it is okay (well, as okay as assembler can be), but I'm getting some problems with gas. It seems that I can call functions only once. After that, any subsequent call opcode with the same function name will fail. I must be doing something terribly wrong, though I can't see what. Take this small C function for instance: void path_free(path_t path) { if (path == NULL) return; free(((point_list_t*)path)->points); free(path); } I "translated" it to assembler like that: .globl _path_free _path_free: push rbp mov rbp, rsp cmp rdi, 0 jz byebye push rdi mov rdi, qword ptr [rdi] call _free pop rdi sub rsp, 8 call _free byebye: leave ret This triggers the following error for the second call _free: suffix or operands invalid for ``call''. And if I change it to something else, like free2, everything works (until link time, that is). Assembler code gcc -S gave me looks very similar to what I've done (except it's in AT&T syntax), so I'm kind of lost. I'm doing this on Mac OS X under the x86_64 architecture.

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• Is saving to database just to get an ID a bad hack?

  - by Narsil

  I hope the title is not too confusing. I am trying to make folders with linq-to-sql objects' IDs. Actually I have to create folders before I should save them. I will use them to keep user uploaded files. As you can see I have to create the folder with the FileID before I can save it there. So I just save a record which will be edited or maybe deleted File newFile = new File(); ...//add some values to fields so they don't throw rule violations db.AddFile(newFile); db.Save(); System.IO.Directory.CreateDirectory("..Uploads/"+newFile.FileId.ToString()); After that I will have to edit some fields and save again. Of course user might stop upload and I would have to delete it. I know I can write a stored procedure to get the next available FileID but some other upload happening at the same time would get the same number. So they would write in same directory which is a thing I don't want. Should I go on with this, would there be some problems? Can you think of a better way?

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• Windows batch - loop over folder string and parse out last folder name

  - by Tim Peel

  Hi, I need to grab the folder name of a currently executing batch file. I have been trying to loop over the current directory using the following syntax (which is wrong at present): set mydir = %~p0 for /F "delims=\" %i IN (%mydir%) DO @echo %i Couple of issues in that I cannot seem to pass the 'mydir' variable value in as the search string. It only seems to work if I pass in commands; I have the syntax wrong and cannot work out why. My thinking was to loop over the folder string with a '\' delimiter but this is causing problems too. If I set a variable on each loop then the last value set will be the current folder name. For example, given the following path: C:\Folder1\Folder2\Folder3\Archive.bat I would expect to parse out the value 'Folder3'. I need to parse that value out as its name will be part of another folder I am going to create further down in the batch file. Many thanks if anyone can help. I may be barking up the wrong tree completely so any other approaches would be greatly received also. Tim

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• Dynamically add items to Tkinter Canvas

  - by nick369

  I'm attempting to learn Tkinter with the goal of being able to create a 'real-time' scope to plot data. As a test, I'm trying to draw a polygon on the canvas every time the 'draw' button is pressed. The triangle position is randomized. I have two problems: There is a triangle on the canvas as soon as the program starts, why and how do I fix this? It doesn't draw any triangles when I press the button, at least none that I can see. CODE from Tkinter import * from random import randint class App: def __init__(self,master): #frame = Frame(master) #frame.pack(side = LEFT) self.plotspc = Canvas(master,height = 100, width = 200, bg = "white") self.plotspc.grid(row=0,column = 2, rowspan = 5) self.button = Button(master, text = "Quit", fg = "red", \ command = master.quit) self.button.grid(row=0,column=0) self.drawbutton = Button(master, text = "Draw", command = \ self.pt([50,50])) self.drawbutton.grid(row = 0, column = 1) def pt(self, coords): coords[0] = coords[0] + randint(-20,20) coords[1] = coords[1] + randint(-20,20) x = (0,5,10) y = (0,10,0) xp = [coords[0] + xv for xv in x] yp = [coords[1] + yv for yv in y] ptf = zip(xp,yp) self.plotspc.create_polygon(*ptf) if _name_ == "_main_": root = Tk() app = App(root) root.mainloop() The code is formatting strangely within the code tags, I have no idea how to fix this.

