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• Constraint Satisfaction Problem

  - by Carl Smotricz

  I'm struggling my way through Artificial Intelligence: A Modern Approach in order to alleviate my natural stupidity. In trying to solve some of the exercises, I've come up against the "Who Owns the Zebra" problem, Exercise 5.13 in Chapter 5. This has been a topic here on SO but the responses mostly addressed the question "how would you solve this if you had a free choice of problem solving software available?" I accept that Prolog is a very appropriate programming language for this kind of problem, and there are some fine packages available, e.g. in Python as shown by the top-ranked answer and also standalone. Alas, none of this is helping me "tough it out" in a way as outlined by the book. The book appears to suggest building a set of dual or perhaps global constraints, and then implementing some of the algorithms mentioned to find a solution. I'm having a lot of trouble coming up with a set of constraints suitable for modelling the problem. I'm studying this on my own so I don't have access to a professor or TA to get me over the hump - this is where I'm asking for your help. I see little similarity to the examples in the chapter. I was eager to build dual constraints and started out by creating (the logical equivalent of) 25 variables: nationality1, nationality2, nationality3, ... nationality5, pet1, pet2, pet3, ... pet5, drink1 ... drink5 and so on, where the number was indicative of the house's position. This is fine for building the unary constraints, e.g. The Norwegian lives in the first house: nationality1 = { :norway }. But most of the constraints are a combination of two such variables through a common house number, e.g. The Swede has a dog: nationality[n] = { :sweden } AND pet[n] = { :dog } where n can range from 1 to 5, obviously. Or stated another way: nationality1 = { :sweden } AND pet1 = { :dog } XOR nationality2 = { :sweden } AND pet2 = { :dog } XOR nationality3 = { :sweden } AND pet3 = { :dog } XOR nationality4 = { :sweden } AND pet4 = { :dog } XOR nationality5 = { :sweden } AND pet5 = { :dog } ...which has a decidedly different feel to it than the "list of tuples" advocated by the book: ( X1, X2, X3 = { val1, val2, val3 }, { val4, val5, val6 }, ... ) I'm not looking for a solution per se; I'm looking for a start on how to model this problem in a way that's compatible with the book's approach. Any help appreciated.

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• Help choosing authentication method

  - by Dima

  I need to choose an authentication method for an application installed and integrated in customers environment. There are two types of environments - windows and linux/unix. Application is user based, no web stuff, pure Java. The requirement is to authenticate users which will use my application against customer provided user base. Meaning, customer installs my app, but uses his own users to grant or deny access to my app. Typical, right? I have three options to consider and I need to pick up the one which would be a) the most flexible to cover most common modern environments and b) would take least effort while stay robust and standard. Option (1) - Authenticate locally managing user credentials in some local storage, e.g. file. Customer would then add his users to my application and it will then check the passwords. Simple, clumsy but would work. Customers would have to punch every user they want to grant access to my app using some UI we will have to provide. Lots of work for me, headache to the customer. Option (2) - Use LDAP authentication. Customers would tell my app where to look for users and I will walk their directory resolving names into user names and trying to bind with found password. This is better approach IMO, but more fragile because I will have to walk an unknown directory structure and who knows if this will be permitted everywhere. Would be harder to test since there are many LDAP implementation out there, last thing I want is drowning in this voodoo. Option(3) - Use plain Kerberos authentication. Customers would tell my app what realm (domain) and which KDC (key distribution center) to use. In ideal world these two parameters would be all I need to set while customers could use their own administration tools to configure domain and kdc. My application would simply delegate user credentials to this third party (using JAAS or Spring security) and consider success when third party is happy with them. I personally prefer #3, but not sure what surprises I might face. Would this cover windows and *nix systems entirely? Is there another option to consider?

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• Help with iphone dev - beyond bounds error

  - by dusk

  I'm just learning iphone development, so please forgive me for what is probably a beginner error. I've searched around and haven't found anything specific to my problem, so hopefully it is an easy fix. The book has examples of building a table from data hard coded via an array. Unfortunately it never really tells you how to get data from a URL, so I've had to look that up and that is where my problems show up. When I debug in xcode, it seems like the count is correct, so I don't understand why it is going out of bounds? This is the error message: 2010-05-03 12:50:42.705 Simple Table[3310:20b] *** Terminating app due to uncaught exception 'NSRangeException', reason: '*** -[NSCFArray objectAtIndex:]: index (1) beyond bounds (0)' My URL returns the following string: first,second,third,fourth And here is the iphone code with the book's working example commented out #import "Simple_TableViewController.h" @implementation Simple_TableViewController @synthesize listData; - (void)viewDidLoad { /* //working code from book NSArray *array = [[NSArray alloc] initWithObjects:@"Sleepy", @"Sneezy", @"Bashful", @"Bashful", @"Happy", @"Doc", @"Grumpy", @"Thorin", @"Dorin", @"Norin", @"Ori", @"Balin", @"Dwalin", @"Fili", @"Kili", @"Oin", @"Gloin", @"Bifur", @"Bofur", @"Bombur", nil]; self.listData = array; [array release]; */ //code from interwebz that crashes NSString *urlstr = [[NSString alloc] initWithFormat:@"http://www.mysite.com/folder/iphone-test.php"]; NSURL *url = [[NSURL alloc] initWithString:urlstr]; NSString *ans = [NSString stringWithContentsOfURL:url]; NSArray *listItems = [ans componentsSeparatedByString:@","]; self.listData = listItems; [urlstr release]; [url release]; [ans release]; [listItems release]; [super viewDidLoad]; } - (void)didReceiveMemoryWarning { // Releases the view if it doesn't have a superview. [super didReceiveMemoryWarning]; // Release any cached data, images, etc that aren't in use. } - (void)viewDidUnload { // Release any retained subviews of the main view. // e.g. self.myOutlet = nil; self.listData = nil; [super viewDidUnload]; } - (void)dealloc { [listData release]; [super dealloc]; } #pragma mark - #pragma mark Table View Data Source Methods - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section { return [self.listData count]; } - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { static NSString *SimpleTableIdentifier = @"SimpleTableIdentifier"; UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:SimpleTableIdentifier]; if (cell == nil) { cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:SimpleTableIdentifier] autorelease]; } NSUInteger row = [indexPath row]; cell.textLabel.text = [listData objectAtIndex:row]; return cell; } @end

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• What's the best way to do base36 arithmetic in perl?

