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  • Raising C# events with an extension method - is it bad?

    - by Kyralessa
    We're all familiar with the horror that is C# event declaration. To ensure thread-safety, the standard is to write something like this: public event EventHandler SomethingHappened; protected virtual void OnSomethingHappened(EventArgs e) { var handler = SomethingHappened; if (handler != null) handler(this, e); } Recently in some other question on this board (which I can't find now), someone pointed out that extension methods could be used nicely in this scenario. Here's one way to do it: static public class EventExtensions { static public void RaiseEvent(this EventHandler @event, object sender, EventArgs e) { var handler = @event; if (handler != null) handler(sender, e); } static public void RaiseEvent<T>(this EventHandler<T> @event, object sender, T e) where T : EventArgs { var handler = @event; if (handler != null) handler(sender, e); } } With these extension methods in place, all you need to declare and raise an event is something like this: public event EventHandler SomethingHappened; void SomeMethod() { this.SomethingHappened.RaiseEvent(this, EventArgs.Empty); } My question: Is this a good idea? Are we missing anything by not having the standard On method? (One thing I notice is that it doesn't work with events that have explicit add/remove code.)

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  • Capturing USB Plug/Unplug events in Firemonkey

    - by radsdau
    [RAD Studio XE3 / C++] I have a FMX project running in Windows only at this stage, but I need to detect events when USB devices are connected and disconnected. I have a similar VCL app that can do this fine, but the Application-HookMainWindow is not exposed in FMX (only VCL). Is there an elegant way to handle this? Or do I have to hack some VCL stuff into my FMX app to make that work? I'd imagine I have to abstract it so I can support other platforms down the track. For the meantime though I need to get the Windows solution working. If the 'VCL hack' thing is required, how would I reference the vcl::Forms::Application from within my Fmx app? Cheers.

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  • Handling log-in / log-out via Objective-c

    - by squeezemylime
    Having a real problem with this one...Tried using cookies to store variables, etc. but no luck. Writing an iPhone app where the User has to log in. There is an HTTPS call to get the person's userid, which is used practically everywhere else in the app, so that either has to be stored in a global variable or a cookie (for sending messages to other users, etc.) I tried the cookie route, but am having great difficulty storing (and retriving) a user ID in a cookie. The User should be able to then close out of the app and then reboot it and have the app retain their User ID as well, so I'm not sure global variables are necessarily the solution to this. Are there any best practices or suggestions?

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  • User entered value validation and level of error catching

    - by Terry
    May I ask should the error catching code be placed at the lowest level or at the top as I am not sure what is the best practice? I prefer placing at the bottom, example a, as Example a public static void Main(string[] args) { string operation = args[0]; int value = Convert.ToInt32(args[1]); if (operation == "date") { DoDate(value); } else if (operation == "month") { DoMonth(value); } } public static void DoMonth(int month) { if (month < 1 || month > 12) { throw new Exception(""); } } public static void DoDate(int date) { if (date < 1 || date > 31) { throw new Exception(""); } } or example b public static void Main(string[] args) { string operation = args[0]; int value = Convert.ToInt32(args[1]); if (operation == "date" && (date < 1 || date > 12)) { throw new Exception(""); } else if (operation == "month" && (month < 1 || month > 31)) { throw new Exception(""); } if (operation == "date") { DoDate(value); } else if (operation == "month") { DoMonth(value); } } public static void DoMonth(int month) { } public static void DoDate(int date) { }

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  • Is there a way to catch Fatal error in PHP?

    - by Josef Sábl
    I have this line of PHP code: thisFunctionDoesNotExist(); And it stops script execution with: Fatal error: Call to undefined function I tried using set_error_handler and it does help for warning type of errors. But not for fatal errors. As I understand it from various threads on internet it should be possible to handle by set_error_handler, but I cannot make it work. Can you please post working example?

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  • Are event handlerss in JavaScript called in order?

