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• Console Application Structure

  - by Paul Fox

  I've written several .Net Console Applications over the past 6 months and we have many more throughout different projects in our organization. I generally stick to the same standard format/structure for my Console Applications. Unfortunately, many of our console applications do not. I have been looking into ways of standardizing the structure of these Console Applications. I would also like to provide a framework for the basic structure of a Console Application and provide easy access to standard ways of handling things such as argument passing, logging, etc. Can anyone suggest Best Practices for addressing these concerns? I have been reading this MSDN article on Console Applications in .Net which suggests a Design Pattern for Console Apps. The example uses a Template Method pattern to handle some of the concerns I listed earlier. Two negatives of using this approach are listed in the article. Ending up with twice as many classes Having many simple, similar classes Can anyone suggest better, or more standard, ways of handling this? What about listing additional negatives with this approach?

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• How can I keep curl output out of mail from my cronjob?

  - by Russell C.

  I have written a Perl script that runs as a daily crontab job that uploads files to Amazon S3 via CURL. I want the output of the cron job emailed to me which works fine but I don't want that email to include messages related to the CURL upload (only those message my script is outputting). Here are the CURL related messages I'm seeing in the daily email right now: % Total % Received % Xferd Average Speed Time Time Time Current Dload Upload Total Spent Left Speed 0 230M 0 0 0 0 0 0 --:--:-- --:--:-- --:--:-- 0 0 230M 0 0 0 544k 0 1519k 0:02:35 --:--:-- 0:02:35 1807k 0 230M 0 0 0 1744k 0 1286k 0:03:03 0:00:01 0:03:02 1342k 1 230M 0 0 1 2880k 0 1219k 0:03:13 0:00:02 0:03:11 1250k 1 230M 0 0 1 4016k 0 1198k 0:03:17 0:00:03 0:03:14 1218k 2 230M 0 0 2 5168k 0 1186k 0:03:19 0:00:04 0:03:15 1202k 2 230M 0 0 2 6336k 0 1181k 0:03:19 0:00:05 0:03:14 1157k 3 230M 0 0 3 7488k 0 1177k 0:03:20 0:00:06 0:03:14 1147k 3 230M 0 0 3 8592k 0 1167k 0:03:22 0:00:07 0:03:15 1142k 4 230M 0 0 4 9744k 0 1166k 0:03:22 0:00:08 0:03:14 1145k 4 230M 0 0 4 10.6M 0 1163k 0:03:23 0:00:09 0:03:14 1142k 5 230M 0 0 5 11.7M 0 1161k 0:03:23 0:00:10 0:03:13 1140k 5 230M 0 0 5 12.8M 0 1158k 0:03:23 0:00:11 0:03:12 1133k 6 230M 0 0 6 13.9M 0 1155k 0:03:24 0:00:12 0:03:12 1138k 6 230M 0 0 6 15.0M 0 1155k 0:03:24 0:00:13 0:03:11 1138k 7 230M 0 0 7 16.1M 0 1152k 0:03:25 0:00:14 0:03:11 1131k 7 230M 0 0 7 17.2M 0 1152k 0:03:25 0:00:15 0:03:10 1132k 7 230M 0 0 7 18.4M 0 1152k 0:03:24 0:00:16 0:03:08 1140k I am using a simple Perl system() call to invoke CURL. Does anyone know what command line argument I can supply CURL to turn off the reporting of the upload progress?

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• AIX specific socket programming query

  - by kumar_m_kiran

  Hi All, Question 1 From SUSE man pages, I get the below details for socket connect options If the initiating socket is connection-mode, then connect() shall attempt to establish a connection to the address specified by the address argument. If the connection cannot be established immediately and O_NONBLOCK is not set for the file descriptor for the socket, connect() shall block for up to an unspecified timeout interval until the connection is established. If the timeout interval expires before the connection is established, connect() shall fail and the connection attempt shall be aborted. If connect() is interrupted by a signal that is caught while blocked waiting to establish a connection, connect() shall fail and set errno to [EINTR], but the connection request shall not be aborted, and the connection shall be established asynchronously. Question : Is the above contents valid for AIX OS (especially the connection time-out, timed wait ...etc)?Because I do not see it in AIX man pages (5.1 and 5.3) Question 2 I have a client socket whose attributes are a. SO_RCVTIMEO ,SO_SNDTIMEO are set for 5 seconds. b. AF_INET and SOCK_STREAM. c. SO_LINGER with linger on and time is 5 seconds. d. SO_REUSEADDR is set. Note that the client socket is not O_NONBLOCK. Question : Now since O_NONBLOCK is not set and SO_RCVTIMEO and SO_SNDTIMEO is set for 5 seconds, does it mean a. connect in NON Blocking or Blocking? b. If blocking, is it timed blocking or "infinite" time blocking? c. If it is infinite, How do I establish a "connect" system call which is O_BLOCKING with timeout to t secs. Sorry if the questions are be very naive. Thanks in advance for your input.

