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  • The Evolution Of C#

    - by Paulo Morgado
    The first release of C# (C# 1.0) was all about building a new language for managed code that appealed, mostly, to C++ and Java programmers. The second release (C# 2.0) was mostly about adding what wasn’t time to built into the 1.0 release. The main feature for this release was Generics. The third release (C# 3.0) was all about reducing the impedance mismatch between general purpose programming languages and databases. To achieve this goal, several functional programming features were added to the language and LINQ was born. Going forward, new trends are showing up in the industry and modern programming languages need to be more: Declarative With imperative languages, although having the eye on the what, programs need to focus on the how. This leads to over specification of the solution to the problem in hand, making next to impossible to the execution engine to be smart about the execution of the program and optimize it to run it more efficiently (given the hardware available, for example). Declarative languages, on the other hand, focus only on the what and leave the how to the execution engine. LINQ made C# more declarative by using higher level constructs like orderby and group by that give the execution engine a much better chance of optimizing the execution (by parallelizing it, for example). Concurrent Concurrency is hard and needs to be thought about and it’s very hard to shoehorn it into a programming language. Parallel.For (from the parallel extensions) looks like a parallel for because enough expressiveness has been built into C# 3.0 to allow this without having to commit to specific language syntax. Dynamic There was been lots of debate on which ones are the better programming languages: static or dynamic. The fact is that both have good qualities and users of both types of languages want to have it all. All these trends require a paradigm switch. C# is, in many ways, already a multi-paradigm language. It’s still very object oriented (class oriented as some might say) but it can be argued that C# 3.0 has become a functional programming language because it has all the cornerstones of what a functional programming language needs. Moving forward, will have even more. Besides the influence of these trends, there was a decision of co-evolution of the C# and Visual Basic programming languages. Since its inception, there was been some effort to position C# and Visual Basic against each other and to try to explain what should be done with each language or what kind of programmers use one or the other. Each language should be chosen based on the past experience and familiarity of the developer/team/project/company and not by particular features. In the past, every time a feature was added to one language, the users of the other wanted that feature too. Going forward, when a feature is added to one language, the other will work hard to add the same feature. This doesn’t mean that XML literals will be added to C# (because almost the same can be achieved with LINQ To XML), but Visual Basic will have auto-implemented properties. Most of these features require or are built on top of features of the .NET Framework and, the focus for C# 4.0 was on dynamic programming. Not just dynamic types but being able to talk with anything that isn’t a .NET class. Also introduced in C# 4.0 is co-variance and contra-variance for generic interfaces and delegates. Stay tuned for more on the new C# 4.0 features.

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  • reinventing the wheels: Node.JS/Event-driven programming v.s. Functional Programming?

    - by ivanTheTerrible
    Now there's all the hype lately about Node.JS, an event driven framework using Javascript callbacks. To my limited understanding, its primary advantage seems to be that you don't have to wait step by step sequentially (for example, you can fetch the SQL results, while calling other functions too). So my question is: how is this different, or better than just functional languages, like CL, Haskell, Clojure etc? If not better, then why don't people just do functional languages then (instead of reinventing the wheel with Javascript)? Please note that I have none experience in either Node.JS nor functional programming. So some basic explanation can be helpful.

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  • Java GUI libraries

    - by Dan
    I have been working with the Swing library for a long time, I'm working on a new project for school and due to the nature of the program it can't look like a generic/boring swing gui. So my question is does anyone know of an interesting java gui library that is not swing or awt?

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  • Hybrid static/dynamic Google Map

    - by jonathanconway
    Ever noticed that when you go to maps.google.com and do a search (say, car wash), it renders a lot of results (represented by small circles) and a few prominent ones (seen as regular-size pins)? Notice how quickly it does this? From what I can tell from analyzing this in Firebug, much of this is generated on the server and sent to the client as a static image. However, it's still dynamic. You can still zoom in and out, or click on a result and see a dynamic InfoWindow rendered. Google have made the map quick and smooth using static images, while still making it flexible. Is there a way to do this kind of 'pre-loading' with my own Google Map (implemented with the Google Maps API)?

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  • Is there a pure-managed DirectX wrapper?