    - by musicfreak
    I know this is a simple question, but I haven't had the chance to test it in any browser other than Firefox. If I attach multiple event handlers to a single event on a single DOM element, are the event handlers guaranteed to be called in the order they were added? Or should I not rely on this behavior?

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  • Gracefully handling screen orientation change during activity start

    - by Steve H
    I'm trying to find a way to properly handle setting up an activity where its orientation is determined from data in the intent that launched it. This is for a game where the user can choose levels, some of which are int portrait orientation and some are landscape orientation. The problem I'm facing is that setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE) doesn't take effect until the activity is fully loaded. This is a problem for me because I do some loading and image processing during startup, which I'd like to only have to do once. Currently, if the user chose a landscape level: the activity starts onCreate(), defaulting to portrait discovers from analysing its launching Intent that it should be in landscape orientation continues regardless all the way to onResume(), loading information and performing other setup tasks at this point setRequestedOrientation kicks in so the application runs through onPause() to onDestroy() it then again starts up from onCreate() and runs to onResume() repeating the setup from earlier Is there a way to avoid that and have it not perform the loading twice? For example, ideally, the activity would know before even onCreate was called whether it should be landscape or portrait depending on some property of the launching intent, but unless I've missed something that isn't possible. I've managed to hack together a way to avoid repeating the loading by checking a boolean before the time-consuming loading steps, but that doesn't seem like the right way of doing it. I imagine I could override onSaveInstanceState, but that would require a lot of additional coding. Is there a simple way to do this? Thanks!

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  • Complex sound handling (I.E. pitch change while looping)