  - by DVK

  What's the best way to do base36 arithmetic in Perl? To be more specific, I need to be able to do the following: Operate on positive N-digit numbers in base 36 (e.g. digits are 0-9 A-Z) N is finite, say 9 Provide basic arithmetic, at the very least the following 3: Addition (A+B) Subtraction (A-B) Whole division, e.g. floor(A/B). Strictly speaking, I don't really need a base10 conversion ability - the numbers will 100% of time be in base36. So I'm quite OK if the solution does NOT implement conversion from base36 back to base10 and vice versa. I don't much care whether the solution is brute-force "convert to base 10 and back" or converting to binary, or some more elegant approach "natively" performing baseN operations (as stated above, to/from base10 conversion is not a requirement). My only 3 considerations are: It fits the minimum specifications above It's "standard". Currently we're using and old homegrown module based on base10 conversion done by hand that is buggy and sucks. I'd much rather replace that with some commonly used CPAN solution instead of re-writing my own bicycle from scratch, but I'm perfectly capable of building it if no better standard possibility exists. It must be fast-ish (though not lightning fast). Something that takes 1 second to sum up 2 9-digit base36 numbers is worse than anything I can roll on my own :) P.S. Just to provide some context in case people decide to solve my XY problem for me in addition to answering the technical question above :) We have a fairly large tree (stored in DB as a bunch of edges), and we need to superimpose order on a subset of that tree. The tree dimentions are big both depth- and breadth- wise. The tree is VERY actively updated (inserts and deletes and branch moves). This is currently done by having a second table with 3 columns: parent_vertex, child_vertex, local_order, where local_order is an 9-character string built of A-Z0-9 (e.g. base 36 number). Additional considerations: It is required that the local order is unique per child (and obviously unique per parent), Any complete re-ordering of a parent is somewhat expensive, and thus the implementation is to try and assign - for a parent with X children - the orders which are somewhat evenly distributed between 0 and 36**10-1, so that almost no tree inserts result in a full re-ordering.

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• Lua and Objective C not running script.

  - by beta

  I am trying to create an objective c interface that encapsulates the functionality of storing and running a lua script (compiled or not.) My code for the script interface is as follows: #import <Cocoa/Cocoa.h> #import "Types.h" #import "lua.h" #include "lualib.h" #include "lauxlib.h" @interface Script : NSObject<NSCoding> { @public s32 size; s8* data; BOOL done; } @property s32 size; @property s8* data; @property BOOL done; - (id) initWithScript: (u8*)data andSize:(s32)size; - (id) initFromFile: (const char*)file; - (void) runWithState: (lua_State*)state; - (void) encodeWithCoder: (NSCoder*)coder; - (id) initWithCoder: (NSCoder*)coder; @end #import "Script.h" @implementation Script @synthesize size; @synthesize data; @synthesize done; - (id) initWithScript: (s8*)d andSize:(s32)s { self = [super init]; self->size = s; self->data = d; return self; } - (id) initFromFile:(const char *)file { FILE* p; p = fopen(file, "rb"); if(p == NULL) return [super init]; fseek(p, 0, SEEK_END); s32 fs = ftell(p); rewind(p); u8* buffer = (u8*)malloc(fs); fread(buffer, 1, fs, p); fclose(p); return [self initWithScript:buffer andSize:size]; } - (void) runWithState: (lua_State*)state { if(luaL_loadbuffer(state, [self data], [self size], "Script") != 0) { NSLog(@"Error loading lua chunk."); return; } lua_pcall(state, 0, LUA_MULTRET, 0); } - (void) encodeWithCoder: (NSCoder*)coder { [coder encodeInt: size forKey: @"Script.size"]; [coder encodeBytes:data length:size forKey:@"Script.data"]; } - (id) initWithCoder: (NSCoder*)coder { self = [super init]; NSUInteger actualSize; size = [coder decodeIntForKey: @"Script.size"]; data = [[coder decodeBytesForKey:@"Script.data" returnedLength:&actualSize] retain]; return self; } @end Here is the main method: #import "Script.h" int main(int argc, char* argv[]) { Script* script = [[Script alloc] initFromFile:"./test.lua"]; lua_State* state = luaL_newstate(); luaL_openlibs(state); luaL_dostring(state, "print(_VERSION)"); [script runWithState:state]; luaL_dostring(state, "print(_VERSION)"); lua_close(state); } And the lua script is just: print("O Hai World!") Loading the file is correct, but I think it messes up at pcall. Any Help is greatly appreciated. Heading

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• JQuery autocomplete: is not working asp.net

  - by Abu Hamzah

  is that something wrong in the below code? its not firing at all edit <%@ Page Language="C#" AutoEventWireup="true" CodeBehind="HostPage.aspx.cs" Inherits="HostPage" %> <!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 runat="server"> <title>Untitled Page</title> <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.4/jquery.min.js"></script> <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8/jquery-ui.min.js"></script> <link rel="stylesheet" href="http://dev.jquery.com/view/trunk/plugins/autocomplete/jquery.autocomplete.css" type="text/css" /> <script type="text/javascript" src="http://dev.jquery.com/view/trunk/plugins/autocomplete/jquery.autocomplete.js"></script> </head> <body> <form id="form1" runat="server"> <script type="text/javascript"> $(document).ready(function() { $("#<%=txtHost.UniqueID %>").autocomplete("HostService.asmx/GetHosts", { dataType: 'json' , contentType: "application/json; charset=utf-8" , parse: function(data) { var rows = Array(); debugger for (var i = 0; i < data.length; i++) { rows[i] = { data: data[i], value: data[i].LName, result: data[i].LName }; } return rows; } , formatItem: function(row, i, max) { return data.LName + ", " + data.FName; } }); }); </script> <div> <asp:Label runat="server" ID='Label4' >Host Name:</asp:Label> <asp:TextBox ID="txtHost" runat='server'></asp:TextBox> <p> </div> </form> </body> </html>

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• What is the best algorithm for this problem?

  - by mark

  What is the most efficient algorithm to solve the following problem? Given 6 arrays, D1,D2,D3,D4,D5 and D6 each containing 6 numbers like: D1[0] = number D2[0] = number ...... D6[0] = number D1[1] = another number D2[1] = another number .... ..... .... ...... .... D1[5] = yet another number .... ...... .... Given a second array ST1, containing 1 number: ST1[0] = 6 Given a third array ans, containing 6 numbers: ans[0] = 3, ans[1] = 4, ans[2] = 5, ......ans[5] = 8 Using as index for the arrays D1,D2,D3,D4,D5 and D6, the number that goes from 0, to the number stored in ST1[0] minus one, in this example 6, so from 0 to 6-1, compare each res array against each D array My algorithm so far is: I tried to keep everything unlooped as much as possible. EML := ST1[0] //number contained in ST1[0] EML1 := 0 //start index for the arrays D While EML1 < EML if D1[ELM1] = ans[0] goto two if D2[ELM1] = ans[0] goto two if D3[ELM1] = ans[0] goto two if D4[ELM1] = ans[0] goto two if D5[ELM1] = ans[0] goto two if D6[ELM1] = ans[0] goto two ELM1 = ELM1 + 1 return 0 //bad row of numbers, if while ends two: EML1 := 0 start index for arrays Ds While EML1 < EML if D1[ELM1] = ans[1] goto two if D2[ELM1] = ans[1] goto two if D3[ELM1] = ans[1] goto two if D4[ELM1] = ans[1] goto two if D5[ELM1] = ans[1] goto two if D6[ELM1] = ans[1] goto two ELM1 = ELM1 + 1 return 0 three: EML1 := 0 start index for arrays Ds While EML1 < EML if D1[ELM1] = ans[2] goto two if D2[ELM1] = ans[2] goto two if D3[ELM1] = ans[2] goto two if D4[ELM1] = ans[2] goto two if D5[ELM1] = ans[2] goto two if D6[ELM1] = ans[2] goto two ELM1 = ELM1 + 1 return 0 four: EML1 := 0 start index for arrays Ds While EML1 < EML if D1[ELM1] = ans[3] goto two if D2[ELM1] = ans[3] goto two if D3[ELM1] = ans[3] goto two if D4[ELM1] = ans[3] goto two if D5[ELM1] = ans[3] goto two if D6[ELM1] = ans[3] goto two ELM1 = ELM1 + 1 return 0 five: EML1 := 0 start index for arrays Ds While EML1 < EML if D1[ELM1] = ans[4] goto two if D2[ELM1] = ans[4] goto two if D3[ELM1] = ans[4] goto two if D4[ELM1] = ans[4] goto two if D5[ELM1] = ans[4] goto two if D6[ELM1] = ans[4] goto two ELM1 = ELM1 + 1 return 0 six: EML1 := 0 start index for arrays Ds While EML1 < EML if D1[ELM1] = ans[0] return 1 //good row of numbers if D2[ELM1] = ans[0] return 1 if D3[ELM1] = ans[0] return 1 if D4[ELM1] = ans[0] return 1 if D5[ELM1] = ans[0] return 1 if D6[ELM1] = ans[0] return 1 ELM1 = ELM1 + 1 return 0 As language of choice, it would be pure c