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• multiple ajax requests with jquery

  - by Emil

  I got problems with the async nature of Javascript / JQuery. Lets say the following (no latency is counted for, in order to not make it so troublesome); I got three buttons (A, B, C) on a page, each of the buttons adds an item into a shopping cart with one ajax-request each. If I put an intentional delay of 5 seconds in the serverside script (PHP) and pushes the buttons with 1 second apart, I want the result to be the following: Request A, 5 seconds Request B, 6 seconds Request C, 7 seconds However, the result is like this Request A, 5 seconds Request B, 10 seconds Request C, 15 seconds This have to mean that the requests are queued and not run simultaneously, right? Isnt this opposite to what async is? I also tried to add a random get-parameter to the url in order to force some uniqueness to the request, no luck though. I did read a little about this. If you avoid using the same "request object (?)" this problem wont occure. Is it possible to force this behaviour in JQuery? This is the code that I am using $.ajax( { url : strAjaxUrl + '?random=' + Math.floor(Math.random()*9999999999), data : 'ajax=add-to-cart&product=' + product, type : 'GET', success : function(responseData) { // update ui }, error : function(responseData) { // show error } }); I also tried both GET and POST, no difference. I want the requests to be sent right when the button is clicked, not when the previous request is finnished. I want the requests to be run simultaneously, not in a queue.

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• Canceling a WSK I/O operation when driver is unloading

  - by eaducac

  I've been learning how to write drivers with the Windows DDK recently. After creating a few test drivers experimenting with system threads and synchronization, I decided to step it up a notch and write a driver that actually does something, albeit something useless. Currently, my driver connects to my other computer using Winsock Kernel and just loops and echoes back whatever I send to it until it gets the command "exit", which causes it to break out of the loop. In my loop, after I call WskReceive() to get some data from the other computer, I use KeWaitForMultipleObjects() to wait for either of two SynchronizationEvents. BlockEvent gets set by my IRP's CompletionRoutine() to let my thread know that it's received some data from the socket. EndEvent gets set by my DriverUnload() routine to tell the thread that it's being unloaded and it needs to terminate. When I send the "exit" command, the thread terminates with no problems, and I can safely unload the driver afterward. If I try to stop the driver while it's still waiting on data from the other computer, however, it blue screens with the error DRIVER_UNLOADED_WITHOUT_CANCELLING_PENDING_OPERATIONS. After I get the EndEvent but before I exit the loop, I've tried canceling the IRP with IoCancelIrp() and completing it with IoCompleteRequest(), but both of those give me DRIVER_IRQL_NOT_LESS_OR_EQUAL errors. I then tried calling WskDisconnect(), hoping that would cause the receive operation to complete, but that took me back to the CANCELLING_PENDING_OPERATIONS error. How do I cancel my pending I/O operation from my WSK socket at the IRQL I'm running at when the driver is unloaded?

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• How to exit current activity to homescreen (without using "Home" button)?

  - by steff

  Hi everyone, I am sure this will have been answered but I proved unable to find it. So please excuse my redundancy. What I am trying to do is emulating the "Home" button which takes one back to Android's homescreen. So here is what causes me problems: I have 3 launcher activities. The first one (which is connected to the homescreen icon) is just a (password protected) configuration activity. It will not be used by the user (just admin) One of the other 2 (both accessed via an app widget) is a questionnaire app. I'm allowing to jump back between questions via the Back button or a GUI back button as well. When the questionnaire is finished I sum up the answers given and provide a "Finish" button which should take the user back to the home screen. For the questionnaire app I use a single activity (called ItemActivity) which calls itself (is that recursion as well when using intents?) to jump from one question to another: Questionnaire.serializeToXML(); Intent i = new Intent().setClass(c, ItemActivity.class); if(Questionnaire.instance.getCurrentItemNo() == Questionnaire.instance.getAmountOfItems()) { Questionnaire.instance.setCompleted(true); } else Questionnaire.instance.nextItem(); startActivity(i); The final screen shows something like "Thank you for participating" as well as the formerly described button which should take one back to the homescreen. But I don't really get how to exit the Activity properly. I've e.g. used this.finish(); but this strangely brings up the "Thank you" screen again. So how can I just exit by jumping back to the homescreen?? Sorry for the inconvinience. Regards, Steff

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• Date Picker Control Not Displaying Proper Date (Access 2003)

