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  • How do C and C++ interpreters bind identifiers to functions

    - by sub
    I'm talking about C and/or C++ here as this are the only languages I know used for interpreters where the following could be a problem: If we have an interpreted language X how can a library written for it add functions to the language which can then be called from within programs written in the language? PHP example: substr( $str, 5, 10 ); How is the function substr added to the "function pool" of PHP so it can be called from within scripts? It is easy for PHP storing all registered function names in an array and searching through it as a function is called in a script. However, as there obviously is no eval in C(++), how can the function then be called? I assume PHP doesn't have 100MB of code like: if( identifier == "substr" ) { return PHP_SUBSTR(...); } else if( ... ) { ... } Ha ha, that would be pretty funny. I hope you have understood my question so far. How do C/C++ interpreters solve this problem? How can I solve this for my own experimental toy interpreter?

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  • Problems with Window Functions Wndproc and about

    - by BrianHuangverinem
    I really having problems with this problem ,it would be nice if someone help me on this. Every time I try to build my source file the same errors occur every time for the two window functions CALLBACK Wndproc and CALLBACK About. error: "local function definitions are illegal" Can you tell me what mistake I made? LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam) { int wmId, wmEvent; PAINTSTRUCT ps; HDC hdc; wmId = LOWORD(wParam); wmEvent = HIWORD(wParam); switch (message) { case WM_COMMAND: // Parse the menu selections: switch (wmId) { case IDM_ABOUT: DialogBox(hInst, MAKEINTRESOURCE(IDD_ABOUTBOX), hWnd, About); break; case IDM_EXIT: DestroyWindow(hWnd); break; default: return DefWindowProc(hWnd, message, wParam, lParam); } break; case WM_PAINT: hdc = BeginPaint(hWnd, &ps); CaptureImage(hWnd); EndPaint(hWnd, &ps); break; case WM_DESTROY: PostQuitMessage(0); break; default: return DefWindowProc(hWnd, message, wParam, lParam); } return 0; } // Message handler for about box. INT_PTR CALLBACK About(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam) { UNREFERENCED_PARAMETER(lParam); switch (message) { case WM_INITDIALOG: return (INT_PTR)TRUE; case WM_COMMAND: if (LOWORD(wParam) == IDOK || LOWORD(wParam) == IDCANCEL) { EndDialog(hDlg, LOWORD(wParam)); return (INT_PTR)TRUE; } break; } return (INT_PTR)FALSE; }

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  • PHP checking/refreashing functions

    - by user1284360
    ok i have a main document that displays a chatbox, what i want is for the chatbox to refreash on everyone who is logged in's screen whenever someone posts a new message... ive tried many methods including sleep timers and new functions that call then sleep and get recalled but this just generates an endless line of the same or little diffrent data making the form unusable until error... this is my code <?php // set error reporting level if (version_compare(phpversion(), "5.3.0", ">=") == 1) error_reporting(E_ALL & ~E_NOTICE & ~E_DEPRECATED); else error_reporting(E_ALL & ~E_NOTICE); require_once('inc/login.inc.php'); require_once('inc/chat.inc.php'); // initialization of login system and generation code $oSimpleLoginSystem = new SimpleLoginSystem(); $oSimpleChat = new SimpleChat(); // draw login box echo $oSimpleLoginSystem->getLoginBox(); // draw chat application $sChatResult = '<font color="0x99000"> <a href="Register_form.html">New Account</a><br> login to send a message<br> or register for a new account</font>'; if ($_COOKIE['member_name'] && $_COOKIE['member_pass']) { if ($oSimpleLoginSystem->check_login($_COOKIE['member_name'], $_COOKIE['member_pass'])) { $sChatResult = ""; if($oSimpleLoginSystem->check_privledges($_COOKIE['member_name']) >= 2) { $sChatResult .= "<br>privledge check Working<br>"; } $sChatResult .= "<form action=$_SERVER[PHP_SELF] method='post'> <input type='hidden' name='foo' value='<?= $foo ?>' /> <input type='submit' name='submit' value='Refresh Messages' /> </form>"; $sChatResult .= $oSimpleChat->acceptMessages(); $sChatResult .= "<br><br>"; $sChatResult .= $oSimpleChat->getMessages(); } } echo $sChatResult; ?>

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  • How to override jquery's show() and hide() functions

    - by Max Williams
    hi all Short version of question: see title Long version of question: I've used jquery's show() and hide() functions extensively in my code and just encountered a bit of a problem: they work by changing the display attribute of the element to 'block' or 'none' respectively, so that if you have somethin that has display: inline and then hide and show it, you've changed its display to block, which screws up the layout in a couple of cases. In my code, whenever i want something to be hidden initially i give it a class 'hidden'. This class is simply {display: none}. I'd like the change show and hide to remove or add this class, instead of directly changing the display attribute, so that if you add the hidden class and then remove it again (ie hide and show something) then it's back to exactly how it was to start off with (since adding a class overrides the attributes rather than directly changing them). Something like this (this is a little pseucodey as i don't know how to set the function up properly - let's assume that 'this' is the object that show/hide was called on) function show(){ this.removeClass("hidden"); } function hide(){ this.addClass("hidden"); } how and where would i go about overriding the jquery methods? (I'm not a javascript expert) thanks - max

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  • What are the linkage of the following functions?

    - by Derui Si
    When I was reading the c++ 03 standard (7.1.1 Storage class specifiers [dcl.stc]), there are some examples as below, I'm not able to tell how the linkage of each successive declarations is determined? Could anyone help here? Thanks in advance! static char* f(); // f() has internal linkage char* f() { /* ... */ } // f() still has internal linkage char* g(); // g() has external linkage static char* g() { /* ... */ } // error: inconsistent linkage void h(); inline void h(); // external linkage inline void l(); void l(); // external linkage inline void m(); extern void m(); // external linkage static void n(); inline void n(); // internal linkage static int a; // a has internal linkage int a; // error: two definitions static int b; // b has internal linkage extern int b; // b still has internal linkage int c; // c has external linkage static int c; // error: inconsistent linkage extern int d; // d has external linkage static int d; // error: inconsistent linkage UPD: Additionally, how can I understand the statement in the standard, " The linkages implied by successive declarations for a given entity shall agree. That is, within a given scope, each declaration declaring the same object name or the same overloading of a function name shall imply the same linkage. Each function in a given set of overloaded functions can have a different linkage, however."