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• Sharepoint web part stops working because of Resources.en-US.resx file

  - by Eric C

  I've been developing a Sharepoint web part, which had been working fine upon deployment. The web part has been developed with WSP Builder, packaged up and then deployed via stsadm. The web part has been deployed tens, if not a hundred times to the dev box with no problems. Now, the web part throws an error which breaks the page it's on: Object reference not set to an instance of an object. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.NullReferenceException: Object reference not set to an instance of an object. Source Error: An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below. Stack Trace: [NullReferenceException: Object reference not set to an instance of an object.] NYCIRB.DMS.WebParts.SearchUpload.SearchUpload.HandleException(Exception ex) +62 NYCIRB.DMS.WebParts.SearchUpload.SearchUpload.OnLoad(EventArgs e) +214 System.Web.UI.Control.LoadRecursive() +50 System.Web.UI.Control.LoadRecursive() +141 System.Web.UI.Control.LoadRecursive() +141 System.Web.UI.Control.LoadRecursive() +141 System.Web.UI.Control.LoadRecursive() +141 System.Web.UI.Control.LoadRecursive() +141 System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +627 When looking through my Sharepoint logs, I find these errors repeated over and over which correspond to the time the web part was attempted to be loaded: 01/19/2009 10:53:14.43 w3wp.exe (0x05E0) 0x00FC Windows SharePoint Services General 72kg High (#2: Cannot open "Resources.en-US.resx": no such file or folder.) 01/19/2009 10:53:14.43 w3wp.exe (0x05E0) 0x00FC Windows SharePoint Services General 8e26 Medium Failed to open the language resource for Fea367b94a9-4a15-42ba-b4a2-32420363e018 keyfile Resources. 01/19/2009 10:53:17.55 w3wp.exe (0x05E0) 0x00FC Windows SharePoint Services General 8e25 Medium Failed to look up string with key "XomlUrl", keyfile core. 01/19/2009 10:53:17.55 w3wp.exe (0x05E0) 0x00FC Windows SharePoint Services General 8l3c Medium Localized resource for token 'XomlUrl' could not be found for file with path: "C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\12\Template\Features\Fields\fieldswss.xml". 01/19/2009 10:53:17.55 w3wp.exe (0x05E0) 0x00FC Windows SharePoint Services General 8e25 Medium Failed to look up string with key "RulesUrl", keyfile core. 01/19/2009 10:53:17.55 w3wp.exe (0x05E0) 0x00FC Windows SharePoint Services General 8l3c Medium Localized resource for token 'RulesUrl' could not be found for file with path: "C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\12\Template\Features\Fields\fieldswss.xml". I've retracted the web part manually through Solution Management, retracted through stsadm, checked for the existence of the resource file, which is nowhere to be found. I'm pretty much at a loss to why this happened or how to resolve it.

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• Structuring Win32 GUI code

  - by kraf

  I wish to improve my code and file structure in larger Win32 projects with plenty of windows and controls. Currently, I tend to have one header and one source file for the entire implementation of a window or dialog. This works fine for small projects, but now it has come to the point where these implementations are starting to reach 1000-2000 lines, which is tedious to browse. A typical source file of mine looks like this: static LRESULT CALLBACK on_create(const HWND hwnd, WPARAM wp, LPARAM lp) { setup_menu(hwnd); setup_list(hwnd); setup_context_menu(hwnd); /* clip */ return 0; } static LRESULT CALLBACK on_notify(HWND hwnd, UINT msg, WPARAM wp, LPARAM lp) { const NMHDR* header = (const NMHDR*)lp; /* At this point I feel that the control's event handlers doesn't * necessarily belong in the same source file. Perhaps I could move * each control's creation code and event handlers into a separate * source file? Good practice or cause of confusion? */ switch (header->idFrom) { case IDC_WINDOW_LIST: switch (header->code) { case NM_RCLICK: return on_window_list_right_click(hwnd, wp, lp); /* clip */ } } } static LRESULT CALLBACK wndmain_proc(HWND hwnd, UINT msg, WPARAM wp, LPARAM lp) { switch (msg) { case WM_CREATE: return on_create(hwnd, wp, lp); case WM_CLOSE: return on_close(hwnd, wp, lp); case WM_NOTIFY: return on_notify(hwnd, wp, lp); /* It doesn't matter much how the window proc looks as it just forwards * events to the appropriate handler. */ /* clip */ default: return DefWindowProc(hwnd, msg, wp, lp); } } But now as the window has a lot more controls, and these controls in turn have their own message handlers, and then there's the menu click handlers, and so on... I'm getting lost, and I really need advice on how to structure this mess up in a good and sensible way. I have tried to find good open source examples of structuring Win32 code, but I just get more confused since there are hundreds of files, and within each of these files that seem GUI related, the Win32 GUI code seems so far encapsulated away. And when I finally find a CreateWindowEx statement, the window proc is nowhere to be found. Any advice on how to structure all the code while remaining sane would be greatly appreciated. Thanks! I don't wish to use any libraries or frameworks as I find the Win32 API interesting and valuable for learning. Any insight into how you structure your own GUI code could perhaps serve as inspiration.

