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  • Why can I call a non-const member function pointer from a const method?

    - by sdg
    A co-worker asked about some code like this that originally had templates in it. I have removed the templates, but the core question remains: why does this compile OK? #include <iostream> class X { public: void foo() { std::cout << "Here\n"; } }; typedef void (X::*XFUNC)() ; class CX { public: explicit CX(X& t, XFUNC xF) : object(t), F(xF) {} void execute() const { (object.*F)(); } private: X& object; XFUNC F; }; int main(int argc, char* argv[]) { X x; const CX cx(x,&X::foo); cx.execute(); return 0; } Given that CX is a const object, and its member function execute is const, therefore inside CX::execute the this pointer is const. But I am able to call a non-const member function through a member function pointer. Are member function pointers a documented hole in the const-ness of the world? What (presumably obvious to others) issue have we missed?

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  • "Thread-Safe Calls" with "Invoke" method to Winform control leads very heavy memory leak!!

    - by konnychen
    In the following link: "Make Thread-Safe Calls to Windows Forms Controls http://msdn.microsoft.com/en-us/library/ms171728.aspx" We can see an example which provide cross tread access to a winform control. But if the thread is in a while loop, it will cause the heavy memory leak. As I use taskmanage I can see the memory is increasing. Can anyone help me to solve the problem? oThread2 = new Thread(new ThreadStart(Cyclic_Call)); oThread2.Start(); delegate void SetText_lab_Statubar(string text); private void m_SetText_lab_Statubar(string text) { if (this.lab_Statubar.InvokeRequired) { SetText_lab_Statubar d = new SetText_lab_Statubar(m_SetText_lab_Statubar); this.Invoke(d, new object[] { text }); } else { this.lab_Statubar.Text = text; } } private void Cyclic_Call() { do { this.m_SetText_lab_Statubar("This string is set from thread"); Thread.Sleep(100); } while (!b_AbortThraed); }

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  • why does this knockout method receive a form element instead of the object its nested in?

    - by ladookie
    I have this HTML: <ul class="chat_list" data-bind="foreach: chats"> <li> <div class="chat_response" data-bind="visible: CommentList().length == 0"> <form data-bind="submit: $root.addComment"> <input class="comment_field" placeholder="Comment…" data-bind="value: NewCommentText" /> </form> </div> </li> </ul> and this JavaScript: function ChatListViewModel(chats) { // var self = this; self.chats = ko.observableArray(ko.utils.arrayMap(chats, function (chat) { return { CourseItemDescription: chat.CourseItemDescription, CommentList: ko.observableArray(chat.CommentList), CourseItemID: chat.CourseItemID, UserName: chat.UserName, ChatGroupNumber: chat.ChatGroupNumber, ChatCount: chat.ChatCount, NewCommentText: ko.observable("") }; })); self.newChatText = ko.observable(); self.addComment = function (chat) { var newComment = { CourseItemDescription: chat.NewCommentText(), ParentCourseItemID: chat.CourseItemID, CourseID: $.CourseLogic.dataitem.CourseID, AccountID: $.CourseLogic.dataitem.AccountID, SystemObjectID: $.CourseLogic.dataitem.CommentSystemObjectID, SystemObjectName: "Comments", UserName: chat.UserName }; chat.CommentList.push(newComment); chat.NewCommentText(""); }; } ko.applyBindings(new ChatListViewModel(initialData)); When I go into the debugger it shows that the chat parameter of the addComment() function is a form element instead of a chat object. Why is this happening?

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  • How does a custom accessor method implementation in Core Data look like?

    - by dontWatchMyProfile
    The documentation is pretty confusing on this one: The implementation of accessor methods you write for subclasses of NSManagedObject is typically different from those you write for other classes. If you do not provide custom instance variables, you retrieve property values from and save values into the internal store using primitive accessor methods. You must ensure that you invoke the relevant access and change notification methods (willAccessValueForKey:, didAccessValueForKey:, willChangeValueForKey:, didChangeValueForKey:, willChangeValueForKey:withSetMutation:usingObjects:, and didChangeValueForKey:withSetMutation:usingObjects:). NSManagedObject disables automatic key-value observing (KVO, see Key-Value Observing Programming Guide) change notifications, and the primitive accessor methods do not invoke the access and change notification methods. In accessor methods for properties that are not defined in the entity model, you can either enable automatic change notifications or invoke the appropriate change notification methods. Are there any examples that show how these look like?