    - by Matthew
    Hi everyone I've been meaning to learn Java for a while now (I usually keep myself in languages like C and Lua) but buying an android phone seems like an excellent time to start. now after going through the lovely set of tutorials and a while spent buried in source code I'm beginning to get the feel for it so what's my next step? well to dive in with a fully featured application with graphics, sound, sensor use, touch response and a full menu. hmm now there's a slight conundrum since i can continue to use cryptic references to my project or risk telling you what the application is but at the same time its going to make me look like a raving sci-fi nerd so bare with me for the brief... A semi-working sonic screwdriver (oh yes!) my grand idea was to make an animated screwdriver where sliding the controls up and down modulate the frequency and that frequency dictates the sensor data it returns. now I have a semi-working sound system but its pretty poor for what its designed to represent and I just wouldn't be happy producing a sub-par end product whether its my first or not. the problem : sound must begin looping when the user presses down on the control the sound must stop when the user releases the control when moving the control up or down the sound effect must change pitch accordingly if the user doesn't remove there finger before backing out of the application it must plate the casing of there device with gold (Easter egg ;P) now I'm aware of how monolithic the first 3 look and that's why I would really appreciate any help I can get. sorry for how bad this code looks but my general plan is to create the functional components then refine the code later, no good painting the walls if the roofs not finished. here's my user input, he set slide stuff is used in the graphics for the control @Override public boolean onTouchEvent(MotionEvent event) { //motion event for the screwdriver view if(event.getAction() == MotionEvent.ACTION_DOWN) { //make sure the users at least trying to touch the slider if (event.getY() > SonicSlideYTop && event.getY() < SonicSlideYBottom) { //power setup, im using 1.5 to help out the rate on soundpool since it likes 0.5 to 1.5 SonicPower = 1.5f - ((event.getY() - SonicSlideYTop) / SonicSlideLength); //just goes into a method which sets a private variable in my sound pool class thing mSonicAudio.setPower(1, SonicPower); //this handles the slides graphics setSlideY ( (int) event.getY() ); @Override public boolean onTouchEvent(MotionEvent event) { //motion event for the screwdriver view if(event.getAction() == MotionEvent.ACTION_DOWN) { //make sure the users at least trying to touch the slider if (event.getY() > SonicSlideYTop && event.getY() < SonicSlideYBottom) { //power setup, im using 1.5 to help out the rate on soundpool since it likes 0.5 to 1.5 SonicPower = 1.5f - ((event.getY() - SonicSlideYTop) / SonicSlideLength); //just goes into a method which sets a private variable in my sound pool class thing mSonicAudio.setPower(1, SonicPower); //this handles the slides graphics setSlideY ( (int) event.getY() ); //this is from my latest attempt at loop pitch change, look for this in my soundPool class mSonicAudio.startLoopedSound(); } } if(event.getAction() == MotionEvent.ACTION_MOVE) { if (event.getY() > SonicSlideYTop && event.getY() < SonicSlideYBottom) { SonicPower = 1.5f - ((event.getY() - SonicSlideYTop) / SonicSlideLength); mSonicAudio.setPower(1, SonicPower); setSlideY ( (int) event.getY() ); } } if(event.getAction() == MotionEvent.ACTION_UP) { mSonicAudio.stopLoopedSound(); SonicPower = 1.5f - ((event.getY() - SonicSlideYTop) / SonicSlideLength); mSonicAudio.setPower(1, SonicPower); } return true; } and here's where those methods end up in my sound pool class its horribly messy but that's because I've been trying a ton of variants to get this to work, you will also notice that I begin to hard code the index, again I was trying to get the methods to work before making them work well. package com.mattster.sonicscrewdriver; import java.util.HashMap; import android.content.Context; import android.media.AudioManager; import android.media.SoundPool; public class SoundManager { private float mPowerLvl = 1f; private SoundPool mSoundPool; private HashMap mSoundPoolMap; private AudioManager mAudioManager; private Context mContext; private int streamVolume; private int LoopState; private long mLastTime; public SoundManager() { } public void initSounds(Context theContext) { mContext = theContext; mSoundPool = new SoundPool(2, AudioManager.STREAM_MUSIC, 0); mSoundPoolMap = new HashMap<Integer, Integer>(); mAudioManager = (AudioManager)mContext.getSystemService(Context.AUDIO_SERVICE); streamVolume = mAudioManager.getStreamVolume(AudioManager.STREAM_MUSIC); } public void addSound(int index,int SoundID) { mSoundPoolMap.put(1, mSoundPool.load(mContext, SoundID, 1)); } public void playUpdate(int index) { if( LoopState == 1) { long now = System.currentTimeMillis(); if (now > mLastTime) { mSoundPool.play(mSoundPoolMap.get(1), streamVolume, streamVolume, 1, 0, mPowerLvl); mLastTime = System.currentTimeMillis() + 250; } } } public void stopLoopedSound() { LoopState = 0; mSoundPool.setVolume(mSoundPoolMap.get(1), 0, 0); mSoundPool.stop(mSoundPoolMap.get(1)); } public void startLoopedSound() { LoopState = 1; } public void setPower(int index, float mPower) { mPowerLvl = mPower; mSoundPool.setRate(mSoundPoolMap.get(1), mPowerLvl); } } ah ha! I almost forgot, that looks pretty ineffective but I omitted my thread which actuality updates it, nothing fancy it just calls : mSonicAudio.playUpdate(1); thanks in advance, Matthew

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  • Handling dynamic data from javascript or rails

    - by 99miles
    I have page consisting of a calendar view ( http://code.google.com/p/calendardateselect/ ) as well as divs, each of which contain information about a person. In each div I want to have a link to a new controller and action, and pass the id for the person and the date selected in the calendar. I can think of a one way, but I'm thinking there's likely a better solution: 1) Do something like: =link_to_function "Week", "weekClicked(#{person.id})" Then in the weekClicked() javascript method I get the selected date from the calendar, such as: $('e_date').selected_date; then with javascript I could make a post request as mentioned here: http://stackoverflow.com/questions/133925/javascript-post-request-like-a-form-submit 2) Or, is there a way that I could make each link a button in it's own form and maybe have a hidden field that gets the selected date from the calendar as or before the form is submitted? I tried this too, but couldn't figure it out. This definitely seems like it's more on the right track than #1. Thanks.

