callback

Rails after_create callback can't access model's attributes

I can't access my model's attributes in the after_create callback... seems like I should be able to right? controller: @dog = Dog.new(:color => 'brown', :gender => 'male') @dog.user_id = current_user.id @dog.save model: class Dog < ActiveRecord::Base def after_create logger.debug "[DOG CREATED] color:#{color} gender:#{gender} ...

Why do you need "extern C" for C++ callbacks to C functions?

Hello, I find such examples in Boost code. namespace boost { namespace { extern "C" void *thread_proxy(void *f) { .... } } // anonymous void thread::thread_start(...) { ... pthread_create(something,0,&thread_proxy,something_else); ... } } // boost Why do you actually need thi...

empty() not a valid callback?

I'm trying to use empty() in array mapping in php. I'm getting errors that it's not a valid callback. $ cat test.php <? $arrays = array( 'arrEmpty' => array( '','','' ), ); foreach ( $arrays as $key => $array ) { echo $key . "\n"; echo array_reduce( $array, "empty" ); var_dump( array_map("empty...

NullReference Exception is thrown while getting a callback channel

Hi! I am trying to get along with WCF's duplex contracts. A code from this article (http://msdn.microsoft.com/en-us/library/ms731184.aspx) ICalculatorDuplexCallback callback = null; callback = OperationContext.Current.GetCallbackChannel(); throws a NullReferenceException. So how can i manage this? Thanks for your attention! ...

Java RMI timeout in callback

We are using Java RMI for communication. An RMI client passes a processing request and an object with a callback method to an RMI server. The server invokes the callback when it is done with processing. The setup is similar to the one described in RMI Callbacks. Occasionally we are getting a "read time out" exception in the server upon ...

Back-to-back ajax long poll without a recursive callback function.

I'm trying to make long poll ajax calls, back to back. The problem with the current way I'm doing it is that I make each successive call from the callback function of the previous call. Is this a problem? Firebug doesn't show any of my ajax calls as completed, even thought the data is returned and the callback is executed. The recursive ...

How to use SAPI's SetNotifyCallbackFunction() in a CLR project with Windows Form as the interface window?

Hi, I'm trying to write a dll plugin for Winamp. I'm using Microsoft Visual Studio 2008 and Microsoft SAPI 5.1. I created the interface window using Windows Form (System::Windows::Forms::Form). I tried to use SetNotifyWIndowMessage(), but the method is never called when I speak to the microphone. So I tried using SetNotifyCallbackFunct...

Duplex Contract GetCallbackChannel always returns a null-instance

Hi! Here is the server code: using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.ServiceModel; using System.Runtime.Serialization; using System.ServiceModel.Description; namespace Console_Chat { [ServiceContract(SessionMode = SessionMode.Required, CallbackContr...

pb with callback in the python optparse module

Hi Guys, I'm playing with Python 2.6 and its optparse module. I would like to convert one of my arguments to a datetime through a callback but it fails. Here is the code: def parsedate(option, opt_str, value, parser): option.date = datetime.strptime(value, "%Y/%m/%d") def parse_options(args): parser = OptionParser(usage="%p...

What are the use cases for closures/callback functions in Javascript?

I was listening to Crockford's talk on Javascript closures and am convinced of the benefit of information hiding, but I do not have a firm understanding of when to use callback functions. It is mostly a true statement that a person could accomplish the same functionality with or without callbacks. As someone who is writing code, what h...

Returning a Value From the Bit.ly JS API Callback

Hey all, I am attempting to turn this "one shot" script into something more extensible. The problem is that I cannot figure out how to get the callback function to set a value outside of itself (please note that references to the Bit.ly API and the prototype.js frame work which are required have been left out due to login and apiKey in...

jQuery.post dynamic data callback function

I have a script that requires quite e few seconds of processing, up to about minute. The script resizes an array of images, sharpens them and finally zips them up for the user to download. Now I need some sort of progress messages. I was thinking that with jQuery's .post() method the data from the callback function would progressively u...

Why doesn't SAPI's ISpNotifySource::SetNotifyWindowMessage() send the notification to my WndProc()?

I'm using WinForms, and I'm trying to get SetNotifyWindowMessage() to send a message to the WndProc, but it does not do so. The function call: HRESULT initSAPI(HWND hWnd) { ... if(FAILED( g_cpRecoCtxt->SetNotifyWindowMessage( hWnd, WM_RECOEVENT, 0, 0 ))) MessageBoxW(hWnd, L"Error sending window message", L"SAPI Initialization E...

Callbacks in C#

I started coding in C# and have never had the opportunity to use callbacks though I have used delegates for event wiring. What is the real application of callbacks. I would be grateful if you could give some link that explains about callbacks in a straight forward way without C++ prerequisites. ...

[c++] accessing the hidden 'this' pointer

I have a GUI architecture wherein elements fire events like so: guiManager->fireEvent(BUTTON_CLICKED, this); Every single event fired passes 'this' as the caller of the event. There is never a time I dont want to pass 'this', and further, no pointer except for 'this' should ever be passed. This brings me to a problem: How can I asse...

Call a constructor from variable arguments with PHP

Hello guys, I have a function that takes variadic arguments, that I obtain from func_get_args(). This function needs to call a constructor with those arguments. However, I don't know how to do it. With call_user_func, you can call functions with an array of arguments, but how would you call a constructor from it? I can't just pass the...

Return variable in function from method callback data in same function

How do I return the latlon variable for codeAddress function. return latlon doesn't work, probably because of scope but I am unsure how to make it work. function codeAddress(addr) { if (geocoder) { geocoder.geocode({ 'address': addr}, function(results, status) { if (status == google.maps.Geocoder...

Receiving an object in a unmanaged callback function

Eg. I have following delegate method I want to use as a callback function with unmanaged code: public delegate void Callback(IntPtr myObject); Callback callback; I register it in the following way: [DllImport("a.dll")] public static void registerCallback(IntPtr callbackFunction, IntPtr anObject); // ... this.myObject = new MyClas...

Jquery AJAX and figuring out how NOT to nest callbacks for multiple reloads.

I have a site with a few containers that need to load content dynamically via AJAX. Most of the links inside of the containers actually load new data in that same container. I.E: $("#navmenu_item1").click(function() { $("#navmenu").load(blah); }); When I click on a link, lets say "logout," and the menu reloads with the updated logi...

CodeIgniter Unable to Access Error Message Error

Hi, I've created this registration form for registering new users to a website using CodeIgniter. My problem is, whenever I enter a username that already exists in my database, instead of giving me my error message which explains this to the user, it instead gives me this error message: Unable to access an error message corresponding...