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  • Calling Multiple functions simultaneously

    - by Noob
    I'm trying to call two different functions for two different HTML elements at the same time, but the second function isn't being read at all. I'm also trying to use the id to specify which corresponding elements to grab data from. Here's what I have: function changeImage(id) { var s = document.getElementById('showcase'); var simg = s.getElementsByTagName('img'); var slen = simg.length; for(i=0; i < slen; i++) { simg[i].style.display = 'none'; } $('#' + id).fadeIn('slow', 0); function createComment(jim) { //alert('hello?'); var d = document.getElementById('description'); var dh = document.getElementsByTagName('p'); var dlen = dh.length; //alert(dh); for(i=0; i < dlen; i++) { alert(dh); dh[i].style.display = 'none'; } $('#' + jim).fadeIn('slow', 0); }

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  • Using enum values to represent binary operators (or functions)

    - by Bears will eat you
    I'm looking for an elegant way to use values in a Java enum to represent operations or functions. My guess is, since this is Java, there just isn't going to be a nice way to do it, but here goes anyway. My enum looks something like this: public enum Operator { LT, LTEQ, EQEQ, GT, GTEQ, NEQ; ... } where LT means < (less than), LTEQ means <= (less than or equal to), etc - you get the idea. Now I want to actually use these enum values to apply an operator. I know I could do this just using a whole bunch of if-statements, but that's the ugly, OO way, e.g.: int a = ..., b = ...; Operator foo = ...; // one of the enum values if (foo == Operator.LT) { return a < b; } else if (foo == Operator.LTEQ) { return a <= b; } else if ... // etc What I'd like to be able to do is cut out this structure and use some sort of first-class function or even polymorphism, but I'm not really sure how. Something like: int a = ..., b = ...; Operator foo = ...; return foo.apply(a, b); or even int a = ..., b = ...; Operator foo = ...; return a foo.convertToOperator() b; But as far as I've seen, I don't think it's possible to return an operator or function (at least, not without using some 3rd-party library). Any suggestions?

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  • Javascript object properties access functions in parent constructor?

    - by Bob Spryn
    So I'm using this pretty standard jquery plugin pattern whereby you can grab an api after applying the jquery function to a specific instance. This API is essentially a javascript object with a bunch of methods and data. So I wanted to essentially create some private internal methods for the object only to manipulate data etc, which just doesn't need to be available as part of the API. So I tried this: // API returned with new $.TranslationUI(options, container) $.TranslationUI = function (options, container) { // private function? function monkey(){ console.log("blah blah blah"); } // extend the default settings with the options object passed this.settings = $.extend({},$.TranslationUI.defaultSettings,options); // set a reference for the container dom element this.container = container; // call the init function this.init(); }; The problem I'm running into is that init can't call that function "monkey". I'm not understanding the explanation behind why it can't. Is it because init is a prototype method?($.TranslationUI's prototype is extended with a bunch of methods including init elsewhere in the code) $.extend($.TranslationUI, { prototype: { init : function(){ // doesn't work monkey(); // editing flag this.editing = false; // init event delegates here for // languagepicker $(this.settings.languageSelector, this.container).bind("click", {self: this}, this.selectLanguage); } } }); Any explanations would be helpful. Would love other thoughts on creating private methods with this model too. These particular functions don't HAVE to be in prototype, and I don't NEED private methods protected from being used externally, but I want to know how should I have that requirement in the future.

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  • JS best practice for member functions

    - by MickMalone1983
    I'm writing a little mobile games library, and I'm not sure the best practice for declaring member functions of instantiated function objects. For instance, I might create a simple object with one property, and a method to print it: function Foo(id){ this.id = id; this.print = function(){ console.log(this.id); }; }; However, a function which does not need access to 'private' members of the function does not need to be declared in the function at all. I could equally have written: function print(){ console.log(this.id); }; function Foo(id){ this.id = id; this.print = print; }; When the function is invoked through an instance of Foo, the instance becomes the context for this, so the output is the same in either case. I'm not entirely sure how memory is allocated with JS, and I can't find anything that I can understand about something this specific, but it seems to me that with the first example all members of Foo, including the print function, are duplicated each time it is instantiated - but with the second, it just gets a pointer to one, pre-declared function, which would save any more memory having to be allocated as more instances of Foo are created. Am I correct, and if I am, is there any memory/performance benefit to doing this?

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  • Problems Allocating Objects of Derived Class Where Base Class has Abstract Virtual Functions