  - by JPM

  Hi everyone, I just have a quick question. I am maintaining an app for my summer co-op position, and a new requirement came down today where the user requested to have a date control added to a form to mark the date of when an employee is "laid off". This control is enabled/disabled by a toggle button, and has its control source bound to a field that I added in the database. All the functionality has been added and tested, but.... The issue I am having is that the date picker is on a tab control (the 2nd page) and I am having problems trying to get the control to display the date that is stored in the field I created. I know the control is storing any changes made using it, but since the user asked to move the control over to the 2nd tab (it was on the first), it just shows today's date, not the date entered using the control. To make things a little more strange, if I place the control anywhere except the tab control, it seems to be working fine. I've even placed a textbox on the tab and set its control source to the database field, and it displays just fine. What gives? And I have registered the .ocx with Access, and as I mentioned before, the actual database is storing the data. Just not displaying it. Any ideas as to what I am doing wrong?

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• Minimal assembler program for CP/M 3.1 (z80)

  - by Andrew J. Brehm

  I seem to be losing the battle against my stupidity. This site explains the system calls under various versions of CP/M. However, when I try to use call 2 (C_WRITE, console output), nothing much happens. I have the following code. ORG 100h LD E,'a' LD C,2 CALL 5 CALL 0 I recite this here from memory. If there are typos, rest assured they were not in the original since the file did compile and I had a COM file to start. I am thinking the lines mean the following: Make sure this gets loaded at address 100h (0h to FFh being the zero page). Load ASCII 'a' into E register for system call 2. Load integer 2 into C register for system call 2. Make system call (JMP to system call is at address 5 in zero page). End program (Exit command is at address 0 in zero page). The program starts and exits with no problems. If I remove the last command, it hangs the computer (which I guess is also expected and shows that CALL 0 works). However, it does not print the ASCII character. (But it does print an extra new line, but the system might have done that.) How can I get my CP/M program to do what the system call is supposed to do? What am I doing wrong?

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• NullPointerException in NetBeans 6.5 IDE itself

  - by titaniumdecoy

  When I use NetBeans for almost any task (in particular, attempting to open a project), a red minus sign in the bottom right corner of the IDE starts blinking and I get the following NullPointerException error when I click it. Unfortunately I cannot reinstall NetBeans since I am using a shared computer lab account. java.lang.NullPointerException at org.openide.util.Exceptions.attachMessage(Unknown Source) at org.netbeans.modules.project.ant.Util$ErrHandler.annotate(Unknown Source) at org.netbeans.modules.project.ant.Util$ErrHandler.fatalError(Unknown Source) at com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper.fatalError(ErrorHandlerWrapper.java:177) at com.sun.org.apache.xerces.internal.impl.XMLErrorReporter.reportError(XMLErrorReporter.java:388) at com.sun.org.apache.xerces.internal.impl.XMLScanner.reportFatalError(XMLScanner.java:1414) at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl$PrologDriver.next(XMLDocumentScannerImpl.java:925) at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(XMLDocumentScannerImpl.java:648) at com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl.next(XMLNSDocumentScannerImpl.java:140) at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(XMLDocumentFragmentScannerImpl.java:510) at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:807) at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:737) at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(XMLParser.java:107) at com.sun.org.apache.xerces.internal.parsers.DOMParser.parse(DOMParser.java:225) at com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl.parse(DocumentBuilderImpl.java:283) at org.openide.xml.XMLUtil.parse(Unknown Source) at org.netbeans.modules.project.ant.AntBasedProjectFactorySingleton.loadProjectXml(Unknown Source) at org.netbeans.modules.project.ant.AntBasedProjectFactorySingleton.loadProject(Unknown Source) at org.netbeans.api.project.ProjectManager.createProject(Unknown Source) at org.netbeans.api.project.ProjectManager.access$300(Unknown Source) at org.netbeans.api.project.ProjectManager$2.run(Unknown Source) at org.netbeans.api.project.ProjectManager$2.run(Unknown Source) at org.openide.util.Mutex.readAccess(Unknown Source) at org.netbeans.api.project.ProjectManager.findProject(Unknown Source) at org.netbeans.modules.project.ui.OpenProjectList.fileToProject(Unknown Source) at org.netbeans.modules.project.ui.ProjectChooserAccessory$ProjectFileView.run(Unknown Source) at org.openide.util.RequestProcessor$Task.run(Unknown Source) [catch] at org.openide.util.RequestProcessor$Processor.run(Unknown Source) I have recently had problems with going over my disk space quota on this computer lab account. I cleaned up my files and I now have about 10MB free. I'm not sure whether or not this is related to the problem with NetBeans.