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• Scala actors: receive vs react

  - by jqno

  Let me first say that I have quite a lot of Java experience, but have only recently become interested in functional languages. Recently I've started looking at Scala, which seems like a very nice language. However, I've been reading about Scala's Actor framework in Programming in Scala, and there's one thing I don't understand. In chapter 30.4 it says that using react instead of receive makes it possible to re-use threads, which is good for performance, since threads are expensive in the JVM. Does this mean that, as long as I remember to call react instead of receive, I can start as many Actors as I like? Before discovering Scala, I've been playing with Erlang, and the author of Programming Erlang boasts about spawning over 200,000 processes without breaking a sweat. I'd hate to do that with Java threads. What kind of limits am I looking at in Scala as compared to Erlang (and Java)? Also, how does this thread re-use work in Scala? Let's assume, for simplicity, that I have only one thread. Will all the actors that I start run sequentially in this thread, or will some sort of task-switching take place? For example, if I start two actors that ping-pong messages to each other, will I risk deadlock if they're started in the same thread? According to Programming in Scala, writing actors to use react is more difficult than with receive. This sounds plausible, since react doesn't return. However, the book goes on to show how you can put a react inside a loop using Actor.loop. As a result, you get loop { react { ... } } which, to me, seems pretty similar to while (true) { receive { ... } } which is used earlier in the book. Still, the book says that "in practice, programs will need at least a few receive's". So what am I missing here? What can receive do that react cannot, besides return? And why do I care? Finally, coming to the core of what I don't understand: the book keeps mentioning how using react makes it possible to discard the call stack to re-use the thread. How does that work? Why is it necessary to discard the call stack? And why can the call stack be discarded when a function terminates by throwing an exception (react), but not when it terminates by returning (receive)? I have the impression that Programming in Scala has been glossing over some of the key issues here, which is a shame, because otherwise it's a truly excellent book.

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• SBT run differences between scala and java?

  - by Eric Cartner

  I'm trying to follow the log4j2 configuration tutorials in a SBT 0.12.1 project. Here is my build.sbt: name := "Logging Test" version := "0.0" scalaVersion := "2.9.2" libraryDependencies ++= Seq( "org.apache.logging.log4j" % "log4j-api" % "2.0-beta3", "org.apache.logging.log4j" % "log4j-core" % "2.0-beta3" ) When I run the main() defined in src/main/scala/logtest/Foo.scala: package logtest import org.apache.logging.log4j.{Logger, LogManager} object Foo { private val logger = LogManager.getLogger(getClass()) def main(args: Array[String]) { logger.trace("Entering application.") val bar = new Bar() if (!bar.doIt()) logger.error("Didn't do it.") logger.trace("Exiting application.") } } I get the output I was expecting given that src/main/resources/log4j2.xml sets the root logging level to trace: [info] Running logtest.Foo 08:39:55.627 [run-main] TRACE logtest.Foo$ - Entering application. 08:39:55.630 [run-main] TRACE logtest.Bar - entry 08:39:55.630 [run-main] ERROR logtest.Bar - Did it again! 08:39:55.630 [run-main] TRACE logtest.Bar - exit with (false) 08:39:55.630 [run-main] ERROR logtest.Foo$ - Didn't do it. 08:39:55.630 [run-main] TRACE logtest.Foo$ - Exiting application. However, when I run the main() defined in src/main/java/logtest/LoggerTest.java: package logtest; import org.apache.logging.log4j.Logger; import org.apache.logging.log4j.LogManager; public class LoggerTest { private static Logger logger = LogManager.getLogger(LoggerTest.class.getName()); public static void main(String[] args) { logger.trace("Entering application."); Bar bar = new Bar(); if (!bar.doIt()) logger.error("Didn't do it."); logger.trace("Exiting application."); } } I get the output: [info] Running logtest.LoggerTest ERROR StatusLogger Unable to locate a logging implementation, using SimpleLogger ERROR Bar Did it again! ERROR LoggerTest Didn't do it. From what I can tell, ERROR StatusLogger Unable to ... is usually a sign that log4j-core is not on my classpath. The lack of TRACE messages seems to indicate that my log4j2.xml settings aren't on the classpath either. Why should there be any difference in classpath if I'm running Foo.main versus LoggerTest.main? Or is there something else causing this behavior? Update I used SBT Assembly to build a fat jar of this project and specified logtest.LoggerTest to be the main class. Running it from the command line produced correct results: Eric-Cartners-iMac:target ecartner$ java -jar "Logging Test-assembly-0.0.jar" 10:52:23.220 [main] TRACE logtest.LoggerTest - Entering application. 10:52:23.221 [main] TRACE logtest.Bar - entry 10:52:23.221 [main] ERROR logtest.Bar - Did it again! 10:52:23.221 [main] TRACE logtest.Bar - exit with (false) 10:52:23.221 [main] ERROR logtest.LoggerTest - Didn't do it. 10:52:23.221 [main] TRACE logtest.LoggerTest - Exiting application.

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• How to have member variables and public methods in a jQuery plugin?

  - by user169867

  I'm trying to create a jQuery plugin that will create something like an autoCompleteBox but with custom features. How do I store member variables for each matching jQuery element? For example I'll need to store a timerID for each. I'd also like to store references to some of the DOM elements that make up the control. I'd like to be able to make a public method that works something like: $("#myCtrl").autoCompleteEx.addItem("1"); But in the implementation of addItem() how can I access the member variables for that particular object like its timerID or whatever? Below is what I have so far... Thanks for any help or suggestions! (function($) { //Attach this new method to jQuery $.fn.autoCompleteEx = function(options) { //Merge Given Options W/ Defaults, But Don't Alter Either var opts = $.extend({}, $.fn.autoCompleteEx.defaults, options); //Iterate over the current set of matched elements return this.each(function() { var acx = $(this); //Get JQuery Version Of Element (Should Be Div) //Give Div Correct Class & Add <ul> w/ input item to it acx.addClass("autoCompleteEx"); acx.html("<ul><li class=\"input\"><input type=\"text\"/></li></ul>"); //Grab Input As JQ Object var input = $("input", acx); //Wireup Div acx.click(function() { input.focus().val( input.val() ); }); //Wireup Input input.keydown(function(e) { var kc = e.keyCode; if(kc == 13) //Enter { } else if(kc == 27) //Esc { } else { //Resize TextArea To Input var width = 50 + (_txtArea.val().length*10); _txtArea.css("width", width+"px"); } }); }); //End Each JQ Element }; //End autoCompleteEx() //Private Functions function junk() { }; //Public Functions $.fn.autoCompleteEx.addItem = function(id,txt) { var x = this; var y = 0; }; //Default Settings $.fn.autoCompleteEx.defaults = { minChars: 2, delay: 300, maxItems: 1 }; //End Of Closure })(jQuery);

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• NHibernate Tutorial Run-Time Error: HibernateException