    - by user1743901
    I am trying to get this Zombie/Human agent based simulation running, but I am having problems with these derived classes (Human and Zombie) who have parent class "Creature". I have 3 virtual functions declared in "Creature" and all three of these are re-declared AND DEFINED in both "Human" and "Zombie". But for some reason when I have my program call "new" to allocate memory for objects of type Human or Zombie, it complains about the virtual functions being abstract. Here's the code: definitions.h #ifndef definitions_h #define definitions_h class Creature; class Item; class Coords; class Grid { public: Creature*** cboard; Item*** iboard; int WIDTH; int HEIGHT; Grid(int WIDTHVALUE, int HEIGHTVALUE); void FillGrid(); //initializes grid object with humans and zombies void Refresh(); //calls Creature::Die(),Move(),Attack(),Breed() on every square void UpdateBuffer(char** buffer); bool isEmpty(int startx, int starty, int dir); char CreatureType(int xcoord, int ycoord); char CreatureType(int startx, int starty, int dir); }; class Random { public: int* rptr; void Print(); Random(int MIN, int MAX, int LEN); ~Random(); private: bool alreadyused(int checkthis, int len, int* rptr); bool isClean(); int len; }; class Coords { public: int x; int y; int MaxX; int MaxY; Coords() {x=0; y=0; MaxX=0; MaxY=0;} Coords(int X, int Y, int WIDTH, int HEIGHT) {x=X; y=Y; MaxX=WIDTH; MaxY=HEIGHT; } void MoveRight(); void MoveLeft(); void MoveUp(); void MoveDown(); void MoveUpRight(); void MoveUpLeft(); void MoveDownRight(); void MoveDownLeft(); void MoveDir(int dir); void setx(int X) {x=X;} void sety(int Y) {y=Y;} }; class Creature { public: bool alive; Coords Location; char displayletter; Creature() {Location.x=0; Location.y=0;} Creature(int i, int j) {Location.setx(i); Location.sety(j);} virtual void Attack() =0; virtual void AttackCreature(Grid G, int attackdirection) =0; virtual void Breed() =0; void Die(); void Move(Grid G); int DecideSquare(Grid G); void MoveTo(Grid G, int dir); }; class Human : public Creature { public: bool armed; //if armed, chances of winning fight increased for next fight bool vaccinated; //if vaccinated, no chance of getting infected int bitecount; //if a human is bitten, bite count is set to a random number int breedcount; //if a human goes x steps without combat, will breed if next to a human int starvecount; //if a human does not eat in x steps, will die Human() {displayletter='H';} Human(int i, int j) {displayletter='H';} void Attack(Grid G); void AttackCreature(Grid G, int attackdirection); void Breed(Grid G); //will breed after x steps and next to human int DecideAttack(Grid G); }; class Zombie : public Creature { public: Zombie() {displayletter='Z';} Zombie(int i, int j) {displayletter='Z';} void Attack(Grid G); void AttackCreature(Grid G, int attackdirection); void Breed() {} //does nothing int DecideAttack(Grid G); void AttackCreature(Grid G, int attackdirection); }; class Item { }; #endif definitions.cpp #include <cstdlib> #include "definitions.h" Random::Random(int MIN, int MAX, int LEN) //constructor { len=LEN; rptr=new int[LEN]; //allocate array of given length for (int i=0; i<LEN; i++) { int random; do { random = rand() % (MAX-MIN+1) + MIN; } while (alreadyused(random,LEN,rptr)); rptr[i]=random; } } bool Random::alreadyused(int checkthis, int len, int* rptr) { for (int i=0; i<len; i++) { if (rptr[i]==checkthis) return 1; } return 0; } Random::~Random() { delete rptr; } Grid::Grid(int WIDTHVALUE, int HEIGHTVALUE) { WIDTH = WIDTHVALUE; HEIGHT = HEIGHTVALUE; //builds 2d array of creature pointers cboard = new Creature**[WIDTH]; for(int i=0; i<WIDTH; i++) { cboard[i] = new Creature*[HEIGHT]; } //builds 2d array of item pointers iboard = new Item**[WIDTH]; for (int i=0; i<WIDTH; i++) { iboard[i] = new Item*[HEIGHT]; } } void Grid::FillGrid() { /* For each creature pointer in grid, randomly selects whether to initalize as zombie, human, or empty square. This methodology can be changed to initialize different creature types with different probabilities */ int random; for (int i=0; i<WIDTH; i++) { for (int j=0; j<HEIGHT; j++) { Random X(1,100,1); //create a single random integer from [1,100] at X.rptr random=*(X.rptr); if (random < 20) cboard[i][j] = new Human(i,j); else if (random < 40) cboard[i][j] = new Zombie(i,j); else cboard[i][j] = NULL; } } //at this point every creature pointer should be pointing to either //a zombie, human, or NULL with varying probabilities } void Grid::UpdateBuffer(char** buffer) { for (int i=0; i<WIDTH; i++) { for (int j=0; j<HEIGHT; j++) { if (cboard[i][j]) buffer[i][j]=cboard[i][j]->displayletter; else buffer[i][j]=' '; } } } bool Grid::isEmpty(int startx, int starty, int dir) { Coords StartLocation(startx,starty,WIDTH,HEIGHT); switch(dir) { case 1: StartLocation.MoveUp(); if (cboard[StartLocation.x][StartLocation.y]) return 0; case 2: StartLocation.MoveUpRight(); if (cboard[StartLocation.x][StartLocation.y]) return 0; case 3: StartLocation.MoveRight(); if (cboard[StartLocation.x][StartLocation.y]) return 0; case 4: StartLocation.MoveDownRight(); if (cboard[StartLocation.x][StartLocation.y]) return 0; case 5: StartLocation.MoveDown(); if (cboard[StartLocation.x][StartLocation.y]) return 0; case 6: StartLocation.MoveDownLeft(); if (cboard[StartLocation.x][StartLocation.y]) return 0; case 7: StartLocation.MoveLeft(); if (cboard[StartLocation.x][StartLocation.y]) return 0; case 8: StartLocation.MoveUpLeft(); if (cboard[StartLocation.x][StartLocation.y]) return 0; } return 1; } char Grid::CreatureType(int xcoord, int ycoord) { if (cboard[xcoord][ycoord]) //if there is a creature at location xcoord,ycoord return (cboard[xcoord][ycoord]->displayletter); else //if pointer at location xcoord,ycoord is null, return null char return '\0'; } char Grid::CreatureType(int startx, int starty, int dir) { Coords StartLocation(startx,starty,WIDTH,HEIGHT); switch(dir) { case 1: StartLocation.MoveUp(); if (cboard[StartLocation.x][StartLocation.y]) return (cboard[StartLocation.x][StartLocation.y]->displayletter); case 2: StartLocation.MoveUpRight(); if (cboard[StartLocation.x][StartLocation.y]) return (cboard[StartLocation.x][StartLocation.y]->displayletter); case 3: StartLocation.MoveRight(); if (cboard[StartLocation.x][StartLocation.y]) return (cboard[StartLocation.x][StartLocation.y]->displayletter); case 4: StartLocation.MoveDownRight(); if (cboard[StartLocation.x][StartLocation.y]) return (cboard[StartLocation.x][StartLocation.y]->displayletter); case 5: StartLocation.MoveDown(); if (cboard[StartLocation.x][StartLocation.y]) return (cboard[StartLocation.x][StartLocation.y]->displayletter); case 6: StartLocation.MoveDownLeft(); if (cboard[StartLocation.x][StartLocation.y]) return (cboard[StartLocation.x][StartLocation.y]->displayletter); case 7: StartLocation.MoveLeft(); if (cboard[StartLocation.x][StartLocation.y]) return (cboard[StartLocation.x][StartLocation.y]->displayletter); case 8: StartLocation.MoveUpLeft(); if (cboard[StartLocation.x][StartLocation.y]) return (cboard[StartLocation.x][StartLocation.y]->displayletter); } //if function hasn't returned by now, square being looked at is pointer to null return '\0'; //return null char } void Coords::MoveRight() {(x==MaxX)? (x=0):(x++);} void Coords::MoveLeft() {(x==0)? (x=MaxX):(x--);} void Coords::MoveUp() {(y==0)? (y=MaxY):(y--);} void Coords::MoveDown() {(y==MaxY)? (y=0):(y++);} void Coords::MoveUpRight() {MoveUp(); MoveRight();} void Coords::MoveUpLeft() {MoveUp(); MoveLeft();} void Coords::MoveDownRight() {MoveDown(); MoveRight();} void Coords::MoveDownLeft() {MoveDown(); MoveLeft();} void Coords::MoveDir(int dir) { switch(dir) { case 1: MoveUp(); break; case 2: MoveUpRight(); break; case 3: MoveRight(); break; case 4: MoveDownRight(); break; case 5: MoveDown(); break; case 6: MoveDownLeft(); break; case 7: MoveLeft(); break; case 8: MoveUpLeft(); break; case 0: break; } } void Creature::Move(Grid G) { int movedir=DecideSquare(G); MoveTo(G,movedir); } int Creature::DecideSquare(Grid G) { Random X(1,8,8); //X.rptr now points to 8 unique random integers from [1,8] for (int i=0; i<8; i++) { int dir=X.rptr[i]; if (G.isEmpty(Location.x,Location.y,dir)) return dir; } return 0; } void Creature::MoveTo(Grid G, int dir) { Coords OldLocation=Location; Location.MoveDir(dir); G.cboard[Location.x][Location.y]=this; //point new location to this creature G.cboard[OldLocation.x][OldLocation.y]=NULL; //point old location to NULL } void Creature::Die() { if (!alive) { delete this; this=NULL; } } void Human::Breed(Grid G) { if (!breedcount) { Coords BreedLocation=Location; Random X(1,8,8); for (int i=0; i<8; i++) { BreedLocation.MoveDir(X.rptr[i]); if (!G.cboard[BreedLocation.x][BreedLocation.y]) { G.cboard[BreedLocation.x][BreedLocation.y])=new Human(BreedLocation.x,BreedLocation.y); return; } } } } int Human::DecideAttack(Grid G) { Coords AttackLocation=Location; Random X(1,8,8); int attackdir; for (int i=0; i<8; i++) { attackdir=X.rptr[i]; switch(G.CreatureType(Location.x,Location.y,attackdir)) { case 'H': break; case 'Z': return attackdir; case '\0': break; default: break; } } return 0; //no zombies! } int AttackRoll(int para1, int para2) { //outcome 1: Zombie wins, human dies //outcome 2: Human wins, zombie dies //outcome 3: Human wins, zombie dies, but human is bitten Random X(1,100,1); int roll= *(X.rptr); if (roll < para1) return 1; else if (roll < para2) return 2; else return 3; } void Human::AttackCreature(Grid G, int attackdirection) { Coords AttackLocation=Location; AttackLocation.MoveDir(attackdirection); int para1=33; int para2=33; if (vaccinated) para2=101; //makes attackroll > para 2 impossible, never gets infected if (armed) para1-=16; //reduces chance of zombie winning fight int roll=AttackRoll(para1,para2); //outcome 1: Zombie wins, human dies //outcome 2: Human wins, zombie dies //outcome 3: Human wins, zombie dies, but human is bitten switch(roll) { case 1: alive=0; //human (this) dies return; case 2: G.cboard[AttackLocation.x][AttackLocation.y]->alive=0; return; //zombie dies case 3: G.cboard[AttackLocation.x][AttackLocation.y]->alive=0; //zombie dies Random X(3,7,1); //human is bitten bitecount=*(X.rptr); return; } } int Zombie::DecideAttack(Grid G) { Coords AttackLocation=Location; Random X(1,8,8); int attackdir; for (int i=0; i<8; i++) { attackdir=X.rptr[i]; switch(G.CreatureType(Location.x,Location.y,attackdir)) { case 'H': return attackdir; case 'Z': break; case '\0': break; default: break; } } return 0; //no zombies! } void Zombie::AttackCreature(Grid G, int attackdirection) { int reversedirection; if (attackdirection < 9 && attackdirection>0) { (attackdirection<5)? (reversedirection=attackdirection+4):(reversedirection=attackdirection-4); } else reversedirection=0; //this should never happen //when a zombie attacks a human, the Human::AttackZombie() function is called //in the "reverse" direction, utilizing that function that has already been written Coords ZombieLocation=Location; Coords HumanLocation=Location; HumanLocation.MoveDir(attackdirection); if (G.cboard[HumanLocation.x][HumanLocation.y]) //if there is a human there, which there should be G.cboard[HumanLocation.x][HumanLocation.y]->AttackCreature(G,reversedirection); } void Zombie::Attack(Grid G) { int attackdirection=DecideAttack(G); AttackCreature(G,attackdirection); } main.cpp #include <cstdlib> #include <iostream> #include "definitions.h" using namespace std; int main(int argc, char *argv[]) { Grid G(500,500); system("PAUSE"); return EXIT_SUCCESS; }