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  • LINQ method chaining and granular error handling

    - by Clafou
    I have a method which can be written pretty neatly through method chaining: return viewer.ServerReport.GetParameters() .Single(p => p.Name == Convention.Ssrs.RegionParamName) .ValidValues .Select(v => v.Value); However I'd like to be able to do some checks at each point as I wish to provide helpful diagnostics information if any of the chained methods returns unexpected results. To achieve this, I need to break up all my chaining and follow each call with an if block. It makes the code a lot less readable. Ideally I'd like to be able to weave in some chained method calls which would allow me to handle unexpected outcomes at each point (e.g. throw a meaningful exception such as new ConventionException("The report contains no parameter") if the first method returns an empty collection). Can anyone suggest a simple way to achieve such a thing?

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  • How to get the current eventNumber for creating an event with NSEvent

    - by Chris
    Hello I'm creating an os x application for which I try to add a remote interface. For this I need to be able to send mouse down and mouse up commands to the window of my application. I found code with which I can successfully do this, it looks as follows: int mask = 0x100; NSEvent* eventMouseDown = [NSEvent mouseEventWithType:NSLeftMouseDown location:p modifierFlags:mask timestamp:[NSDate timeIntervalSinceSystemStartup] windowNumber:[w windowNumber] context:[NSGraphicsContext graphicsContextWithWindow:w] eventNumber:++eventCounter +42599 clickCount:1 pressure:0]; NSLog(@"Mouse down event: %@", eventMouseDown); [[NSApplication sharedApplication] sendEvent:eventMouseDown]; I have only one problem with this code thought and this is the eventNumer parameter. As far as I found out it is a number which get increased with each event. But I cannot find a way to find the current number from where on I need to increase. The number I use there currently is just try and error and also does not seam to work always.

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  • SQL Server catch error from extended stored procedure

    - by haxelit
    Hello I have an extended stored procedure that sends an error message. srv_sendmsg(pSrvProc, SRV_MSG_ERROR, errorNum, SRV_FATAL_SERVER, 1, NULL, 0, (DBUSMALLINT) __LINE__, buff, SRV_NULLTERM); I've set the severity to SVR_FATAL_SERVER just as a test to see if I can cause the message to throw an exception in the sql. In my SQL i'm doing: BEGIN TRY EXEC dbo.xp_somethingCool SET @Error = @@ERROR END TRY BEGIN CATCH PRINT 'AN Error occoured!' SELECT ERROR_NUMBER() AS ErrorNumber ,ERROR_MESSAGE() AS ErrorMessage; END CATCH I would think that when my xp sends the error message the tsql would catch the error and select the error_number and error_message. Instead what ends up happening is that the xp sends the message and the T-SQL continues on its way like nothing happened. The @@Error variable doesn't get set either. So I was wondering if there was any trick to getting SQL to catch an error from an XP ? Thanks, Raul

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  • How to listen to keyboard events in GWT table?

    - by Olaf Mertens
    In my GWT program I have a table that has a selected row. I'd like to move the row selection with the up- and down-keys on the keyboard. So I have to catch the key events somehow. The GWT docs handle key events in input fields only. But I don't have an input field! Is this possible at all? Maybe it is a DOM/Javascript restriction that GWT cannot work around...

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  • isset($var) vs. @$var

    - by Josso
    Is this an okay practice or an acceptable way to use PHP's error suppressing? if (isset($_REQUEST['id'] && $_REQUEST['id'] == 6) { echo 'hi'; } if (@$_REQUEST['id'] == 6) { echo 'hi'; }

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  • Event Handling in Chaco

    - by awegawef
    When hovering over a data point in Chaco, I would like a small text box to appear, with the text I desire. Also, when I click on a data point (or close enough), I would like my program to take a certain action. I have seen relevant parts of the Chaco documentation, but implementing them has proved difficult. Any help would be appreciated. Thanks.