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• Set HttpContext.Current.User from Thread.CurrentPrincipal

  - by Argons

  I have a security manager in my application that works for both windows and web, the process is simple, just takes the user and pwd and authenticates them against a database then sets the Thread.CurrentPrincipal with a custom principal. For windows applications this works fine, but I have problems with web applications. After the process of authentication, when I'm trying to set the Current.User to the custom principal from Thread.CurrentPrincipal this last one contains a GenericPrincipal. Am I doing something wrong? This is my code: Login.aspx protected void btnAuthenticate_Click(object sender, EventArgs e) { Authenticate("user","pwd"); FormsAuthenticationTicket authenticationTicket = new FormsAuthenticationTicket(1, "user", DateTime.Now, DateTime.Now.AddMinutes(30), false, ""); string ticket = FormsAuthentication.Encrypt(authenticationTicket); HttpCookie authenticationCookie = new HttpCookie(FormsAuthentication.FormsCookieName, ticket); Response.Cookies.Add(authenticationCookie); Response.Redirect(FormsAuthentication.GetRedirectUrl("user", false)); } Global.asax (This is where the problem appears) protected void Application_AuthenticateRequest(object sender, EventArgs e) { HttpCookie authCookie = Context.Request.Cookies[FormsAuthentication.FormsCookieName]; if (authCookie == null) return; if (HttpContext.Current.User != null && HttpContext.Current.User.Identity.IsAuthenticated && HttpContext.Current.User.Identity is FormsIdentity) { HttpContext.Current.User = System.Threading.Thread.CurrentPrincipal; //Here the value is GenericPrincipal } Thanks in advance for any help. }

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• CSS Background image in Redmine template arbitrarily not loading

  - by Pekka

  I`m in the process of building a template for Redmine (a project management system based on Ruby on Rails.) Ruby is running on a virtual server from a Bitnami.org installation package. The OS is Windows. The template essentially consists of a styles.css file. In that file, I have the following line: #header { padding: 0px; padding-top: 48px; background-color: #62DFFF; background-image: url(../images/bkg.jpg) background-position: center bottom; background-repeat: repeat-x; height:150px; } It's a header element with a background image. The problem: This background image arbitrarily appears and disappears when reloading. Say you reload ten times in twenty seconds; the image will appear in two instances, and be missing in the 18 others. I would have put this down to server problems, but the weird thing is that when it's missing, the request for the image doesn't appear in Firebug's net tab at all. Even if it were cached, the request should be there. Raw screenshots of the identical page on two reloads: I am 100% sure the CSS file does not change in between. I have examined both instances with Firebug and the CSS is identical. It happens in both Firefox and Chrome so it must be something basic I'm overlooking. What could be causing a browser not to load a resource at all? I have zero idea about Ruby nor Rails - getting Redmine running and customized is all I have ever had to do with this platform - so I don't really know where to look. Apache's, Mongrel's and Redmine's error logs look fine, though.

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• CakePHP: Missing database table

  - by Justin

  I have a CakePHP application that is running fine locally. I uploaded it to a production server and the first page that uses a database connection gives the "Missing Database Table" error. When I look at the controller dump, it's complaining about the first table. I've tried a variety of things to fix this problem, with no luck: I've confirmed that at the command line I can login with the given MySQL credentials in database.php I've confirmed this table exists I've tried using the MySQL root credentials (temporarily) to see if the problem lies with permissions of the user. The same error appeared. My debug level is currently set to 3 I've deleted the entire contents of /app/tmp/cache I've set 777 permissions on /app/tmp* I've confirmed that I can run DESCRIBE commands at the commant line MySQL when logged in with the MySQL credentials used by by the application I've verified that the CakePHP log file only contains the error I'm setting in the browser window. I've tried all the suggestions I could find in similar postings on SO I've Googled around and didn't find any other ideas I think I've eliminating the obvious problems and my research isn't turning anything up. I feel like I'm missing something obvious. Any ideas?

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• Why this code generates different numbers?