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• Passing an arbritrary JavaScript object in Xul

  - by Tom Brito

  I'm following this example to pass an object to a window, but when it as an argument it's with "undefined" value. This is my first window (obs. dump is the way to print to console when debug options are turned on): <?xml version="1.0"?> <?xml-stylesheet href="chrome://global/skin/" type="text/css"?> <!DOCTYPE window SYSTEM "chrome://XulWindowArgTest/locale/XulWindowArgTest.dtd"> <window id="windowID" width="400" height="300" xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"> <script> <![CDATA[ function onClickMe(event) { dump("begin\n"); try { var args = { param1: true, param2: 42 }; args.wrappedJSObject = args; var watcher = Components.classes["@mozilla.org/embedcomp/window-watcher;1"].getService(Components.interfaces.nsIWindowWatcher); watcher.openWindow(null, "chrome://XulWindowArgTest/content/about.xul", "windowName", "chrome", args); } catch (e) { dump("error: " + e + "\n"); } dump("end\n"); } ]]> </script> <button label="Click me !" oncommand="onClickMe();" /> </window> and my second window: <?xml version="1.0"?> <?xml-stylesheet href="chrome://global/skin/" type="text/css"?> <!DOCTYPE window SYSTEM "chrome://XulWindowArgTest/locale/XulWindowArgTest.dtd"> <window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul" onload="onload()"> <script> <![CDATA[ function onload() { dump('arg = ' + window.arguments[0].wrappedJSObject + "\n"); } ]]> </script> <label value="test" /> </window> when the second window loads, it calls the onload and prints: arg = undefined Any idea how to fix it?

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• sort elements in jQuery object

  - by Fresheyeball

  <div class="myClass">1</div> <div class="myClass">2</div> <div class="myClass">3</div> <div class="myClass">4</div> <div class="myClass">5</div> <div class="myClass">6</div> var $myClass = $('.myClass'); $myClass.eq(0).text() //returns '1' $myClass.eq(4).text() //returns '5' $myClass.eq(5).text() //returns '6' What I want to do is reorder the objects in jQuery manually. //fantasy command reversing $myClass.eqSorter([5,4,3,2,1,0]); $myClass.eq(0).text() //returns '6' $myClass.eq(5).text() //returns '1' What I really want is to allow a fully custom order input //fantasy command custom ordering $myClass.eqSorter([3,5,4,2,0,1]); $myClass.eq(0).text() //returns '4' $myClass.eq(5).text() //returns '2' Now I've looked at basic ways of doing this like .sort as a part of javascript, but .sort takes a dynamic argument the compares things, and does not allow for a fully custom order. I also looked at making a new blank jquery object that I could pass elements into like this $newObjectVar.eq(0) = $myClass.eq(3); for example. But as of yet I have not found a way to make a blank jQuery object like this.

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• Aquireing the entire string sent to the shell for execution

  - by user294567

  I have a bash script that looks like this (called job_result.sh): #!/bin/bash $* && zenity --title "Job result" --info --text "SUCSESS: Job '$*'completed" && while pidof zenity > /dev/null; do /usr/bin/wmctrl -a "Job Result" && sleep 2; done When i execute it with: $ ./job_result.sh echo "arf" && sleep 10 I want the following to happen: $ echo "arf" && sleep 10 && zenity --title "Job result" --info --text "SUCSESS: Job '$*'completed" && while pidof zenity > /dev/null; do /usr/bin/wmctrl -a "Job Result" && sleep 2; done But it seems the following is happening: $ echo "arf" && zenity --title "Job result" --info --text "SUCSESS: Job '$*'completed" && while pidof zenity > /dev/null; do /usr/bin/wmctrl -a "Job Result" && sleep 2; done Question: How do i get hold of the entire shell argument? And not just the part until &&?