    - by Cody Brocious
    I'm currently in need of a purely managed code DirectX wrapper for .NET. While SlimDX is great, its use of unmanaged code makes it impossible to perform proper dead code analysis on, for the purpose of merging it into your assemblies. With a pure managed wrapper, I'd be able to include just the pieces I use in my assembly, allowing very, very small binaries (my goal is to be able to write 64k demos entirely using .NET). Does such a thing exist, or am I going to be getting intimate with P/Invoke?

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  • DOS batch file to enter commands in proprietary java app and receive feedback?

    - by Justine
    Hello, I'm working on a project in which I'd like to be able to turn lights on and off in the Duke Smart Home via a high frequency chirp. The lighting system is called Clipsal Square-D and the program that gives a user access to the lighting controls is called CGate. I was planning on doing some signal processing in Matlab, then create a batch file from Matlab to interact with Cgate. Cgate is a proprietary Java app that, if run from a DOS command line, opens up another window that looks like the command prompt. I have a batch file that can check to see if Cgate is running and if not, open it. But what I can't figure out how to do is actually run commands in the Cgate program from the batch file and likewise, take the response from Cgate. An example of such a command is "noop," which should return "200 OK." Any help would be much appreciated! Thank you very much in advance :) (here's my existing batch file by the way) @ECHO off goto checkIfOpen :checkIfOpen REM pv finds all open processes and puts it in result.txt %SystemRoot%\pv\pv.exe %SystemRoot%\pv\pv.exe result.txt REM if result has the word notepad in it then notepad is running REM if not then it opens notepad FIND "notepad.exe" result.txt IF ERRORLEVEL 1 START %SystemRoot%\system32\Clipsal\C-Gate2\cgate.exe goto end :end

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  • R: ggplot2, how to add a number of layers to a plot at once to reduce code

    - by John
    library(ggplot2) This code produces a nice looking plot: qplot(cty, hwy, data = mpg, colour = displ) + scale_y_log2() + labs(x="x axis") + labs(y="y axis") + opts(title = "my title") But I want to setup variables to try and to reduce code repetition: log_scale <- scale_y_log2() xscale <- labs(x="x axis") yscale <- labs(y="y axis") title <- opts(title = "my title") my_scales <- c(log_scale, xscale, yscale, title) # make a variable to hold the scale info changes above So that I can do this and add a bunch of things at the same time: qplot(cty, hwy, data = mpg, colour = displ) + my_scales # add these to your plot. but I get this error: Error in object$class : $ operator is invalid for atomic vectors I realize that the things going into my_scales need to be layers / different types of objects, but I don't see what they should be.

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  • dhtmlx grid in xhtml page

    - by user302254
    I need the dxhtmlgrid to work in a xhtml page. All the examples are in plain html and when I try and convert to xhtml I get errors. Can anyone help me get a dhtmlxgrid to work in a xhtml page? I am generating my grid from a table: http://dhtmlx.com/docs/products/dhtmlxGrid/samples/12_initialization_loading/03_grid_int_from_html.html I get the following javascript error message: this.hdr.rows is undefined [Break on this error] this.cellWidthPX[fcols[i]]=next;summ+...etTimeout(function(){self.setSizes()

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  • jQuery - Finding the element index relative to its container

    - by Hary
    Here's my HTMl structure: <div id="main"> <div id="inner-1"> <img /> <img /> <img /> </div> <div id="inner-2"> <img /> <img class="selected" /> <img /> </div> <div id="inner-3"> <img /> <img /> <img /> </div> </div> What I'm trying to do is get the index of the img.selected element relative to the #main div. So in this example, the index should be 4 (assuming 0 based index) and not 1. My usual way to go about getting indexes is using $element.prevAll().length but, obviously, that will return the index relative to the #inner-2 div. I've tried using $('img.selected').prevAll('#main').length but that's returning 0 :/

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  • Submit WordPress form password programmatically

    - by songdogtech
    How can I let a user access a WordPress protected page with a URL that will submit the password in the form below? I want to be able to let a user get to a password protected WordPress page without needing to type the password, so when they go to the page, the password is submitted by a POST URL on page load. This not intended to be secure in any respect; I'll need to hardcode the password in the URL and the PHP. It's just for simplicity for the user, and once they're in, the cookie will let them in for 10 more days. I will select the particular user with separate PHP function that determines their IP or WordPress login status. I used Wireshark to find the POST string: post_password=mypassword&Submit=Submit but using this URL mydomain.com/wp-pass.php?post_password=mypassword&Submit=Submit gives me a blank page. This is the form: <form action="http://mydomain.com/wp-pass.php" method="post"> Password: <input name="post_password" type="password" size="20" /> <input type="submit" name="Submit" value="Submit" /></form> This is wp-pass.php: <?php require( dirname(__FILE__) . '/wp-load.php'); if ( get_magic_quotes_gpc() ) $_POST['post_password'] = stripslashes($_POST['post_password']); setcookie('wp-postpass_' . COOKIEHASH, $_POST['post_password'], time() + 864000, COOKIEPATH); wp_safe_redirect(wp_get_referer()); ?> What am I doing wrong? Or is there a better way to let a user into a password protected page automatically?