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  • C# Monte Carlo Incremental Risk Calculation optimisation, random numbers, parallel execution

    - by m3ntat
    My current task is to optimise a Monte Carlo Simulation that calculates Capital Adequacy figures by region for a set of Obligors. It is running about 10 x too slow for where it will need to be in production and number or daily runs required. Additionally the granularity of the result figures will need to be improved down to desk possibly book level at some stage, the code I've been given is basically a prototype which is used by business units in a semi production capacity. The application is currently single threaded so I'll need to make it multi-threaded, may look at System.Threading.ThreadPool or the Microsoft Parallel Extensions library but I'm constrained to .NET 2 on the server at this bank so I may have to consider this guy's port, http://www.codeproject.com/KB/cs/aforge_parallel.aspx. I am trying my best to get them to upgrade to .NET 3.5 SP1 but it's a major exercise in an organisation of this size and might not be possible in my contract time frames. I've profiled the application using the trial of dotTrace (http://www.jetbrains.com/profiler). What other good profilers exist? Free ones? A lot of the execution time is spent generating uniform random numbers and then translating this to a normally distributed random number. They are using a C# Mersenne twister implementation. I am not sure where they got it or if it's the best way to go about this (or best implementation) to generate the uniform random numbers. Then this is translated to a normally distributed version for use in the calculation (I haven't delved into the translation code yet). Also what is the experience using the following? http://quantlib.org http://www.qlnet.org (C# port of quantlib) or http://www.boost.org Any alternatives you know of? I'm a C# developer so would prefer C#, but a wrapper to C++ shouldn't be a problem, should it? Maybe even faster leveraging the C++ implementations. I am thinking some of these libraries will have the fastest method to directly generate normally distributed random numbers, without the translation step. Also they may have some other functions that will be helpful in the subsequent calculations. Also the computer this is on is a quad core Opteron 275, 8 GB memory but Windows Server 2003 Enterprise 32 bit. Should I advise them to upgrade to a 64 bit OS? Any links to articles supporting this decision would really be appreciated. Anyway, any advice and help you may have is really appreciated.