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• Trying to create a group of button sprites

  - by user1449653

  Good day, I have like 15 images I need to be buttons. I have buttons working with a Box() (Box - looks like this) class Box(pygame.sprite.Sprite): def __init__(self): pygame.sprite.Sprite.__init__(self) self.image = pygame.Surface((35, 30)) self.image = self.image.convert() self.image.fill((255, 0, 0)) self.rect = self.image.get_rect() self.rect.centerx = 25 self.rect.centery = 505 self.dx = 10 self.dy = 10 I am trying to make the buttons work with image sprites. So I attempted to copy the class style of the box and do the same for my Icons.. code looks like this... class Icons(pygame.sprite.Sprite): def __init__(self): pygame.sprite.Sprite.__init__(self) self.image = pygame.image.load("images/airbrushIC.gif").convert() self.rect = self.image.get_rect() self.rect.x = 25 self.rect.y = 550 the code in the main() rect = image.get_rect() rect.x = 25 rect.y = 550 ic1 = Icons((screen.get_rect().x, screen.get_rect().y)) screen.blit(ic1.image, ic1.rect) pygame.display.update() This code produces a positional (accepts 1 argument but 2 are there) error or an image is not referenced error (inside the Icon class). I'm unsure if this is the right way to go about this anyways.. I know for sure that I need to load all the images (as sprites)... store them in an array... and then have my mouse check if it is clicking one of the items in the array using a for loop. Thanks. EDIT QUESTION 2: class Icons(pygame.sprite.Sprite): def init(self, *args): pygame.sprite.Sprite.init(self, *args) self.image = pygame.image.load("images/airbrushIC.gif").convert() self.rect = self.image.get_rect() ic1 = self.image self.rect.x = 10 self.rect.y = 490 self.image = pygame.image.load("images/fillIC.gif").convert() self.rect = self.image.get_rect() ic2 = self.image self.rect.x = 10 self.rect.y = 540 Thanks to your help I got the Icons class loading ONE image. Its not loading both. Obviously because its being overwritten by the second one. It seems that "class" for this purpose isn't what I need. Which begs the question how I make sprites outside of a class.. If there is a way to make the class work please let me know.

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• Doesn't (didn't) Scala have automatically generated setters?

  - by Malvolio

  Google and my failing memory are both giving me hints that it does, but every attempt is coming up dry. class Y { var y = 0 } var m = new Y() m.y_(3) error: value y_ is not a member of Y Please tell me I am doing something wrong. (Also: please tell me what it is I am doing wrong.) EDIT The thing I am not doing wrong, or at least not the only thing I am doing wrong, is the way I am invoking the setter. The following things also fail, all with the same error message: m.y_ // should be a function valued expression m.y_ = (3) // suggested by Google and by Mchl f(m.y_) // where f takes Int => Unit as an argument f(m.y) // complains that I am passing in Int not a function I am doing this all through SimplyScala, because I'm too lazy and impatient to set up Scala on my tiny home machine. Hope it isn't that... And the winner is ... Fabian, who pointed out that I can't have a space between the _ and the =. I thought out why this should be and then it occurred to me: The name of the setter for y is not y_, it is y_= ! Observe: class Y { var y = 0 } var m = new Y() m.y_=(3) m.y res1: Int = 3 m.y_= error: missing arguments for method y_= in class Y; follow this method with `_` if you want to treat it as a partially applied function m.y_= ^ m.y_=_ res2: (Int) => Unit = def four(f : Int => Unit) = f(4) four(m.y_=) m.y res3: Int = 4 Another successful day on StackExchange.

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• Search string in file (C)

  - by chutsu

  So my code isn't working... test.c:27: warning: passing argument 1 of ‘search’ from incompatible pointer type which is the fgets line. My code opens a file, reads the file line by line, and I'm trying to create a "search" function that will return a value that indicates whether that string is found on that line of the file. My ultimate goal is to achieve a search and replace program. But one step at a time eh? this is what I have so far: #include <stdio.h> #include <string.h> int search(const char *content[], const char *search_term) { int t; for(t=0; content[t]; ++t){ if(!strcmp(content[t], search_term)){ return t; // found } } return 0; // not found } int main(int argc, char *argv[]) { FILE *file; char line[BUFSIZ]; int linenumber=0; char term[20] = "hello world"; file = fopen(argv[1], "r"); if(file != NULL){ while(fgets(line, sizeof(line), file)){ if(search(line, term) != -1){ printf("Search Term Found!!\n"); } ++linenumber; } } else{ perror(argv[1]); } fclose(file); return 0; }