  - by frbry

  Hello, I have this function that creates a unique number for hard-disk and CPU combination. DWORD hw_hash() { char drv[4]; char szNameBuffer[256]; DWORD dwHddUnique; DWORD dwProcessorUnique; DWORD dwUniqueKey; char *sysDrive = getenv ("SystemDrive"); strcpy(drv, sysDrive); drv[2] = '\\'; drv[3] = 0; GetVolumeInformation(drv, szNameBuffer, 256, &dwHddUnique, NULL, NULL, NULL, NULL); SYSTEM_INFO si; GetSystemInfo(&si); dwProcessorUnique = si.dwProcessorType + si.wProcessorArchitecture + si.wProcessorRevision; dwUniqueKey = dwProcessorUnique + dwHddUnique; return dwUniqueKey; } It returns different numbers if I format my hard-disk and install a new Windows. Any ideas, why? Thank you. Edit: OK, Got it: This function returns the volume serial number that the operating system assigns when a hard disk is formatted. To programmatically obtain the hard disk's serial number that the manufacturer assigns, use the Windows Management Instrumentation (WMI) Win32_PhysicalMedia property SerialNumber. I should do more research before posting my problems online. Sorry to bother you, let's keep this here in case anybody else can need it.

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• javascript innerHTML without childNodes?

  - by John Doe

  hi all im having a firefox issue where i dont see the wood for the trees using ajax i get html source from a php script this html code contains a tag and within the tbody some more tr/td's now i want to append this tbody plaincode to an existing table. but there is one more condition: the table is part of a form and thus contains checkboxe's and drop down's. if i would use table.innerHTML += content; firefox reloads the table and reset's all elements within it which isnt very userfriendly as id like to have what i have is this // content equals transport.responseText from ajax request function appendToTable(content){ var wrapper = document.createElement('table'); wrapper.innerHTML = content; wrapper.setAttribute('id', 'wrappid'); wrapper.style.display = 'none'; document.body.appendChild(wrapper); // get the parsed element - well it should be wrapper = document.getElementById('wrappid'); // the destination table table = document.getElementById('tableid'); // firebug prints a table element - seems right console.log(wrapper); // firebug prints the content ive inserted - seems right console.log(wrapper.innerHTML); var i = 0; // childNodes is iterated 2 times, both are textnode's // the second one seems to be a simple '\n' for(i=0;i<wrapper.childNodes.length;i++){ // firebug prints 'undefined' - wth!?? console.log(wrapper.childNodes[i].innerHTML); // firebug prints a textnode element - <TextNode textContent=" "> console.log(wrapper.childNodes[i]); table.appendChild(wrapper.childNodes[i]); } // WEIRD: firebug has no problems showing the 'wrappid' table and its contents in the html view - which seems there are the elements i want and not textelements } either this is so trivial that i dont see the problem OR its a corner case and i hope someone here has that much of expirience to give an advice on this - anyone can imagine why i get textnodes and not the finally parsed dom elements i expect? btw: btw i cant give a full example cause i cant write a smaller non working piece of code its one of those bugs that occure in the wild and not in my testset thx all

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• handling large arrays with array_diff

  - by bigmac

  I have been trying to compare two arrays. Using array_intersect presents no problems. When using array_diff and arrays with ~5,000 values, it works. When I get to ~10,000 values, the script dies when I get to array_diff. Turning on error_reporting did not produce anything. I tried creating my own array_diff function: function manual_array_diff($arraya, $arrayb) { foreach ($arraya as $keya => $valuea) { if (in_array($valuea, $arrayb)) { unset($arraya[$keya]); } } return $arraya; } source: http://stackoverflow.com/questions/2479963/how-does-array-diff-work I would expect it to be less efficient that than the official array_diff, but it can handle arrays of ~10,000. Unfortunately, both array_diffs fail when I get to ~15,000. I tried the same code on a different machine and it runs fine, so it's not an issue with the code or PHP. There must be some limit set somewhere on that particular server. Any idea how I can get around that limit or alter it or just find out what it is?