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  • What does Method = "put document: 12.0.0.4518" means?

    - by Pari
    Hi All, I was trying to upload large size file on Sharepoint. And got following code sample (i.e FrontPage RPC (Remote Procedure Calls)) I am not getting use of "put document: 12.0.0.4518" and "string serviceName = "http://servername/sitename/_vti_bin/_vti_aut/author.dll";". I have worked on code but it is showing " Response time Out" error. But since i can't understand the code.It is not possible for me to solve this or any future problem.

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  • What are block expressions actually good for?

    - by Helper Method
    I just solved the first problem from Project Euler in JavaFX for the fun of it and wondered what block expressions are actually good for? Why are they superior to functions? Is it the because of the narrowed scope? Less to write? Performance? Here's the Euler example. I used a block here but I don't know if it actually makes sense // sums up all number from low to high exclusive which are divisible by a or b function sumDivisibleBy(a: Integer, b: Integer, high: Integer) { def low = if (a <= b) a else b; def sum = { var result = 0; for (i in [low .. <high] where i mod 3 == 0 or i mod 5 == 0) { result += i } result } } Does a block makes sense here?

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  • Is it bad practice to have a long initialization method?

    - by Paperflyer
    many people have argued about function size. They say that functions in general should be pretty short. Opinions vary from something like 15 lines to "about one screen", which today is probably about 40-80 lines. Also, functions should always fulfill one task only. However, there is one kind of function that frequently fails in both criteria in my code: initialization functions. For example in an audio application, the audio hardware/API has to be set up, audio data has to be converted to a suitable format and the object state has to properly initialized. These are clearly three different tasks and depending on the API this can easily span more than 50 lines. The thing with init-functions is that they are generally only called once, so there is no need to re-use any of the components. Would you still break them up into several smaller functions would you consider big initialization functions to be ok?

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  • How perform USort() on an Array of Objects class definition as a method?

    - by user558724
    class Contact{ public $name; public $bgcolor; public $lgcolor; public $email; public $element; public function __construct($name, $bgcolor, $lgcolor, $email, $element) { $this->name = $name; $this->bgcolor = $bgcolor; $this->lgcolor = $lgcolor; $this->email = $email; $this->element = $element; } public static function sortByName(Contact $p1, Contact $p2) { return strcmp($p1->name, $p2->name); } } class ContactList implements Iterator, ArrayAccess { protected $_label; protected $_contacts = array(); public function __construct($label) { $this->_label = $label; } public function getLabel() { return $this->_label; } public function addContact(Contact $contact) { $this->_contacts[] = $contact; } public function current() { return current($this->_contacts); } public function key() { return key($this->_contacts); } public function next() { return next($this->_contacts); } public function rewind() { return reset($this->_contacts); } public function valid() { return current($this->_contacts); } public function offsetGet($offset) { return $this->_contacts[$offset]; } public function offsetSet($offset, $data) { if (!$data instanceof Contact) throw new InvalidArgumentException('Only Contact objects allowed in a ContactList'); if ($offset == '') { $this->_contacts[] = $data; } else { $this->_contacts[$offset] = $data; } } public function offsetUnset($offset) { unset($this->_contacts[$offset]); } public function offsetExists($offset) { return isset($this->_contacts[$offset]); } public function sort($attribute = 'name') { $sortFct = 'sortBy' . ucfirst(strtolower($attribute)); if (!in_array($sortFct, get_class_methods('Contact'))) { throw new Exception('contact->sort(): Can\'t sort by ' . $attribute); } usort($this->contact, 'ContactList::' . $sortFct); } } public function Sort($property, $asc=true) { // this is where sorting logic takes place $_pd = $this->_contact->getProperty($property); if ($_pd == null) { user_error('Property '.$property.' does not exist in class '.$this->_contact->getName(), E_WARNING); return; } // set sortDescriptor ContactList::$sortProperty = $_pd; // and apply sorting usort($this->_array, array('ContactList', ($asc?'USortAsc':'USortDesc'))); } function getItems(){ return $this->_array; } class SortableItem extends ContactList { static public $sortProperty; static function USortAsc($a, $b) { /*@var $_pd ReflectionProperty*/ /* $_pd = self::$sortProperty; if ($_pd !== null) { if ($_pd->getValue($a) === $_pd->getValue($b)) return 0; else return (($_pd->getValue($a) < $_pd->getValue($b))?-1:1); } return 0; } static function USortDesc($a, $b) { return -(self::USortAsc($a,$b)); } } This approach keeps giving me PHP Warnings: usort() [function.usort]: of all kinds which I can provide later as needed to comment out those methods and definitions in order to test and fix some minor bugs of our program. **$billy parameters are already defined. $all -> addContact($billy); // --> ended up adding each contact manually above $all->Sort('name',true); $items = $all->getItems(); foreach($items as $contact) { echo $contact->__toString(); } $all->sort(); The reason for using usort is to re-arrange the order alphabetically by name but somehow is either stating that the function comparison needs to be an array or another errors which obviously I have seemed to pass. Any help would be greatly appreciated, thanks in advance.