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  • Importing Conditionally Compiled Functions From a Perl Module

    - by Robert S. Barnes
    I have a set of logging and debugging functions which I want to use across multiple modules / objects. I'd like to be able to turn them on / off globally using a command line switch. The following code does this, however, I would like to be able to omit the package name and keep everything in a single file. This is related to two previous questions I asked, here and here. #! /usr/bin/perl -w use strict; use Getopt::Long; { package LogFuncs; use threads; use Time::HiRes qw( gettimeofday ); # provide tcpdump style time stamp sub _gf_time { my ( $seconds, $microseconds ) = gettimeofday(); my @time = localtime($seconds); return sprintf( "%02d:%02d:%02d.%06ld", $time[2], $time[1], $time[0], $microseconds ); } sub logerr; sub compile { my %params = @_; *logerr = $params{do_logging} ? sub { my $msg = shift; warn _gf_time() . " Thread " . threads->tid() . ": $msg\n"; } : sub { }; } } { package FooObj; sub new { my $class = shift; bless {}, $class; }; sub foo_work { my $self = shift; # do some foo work LogFuncs::logerr($self); } } { package BarObj; sub new { my $class = shift; my $data = { fooObj => FooObj->new() }; bless $data, $class; } sub bar_work { my $self = shift; $self->{fooObj}->foo_work(); LogFuncs::logerr($self); } } my $do_logging = 0; GetOptions( "do_logging" => \$do_logging, ); LogFuncs::compile(do_logging => $do_logging); my $bar = BarObj->new(); LogFuncs::logerr("Created $bar"); $bar->bar_work();

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  • More GCC link time issues: undefined reference to main

    - by vikramtheone
    Hi Guys, I'm writing software for a Cortex-A8 processor and I have to write some ARM assembly code to access specific registers. I'm making use of the gnu compilers and related tool chains, these tools are installed on the processor board(Freescale i.MX515) with Ubuntu. I make a connection to it from my host PC(Windows) using WinSCP and the PuTTY terminal. As usual I started with a simple C project having main.c and functions.s. I compile the main.c using GCC, assemble the functions.s using as and link the generated object files using once again GCC, but I get strange errors during this process. An important finding - Meanwhile, I found out that my assembly code may have some issues because when I individually assemble it using the command as -o functions.o functions.s and try running the generated functions.o using ./functions.o command, the bash shell is failing to recognize this file as an executable(on pressing tab functions.o is not getting selected/PuTTY is not highlighting the file). Can anyone suggest whats happening here? Are there any specific options I have to send, to GCC during the linking process? The errors I see are strange and beyond my understanding, I don't understand to what the GCC is referring. I'm pasting here the contents of main.c, functions.s, the Makefile and the list of errors. Help, please!!! Vikram main.c #include <stdio.h> #include <stdlib.h> int main(void) { puts("!!!Hello World!!!"); /* prints !!!Hello World!!! */ return EXIT_SUCCESS; } functions.s * Main program */ .equ STACK_TOP, 0x20000800 .text .global _start .syntax unified _start: .word STACK_TOP, start .type start, function start: movs r0, #10 movs r1, #0 .end Makefile all: hello hello: main.o functions.o gcc -o main.o functions.o main.o: main.c gcc -c -mcpu=cortex-a8 main.c functions.o: functions.s as -mcpu=cortex-a8 -o functions.o functions.s Errors ubuntu@ubuntu-desktop:~/Documents/Project/Others/helloworld$ make gcc -c -mcpu=cortex-a8 main.c as -mcpu=cortex-a8 -o functions.o functions.s gcc -o main.o functions.o functions.o: In function `_start': (.text+0x0): multiple definition of `_start' /usr/lib/gcc/arm-linux-gnueabi/4.3.3/../../../crt1.o:init.c:(.text+0x0): first defined here /usr/lib/gcc/arm-linux-gnueabi/4.3.3/../../../crt1.o: In function `_start': init.c:(.text+0x30): undefined reference to `main' collect2: ld returned 1 exit status make: *** [hello] Error 1

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  • Jquery toggle functions

    - by ozsenegal
    I've a code to sort table using Jquery.I use toggle function to alternate clicks,and toggle beetween 'ascend' and 'descend' sort.Once you click header's table it should sort it contents. However,there's a bug: I click once,it sorts,then when i click again,nothing happens.I need to click again (second time) to execute the second function,and sort again. Toggle should switch functions with single clicks,not double,am i right? Here is the code: firstRow.toggle(function() { $(this).find("th:first").removeClass("ascendFirst").addClass("descendFirst"); $(this).find("th:not(first)").removeClass("ascend").addClass("descend"); sorted = $.makeArray($("td:eq(0)", "tr")).sort().reverse(); sorted2 = $.makeArray($("td:eq(1)", "tr")).sort().reverse(); sorted3 = $.makeArray($("td:eq(2)", "tr")).sort().reverse(); for (var i = 0; i < sorted.length; i++) { $("td", "tr:eq(" + (i + 1) + ")").remove(); $("tr:eq(" + (i + 1) + ")").append($("<td></td>").text($(sorted[i]).text())); $("tr:eq(" + (i + 1) + ")").append($("<td></td>").text($(sorted2[i]).text())); $("tr:eq(" + (i + 1) + ")").append($("<td></td>").text($(sorted3[i]).text())); } }, function() { $(this).find("th:first").removeClass("descendFirst").addClass("ascendFirst"); $(this).find("th:not(first)").removeClass("descend").addClass("ascend"); sorted = $.makeArray($("td:eq(0)", "tr")).sort(); sorted2 = $.makeArray($("td:eq(1)", "tr")).sort(); sorted3 = $.makeArray($("td:eq(2)", "tr")).sort(); for (var i = 0; i < sorted.length; i++) { $("td", "tr:eq(" + (i + 1) + ")").remove(); $("tr:eq(" + (i + 1) + ")").append($("<td></td>").text($(sorted[i]).text())); $("tr:eq(" + (i + 1) + ")").append($("<td></td>").text($(sorted2[i]).text())); $("tr:eq(" + (i + 1) + ")").append($("<td></td>").text($(sorted3[i]).text())); } });

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  • C++ DLL creation for C# project - No functions exported