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• Kernighan & Ritchie word count example program in a functional language

  - by Frank

  I have been reading a little bit about functional programming on the web lately and I think I got a basic idea about the concepts behind it. I'm curious how everyday programming problems which involve some kind of state are solved in a pure functional programing language. For example: how would the word count program from the book 'The C programming Language' be implemented in a pure functional language? Any contributions are welcome as long as the solution is in a pure functional style. Here's the word count C code from the book: #include <stdio.h> #define IN 1 /* inside a word */ #define OUT 0 /* outside a word */ /* count lines, words, and characters in input */ main() { int c, nl, nw, nc, state; state = OUT; nl = nw = nc = 0; while ((c = getchar()) != EOF) { ++nc; if (c == '\n') ++nl; if (c == ' ' || c == '\n' || c = '\t') state = OUT; else if (state == OUT) { state = IN; ++nw; } } printf("%d %d %d\n", nl, nw, nc); }

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• Some clarification needed about synchronous versus asynchronous asio operations

  - by Old newbie

  As far as I know, the main difference between synchronous and asynchronous operations. I.e. write() or read() vs async_write() and async_read() is that the former, don't return until the operation finish -or error-, and the last ones, returns inmediately. Due the fact that the asynchronous operations are controlled by an io_service.run() that does not finish until the controlled operations has finalized. It seems to me that in sequencial operations as those involved in TCP/IP connections with protocols such as POP3, in which the operaton is a sequence such as: C: <connect> S: Ok. C: User... S: Ok. C: Password S: Ok. C: Command S: answer C: Command S: answer ... C: bye S: <close> The difference between synchronous/asynchronous opperatons does not make much sense. Of course, in both operations there is allways the risk that the program flow stops indefinitely by some circunstance -there the use of timers-, but I would like know some more authorized opinions in this matter. I must admit that the question is rather ill-defined, but I like hear some advices about when use one or other, because I've problems in debugging with MS Visual Studio, asynchronous SSL operations in a POP3 client in wich I'm working now -about some of who surely I would write here soon-, and sometimes think that perhaps is a bad idea use asynchronous in this. Not to say that I'm an absolute newbie with this librarys, that additionally to the difficult with the idioma, and some obscure concepts in the STL, must suffer the brevity of the asio documentation.

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• Technical choices in unmarshaling hash-consed data

  - by Pascal Cuoq

  There seems to be quite a bit of folklore knowledge floating about in restricted circles about the pitfalls of hash-consing combined with marshaling-unmarshaling of data. I am looking for citable references to these tidbits. For instance, someone once pointed me to library aterm and mentioned that the authors had clearly thought about this and that the representation on disk was bottom-up (children of a node come before the node itself in the data stream). This is indeed the right way to do things when you need to re-share each node (with a possible identical node already in memory). This re-sharing pass needs to be done bottom-up, so the unmarshaling itself might as well be, too, so that it's possible to do everything in a single pass. I am in the process of describing difficulties encountered in our own context, and the solutions we found. I would appreciate any citable reference to the kind of aforementioned folklore knowledge. Some people obviously have encountered the problems before (the aterm library is only one example). But I didn't find anything in writing. Even the little piece of information I have about aterm is hear-say. I am not worried it's not reliable (you can't make this up), but "personal communication" and "look how it's done in the source code" are considered poor form in citations. I have enough references on hash-consing alone. I am only interested in references where it interferes with other aspects of programming, such as marshaling or distribution.

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• ArrayList<String> NullPointerException

  - by Carlucho

  Am trying to solve a labyrinth by DFS, using adj List to represent the vertices and edges of the graph. In total there are 12 nodes (3 rows[A,B,C] * 4 cols[0,..,3]). My program starts by saving all the vertex labels (A0,..C3), so far so good, then checks the adjacent nodes, also no problems, if movement is possible, it proceeds to create the edge, here its where al goes wrong. adjList[i].add(vList[j].label); I used the debugger and found that vList[j].label is not null it contains a correct string (ie. "B1"). The only variables which show null are in adjList[i], which leads me to believe i have implemented it wrongly. this is how i did it. public class GraphList { private ArrayList<String>[] adjList; ... public GraphList(int vertexcount) { adjList = (ArrayList<String>[]) new ArrayList[vertexCount]; ... } ... public void addEdge(int i, int j) { adjList[i].add(vList[j].label); //NULLPOINTEREXCEPTION HERE } ... } I will really appreaciate if anyone can point me on the right track regrading to what its going wrong... Thanks!