  - by Kashif

  I'm a newbie at NHibernate so please go easy on me if I have asked a stupid question... I am following the tutorial for NHibernate posted here and am getting a run-time error of type "HibernateException" The code in question looks like this: using System; using System.Collections.Generic; using System.Linq; using System.Text; using FirstSolution; using NHibernate.Cfg; using NHibernate.Tool.hbm2ddl; using NUnit.Framework; namespace FirstSolution.Tests { [TestFixture] public class GenerateSchema_Fixture { [Test] public void Can_generate_schema() { var cfg = new Configuration(); cfg.Configure(); cfg.AddAssembly(typeof(Product).Assembly); new SchemaExport(cfg).Execute(false, true, false); } } } The line I am getting the error at is: cfg.AddAssembly(typeof(Product).Assembly); The inner-most exception is: The IDbCommand and IDbConnection implementation in the assembly System.Data.SqlServerCe could not be found And here's my stack trace: at NHibernate.Connection.ConnectionProvider.ConfigureDriver(IDictionary`2 settings) at NHibernate.Connection.ConnectionProvider.Configure(IDictionary`2 settings) at NHibernate.Connection.ConnectionProviderFactory.NewConnectionProvider(IDictionary`2 settings) at NHibernate.Tool.hbm2ddl.SchemaExport.Execute(Action`1 scriptAction, Boolean export, Boolean justDrop) at NHibernate.Tool.hbm2ddl.SchemaExport.Execute(Boolean script, Boolean export, Boolean justDrop) at FirstSolution.Tests.GenerateSchema_Fixture.Can_generate_schema() in C:\Users\Kash\Documents\Visual Studio 2010\Projects\FirstSolution\FirstSolution\GenerateSchema_Fixture.cs:line 23 at HibernateUnitTest.Form1.button1_Click(Object sender, EventArgs e) in C:\Users\Kash\Documents\Visual Studio 2010\Projects\FirstSolution\HibernateUnitTest\Form1.cs:line 23 at System.Windows.Forms.Control.OnClick(EventArgs e) at System.Windows.Forms.Button.OnClick(EventArgs e) at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent) at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks) at System.Windows.Forms.Control.WndProc(Message& m) at System.Windows.Forms.ButtonBase.WndProc(Message& m) at System.Windows.Forms.Button.WndProc(Message& m) at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m) at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m) at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam) at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg) at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr dwComponentID, Int32 reason, Int32 pvLoopData) at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context) at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context) at System.Windows.Forms.Application.Run(Form mainForm) at HibernateUnitTest.Program.Main() in C:\Users\Kash\Documents\Visual Studio 2010\Projects\FirstSolution\HibernateUnitTest\Program.cs:line 18 at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args) at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args) at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly() at System.Threading.ThreadHelper.ThreadStart_Context(Object state) at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean ignoreSyncCtx) at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Threading.ThreadHelper.ThreadStart() I've made sure that System.Data.SqlServerCe has been referenced and that its Copy Local property is set to True. The error persists, however. Your help would be appreciated. Thanks.

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• Unit finalization order for application, compiled with run-time packages?

  - by Alexander

  I need to execute my code after finalization of SysUtils unit. I've placed my code in separate unit and included it first in uses clause of dpr-file, like this: project Project1; uses MyUnit, // <- my separate unit SysUtils, Classes, SomeOtherUnits; procedure Test; begin // end; begin SetProc(Test); end. MyUnit looks like this: unit MyUnit; interface procedure SetProc(AProc: TProcedure); implementation var Test: TProcedure; procedure SetProc(AProc: TProcedure); begin Test := AProc; end; initialization finalization Test; end. Note that MyUnit doesn't have any uses. This is usual Windows exe, no console, without forms and compiled with default run-time packages. MyUnit is not part of any package (but I've tried to use it from package too). I expect that finalization section of MyUnit will be executed after finalization section of SysUtils. This is what Delphi's help tells me. However, this is not always the case. I have 2 test apps, which differs a bit by code in Test routine/dpr-file and units, listed in uses. MyUnit, however, is listed first in all cases. One application is run as expected: Halt0 - FinalizeUnits - ...other units... - SysUtils's finalization - MyUnit's finalization - ...other units... But the second is not. MyUnit's finalization is invoked before SysUtils's finalization. The actual call chain looks like this: Halt0 - FinalizeUnits - ...other units... - SysUtils's finalization (skipped) - MyUnit's finalization - ...other units... - SysUtils's finalization (executed) Both projects have very similar settings. I tried a lot to remove/minimize their differences, but I still do not see a reason for this behaviour. I've tried to debug this and found out that: it seems that every unit have some kind of reference counting. And it seems that InitTable contains multiply references to the same unit. When SysUtils's finalization section is called first time - it change reference counter and do nothing. Then MyUnit's finalization is executed. And then SysUtils is called again, but this time ref-count reaches zero and finalization section is executed: Finalization: // SysUtils' finalization 5003B3F0 55 push ebp // here and below is some form of stub 5003B3F1 8BEC mov ebp,esp 5003B3F3 33C0 xor eax,eax 5003B3F5 55 push ebp 5003B3F6 688EB50350 push $5003b58e 5003B3FB 64FF30 push dword ptr fs:[eax] 5003B3FE 648920 mov fs:[eax],esp 5003B401 FF05DCAD1150 inc dword ptr [$5011addc] // here: some sort of reference counter 5003B407 0F8573010000 jnz $5003b580 // <- this jump skips execution of finalization for first call 5003B40D B8CC4D0350 mov eax,$50034dcc // here and below is actual SysUtils' finalization section ... Can anyone can shred light on this issue? Am I missing something?

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• Display lable character by character using javascript

  - by Muhammad Sajid

  Hi, I am creating Hang a Man using PHP, MySQL & Javascript. Every thing is going perfect, I get a word randomly from DB show it as a label apply it a class where display = none. Now when I click on a Character that character become disable fine which i actually want but the label-character does not show. My code is: <link href="style.css" rel="stylesheet" type="text/css" media="screen" /> <?php include( 'config.php' ); $question = questions(); // Get question. $alpha = alphabats(); // Get alphabets. ?> <script language="javascript"> function clickMe( name ){ var question = '<?php echo $question; ?>'; var questionLen = <?php echo strlen($question); ?>; for ( var i = 0; i < questionLen; i++ ){ if ( question[i] == name ){ var link = document.getElementById( name ); link.style.display = 'none'; var label = document.getElementById( 'questionLabel' + i ); label.style.display = 'none'; } } } </script> <div> <table align="center" style="border:solid 1px"> <tr> <?php for ( $i = 0; $i < 26; $i++ ) { echo "<td><a href='#' id=$alpha[$i] name=$alpha[$i] onclick=clickMe('$alpha[$i]');>". $alpha[$i] ."</a>&nbsp;</td>"; } ?> </tr> </table> <br/> <table align="center" style="border:solid 1px"> <tr> <?php for ( $i = 0; $i < strlen($question); $i++ ) { echo "<td class='question'><label id=questionLabel$i >". $question[$i] ."</label></td>"; } ?> </tr> </table> </div>

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• Function-Local Static Const variable Initialization semantics.