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• Why Is the sender type null when dealing with events

  - by ChloeRadshaw

  From C# Via CLR: Note A lot of people wonder why the event pattern requires the sender parameter to always be of type Object After all, since the MailManager will be the only type raising an event with a NewMail EventArgs object, it makes more sense for the callback method to be prototyped like this: void MethodName(Mai l Manager sender, NewMail EventArgs e); The pattern requires the sender parameter to be of type Object mostly because of inheritance What if Mai lManager were used as a base class for SmtpMailManager? In this case, the callback method should have the sender parameter prototyped as SmtpMailManager instead of Mail Manager, but this can’t happen because SmtpMai lManager just inherited the NewMai l event So the code that was expecting SmtpMail Manager to raise the event must still have to cast the sender argument to SmtpMailManager In other words, the cast is still required, so the sender parameter might as well be typed as Obj ect The next reason for typing the sender parameter as Obj ect is just fexibility It allows the delegate to be used by multiple types that offer an event that passes a NewMail EventArgs object For example, a PopMai lManager class could use the delegate even if this class were not derived from Mail Manager I just simply cannot understand why the sender is an object - Why can it not be generified? so most of the time we do not need to do generic casts

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• Haskell: Dealing With Types And Exceptions

  - by Douglas Brunner

  I'd like to know the "Haskell way" to catch and handle exceptions. As shown below, I understand the basic syntax, but I'm not sure how to deal with the type system in this situation. The below code attempts to return the value of the requested environment variable. Obviously if that variable isn't there I want to catch the exception and return Nothing. getEnvVar x = do { var <- getEnv x; Just var; } `catch` \ex -> do { Nothing } Here is the error: Couldn't match expected type `IO a' against inferred type `Maybe String' In the expression: Just var In the first argument of `catch', namely `do { var <- getEnv x; Just var }' In the expression: do { var <- getEnv x; Just var } `catch` \ ex -> do { Nothing } I could return string values: getRequestURI x = do { requestURI <- getEnv x; return requestURI; } `catch` \ex -> do { return "" } however, this doesn't feel like the Haskell way. What is the Haskell way?

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• Passing.getText() String to another class

  - by DanMc

  I'm currently working on a first year university project and I have a problem, although I doubt it's a very complicated one, but I've been searching and I just can't find a suitable answer to it. The problem concerns two classes. A gui class (class1) and another class (class2). I have a JTextField in class1 and am trying to pass through the .getText() value to class2 and store it in a String type variable. The current code I'm trying to achieve this with is the following: (Class1) private JTextField textField = new JTextField("Something"); ... public String getTextFieldString() { return textField.getText(); } (Class2) private c1 Class1 = new Class1(); private String s = new String(); ... s = c1.getTextFieldString(); I'm pretty new to coding, I've read that maybe I need to pass through an argument somewhere and I assume that's because textField is not static in itself, it changes when somebody enters a new value. (sorry for stating the obvious there.) Anyway, help is appreciated. Thanks a lot!

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• Getting memory leak at NSURL connection in Iphone sdk.

  - by monish

  Hi guys, Here Im getting leak at the NSURL connection in my libxml parser can anyone tell how to resolve it. The code where leak generates is: - (BOOL)parseWithLibXML2Parser { BOOL success = NO; ZohoAppDelegate *appDelegate = (ZohoAppDelegate*) [ [UIApplication sharedApplication] delegate]; NSString* curl; if ([cName length] == 0) { curl = @"https://invoice.zoho.com/api/view/settings/currencies?ticket="; curl = [curl stringByAppendingString:appDelegate.ticket]; curl = [curl stringByAppendingString:@"&apikey="]; curl = [curl stringByAppendingString:appDelegate.apiKey]; curl = [curl stringByReplacingOccurrencesOfString:@"\n" withString:@""]; } NSURLRequest *theRequest = [NSURLRequest requestWithURL:[NSURL URLWithString:curl]]; NSLog(@"the request parserWithLibXml2Parser %@",theRequest); NSURLConnection *con = [[[NSURLConnection alloc] initWithRequest:theRequest delegate:self] autorelease];//Memory leak generated here at this line of code. //self.connection = con; //[con release]; // This creates a context for "push" parsing in which chunks of data that are // not "well balanced" can be passed to the context for streaming parsing. // The handler structure defined above will be used for all the parsing. The // second argument, self, will be passed as user data to each of the SAX // handlers. The last three arguments are left blank to avoid creating a tree // in memory. _xmlParserContext = xmlCreatePushParserCtxt(&simpleSAXHandlerStruct, self, NULL, 0, NULL); if(con != nil) { do { [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate distantFuture]]; } while (!_done && !self.error); } if(self.error) { //NSLog(@"parsing error"); [self.delegate parser:self encounteredError:nil]; } else { success = YES; } return success; } Anyone's help will be muck appreciated . Thank you, Monish.