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• Create a Task list, with tasks without executing

  - by Ernesto Araya Eguren

  I have an async method private async Task DoSomething(CancellationToken token) a list of Tasks private List<Task> workers = new List<Task>(); and I have to create N threads that runs that method public void CreateThreads(int n) { tokenSource = new CancellationTokenSource(); token = tokenSource.Token; for (int i = 0; i < n; i++) { workers.Add(DoSomething(token)); } } but the problem is that those have to run at a given time public async Task StartAllWorkers() { if (0 < workers.Count) { try { while (0 < workers.Count) { Task finishedWorker = await Task.WhenAny(workers.ToArray()); workers.Remove(finishedWorker); finishedWorker.Dispose(); } if (workers.Count == 0) { tokenSource = null; } } catch (OperationCanceledException) { throw; } } } but actually they run when i call the CreateThreads Method (before the StartAllWorkers). I searched for keywords and problems like mine but couldn't find anything about stopping the task from running. I've tried a lot of different aproaches but anything that could solve my problem entirely. For example, moving the code from DoSomething into a workers.Add(new Task(async () => { }, token)); would run the StartAllWorkers(), but the threads will never actually start. There is another method for calling the tokenSource.Cancel().

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• Namespace constants and use as

  - by GordonM

  I'm having some problems with using constants from a namespace. If I define the constant and try to use as it, PHP seems unable to find it. For example, in my file with the constants I have code along the lines of the following: namespace \my\namespace\for\constants; const DS = DIRECTORY_SEPARATOR; Then in the consuming file I have: namespace \some\other\namespace; use \my\namespace\for\constants\DS as DS; echo (realpath (DS . 'usr' . DS 'local')); However, instead of echoing '/usr/local' as expected I get the following notice and an empty string. Notice: Use of undefined constant DS - assumed 'DS' If I change the code as follows: use \my\namespace\for\constants as cns; echo (realpath (cns\DS . 'usr' . cns\DS 'local')); I get the expected result, but it's obviously quite a bit less convenient than just being able to pull the constants in directly. You can alias a class/interface/trait in a namespace, are you not able to alias a constant too? If you can do it, then how?

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• LINQ to Sql: Insert instead of Update

  - by Christina Mayers

  I am stuck with this problems for a long time now. Everything I try to do is insert a row in my DB if it's new information - if not update the existing one. I've updated many entities in my life before - but what's wrong with this code is beyond me (probably something pretty basic) I guess I can't see the wood for the trees... private Models.databaseDataContext db = new Models.databaseDataContext(); internal void StoreInformations(IEnumerable<EntityType> iEnumerable) { foreach (EntityType item in iEnumerable) { EntityType type = db.EntityType.Where(t => t.Room == item.Room).FirstOrDefault(); if (type == null) { db.EntityType.InsertOnSubmit(item); } else { type.Date = item.Date; type.LastUpdate = DateTime.Now(); type.End = item.End; } } } internal void Save() { db.SubmitChanges(); } Edit: just checked the ChangeSet, there are no updates only inserts. For now I've settled with foreach (EntityType item in iEnumerable) { EntityType type = db.EntityType.Where(t => t.Room == item.Room).FirstOrDefault(); if (type != null) { db.Exams.DeleteOnSubmit(type); } db.EntityType.InsertOnSubmit(item); } but I'd love to do updates and lose these unnecessary delete statements.

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• Flash CS4 [AS3]: Playing Card Deck Array

  - by Ben

  I am looking to make a card game in Flash CS4 using AS3 and I am stuck on the very first step. I have created graphics for a standard 52 card deck of playing cards and imported them into the library in Flash and then proceeded to convert them all to Movie Clips. I have also used the linkage to make them available in the code. The movie clips and the linkage are named in sequence, as in the Ace of Clubs would be C1, two of Diamonds is called D2, Jack of Spades is S11. (C = Clubs, D = Diamonds, S = Spades, H = Hearts and numbers 1 through 13 are the card values. 1 being Ace, 11 being Jack, 12 being Queen, 13 being King). As far as I know my next step would be to arrange the cards into an array. This is the part that I am having problems with. Can someone please point me in the right direction, what would be the best way to do this. Could you provide me with a bit of sample code as well? I have had a look at few tutorials online but they are all telling me different things, some are incomplete and the rest...well...they're just cr*ppy. Thanks in advance! Ben

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