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  • Whats the best method for queuing time-sensitive messages with PHP/MySQL?

    - by Mike Diena
    I'm building an SMS call and response system in a new app that receives a message via an aggregator gateway, checks it for functional keywords (run, stop, ask, etc), then processes it appropriately (save to the database, return an answer, or execute a task based on the users authorization). It's running fine at the moment as there are only a few users, but I figure its going to have more issues as we scale it up. We're currently running it on a single DV machine (mediatemple base dv). My question is this: does it make more sense to set something up like Memcached to run a queue, or a simple database with a daemon running to process each message one by one? I don't have much experience with either, so any advice would be helpful. Since the messaging is somewhat time-sensitive, what would be the fastest and most reliable way to handle this? Also, since we're sending responses, I'll probably need to set up and outbound message queue as well. Would it make sense to use the same concept for both?

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  • Why is my class method not visible when I implement an interface in my class?

    - by Phsika
    i can not see MyLoad.TreeLoader(.... but why i can not see? i implemented iloader to TreeViewLoad. i should see TreeLoader why? namespace Rekursive { public partial class Form1 : Form { public Form1() { InitializeComponent(); } private void Form1_Load(object sender, EventArgs e) { //treeView1.Nodes.Add("Test"); iloader MyLoad = new TreeViewLoad(); MyLoad.loader("test", treeView1, 1); // i can not see MyLoad.TreeLoader(.... but why i can not see? // i implemented iloader to TreeViewLoad. i should see TreeLoader why? //TreeViewLoad myloader = new TreeViewLoad(); } } interface iloader { void loader(string nodeName, TreeView myTre, int id); } class TreeViewLoad : iloader { public void TreeLoader(TreeView tre) { // i will call loader... } public void loader(string nodeName, TreeView myTre, int id) { myTre.Nodes.Add(nodeName + id.ToString()); if (id

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  • How can I memoize a method that may return true or false in Ruby?

    - by Seamus Abshere
    Obviously ||= won't work def x? @x_query ||= expensive_way_to_calculate_x end because if it turns out to be false, then expensive_way_to_calculate_x will get run over and over. Currently the best way I know is to put the memoized true or false into an Array: def x? return @x_query.first if @x_query.is_a?(Array) @x_query = [expensive_way_to_calculate_x] @x_query.first end Is there a more conventional or efficient way of doing this?

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  • Is there an easy method to combine two relative paths in C# ?

    - by Ioannis
    I want to combine two relative paths in C#. For example: string path1 = "/System/Configuration/Panels/Alpha"; string path2 = "Panels/Alpha/Data"; I want to return string result = "/System/Configuration/Panels/Alpha/Data"; I can implement this by splitting the second array and compare it in a for loop but I was wondering if there is something similar to Path.Combine available or if this can be accomplished with regular expressions or Linq? Thanks

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  • Copying 6000 tables and data from sqlserver to oracle ==> fastest method?