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  • efficiently finding the interval with non-zeros in scipy/numpy in Python?

    - by user248237
    suppose I have a python list or a python 1-d array (represented in numpy). assume that there is a contiguous stretch of elements how can I find the start and end coordinates (i.e. indices) of the stretch of non-zeros in this list or array? for example, a = [0, 0, 0, 0, 1, 2, 3, 4] nonzero_coords(a) should return [4, 7]. for: b = [1, 2, 3, 4, 0, 0] nonzero_coords(b) should return [0, 2]. thanks.

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  • simple jquery callback works on .net3.5 but nothing fires on .net 2.0?

    - by CliffC
    hi i have the following jquery postback method on the client <%@ Page Language="C#" AutoEventWireup="true" CodeFile="CallServerWithParameters.aspx.cs" Inherits="CallServerWithParameters" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head runat="server"> <title></title> <script src="jquery-1.2.6.js" type="text/javascript"></script> <script language="javascript"> $(document).ready(function() { $("#txtNoOfMales").change(function() { var ticketRequired = this.value; var options = { type: "POST", url: "CallServerWithParameters.aspx/GetAvailableTicketsForMales", data: "{no:'" + ticketRequired + "'}", contentType: "application/json; charset=utf-8", dataType: "json", success: function(response) { if (response.d != "") { alert(response.d); $("#txtNoOfMales").focus(); } } }; //Call the PageMethods $.ajax(options); }); }); </script> </head> <body> <form id="form1" runat="server"> <div> No of Male Tickets:<asp:TextBox ID="txtNoOfMales" runat="server"></asp:TextBox> </div> </form> </body> </html> and the following web method on the server side using System; using System.Collections.Generic; using System.Web; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.Services; public partial class CallServerWithParameters : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { } [WebMethod] public static string GetAvailableTicketsForMales(int no) { string result = ""; int NoOfTicketsAvailable = 5; if (no > NoOfTicketsAvailable) { result = "Only " + NoOfTicketsAvailable.ToString() + " Male ticket(s) avaialable. Please eneter a lower number!"; } return result; } } problem is everything works fine on .net 3.5 but if i use the same code on .net 2.0 the webmethod event does not get call at all, anybody have any idea what i did wrong? thanks updated with full source code

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  • Is it possible to have a Ocaml function that accepts only integer lists?

    - by Sam
    I'm writing a recursive function in Ocaml that's supposed to count the number of items in an integer list (Yes I know there's a List.length function but I'm trying to do it myself). However the Ocaml compiler/interpreter forces me to use alpha list all the time. So is it wrong to say that, when a function accepts a list as a parameter, the type of that list must always be alpha? Thanks EDIT: the reason why it's inconvenient for me to use alpha lists is because i can't compare the head of the alpha list with an integer value due to type-matching complaints

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  • Do Websites Work?

    A website should, from brochure ware sites through to e-business and e-commerce sites, engage and enable users to interact, transact and share knowledge online. I could quote many statistics about website usage, e-business, e-commerce models and search engine marketing etc, but I won't.

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  • List Management Via MailChimp API

    - by goombaloon
    I'm investigating using the MailChimp API to manage email notifications for a social networking site (similar to how Twitter sends email notifications to followers when a followee posts a new Tweet). My original plan was to have a "follower" list for each user in the app and then send an email to that list each time that user posts new content. However, it appears that the MailChimp API intentionally doesn't support creating campaign lists via the API (for CAN-SPAM reasons). I've read something about list segmentation in MailChimp, but I don't think that helps me with this situation. I'm curious if anyone else has run into a similar requirement to mine and how they dealt with it. Any insights would be most appreciated! Thanks.