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• Error using to_char // to_timetamp

  - by pepersview

  Hello, I have a database in PostgreSQL and I'm developing an application in PHP using this database. The problem is that when I execute the following query I get a nice result in phpPgAdmin but in my PHP application I get an error. The query: SELECT t.t_name, t.t_firstname FROM teachers AS t WHERE t.id_teacher IN (SELECT id_teacher FROM teacher_course AS tcourse JOIN course_timetable AS coursetime ON tcourse.course = coursetime.course AND to_char(to_timestamp('2010-4-12', 'YYYY-MM-DD'),'FMD') = (coursetime.day +1)) AND t.id_teacher NOT IN (SELECT id_teacher FROM teachers_fill WHERE date = '2010-4-12') ORDER BY t.t_name ASC And this is the error in PHP operator does not exist: text = integer (to_timestamp('', 'YYYY-MM-DD'),'FMD') = (courset... ^ HINT: No operator matches the given name and argument type(s). You might need to add explicit type casts. The purpose to solve this error is to use the ORIGINAL query in php with : $date = "2010"."-".$selected_month."-".$selected_day; SELECT t.t_name, t.t_firstname FROM teachers AS t WHERE t.id_teacher IN (SELECT id_teacher FROM teacher_course AS tcourse JOIN course_timetable AS coursetime ON tcourse.course = coursetime.course AND to_char(to_timestamp('$date', 'YYYY-MM-DD'),'FMD') = (coursetime.day +1)) AND t.id_teacher NOT IN (SELECT id_teacher FROM teachers_fill WHERE date = '$date') ORDER BY t.t_name ASC

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• Why it's can be compiled in GNU/C++, can't compiled in VC++2010 RTM?

  - by volnet

  #include #include #include #include "copy_of_auto_ptr.h" #ifdef _MSC_VER #pragma message("#include ") #include // http://gcc.gnu.org/onlinedocs/gcc/Diagnostic-Pragmas.html#Diagnostic-Pragmas #endif /* case 1-4 is the requirement of the auto_ptr. which form http://ptgmedia.pearsoncmg.com/images/020163371X/autoptrupdate/auto_ptr_update.html */ /* case 1. (1) Direct-initialization, same type, e.g. */ std::auto_ptr source_int() { // return std::auto_ptr(new int(3)); std::auto_ptr tmp(new int(3)); return tmp; } /* case 2. (2) Copy-initialization, same type, e.g. */ void sink_int(std::auto_ptr p) { std::cout source_derived() { // return std::auto_ptr(new Derived()); std::auto_ptr tmp(new Derived()); return tmp; } /* case 4. (4) Copy-initialization, base-from-derived, e.g. */ void sink_base( std::auto_ptr p) { p-go(); } int main(void) { /* // auto_ptr */ // case 1. // auto_ptr std::auto_ptr p_int(source_int()); std::cout p_derived(source_derived()); p_derived-go(); // case 4. // auto_ptr sink_base(source_derived()); return 0; } In Eclipse(GNU C++.exe -v gcc version 3.4.5 (mingw-vista special r3)) it's two compile error: Description Resource Path Location Type initializing argument 1 of void sink_base(std::auto_ptr<Base>)' from result ofstd::auto_ptr<_Tp::operator std::auto_ptr<_Tp1() [with _Tp1 = Base, _Tp = Derived]' auto_ptr_ref_research.cpp auto_ptr_ref_research/auto_ptr_ref_research 190 C/C++ Problem Description Resource Path Location Type no matching function for call to `std::auto_ptr::auto_ptr(std::auto_ptr)' auto_ptr_ref_research.cpp auto_ptr_ref_research/auto_ptr_ref_research 190 C/C++ Problem But it's right in VS2010 RTM. Questions: Which compiler stand for the ISO C++ standard? The content of case 4 is the problem "auto_ptr & auto_ptr_ref want to resolve?"