  - by Hassan Syed

  The questions are in bold, for those that cannot be bothered reading a question in depth. This is a followup to this question. It is to do with the initialization semantics of static variables in functions. Static variables should be initialized once, and their internal state might be altered later - as I (currently) do in the linked question. However, the code in question does not require the feature to change the state of the variable later. Let me clarrify my position, since I don't require the string object's internal state to change. The code is for a trait class for meta programming, and as such would would benifit from a const char * const ptr -- thus Ideally a local cost static const variable is needed. My educated guess is that in this case the string in question will be optimally placed in memory by the link-loader, and that the code is more secure and maps to the intended semantics. This leads to the semantics of such a variable "The C++ Programming language Third Edition -- Stroustrup" does not have anything (that I could find) to say about this matter. All that is said is that the variable is initialized once when the flow of control of the thread first reaches the code. This leads me to ponder if the following code would be sensible, and if not what are the intended semantics ?. #include <iostream> const char * const GetString(const char * x_in) { static const char * const x = x_in; return x; } int main() { const char * const temp = GetString("yahoo"); std::cout << temp << std::endl; const char * const temp2 = GetString("yahoo2"); std::cout << temp2 << std::endl; } The following compiles on GCC and prints "yahoo" twice. Which is what I want -- However it might not be standards compliant (which is why I post this question). It might be more elegant to have two functions, "SetString" and "String" where the latter forwards to the first. If it is standards compliant does someone know of a templates implementation in boost (or elsewhere) ?

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• gcc/g++: error when compiling large file

  - by Alexander

  Hi, I have a auto-generated C++ source file, around 40 MB in size. It largely consists of push_back commands for some vectors and string constants that shall be pushed. When I try to compile this file, g++ exits and says that it couldn't reserve enough virtual memory (around 3 GB). Googling this problem, I found that using the command line switches --param ggc-min-expand=0 --param ggc-min-heapsize=4096 may solve the problem. They, however, only seem to work when optimization is turned on. 1) Is this really the solution that I am looking for? 2) Or is there a faster, better (compiling takes ages with these options acitvated) way to do this? Best wishes, Alexander Update: Thanks for all the good ideas. I tried most of them. Using an array instead of several push_back() operations reduced memory usage, but as the file that I was trying to compile was so big, it still crashed, only later. In a way, this behaviour is really interesting, as there is not much to optimize in such a setting -- what does the GCC do behind the scenes that costs so much memory? (I compiled with deactivating all optimizations as well and got the same results) The solution that I switched to now is reading in the original data from a binary object file that I created from the original file using objcopy. This is what I originally did not want to do, because creating the data structures in a higher-level language (in this case Perl) was more convenient than having to do this in C++. However, getting this running under Win32 was more complicated than expected. objcopy seems to generate files in the ELF format, and it seems that some of the problems I had disappeared when I manually set the output format to pe-i386. The symbols in the object file are by standard named after the file name, e.g. converting the file inbuilt_training_data.bin would result in these two symbols: binary_inbuilt_training_data_bin_start and binary_inbuilt_training_data_bin_end. I found some tutorials on the web which claim that these symbols should be declared as extern char _binary_inbuilt_training_data_bin_start;, but this does not seem to be right -- only extern char binary_inbuilt_training_data_bin_start; worked for me.

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• Understanding CLR 2.0 Memory Model

  - by Eloff

  Joe Duffy, gives 6 rules that describe the CLR 2.0+ memory model (it's actual implementation, not any ECMA standard) I'm writing down my attempt at figuring this out, mostly as a way of rubber ducking, but if I make a mistake in my logic, at least someone here will be able to catch it before it causes me grief. Rule 1: Data dependence among loads and stores is never violated. Rule 2: All stores have release semantics, i.e. no load or store may move after one. Rule 3: All volatile loads are acquire, i.e. no load or store may move before one. Rule 4: No loads and stores may ever cross a full-barrier (e.g. Thread.MemoryBarrier, lock acquire, Interlocked.Exchange, Interlocked.CompareExchange, etc.). Rule 5: Loads and stores to the heap may never be introduced. Rule 6: Loads and stores may only be deleted when coalescing adjacent loads and stores from/to the same location. I'm attempting to understand these rules. x = y y = 0 // Cannot move before the previous line according to Rule 1. x = y z = 0 // equates to this sequence of loads and stores before possible re-ordering load y store x load 0 store z Looking at this, it appears that the load 0 can be moved up to before load y, but the stores may not be re-ordered at all. Therefore, if a thread sees z == 0, then it also will see x == y. If y was volatile, then load 0 could not move before load y, otherwise it may. Volatile stores don't seem to have any special properties, no stores can be re-ordered with respect to each other (which is a very strong guarantee!) Full barriers are like a line in the sand which loads and stores can not be moved over. No idea what rule 5 means. I guess rule 6 means if you do: x = y x = z Then it is possible for the CLR to delete both the load to y and the first store to x. x = y z = y // equates to this sequence of loads and stores before possible re-ordering load y store x load y store z // could be re-ordered like this load y load y store x store z // rule 6 applied means this is possible? load y store x // but don't pop y from stack (or first duplicate item on top of stack) store z What if y was volatile? I don't see anything in the rules that prohibits the above optimization from being carried out. This does not violate double-checked locking, because the lock() between the two identical conditions prevents the loads from being moved into adjacent positions, and according to rule 6, that's the only time they can be eliminated. So I think I understand all but rule 5, here. Anyone want to enlighten me (or correct me or add something to any of the above?)

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• Advantage of creating a generic repository vs. specific repository for each object?

  - by LuckyLindy

  We are developing an ASP.NET MVC application, and are now building the repository/service classes. I'm wondering if there are any major advantages to creating a generic IRepository interface that all repositories implement, vs. each Repository having its own unique interface and set of methods. For example: a generic IRepository interface might look like (taken from this answer): public interface IRepository : IDisposable { T[] GetAll<T>(); T[] GetAll<T>(Expression<Func<T, bool>> filter); T GetSingle<T>(Expression<Func<T, bool>> filter); T GetSingle<T>(Expression<Func<T, bool>> filter, List<Expression<Func<T, object>>> subSelectors); void Delete<T>(T entity); void Add<T>(T entity); int SaveChanges(); DbTransaction BeginTransaction(); } Each Repository would implement this interface (e.g. CustomerRepository:IRepository, ProductRepository:IRepository, etc). The alternate that we've followed in prior projects would be: public interface IInvoiceRepository : IDisposable { EntityCollection<InvoiceEntity> GetAllInvoices(int accountId); EntityCollection<InvoiceEntity> GetAllInvoices(DateTime theDate); InvoiceEntity GetSingleInvoice(int id, bool doFetchRelated); InvoiceEntity GetSingleInvoice(DateTime invoiceDate, int accountId); //unique InvoiceEntity CreateInvoice(); InvoiceLineEntity CreateInvoiceLine(); void SaveChanges(InvoiceEntity); //handles inserts or updates void DeleteInvoice(InvoiceEntity); void DeleteInvoiceLine(InvoiceLineEntity); } In the second case, the expressions (LINQ or otherwise) would be entirely contained in the Repository implementation, whoever is implementing the service just needs to know which repository function to call. I guess I don't see the advantage of writing all the expression syntax in the service class and passing to the repository. Wouldn't this mean easy-to-messup LINQ code is being duplicated in many cases? For example, in our old invoicing system, we call InvoiceRepository.GetSingleInvoice(DateTime invoiceDate, int accountId) from a few different services (Customer, Invoice, Account, etc). That seems much cleaner than writing the following in multiple places: rep.GetSingle(x => x.AccountId = someId && x.InvoiceDate = someDate.Date); The only disadvantage I see to using the specific approach is that we could end up with many permutations of Get* functions, but this still seems preferable to pushing the expression logic up into the Service classes. What am I missing?