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  • POSIX AIO Library and Callback Handlers

    - by Charles Salvia
    According to the documentation on aio_read/write, there are basically 2 ways that the AIO library can inform your application that an async file I/O operation has completed. Either 1) you can use a signal, 2) you can use a callback function I think that callback functions are vastly preferable to signals, and would probably be much easier to integrate into higher-level multi-threaded libraries. Unfortunately, the documentation for this functionality is a mess to say the least. Some sources, such as the man page for the sigevent struct, indicate that you need to set the sigev_notify data member in the sigevent struct to SIGEV_CALLBACK and then provide a function handler. Presumably, the handler is invoked in the same thread. Other documentation indicates you need to set sigev_notify to SIGEV_THREAD, which will invoke the callback handler in a newly created thread. In any case, on my Linux system (Ubuntu with a 2.6.28 kernel) SIGEV_CALLBACK doesn't seem to be defined anywhere, but SIGEV_THREAD works as advertised. Unfortunately, creating a new thread to invoke the callback handler seems really inefficient, especially if you need to invoke many handlers. It would be better to use an existing pool of threads, similar to the way most network I/O event demultiplexers work. Some versions of UNIX, such as QNX, include a SIGEV_SIGNAL_THREAD flag, which allows you to invoke handlers using a specified existing thread, but this doesn't seem to be available on Linux, nor does it seem to even be a part of the POSIX standard. So, is it possible to use the POSIX AIO library in a way that invokes user handlers in a pre-allocated background thread/threadpool, rather than creating/destroying a new thread everytime a handler is invoked?

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  • Binary Search Tree Implementation