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• C++: inheritance problem

  - by Helltone

  It's quite hard to explain what I'm trying to do, I'll try: Imagine a base class A which contains some variables, and a set of classes deriving from A which all implement some method bool test() that operates on the variables inherited from A. class A { protected: int somevar; // ... }; class B : public A { public: bool test() { return (somevar == 42); } }; class C : public A { public: bool test() { return (somevar > 23); } }; // ... more classes deriving from A Now I have an instance of class A and I have set the value of somevar. int main(int, char* []) { A a; a.somevar = 42; Now, I need some kind of container that allows me to iterate over the elements i of this container, calling i::test() in the context of a... that is: std::vector<...> vec; // push B and C into vec, this is pseudo-code vec.push_back(&B); vec.push_back(&C); bool ret = true; for(i = vec.begin(); i != vec.end(); ++i) { // call B::test(), C::test(), setting *this to a ret &= ( a .* (&(*i)::test) )(); } return ret; } How can I do this? I've tried two methods: forcing a cast from B::* to A::*, adapting a pointer to call a method of a type on an object of a different type (works, but seems to be bad); using std::bind + the solution above, ugly hack; changing the signature of bool test() so that it takes an argument of type const A& instead of inheriting from A, I don't really like this solution because somevar must be public.

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• Creating simple calculator with bison & flex in C++ (not C)

  - by ak91

  Hey, I would like to create simple C++ calculator using bison and flex. Please note I'm new to the creating parsers. I already found few examples in bison/flex but they were all written in C. My goal is to create C++ code, where classes would contain nodes of values, operations, funcs - to create AST (evaluation would be done just after creating whole AST - starting from the root and going forward). For example: my_var = sqrt(9 ** 2 - 32) + 4 - 20 / 5 my_var * 3 Would be parsed as: = / \ my_var + / \ sqrt - | / \ - 4 / / \ / \ ** 32 20 5 / \ 9 2 and the second AST would look like: * / \ my_var 3 Then following pseudocode reflects AST: ast_root = create_node('=', new_variable("my_var"), exp) where exp is: exp = create_node(OPERATOR, val1, val2) but NOT like this: $$ = $1 OPERATOR $3 because this way I directly get value of operation instead of creation the Node. I believe the Node should contain type (of operation), val1 (Node), val2 (Node). In some cases val2 would be NULL, like above mentioned sqrt which takes in the end one argument. Right? It will be nice if you can propose me C++ skeleton (without evaluation) for above described problem (including *.y file creating AST) to help me understand the way of creating/holding Nodes in AST. Code can be snipped, just to let me get the idea. I'll also be grateful if you point me to an existing (possibly simple) example if you know any. Thank you all for your time and assistance!

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• The sign of zero with float2

  - by JackOLantern

  Consider the following code performing operations on complex numbers with C/C++'s float: float real_part = log(3.f); float imag_part = 0.f; float real_part2 = (imag_part)*(imag_part)-(real_part*real_part); float imag_part2 = (imag_part)*(real_part)+(real_part*imag_part); The result will be real_part2= -1.20695 imag_part2= 0 angle= 3.14159 where angle is the phase of the complex number and, in this case, is pi. Now consider the following code: float real_part = log(3.f); float imag_part = 0.f; float real_part2 = (-imag_part)*(-imag_part)-(real_part)*(real_part); float imag_part2 = (-imag_part)*(real_part)+(real_part)*(-imag_part); The result will be real_part2= -1.20695 imag_part2= 0 angle= -3.14159 The imaginary part of the result is -0 which makes the phase of the result be -pi. Although still accomplishing with the principal argument of a complex number and with the signed property of floating point's 0, this changes is a problem when one is defining functions of complex numbers. For example, if one is defining sqrt of a complex number by the de Moivre formula, this will change the sign of the imaginary part of the result to a wrong value. How to deal with this effect?

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• How do you make an added row from QueryAddRow() the first row of the result from a query?