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• JPA One To Many Relationship Persistence Bug

  - by Brian

  Hey folks, I've got a really weird problem with a bi-directional relationship in jpa (hibernate implementation). A User is based in one Region, and a Region can contain many Users. So...relationship is as follows: Region object: @OneToMany(mappedBy = "region", fetch = FetchType.LAZY, cascade = CascadeType.ALL) public Set<User> getUsers() { return users; } public void setUsers(Set<User> users) { this.users = users; } User object: @ManyToOne(cascade = {CascadeType.PERSIST, CascadeType.MERGE}, fetch = FetchType.EAGER) @JoinColumn(name = "region_fk") public Region getRegion() { return region; } public void setRegion(Region region) { this.region = region; } So, the relationship as you can see above is Lazy on the region side, ie, I don't want the region to eager load all the users. Therefore, I have the following code within my DAO layer to add a user to an existing user to an existing region object... public User setRegionForUser(String username, Long regionId){ Region r = (Region) this.get(Region.class, regionId); User u = (User) this.get(User.class, username); u.setRegion(r); Set<User> users = r.getUsers(); users.add(u); System.out.println("The number of users in the set is: "+users.size()); r.setUsers(users); this.update(r); return (User)this.update(u); } The problem is, when I run a little unit test to add 5 users to my region object, I see that the region.getUsers() set always stays stuck at 1 object...somehow the set isn't getting added to. My unit test code is as follows: public void setUp(){ System.out.println("calling setup method"); Region r = (Region)ManagerFactory.getCountryAndRegionManager().get(Region.class, Long.valueOf("2")); for(int i = 0; i<loop; i++){ User u = new User(); u.setUsername("username_"+i); ManagerFactory.getUserManager().update(u); ManagerFactory.getUserManager().setRegionForUser("username_"+i, Long.valueOf("2")); } } public void tearDown(){ System.out.println("calling teardown method"); for(int i = 0; i<loop; i++){ ManagerFactory.getUserManager().deleteUser("username_"+i); } } public void testGetUsersForRegion(){ Set<User> totalUsers = ManagerFactory.getCountryAndRegionManager().getUsersInRegion(Long.valueOf("2")); System.out.println("Expecting 5, got: "+totalUsers.size()); this.assertEquals(5, totalUsers.size()); } So the test keeps failing saying there is only 1 user instead of the expected 5. Any ideas what I'm doing wrong? thanks very much, Brian

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• Cancel outlook meeting requests via MailMessage in C#

  - by BTmuney

  I'm creating an application using the ASP.NET MVC 1 framework in C#, where I have users that register for events. Upon registering, I create an outlook meeting request public string BuildMeetingRequest(DateTime start, DateTime end, string attendees, string organizer, string subject, string description, string UID, string location) { System.Text.StringBuilder sw = new System.Text.StringBuilder(); sw.AppendLine("BEGIN:VCALENDAR"); sw.AppendLine("VERSION:2.0"); sw.AppendLine("METHOD:REQUEST"); sw.AppendLine("BEGIN:VEVENT"); sw.AppendLine(attendees); sw.AppendLine("CLASS:PUBLIC"); sw.AppendLine(string.Format("CREATED:{0:yyyyMMddTHHmmssZ}", DateTime.UtcNow)); sw.AppendLine("DESCRIPTION:" + description); sw.AppendLine(string.Format("DTEND:{0:yyyyMMddTHHmmssZ}", end)); sw.AppendLine(string.Format("DTSTAMP:{0:yyyyMMddTHHmmssZ}", DateTime.UtcNow)); sw.AppendLine(string.Format("DTSTART:{0:yyyyMMddTHHmmssZ}", start)); sw.AppendLine("ORGANIZER;CN=\"NAME\":mailto:" + organizer); sw.AppendLine("SEQUENCE:0"); sw.AppendLine("UID:" + UID); sw.AppendLine("LOCATION:" + location); sw.AppendLine("SUMMARY;LANGUAGE=en-us:" + subject); sw.AppendLine("BEGIN:VALARM"); sw.AppendLine("TRIGGER:-PT720M"); sw.AppendLine("ACTION:DISPLAY"); sw.AppendLine("DESCRIPTION:Reminder"); sw.AppendLine("END:VALARM"); sw.AppendLine("END:VEVENT"); sw.AppendLine("END:VCALENDAR"); return sw.ToString(); } And once built, I use MailMessage, with an alternate view to send out the meeting request: meetingInfo = BuildMeetingRequest(start, end, attendees, organizer, subject, description, UID, location); System.Net.Mime.ContentType mimeType = new System.Net.Mime.ContentType("text/calendar; method=REQUEST"); AlternateView ICSview = AlternateView.CreateAlternateViewFromString(meetingInfo,mimeType); MailMessage message = new MailMessage(); message.To.Add(to); message.From = new MailAddress(from); message.AlternateViews.Add(ICSview); SmtpClient client = new SmtpClient(); client.Send(message); When users get the email in outlook, it shows up as a meeting request, as opposed to a normal email. This works well for sending out updates to the meeting request as well. The only problem that I am having is that I do not know the proper format for sending out a cancellation. I've attempted to examine some meeting request cancellations in text editors and can't seem to pinpoint the difference in the format between cancelling/creating. Any help on this is greatly appreciated.

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• how to use a tree data structure in C#

  - by matti

  I found an implementation for a tree at this SO question. Unfortunately I don't know how to use it. Also I made a change to it since LinkedList does not have Add method: delegate void TreeVisitor<T>(T nodeData); class NTree<T> { T data; List<NTree<T>> children; public NTree(T data) { this.data = data; children = new List<NTree<T>>(); } public void AddChild(T data) { children.Add(new NTree<T>(data)); } public NTree<T> GetChild(int i) { return children[i]; } public void Traverse(NTree<T> node, TreeVisitor<T> visitor) { visitor(node.data); foreach (NTree<T> kid in node.children) Traverse(kid, visitor); } } I have class named tTable and I want to store it's children and their grandchildren (...) in this tree. My need is to find immediate children and not traverse entire tree. I also might need to find children with some criteria. Let's say tTable has only name and I want to find children with names matching some criteria. tTables constructor gives name a value according to int-value (somehow). How do I use Traverse (write delegate) if I have code like this; int i = 0; Dictionary<string, NTree<tTable>> tableTreeByRootTableName = new Dictionary<string, NTree<tTable>>(); tTable aTable = new tTable(i++); tableTreeByRootTableName[aTable.Name] = new NTree(aTable); tableTreeByRootTableName[aTable.Name].AddChild(new tTable(i++)); tableTreeByRootTableName[aTable.Name].AddChild(new tTable(i++)); tableTreeByRootTableName[aTable.Name].GetChild(1).AddChild(new tTable(i++));