    - by Gabe
    I've searched the forum, and tried to implement the code in the threads I found. But I've been working on this real simple program since about 10am, and can't solve the seg. faults for the life of me. Any ideas on what I'm doing wrong would be greatly appreciated. BST.h (All the implementation problems should be in here.) #ifndef BST_H_ #define BST_H_ #include <stdexcept> #include <iostream> #include "btnode.h" using namespace std; /* A class to represent a templated binary search tree. */ template <typename T> class BST { private: //pointer to the root node in the tree BTNode<T>* root; public: //default constructor to make an empty tree BST(); /* You have to document these 4 functions */ void insert(T value); bool search(const T& value) const; bool search(BTNode<T>* node, const T& value) const; void printInOrder() const; void remove(const T& value); //function to print out a visual representation //of the tree (not just print the tree's values //on a single line) void print() const; private: //recursive helper function for "print()" void print(BTNode<T>* node,int depth) const; }; /* Default constructor to make an empty tree */ template <typename T> BST<T>::BST() { root = NULL; } template <typename T> void BST<T>::insert(T value) { BTNode<T>* newNode = new BTNode<T>(value); cout << newNode->data; if(root == NULL) { root = newNode; return; } BTNode<T>* current = new BTNode<T>(NULL); current = root; current->data = root->data; while(true) { if(current->left == NULL && current->right == NULL) break; if(current->right != NULL && current->left != NULL) { if(newNode->data > current->data) current = current->right; else if(newNode->data < current->data) current = current->left; } else if(current->right != NULL && current->left == NULL) { if(newNode->data < current->data) break; else if(newNode->data > current->data) current = current->right; } else if(current->right == NULL && current->left != NULL) { if(newNode->data > current->data) break; else if(newNode->data < current->data) current = current->left; } } if(current->data > newNode->data) current->left = newNode; else current->right = newNode; return; } //public helper function template <typename T> bool BST<T>::search(const T& value) const { return(search(root,value)); //start at the root } //recursive function template <typename T> bool BST<T>::search(BTNode<T>* node, const T& value) const { if(node == NULL || node->data == value) return(node != NULL); //found or couldn't find value else if(value < node->data) return search(node->left,value); //search left subtree else return search(node->right,value); //search right subtree } template <typename T> void BST<T>::printInOrder() const { //print out the value's in the tree in order // //You may need to use this function as a helper //and create a second recursive function //(see "print()" for an example) } template <typename T> void BST<T>::remove(const T& value) { if(root == NULL) { cout << "Tree is empty. No removal. "<<endl; return; } if(!search(value)) { cout << "Value is not in the tree. No removal." << endl; return; } BTNode<T>* current; BTNode<T>* parent; current = root; parent->left = NULL; parent->right = NULL; cout << root->left << "LEFT " << root->right << "RIGHT " << endl; cout << root->data << " ROOT" << endl; cout << current->data << "CURRENT BEFORE" << endl; while(current != NULL) { cout << "INTkhkjhbljkhblkjhlk " << endl; if(current->data == value) break; else if(value > current->data) { parent = current; current = current->right; } else { parent = current; current = current->left; } } cout << current->data << "CURRENT AFTER" << endl; // 3 cases : //We're looking at a leaf node if(current->left == NULL && current->right == NULL) // It's a leaf { if(parent->left == current) parent->left = NULL; else parent->right = NULL; delete current; cout << "The value " << value << " was removed." << endl; return; } // Node with single child if((current->left == NULL && current->right != NULL) || (current->left != NULL && current->right == NULL)) { if(current->left == NULL && current->right != NULL) { if(parent->left == current) { parent->left = current->right; cout << "The value " << value << " was removed." << endl; delete current; } else { parent->right = current->right; cout << "The value " << value << " was removed." << endl; delete current; } } else // left child present, no right child { if(parent->left == current) { parent->left = current->left; cout << "The value " << value << " was removed." << endl; delete current; } else { parent->right = current->left; cout << "The value " << value << " was removed." << endl; delete current; } } return; } //Node with 2 children - Replace node with smallest value in right subtree. if (current->left != NULL && current->right != NULL) { BTNode<T>* check; check = current->right; if((check->left == NULL) && (check->right == NULL)) { current = check; delete check; current->right = NULL; cout << "The value " << value << " was removed." << endl; } else // right child has children { //if the node's right child has a left child; Move all the way down left to locate smallest element if((current->right)->left != NULL) { BTNode<T>* leftCurrent; BTNode<T>* leftParent; leftParent = current->right; leftCurrent = (current->right)->left; while(leftCurrent->left != NULL) { leftParent = leftCurrent; leftCurrent = leftCurrent->left; } current->data = leftCurrent->data; delete leftCurrent; leftParent->left = NULL; cout << "The value " << value << " was removed." << endl; } else { BTNode<T>* temp; temp = current->right; current->data = temp->data; current->right = temp->right; delete temp; cout << "The value " << value << " was removed." << endl; } } return; } } /* Print out the values in the tree and their relationships visually. Sample output: 22 18 15 10 9 5 3 1 */ template <typename T> void BST<T>::print() const { print(root,0); } template <typename T> void BST<T>::print(BTNode<T>* node,int depth) const { if(node == NULL) { std::cout << std::endl; return; } print(node->right,depth+1); for(int i=0; i < depth; i++) { std::cout << "\t"; } std::cout << node->data << std::endl; print(node->left,depth+1); } #endif main.cpp #include "bst.h" #include <iostream> using namespace std; int main() { BST<int> tree; cout << endl << "LAB #13 - BINARY SEARCH TREE PROGRAM" << endl; cout << "----------------------------------------------------------" << endl; // Insert. cout << endl << "INSERT TESTS" << endl; // No duplicates allowed. tree.insert(0); tree.insert(5); tree.insert(15); tree.insert(25); tree.insert(20); // Search. cout << endl << "SEARCH TESTS" << endl; int x = 0; int y = 1; if(tree.search(x)) cout << "The value " << x << " is on the tree." << endl; else cout << "The value " << x << " is NOT on the tree." << endl; if(tree.search(y)) cout << "The value " << y << " is on the tree." << endl; else cout << "The value " << y << " is NOT on the tree." << endl; // Removal. cout << endl << "REMOVAL TESTS" << endl; tree.remove(0); tree.remove(1); tree.remove(20); // Print. cout << endl << "PRINTED DIAGRAM OF BINARY SEARCH TREE" << endl; cout << "----------------------------------------------------------" << endl; tree.print(); cout << endl << "Program terminated. Goodbye." << endl << endl; } BTNode.h #ifndef BTNODE_H_ #define BTNODE_H_ #include <iostream> /* A class to represent a node in a binary search tree. */ template <typename T> class BTNode { public: //constructor BTNode(T d); //the node's data value T data; //pointer to the node's left child BTNode<T>* left; //pointer to the node's right child BTNode<T>* right; }; /* Simple constructor. Sets the data value of the BTNode to "d" and defaults its left and right child pointers to NULL. */ template <typename T> BTNode<T>::BTNode(T d) : left(NULL), right(NULL) { data = d; } #endif Thanks.

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