    - by nazer555
    i need to copy the tables and data (about 5 yrs data, 6200 tables) stored in sqlserver, i am using datastage and odbc connection to connect and datstage automatically creates the table with data, but its taking 2-3 hours per table as tables are very large(0.5 gig, 300+columns and about 400k rows). How can i achieve this the fastes as at this rate i am able to only copy 5 tables per day but within 30 days i need move over these 6000 tables.

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  • IE 7 activex object (or xmlhttprequest?) open method using POST takes 20-30 seconds to return

    - by Toddeman
    i have a problem that only shows itself in IE7. its a simple ajax call. i got my object (accounting for the browser) so in 7 i SHOULD have an ActiveXObject. when i call open with POST, it takes 20-30 seconds to return. i am using a TON of GET calls to populate information and all of these work (finally, after some bug fixing), but i am NOT a web developer so much like the other bugs i had to fix, i figured i was just missing another IE anomaly. this is not a consistent bug either, which makes it harder to find for me. most times the POST functions like it does in Firefox or Chrome, but maybe 1 out of 4 or 5 will take 20-30 seconds to return. it DOES return correctly when it returns, it just takes a long time. am i missing something simple? or is there a smarter way for me to find out exactly what is going on (like the equivalent of the firebug 'net' tab for windows?).

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  • Is there an encoding method that is mutual to flash and php?

    - by Gus
    I'm base64 encoding a JPG in AS3 and passing it to PHP where it would be decoded. It appears that AS3's encodeToBase64String() function and and PHP's base64_decode() function do not use the same algorithm. Is there a library or API for either language that would allow it to interface with the other? Alternatively, does anyone even know what PHP's default base64 map is? My Google searching is not yielding results.

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  • How to use HTTP method DELETE on Google App Engine?

    - by Jader Dias
    I can use this verb in the Python Windows SDK. But not in production. Why? What am I doing wrong? The error message includes (only seen via firebug or fiddler) Malformed request or something like that My code looks like: from google.appengine.ext import db from google.appengine.ext import webapp class Handler(webapp.RequestHandler): def delete(self): key = self.request.get('key') item = db.get(key) item.delete() self.response.out.write(key)

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  • How can a button click method find out which item is selected in a ListView?

    - by Ian Bayley
    I have a single screen with a bank of buttons below a ListView. Entries on the ListView light up in orange when I scroll so I assume that are selected. When I then press the "Delete" button I want the onClickListener to remove the currently selected entry. But getSelectedItemPosition() always gives me -1. If I can't hope to use the GUI controls in this way, please give me another way of getting the same result. I have even tried setting the onClickListener of the List View to store the index before the button is pressed (in case pressing the button unselects the entry) but even that is always -1 it seems. Here's the code (without the modification which didn't work) package com.bayley; import android.app.Activity; import android.os.Bundle; import android.view.View; import android.widget.ArrayAdapter; import android.widget.Button; import android.widget.EditText; import android.widget.ListView; import java.util.ArrayList; /** * * @author p0074564 */ public class September extends Activity { /** Called when the activity is first created. */ @Override public void onCreate(Bundle icicle) { super.onCreate(icicle); setContentView(R.layout.main); final ListView myListView = (ListView) findViewById(R.id.myListView); Button addButton = (Button) findViewById(R.id.AddButton); Button deleteButton = (Button) findViewById(R.id.DeleteButton); final EditText editText = (EditText) findViewById(R.id.myEditText); final ArrayList<String> todoItems = new ArrayList<String>(); todoItems.add("Monday"); todoItems.add("Tuesday"); todoItems.add("Wednesday"); final ArrayAdapter<String> aa = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, todoItems); myListView.setAdapter(aa); addButton.setOnClickListener(new Button.OnClickListener() { public void onClick(View v) { todoItems.add(editText.getText().toString()); aa.notifyDataSetChanged(); } }); deleteButton.setOnClickListener(new Button.OnClickListener() { public void onClick(View v) { // always returns -1 unfortunately ie nothing is ever selected int index = myListView.getSelectedItemPosition(); if (index >= 0) { todoItems.remove(index); } aa.notifyDataSetChanged(); } }); } }

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