  - by JS

  I am outputting a query but need to specify the first row of the result. I am adding the row with QueryAddRow() and setting the values with QuerySetCell(). I can create the row fine, I can add the content to that row fine. If I leave the argument for the row number off of QuerySetCell() then it all works great as the last result of the query when output. However, I need it to be first row of the query but when I try to set the row attribute with the QuerySetCell it just overwrites the first returned row from my query (i.e. my QueryAddRow() replaces the first record from my query). What I currently have is setting a variable from recordCount and arranging the output but there has to be a really simple way to do this that I am just not getting. This code sets the row value to 1 but overwrites the first returned row from the query. <cfquery name="qxLookup" datasource="#application.datasource#"> SELECT xID, xName, execution FROM table </cfquery> <cfset QueryAddRow(qxLookup)/> <cfset QuerySetCell(qxLookup, "xID","0",1)/> <cfset QuerySetCell(qxLookup, "xName","Delete",1)/> <cfset QuerySetCell(qxLookup, "execution", "Select this to delete",1)/> <cfoutput query="qxLookup"> <tr> <td> <a href="##" onclick="javascript:ColdFusion.navigate('xSelect/x.cfm?xNameVar=#url.xNameVar#&xID=#qxLookup.xID#&xName=#URLEncodedFormat(qxLookup.xName)#', '#xNameVar#');ColdFusion.Window.hide('#url.window#')">#qxLookup.xName#</a> </td> <td>#qxLookup.execution#</td> </tr> </cfoutput> </table> Thanks for any help.

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• Complicated .NET factory design

  - by Tom W

  Hello SO; I'm planning to ask a fairly elaborate question that is also something of a musing here, so bear with me... I'm trying to design a factory implementation for a simulation application. The simulation will consist of different sorts of entities i.e. it is not a homogenous simulation in any respect. As a result, there will be numerous very different concrete implementations and only the very general properties will be abstracted at the top level. What I'd like to be able to do is create new simulation entities by calling a method on the model with a series of named arguments representing the parameters of the entity, and have the model infer what type of object is being described by the inbound parameters (from the names of the parameters and potentially the sequence they occur in) and call a factory method on the appropriate derived class. For example, if I pass the model a pair of parameters (Param1=5000, Param2="Bacon") I would like it to infer that the names Param1 and Param2 'belong' to the class "Blob1" and call a shared function "getBlob1" with named parameters Param1:=5000, Param2:="Bacon" whereas if I pass the model (Param1=5000, Param3=50) it would call a similar factory method for Blob2; because Param1 and Param3 in that order 'belong' to Blob2. I foresee several issues to resolve: Whether or not I can reflect on the available types with string parameter names and how to do this if it's possible Whether or not there's a neat way of doing the appropriate constructor inference from the combinatoric properties of the argument list or whether I'm going to have to bodge something to do it 'by hand'. If possible I'd like the model class to be able to accept parameters as parameters rather than as some collection of keys and values, which would require the model to expose a large number of parametrised methods at runtime without me having to code them explicitly - presumably one for every factory method available in the relevant namespace. What I'm really asking is how you'd go about implementing such a system, rather than whether or not it's fundamentally possible. I don't have the foresight or experience with .NET reflection to be able to figure out a way by myself. Hopefully this will prove an informative discussion.

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• Is it not possible to make a C++ application "Crash Proof"?

  - by Enno Shioji

  Let's say we have an SDK in C++ that accepts some binary data (like a picture) and does something. Is it not possible to make this SDK "crash-proof"? By crash I primarily mean forceful termination by the OS upon memory access violation, due to invalid input passed by the user (like an abnormally short junk data). I have no experience with C++, but when I googled, I found several means that sounded like a solution (use a vector instead of an array, configure the compiler so that automatic bounds check is performed, etc.). When I presented this to the developer, he said it is still not possible.. Not that I don't believe him, but if so, how is language like Java handling this? I thought the JVM performs everytime a bounds check. If so, why can't one do the same thing in C++ manually? UPDATE By "Crash proof" I don't mean that the application does not terminate. I mean it should not abruptly terminate without information of what happened (I mean it will dump core etc., but is it not possible to display a message like "Argument x was not valid" etc.?)