    - by Yeti
    I am working on a project that requires some image processing. The front end of the program is C# (cause the guys thought it is a lot simpler to make the UI in it). However, as the image processing part needs a lot of CPU juice I am making this part in C++. The idea is to link it to the C# project and just call a function from a DLL to make the image processing part and allow to the C# environment to process the data afterwards. Now the only problem is that it seems I am not able to make the DLL. Simply put the compiler refuses to put any function into the DLL that I compile. Because the project requires some development time testing I have created two projects into a C++ solution. One is for the Dll and another console application. The console project holds all the files and I just include the corresponding header into my DLL project file. I thought the compiler should take out the functions that I marked as to be exported and make the DLL from them. Nevertheless this does not happens. Here it is how I defined the function in the header: extern "C" __declspec(dllexport) void _stdcall RobotData(BYTE* buf, int** pToNewBackgroundImage, int* pToBackgroundImage, bool InitFlag, ObjectInformation* robot1, ObjectInformation* robot2, ObjectInformation* robot3, ObjectInformation* robot4, ObjectInformation* puck); extern "C" __declspec(dllexport) CvPoint _stdcall RefPointFinder(IplImage* imgInput, CvRect &imgROI, CvScalar &refHSVColorLow, CvScalar &refHSVColorHi ); Followed by the implementation in the cpp file: extern "C" __declspec(dllexport) CvPoint _stdcall RefPointFinder(IplImage* imgInput, CvRect &imgROI,&refHSVColorLow, CvScalar &refHSVColorHi ) { \\... return cvPoint((int)( M10/M00) + imgROI.x, (int)( M01/M00 ) + imgROI.y) ;} extern "C" __declspec(dllexport) void _stdcall RobotData(BYTE* buf, int** pToNewBackgroundImage, int* pToBackgroundImage, bool InitFlag, ObjectInformation* robot1, ObjectInformation* robot2, ObjectInformation* robot3, ObjectInformation* robot4, ObjectInformation* puck) { \\ ...}; And my main file for the DLL project looks like: #ifdef _MANAGED #pragma managed(push, off) #endif /// <summary> Include files. </summary> #include "..\ImageProcessingDebug\ImageProcessingTest.h" #include "..\ImageProcessingDebug\ImageProcessing.h" BOOL APIENTRY DllMain( HMODULE hModule, DWORD ul_reason_for_call, LPVOID lpReserved) { return TRUE; } #ifdef _MANAGED #pragma managed(pop) #endif Needless to say it does not work. A quick look with DLL export viewer 1.36 reveals that no function is inside the library. I don't get it. What I am doing wrong ? As side not I am using the C++ objects (and here it is the C++ DLL part) such as the vector. However, only for internal usage. These will not appear in the headers of either function as you can observe from the previous code snippets. Any ideas? Thx, Bernat

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  • Passing enums to functions in C++

    - by rocknroll
    Hi all, I have a header file with all the enums listed (#ifndef #define #endif construct has been used to avoid multiple inclusion of the file) that I use in multiple cpp files in my application.One of the enums in the files is enum StatusSubsystem {ENABLED,INCORRECT_FRAME,INVALID_DATA,DISABLED}; There are functions in the application delcared as ShowStatus(const StatusSubsystem&); Earlier in the application when I made calls to the above function like ShowStatus(INCORRECT_FRAME); my application used to compile perfectly. But after some code was added The compilation halts giving the following error: File.cpp:71: error: invalid conversion from `int' to `StatusSubsystem' File.cpp:71: error: initializing argument 1 of `void Class::ShowStatus(const StatusSubsystem&) I checked the code for any conflicting enums in the new code and it looked fine. My Question is what is wrong with the function call that compiler shows as erroneous? For your reference the function definition is: void Class::ShowStatus(const StatusSubsystem& eStatus) { QPalette palette; mStatus=eStatus;//store current Communication status of system if(eStatus==DISABLED) { //select red color for label, if it is to be shown disabled palette.setColor(QPalette::Window,QColor(Qt::red)); mLabel->setText("SYSTEM"); } else if(eStatus==ENABLED) { //select green color for label,if it is to be shown enabled palette.setColor(QPalette::Window,QColor(Qt::green)); mLabel->setText("SYSTEM"); } else if(eStatus==INCORRECT_FRAME) { //select yellow color for label,to show that it is sending incorrect frames palette.setColor(QPalette::Window,QColor(Qt::yellow)); mLabel->setText("SYSTEM(I)"); } //Set the color on the Label mLabel->setPalette(palette); } A strange side effect of this situation is it compiles when I cast all the calls to ShowStatus() as ShowStatus((StatusSubsystem)INCORRECT_FRAME); Though this removes any compilation error, but a strange thing happens. Though I make call to INCORRECT_FRAME above but in function definition it matches with ENABLED. How on earth is that possible? Its like while passing INCORRECT_FRAME by reference, it magically converts to ENABLED, which should be impossible. This is driving me nuts. Can you find any flaw in what I am doing? or is it something else? The application is made using C++,Qt-4.2.1 on RHEL4. Thanks.

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  • How to write my own global lock / unlock functions for PostgreSQL

    - by rafalmag
    I have postgresql (in perlu) function getTravelTime(integer, timestamp), which tries to select data for specified ID and timestamp. If there are no data or if data is old, it downloads them from external server (downloading time ~300ms). Multiple process use this database and this function. There is an error when two process do not find data and download them and try to do an insert to travel_time table (id and timestamp pair have to be unique). I thought about locks. Locking whole table would block all processes and allow only one to proceed. I need to lock only on id and timestamp. pg_advisory_lock seems to lock only in "current session". But my processes uses their own sessions. I tried to write my own lock/unlock functions. Am I doing it right? I use active waiting, how can I omit this? Maybe there is a way to use pg_advisory_lock() as global lock? My code: CREATE TABLE travel_time_locks ( id_key integer NOT NULL, time_key timestamp without time zone NOT NULL, UNIQUE (id_key, time_key) ); ------------ -- Function: mylock(integer, timestamp) DROP FUNCTION IF EXISTS mylock(integer, timestamp) CASCADE; -- Usage: SELECT mylock(1, '2010-03-28T19:45'); -- function tries to do a global lock similar to pg_advisory_lock(key, key) CREATE OR REPLACE FUNCTION mylock(id_input integer, time_input timestamp) RETURNS void AS $BODY$ DECLARE rows int; BEGIN LOOP BEGIN -- active waiting here !!!! :( INSERT INTO travel_time_locks (id_key, time_key) VALUES (id_input, time_input); EXCEPTION WHEN unique_violation THEN CONTINUE; END; EXIT; END LOOP; END; $BODY$ LANGUAGE 'plpgsql' VOLATILE COST 1; ------------ -- Function: myunlock(integer, timestamp) DROP FUNCTION IF EXISTS myunlock(integer, timestamp) CASCADE; -- Usage: SELECT myunlock(1, '2010-03-28T19:45'); -- function tries to do a global unlock similar to pg_advisory_unlock(key, key) CREATE OR REPLACE FUNCTION myunlock(id_input integer, time_input timestamp) RETURNS integer AS $BODY$ DECLARE BEGIN DELETE FROM ONLY travel_time_locks WHERE id_key=id_input AND time_key=time_input; RETURN 1; END; $BODY$ LANGUAGE 'plpgsql' VOLATILE COST 1;

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  • Calling back a functions value

    - by Jason Kelly
    I need your help, I cannot, for the life of me, figure this out. I've had my head wrapped around it only to no avail. Ideally, i'd like to setup two functions. 1 function: select_date() to interact with the user to select a date from the jQuery Date picker. If the dialog is closed then return as null. Then a second function: test() to check wether or not a date was picked/selected.' Here's my delema, when the function test() is executed, an alert box pops up and says "undefined" which means, I never get to select a date and it always being "undefined" I dont see what I am doing wrong here and everything seems logical to me. <!DOCTYPE html> <html> <head> <link href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.21/themes/base/jquery-ui.css" rel="stylesheet" type="text/css"/> <script src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.js"></script> <script src="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.21/jquery-ui.js"></script> <script type="text/javascript"> function select_date() { var sdate $('#dd').dialog({ autoOpen: true, modal: true, overlay: { opacity: 0.5, background: 'black' }, title: "title", height: 265, width: 235, draggable: false, resizable: false }); $('#d1').datepicker({ onSelect: function () { $("#dd").dialog("close"); } }); return sdate } function test() { var x = select_date() alert(x) } </script> <style type="text/css"> #d1 {font-size:64%;} </style> </head> <body> <div id="dd"> <div id="d1"> </div> </div> <a href="javascript:test()">test</a> </body> </html>

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  • PHP resized image functions and S3 upload functions - but how to merge the two?