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  • Ruby Methods: how to return an usage string when insufficient arguments are given

    - by Shyam
    Hi, After I have created a serious bunch of classes (with initialize methods), I am loading these into IRb to test each of them. I do so by creating simple instances and calling their methods to learn their behavior. However sometimes I don't remember exactly what order I was supposed to give the arguments when I call the .new method on the class. It requires me to look back at the code. However, I think it should be easy enough to return a usage message, instead of seeing: ArgumentError: wrong number of arguments (0 for 9) So I prefer to return a string with the human readable arguments, by example using "puts" or just a return of a string. Now I have seen the rescue keyword inside begin-end code, but I wonder how I could catch the ArgumentError when the initialize method is called. Thank you for your answers, feedback and comments!

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  • Good programming style when handling multiple objects

    - by Glitch
    I've been programming a software version of a board game. Thus far I have written the classes which will correspond to physical objects on the game board. I'm well into writing the program logic, however I've found that many of the logic classes require access to the same objects. At first I was passing the appropriate objects to methods as they were called, but this was getting very tedious, particularly when the methods required many objects to perform their tasks. To solve this, I created a class which initialises and stores all the objects I need. This allows me to access an object from any class by calling Assets.dice(), for example. But now that I've thought about it, this doesn't seem right. This is why I'm here, I fear that I've created some sort of god class. Is this fear unfounded, or have I created a recipe for disaster?

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  • Handling undo and edit flag on window with several model objects

    - by Rui Pacheco
    Hi, I've a window that will hold several instances of a model object, listed in a table. The model object is updated using a text view. What is the best way to keep the edit flag and undo manager in synch with the content of the different model objects? I'm thinking creating an instance of the undo manager on the model object and manually set the undo manager for the text view every time the user choses a new model object. Does the undo manager also handle the edited flag?

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  • JSP: How can I still get the code on my error page to run, even if I can't display it?

    - by Josh Hinman
    I've defined an error-page in my web.xml: <error-page> <exception-type>java.lang.Exception</exception-type> <location>/error.jsp</location> </error-page> In that error page, I have a custom tag that I created. The tag handler for this tag e-mails me the stacktrace of whatever error occurred. For the most part this works great. Where it doesn't work great is if the output has already begun being sent to the client at the time the error occurs. In that case, we get this: SEVERE: Exception Processing ErrorPage[exceptionType=java.lang.Exception, location=/error.jsp] java.lang.IllegalStateException I believe this error happens because we can't redirect a request to the error page after output has already started. The work-around I've used is to increase the buffer size on particularly large JSP pages. But I'm trying to write a generic error handler that I can apply to existing applications, and I'm not sure it's feasible to go through hundreds of JSP pages making sure their buffers are big enough. Is there a way to still allow my stack trace e-mail code to execute in this case, even if I can't actually display the error page to the client?

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  • How to get notified about changes on SharePoint groups.

    - by Flo
    Hi, I'm actual looking for a way to get notified about any changes on a SharePoint group. First I though I would be able to this by attaching a event handler to some kind of group list. But unfortunately there are no such list representing SharePoint groups. My second attempt was to bind a event handler to the content type SharePointGroup but this didn't work either. So are there any other options to get notified about events on a SharePoint group? Bye, Flo EDIT: Thanks for the reply so far. I forgot to mention that I've already googled and read about the user information list. Sorry. First I found a forum entry where they post the relative URL to the user information list (_catalogs/users/simple.aspx). When I'm using this link to see the list,it only contains users and no groups. I don't know but perhaps this link does some filtering on the list. The other information I found about in several blog and forum posts was that a event handler attached to the user information list are not fired up on an events. I have to admit after reading that it doesn't work so many times and even on MSDN (http://msdn.microsoft.com/en-us/library/aa979520.aspx), I didn't try it on my own. The problem attaching the event handler to the content type wasn't the attaching thing, the handler simply didn't get fired when I for example changed a group name or deleted a user from the group. I don't have an idea why the handler doesn't get called I pretty sure I implemented the right methods and attached them to the right events. Any other suggestions how to get informed about changes on SharePoint groups?

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