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• Can't make my WCF extension work

  - by Sergio Romero

  I have a WCF solution that consists of the following class libraries: Exercise.Services: Contains the implementation classes for the services. Exercise.ServiceProxy: Contains the classes that are instantiated in the client. Exercise.HttpHost: Contains the services (*.svc files). I'm calling the service from a console application and the "first version" works really well so I took the next step which is to create a custom ServiceHostFactory, ServiceHost, and InstanceProvider so I can use constructor injection in my services as it is explained in this article. These classes are implemented in yet another class library: 4. Exercise.StructureMapWcfExtension Now even though I've modified my service this: <%@ ServiceHost Language="C#" Debug="true" Factory="Exercise.StructureMapWcfExtension.StructureMapServiceHostFactory" Service="Exercise.Services.PurchaseOrderService" %> I always get the following exception: System.ServiceModel.CommunicationException Security negotiation failed because the remote party did not send back a reply in a timely manner. This may be because the underlying transport connection was aborted. It fails in this line of code: public class PurchaseOrderProxy : ClientBase<IPurchaseOrderService>, IPurchaseOrderService { public PurchaseOrderResponse CreatePurchaseOrder(PurchaseOrderRequest purchaseOrderRequest) { return base.Channel.CreatePurchaseOrder(purchaseOrderRequest); //Fails here } } But that is not all, I added a trace to the web.config file and this is the error that appears in the log file: System.InvalidOperationException The service type provided could not be loaded as a service because it does not have a default (parameter-less) constructor. To fix the problem, add a default constructor to the type, or pass an instance of the type to the host. So this means that my ServiceHostFactory is never being hit, I even set a breakpoint in both its constructor and its method and they never get hit. I've added a reference of the StructureMapWcfExtension library to all the other ones (even the console client), one by one to no avail. I also tried to use the option in the host's web.config file to configure the factory like so: <serviceHostingEnvironment> <serviceActivations> <add service="Exercise.Services.PurchaseOrderService" relativeAddress="PurchaseOrderService.svc" factory="Exercise.StructureMapWcfExtension.StructureMapServiceHostFactory"/> </serviceActivations> </serviceHostingEnvironment> That didn't work either. Please I need help in getting this to work so I can incorporate it to our project. Thank you. UPDATE: Here's the service host factory's code: namespace Exercise.StructureMapWcfExtension { public class StructureMapServiceHostFactory : ServiceHostFactory { private readonly Container Container; public StructureMapServiceHostFactory() { Container = new Container(); new ContainerConfigurer().Configure(Container); } protected override ServiceHost CreateServiceHost(Type serviceType, Uri[] baseAddresses) { return new StructureMapServiceHost(Container, serviceType, baseAddresses); } } public class ContainerConfigurer { public void Configure(Container container) { container.Configure(r => r.For<IPurchaseOrderFacade>().Use<PurchaseOrderFacade>()); } } }

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• Observer pattern used with decorator pattern

  - by icelated

  I want to make a program that does an order entry system for beverages. ( i will probably do description, cost) I want to use the Decorator pattern and the observer pattern. I made a UML drawing and saved it as a pic for easy viewing. This site wont let me upload as a word doc so i have to upload a pic - i hope its easily viewable.... I need to know if i am doing the UML / design patterns correctly before moving on to the coding part. Beverage is my abstract component class. Espresso, houseblend, darkroast are my concrete subject classes.. I also have a condiment decorator class milk,mocha,soy,whip. would be my observer? because they would be interested in data changes to cost? Now, would the espresso,houseblend etc, be my SUBJECT and the condiments be my observer? My theory is that Cost is a changes and that the condiments need to know the changes? So, subject = esspresso,houseblend,darkroast,etc.. // they hold cost() Observer = milk,mocha,soy,whip? // they hold cost() would be the concrete components and the milk,mocha,soy,whip? would be the decorator! So, following good software engineering practices "design to an interface and not implementation" or "identify things that change from those that dont" would i need a costbehavior interface? If you look at the UML you will see where i am going with this and see if i am implementing observer + Decorator pattern correctly? I think the decorator is correct. since, the pic is not very viewable i will detail the classes here: Beverage class(register observer, remove observer, notify observer, description) these classes are the concrete beverage classes espresso, houseblend,darkroast, decaf(cost,getdescription,setcost,costchanged) interface observer class(update) // cost? interface costbehavior class(cost) // since this changes? condiment decorator class( getdescription) concrete classes that are linked to the 2 interface s and decorator are: milk,mocha,soy,whip(cost,getdescription,update) these are my decorator/ wrapper classes. Thank you.. Is there a way to make this picture bigger?

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• Optimizing spacing of mesh containing a given set of points

  - by Feynman

  I tried to summarize the this as best as possible in the title. I am writing an initial value problem solver in the most general way possible. I start with an arbitrary number of initial values at arbitrary locations (inside a boundary.) The first part of my program creates a mesh/grid (I am not sure which is the correct nuance), with N points total, that contains all the initial values. My goal is to optimize the mesh such that the spacing is as uniform as possible. My solver seems to work half decently (it needs some more obscure debugging that is not relevant here.) I am starting with one dimension. I intend to generalize the algorithm to an arbitrary number of dimensions once I get it working consistently. I am writing my code in fortran, but feel free to reply with pseudocode or the language of your choice. Allow me to elaborate with an example: Say I am working on a closed interval [1,10] xmin=1 xmax=10 Say I have 3 initial points: xmin, 5 and xmax num_ivc=3 known(num_ivc)=[xmin,5,xmax] //my arrays start at 1. Assume "known" starts sorted I store my mesh/grid points in an array called coord. Say I want 10 points total in my mesh/grid. N=10 coord(10) Remember, all this is arbitrary--except the variable names of course. The algorithm should set coord to {1,2,3,4,5,6,7,8,9,10} Now for a less trivial example: num_ivc=3 known(num_ivc)=[xmin,5.5,xmax or just num_ivc=1 known(num_ivc)=[5.5] Now, would you have 5 evenly spaced points on the interval [1, 5.5] and 5 evenly spaced points on the interval (5.5, 10]? But there is more space between 1 and 5.5 than between 5.5 and 10. So would you have 6 points on [1, 5.5] followed by 4 on (5.5 to 10]. The key is to minimize the difference in spacing. I have been working on this for 2 days straight and I can assure you it is a lot trickier than it sounds. I have written code that only works if N is large only works if N is small only works if it the known points are close together only works if it the known points are far apart only works if at least one of the known points is near a boundary only works if none of the known points are near a boundary So as you can see, I have coded the gamut of almost-solutions. I cannot figure out a way to get it to perform equally well in all possible scenarios (that is, create the optimum spacing.)

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