    - by chocolatecoco
    I am using S3 to store images and I am resizing and compressing images before it gets uploaded using PHP. I'm using this class for storing the images to an S3 bucket - http://undesigned.org.za/2007/10/22/amazon-s3-php-class This all works fine if I'm not doing any file processing before the file is uploaded because it reads the file upload from the $_FILES array. The problem is I am resizing and compressing the image before storing to the S3 bucket. So I'm no longer able to read from the $_FILES array. The functions for resizing: public function resizeImage($newWidth, $newHeight, $option="auto") { // *** Get optimal width and height - based on $option $optionArray = $this->getDimensions($newWidth, $newHeight, $option); $optimalWidth = $optionArray['optimalWidth']; $optimalHeight = $optionArray['optimalHeight']; // *** Resample - create image canvas of x, y size $this->imageResized = imagecreatetruecolor($optimalWidth, $optimalHeight); imagecopyresampled($this->imageResized, $this->image, 0, 0, 0, 0, $optimalWidth, $optimalHeight, $this->width, $this->height); // *** if option is 'crop', then crop too if ($option == 'crop') { $this->crop($optimalWidth, $optimalHeight, $newWidth, $newHeight); } } The script I am using to store the file after resizing and compressing to a local directory: public function saveImage($savePath, $imageQuality="100") { // *** Get extension $extension = strrchr($savePath, '.'); $extension = strtolower($extension); switch($extension) { case '.jpg': case '.jpeg': if (imagetypes() & IMG_JPG) { imagejpeg($this->imageResized, $savePath, $imageQuality); } break; case '.gif': if (imagetypes() & IMG_GIF) { imagegif($this->imageResized, $savePath); } break; case '.png': // *** Scale quality from 0-100 to 0-9 $scaleQuality = round(($imageQuality/100) * 9); // *** Invert quality setting as 0 is best, not 9 $invertScaleQuality = 9 - $scaleQuality; if (imagetypes() & IMG_PNG) { imagepng($this->imageResized, $savePath, $invertScaleQuality); } break; // ... etc default: // *** No extension - No save. break; } imagedestroy($this->imageResized); } with this PHP code to invoke it: $resizeObj = new resize("$images_dir/$filename"); $resizeObj -> resizeImage($thumbnail_width, $thumbnail_height, 'crop'); $resizeObj -> saveImage($images_dir."/tb_".$filename, 90); How do I modify the code above so I can pass it through this function: $s3->putObjectFile($thefile, "s3bucket", $s3directory, S3::ACL_PUBLIC_READ)

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  • validation functions in google apps script is not working properly

    - by chocka
    I create a i/p form in google site using Apps Script and i did the validation using the Apps Script coding. Validation functions available in Apps script is not satisfying all the possibility of checking the error. function validate(e) { var app = UiApp.getActiveApplication(); var flag=0; var text = app.getElementById('name'); var textrequired = app.getElementById('namerequired'); var number = app.getElementById('number'); var numberrequired = app.getElementById('numberrequired'); var email = app.getElementById('email'); var emailrequired = app.getElementById('emailrequired'); var submit = app.getElementById('submit_button'); var valid = app.createClientHandler() .validateNumber(number) .validateNotInteger(text) .validateEmail(email) .forTargets(submit).setEnabled(true) .forTargets(number,text,email).setStyleAttribute("color","black") .forTargets(numberrequired,textrequired,emailrequired).setText('*').setStyleAttribute("color", "red").setVisible(true); var invalidno = app.createClientHandler().validateNotNumber(number).validateMatches(number, '').forTargets(number).setStyleAttribute("color", "red").forTargets(submit).setEnabled(false).forTargets(numberrequired).setText('Please Enter a Valid No.').setStyleAttribute("color", "red").setVisible(true); var validno = app.createClientHandler().validateNumber(number).forTargets(number).setStyleAttribute("color","black").forTargets(numberrequired).setText('*').setStyleAttribute("color", "red").setVisible(true); var invalidText=app.createClientHandler().validateNumber(text).validateMatches(text, '').forTargets(text).setStyleAttribute("color", "red").forTargets(submit).setEnabled(false).forTargets(textrequired).setText('Please Enter a Valid Name.').setStyleAttribute("color", "red").setVisible(true); var validText=app.createClientHandler().validateNotNumber(text).forTargets(text).setStyleAttribute("color","black").forTargets(textrequired).setText('*').setStyleAttribute("color", "red").setVisible(true); var invalidemail=app.createClientHandler().validateNotEmail(email).validateMatches(email, '').forTargets(email).setStyleAttribute("color", "red").forTargets(submit).setEnabled(false).forTargets(emailrequired).setText('Please Enter a Valid Mail-Id.').setStyleAttribute("color", "red").setVisible(true); var validemail=app.createClientHandler().validateEmail(email).forTargets(email).setStyleAttribute("color","black").forTargets(emailrequired).setText('*').setStyleAttribute("color", "red").setVisible(true); number.addKeyPressHandler(invalidno).addKeyPressHandler(validno).addKeyPressHandler(valid).addKeyPressHandler(invalidText).addKeyPressHandler(invalidemail); text.addKeyPressHandler(invalidText).addKeyPressHandler(validText).addKeyPressHandler(valid).addKeyPressHandler(invalidno).addKeyPressHandler(invalidemail); email.addKeyPressHandler(invalidemail).addKeyPressHandler(validemail).addKeyPressHandler(valid).addKeyPressHandler(invalidno).addKeyPressHandler(invalidText); if (text == ''){flag = 1;} if (email == ''){flag = 1;} if (number == ''){flag = 1;} if(flag == 1){submit.setEnabled(false);} return app; } I just placed my Validation function using Apps Script. I don't know why its not satisfying all the possibilities of the validation. And also i have to do is to enable the submit button after all the fields satisfy the validation. After once it enabled, if i make any error in any field it will not get disable correctly. I wrote the coding correctly i think so. Please take a look at my validation function and give me some suggestion to make it possible. Please guide me, Thanks & Regards, chocka.