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• Problems with variadic function (C)

  - by morpheous

  I have the following function from some legacy code that I am maintaining. long getMaxStart(long start, long count, const myStruct *s1, ...) { long i1, maxstart; myStruct *s2; va_list marker; maxstart = start; /*BUGFIX: 003 */ /*(va_start(marker, count);*/ va_start(marker, s1); for (i1 = 1; i1 <= count; i1++) { s2 = va_arg(marker, myStruct *); /* <- s2 is assigned null here */ maxstart = MAX(maxstart, s2->firstvalid); /* <- SEGV here */ } va_end(marker); return (maxstart); } When the function is called with only one myStruct argument, it causes a SEGV. The code compiled and run without crashing on an XP, when I compiled it using VS2005. I have now moved the code to Ubuntu Karmic and I am having problems with the stricter compiler on Linux. Is anyone able to spot what is causing the parameter not to be read correctly in the var_arg() statement? I am compiling using gcc version 4.4.1

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• Where to add an overloaded operator for the tr1::array?

  - by phlipsy

  Since I need to add an operator& for the std::tr1::array<bool, N> I wrote the following lines template<std::size_t N> std::tr1::array<bool, N> operator& (const std::tr1::array<bool, N>& a, const std::tr1::array<bool, N>& b) { std::tr1::array<bool, N> result; std::transform(a.begin(), a.end(), b.begin(), result.begin(), std::logical_and<bool>()); return result; } Now I don't know in which namespace I've to put this function. I considered the std namespace as a restricted area. Only total specialization and overloaded function templates are allowed to be added by the user. Putting it into the global namespace isn't "allowed" either in order to prevent pollution of the global namespace and clashes with other declarations. And finally putting this function into the namespace of the project doesn't work since the compiler won't find it there. What had I best do? I don't want to write a new array class putted into the project namespace. Because in this case the compiler would find the right namespace via argument dependent name lookup. Or is this the only possible way because writing a new operator for existing classes means extending their interfaces and this isn't allowed either for standard classes?

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• C# Casting system.__comobject to class type

  - by ijrufus

  I have an Excel Add-In that I'm currently trying to set up a unit test framework for. For the unit tests I've followed this guide: http://blogs.msdn.com/b/varsha/archive/2010/08/17/writing-automated-test-cases-for-vsto-application.aspx It seems to work fine, until I want to return a class object from my interface. Specifying the class object as the return type throws a "return argument has an invalid type" exception when calling the method. Changing the return type from the class to an object allows me to call the method and get the object, but now I'm unable to cast it as the class and use it as intended, getting this exception message when I try: > Unable to cast COM object of type 'System.__ComObject' to class type > 'anaplan.Utility.XYCoordinates'. Instances of types that represent COM > components cannot be cast to types that do not represent COM > components; however they can be cast to interfaces as long as the > underlying COM component supports QueryInterface calls for the IID of > the interface. I've retrieved the Type name using VisualBasic.Information.TypeName and it's showing it as the class I expect. Is there any way to get the comobject cast back to the class? Or another way to access the properties it has? Or am I just being a bit stupid here?

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• SYN receives RST,ACK very frequently

  - by user1289508

  Hi Socket Programming experts, I am writing a proxy server on Linux for SQL Database server running on Windows. The proxy is coded using bsd sockets and in C, and it is working just fine. When I use a database client (written in JAVA, and running on a Linux box) to fire queries (with a concurrency of 100 or more) directly to the Database server, not experiencing connection resets. But through my proxy I am experiencing many connection resets. Digging deeper I came to know that connection from 'DB client' to 'Proxy' always succeeds but when the 'Proxy' tries to connect to the DB server the connection fails, due to the SYN packet getting RST,ACK. That was to give some background. The question is : Why does sometimes SYN receives RST,ACK? 'DB client(linux)' to 'Server(windows)' ---- Works fine 'DB client(linux) to 'Proxy(Linux)' to 'Server(windows)' ----- problematic I am aware that this can happen in "connection refused" case but this definitely is not that one. SYN flooding might be another scenario, but that does not explain fine behavior while firing to Server directly. I am suspecting some socket option setting may be required, that the client does before connecting and my proxy does not. Please put some light on this. Any help (links or pointers) is most appreciated. Additional info: Wrote a C client that does concurrent connections, which takes concurrency as an argument. Here are my observations: - At 5000 concurrency and above, some connects failed with 'connection refused'. - Below 2000, it works fine. But the actual problem is observed even at a concurrency of 100 or more. Note: The problem is time dependent sometimes it never comes at all and sometimes it is very frequent and DB client (directly to server) works fine at all times .

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