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  • How to call a set of variables functions based on class on a group of elements

    - by user1547007
    I have the following html code: <i class="small ele class1"></i> <i class="medium ele class1"></i> <i class="large ele class1"></i> <div class="clear"></div> <i class="small ele class2"></i> <i class="medium ele class2"></i> <i class="large ele class2"></i> <div class="clear"></div> <i class="small ele class3"></i> <i class="medium ele class3"></i> <i class="large ele class3"></i> <div class="clear"></div> <i class="small ele class4"></i> <i class="medium ele class4"></i> <i class="large ele class4"></i>? And my javascript looks like so: var resize = function(face, s) { var bb = face.getBBox(); console.log(bb); var w = bb.width; var h = bb.height; var max = w; if (h > max) { max = h; } var scale = s / max; var ox = -bb.x+((max-w)/2); var oy = -bb.y+((max-h)/2); console.log(s+' '+h+' '+bb.y); face.attr({ "transform": "s" + scale + "," + scale + ",0,0" + "t" + ox + "," + oy }); } $('.ele').each(function() { var s = $(this).innerWidth(); var paper = Raphael($(this)[0], s, s); var face = $(this).hasClass("class1") ? class1Generator(paper) : class4Generator(paper); /*switch (true) { case $(this).hasClass('class1'): class1Generator(paper); break; case $(this).hasClass('class2'): class2Generator(paper) break; case $(this).hasClass('class3'): class3Generator(paper) break; case $(this).hasClass('class4'): class4Generator(paper) break; }*/ resize(face, s); }); my question is, how could I make this line of code more scalable? I tried using a switch but The script below is calling two functions if one of the elements has a class, but what If i have 10 classes? I don't think is the best solution I created a jsFiddle http://jsfiddle.net/7uUgz/6/ //var face = $(this).hasClass("awesome") ? awesomeGenerator(paper) : awfulGenerator(paper);

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  • Biztalk Schema generator in Visual Studio -- How to enable 'Well-Formed XML' ? [migrated]

    - by user28747
    I have installed Visual Studio 2010 and Biztalk. I create a new Biztalk-project in Visual STudio 2010. I choose 'Add new item' and then 'New generated schema'. Here I can choose 'Document type'. I choose 'Well-Formed XML (Not loaded)' and choose an input file. Now I get the message 'XFW to XSD schema generation module is not installed. Execute 'C:\Program files (X86)\Microsoft Biztalk Server 2010\SDK\Utilities\Schema Generator\InstallWFX.vbs to install the WFX to XSD schema generation module. I try to execute that file and some text hastily appear on the console. I restart Visual Studio 2010, but it still doesn't work. Apparently the execution of the shell script didn't work. I try to restart the computer, but it still doesn't work. Could anyone tell me what to do?

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  • What's the most efficient query?

    - by Aaron Carlino
    I have a table named Projects that has the following relationships: has many Contributions has many Payments In my result set, I need the following aggregate values: Number of unique contributors (DonorID on the Contribution table) Total contributed (SUM of Amount on Contribution table) Total paid (SUM of PaymentAmount on Payment table) Because there are so many aggregate functions and multiple joins, it gets messy do use standard aggregate functions the the GROUP BY clause. I also need the ability to sort and filter these fields. So I've come up with two options: Using subqueries: SELECT Project.ID AS PROJECT_ID, (SELECT SUM(PaymentAmount) FROM Payment WHERE ProjectID = PROJECT_ID) AS TotalPaidBack, (SELECT COUNT(DISTINCT DonorID) FROM Contribution WHERE RecipientID = PROJECT_ID) AS ContributorCount, (SELECT SUM(Amount) FROM Contribution WHERE RecipientID = PROJECT_ID) AS TotalReceived FROM Project; Using a temporary table: DROP TABLE IF EXISTS Project_Temp; CREATE TEMPORARY TABLE Project_Temp (project_id INT NOT NULL, total_payments INT, total_donors INT, total_received INT, PRIMARY KEY(project_id)) ENGINE=MEMORY; INSERT INTO Project_Temp (project_id,total_payments) SELECT `Project`.ID, IFNULL(SUM(PaymentAmount),0) FROM `Project` LEFT JOIN `Payment` ON ProjectID = `Project`.ID GROUP BY 1; INSERT INTO Project_Temp (project_id,total_donors,total_received) SELECT `Project`.ID, IFNULL(COUNT(DISTINCT DonorID),0), IFNULL(SUM(Amount),0) FROM `Project` LEFT JOIN `Contribution` ON RecipientID = `Project`.ID GROUP BY 1 ON DUPLICATE KEY UPDATE total_donors = VALUES(total_donors), total_received = VALUES(total_received); SELECT * FROM Project_Temp; Tests for both are pretty comparable, in the 0.7 - 0.8 seconds range with 1,000 rows. But I'm really concerned about scalability, and I don't want to have to re-engineer everything as my tables grow. What's the best approach?

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  • Semi-generic function

    - by Fredrik Ullner
    I have a bunch of overloaded functions that operate on certain data types such as int, double and strings. Most of these functions perform the same action, where only a specific set of data types are allowed. That means I cannot create a simple generic template function as I lose type safety (and potentially incurring a run-time problem for validation within the function). Is it possible to create a "semi-generic compile time type safe function"? If so, how? If not, is this something that will come up in C++0x? An (non-valid) idea; template <typename T, restrict: int, std::string > void foo(T bar); ... foo((int)0); // OK foo((std::string)"foobar"); // OK foo((double)0.0); // Compile Error Note: I realize I could create a class that has overloaded constructors and assignment operators and pass a variable of that class instead to the function.

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  • How can multiple variables be passed to a function cleanly in C?

    - by aquanar
    I am working on an embedded system that has different output capabilities (digital out, serial, analog, etc). I am trying to figure out a clean way to pass many of the variables that will control those functions. I don't need to pass ALL of them too often, but I was hoping to have a function that would read the input data (in this case from a TCP network), and then parse the data (IE, the 3rd byte contains the states of 8 of the digital outputs (according to which bit in that byte is high or low)), and put that into a variable where I can then use elsewhere in the program. I wanted that function to be separate from the main() function, but to do so would require passing pointers to some 20 or so variables that it would be writing to. I know I could make the variables global, but I am trying to make it easier to debug by making it obvious when a function is allowed to edit that variable, by passing it to the function. My best idea was a struct, and just pass a pointer to it, but wasn't sure if there was a more efficient way, especially since there is only really 1 function that would need to access all of them at once, while most others only require parts of the information that will be stored in this bunch of state variables. So anyway, is there a clean way to send many variables between functions at once that need to be edited?

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