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  • XML/XSL nub: Is it possible to create an COMPOSITE XML/XSLT document?

    - by jmweekes
    I have just recently (like 2 days) started using XSLT documents with XML. I understand the basics and am able to generate a formatted document using an .XML document that references a separate .XSLT document. My question, as in the subject, is "Is it possible to create a SINGLE, composite document that contains both the XML data and XSLT processing/formatting/styling and displays as formatted HTML?" I am writing a desktop application in which I need to generate a formatted document on the fly from XML stored in the database. I want to do this without creating or referencing any actual physical files. I will generate a text string containing the XML/XSLT document and feed this to a WebBrowser component for formatted display. Hopefully what I want to do doesn't totally go against the whole XML/XSLT methodology. Any information, direction or suggestions will be greatly appreciated.

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  • Drop down menu like the default iPad application menus

    - by Ryan French
    Hi Everyone, I'm currently working on my first iOS application to run on the iPad, and I've come across a problem. I have been asked to implement menu's similar to the ones in the default applications such as when you click on the "Calendars" button in the top left of the calendars app. Only issue is, I cant seem to find a standard UI object that looks like these, with the arrow connecting the menu to the button etc. Is this a standard UI component that I should be able to use, or will I have to imitate them by creating a custom object? Thanks for any help.

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  • Image impending other elements in iphone app view!

    - by wayne
    Hi. If someone could help I have a view in my iphone app with an image, a label and a button. I have positioned the image at the back however when I run the simulator the image is all that is showing. I have done exactly the same thing with other views and they work fine but can't get this one to work. I have checked that the image is "send to back" and other elements are at the front. Still no good. Any advice would be much appreciated. Thanks

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  • Make network changes permanent - C++

    - by pparescasellas
    I need to allow an external client to change the IP of the Linux machine where the program is running (C++). I already know how to list all the local interfaces and the current IPs assigned to them. I also know how to programatically change said IPs. What I need to know is how to make this change permanent so, if the machine reboots, it keeps the same network configuration. What's the best way to do this? Manually parsing /etc/network/interfaces? Calling some linux command? Edit: I'm using Debian. Thanks!

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  • C/C++ opaque pointer library

    - by aaa
    hello Is there library/header already written to manage C++ objects from C using opaque pointers/handles? I can write one myself, but I would rather use already made solution, especially if it has fortran bindings. Thanks

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  • Is it wrong for a context (right click) menu be the only way a user can perform a certain task?

    - by Eric
    I'd like to know if it ever makes sense to provide some functionality in a piece of software that is only available to the user through a context (right click) menu. It seems that in most software I've worked with the right click menu is always used as a quick way to get to features that are otherwise available from other buttons or menus. Below is a screen shot of the UI I'm developing. The tree view on the right shows the user's library of catalogs. Users can create new catalogs, or add and remove existing catalogs to and from their library. Catalogs in their library can then be opened or closed, or set to read-only. The screen shot shows the context menu I've created for the browser. Some commands can be executed independently from any specific catalog (New, Add). Yet the other commands must be applied to a specifically selected catalog (Close, Open, Remove, ReadOnly, Refresh, Clean UP, Rename). Currently the "Catalog" menu at the top of the window looks identical to this context menu. Yet I think this may be confusing to the users as the tree view which shows the currently selected catalog may not always be visible. The user may have switched to the Search or Filters tab, or the left pane may be hidden entirely. However, I'm hesitant to change the UI so that the commands that depends on a specifically selected catalog are only available through the context menu.

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  • Does it make sense to test ui components seperately?

    - by Bless Yahu
    I'm working on a webform that has about 15 user controls, separated by context (comments, locations, members/leaders, etc).   If each control can render individually (using real or test data), does it make sense to have a seperate "functional" test page to test them in isolation or is there a better way?

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  • Show progress without using an image

    - by Jon1
    I would like to design a progress bar, without using an image (eg animated gif...). Can this be done with just html css and jquery? trying to be creative here :) Update: the progress percentage cannot be determined, so it has to be a loop

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  • setContentView taking long time (10-15 seconds) to execute

    - by Paul
    I have a large activity that contains 100 or more buttons. But it's working fine once loaded. Problem however is loading. From clicking its launch icon to getting the first view it takes 10-12 seconds. Until the first view, it shows gray title bar in black background. At least, I want to show a simple progress bar or dialog while its loading. But it seems like you cannot show anything before setContentView executed. I think I have tried everything I could without any success. If you can give me any hint or idea, I would be thankful. UPDATE: I found a dramatic resolution. It takes now a second to load the view. I didn't use splash, thread or async task at all - BTW, don't try to use thread or async on UI because Android UI is not thread-safe. Problem was that those buttons were based on a custom class that requires initialization to load same resource. - so 100 or more file operations were happening on setContentView. Making them a just single loading solved my problem.

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  • @MustOverride annotation?

    - by Harrypotter2k5
    In .NET, one can specify a "mustoverride" attribute to a method in a particular superclass to ensure that subclasses override that particular method. I was wondering whether anybody has a custom java annotation that could achieve the same effect. Essentially what i want is to push for subclasses to override a method in a superclass that itself has some logic that must be run-through. I dont want to use abstract methods or interfaces, because i want some common functionality to be run in the super method, but more-or-less produce a compiler warning/error denoting that derivative classes should override a given method.

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  • Why is it possible to have an interface without a return type in PHP?

    - by streetparade
    Why is it possible to create an interface without specifying a return type? Why doesn't this make this interface unusable? This makes it more Clear: Interface run { public function getInteger(); } class MyString implements run { public function myNumber() { } public function getInteger() { return "Not a number"; } } In Java every Interface has a return type like Integer, String or Void I know that PHP is unfortunately a loosely typed Language but isn't there a Solution to that Problem? Is it possible to define an Interface with a return type like Integer?

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  • Resized XIB still full size

    - by James
    Building an iPad app. I have a button on my main view that I want to launch a help window. The help window is fairly involved and has its own xib/controller. I resized the help window's XIB and saved it. I instantiated it and added it to the application controller's views as a modal. For some reason this window is still taking up the entire screen. What I really want to do is have a "view" that's maybe 70% of the width and height that lays over the normal view as a modal. How is this accomplished normally? I want it to require that they hit a button to close it. Thanks

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  • ASA 5505 Vlan question

    - by Wayne
    I am setting up a cisco asa 5505 with the base license. I can communicate from inside-outside, outside-inside, inside-home, which is my desired traffic security. I can get http, ssh, and other access from inside-home, but I can't ping from inside-home (192.168.110.0 host to 192.168.7.1 or 192.168.7.0 host). Can someone explain. My config is listed below interface Vlan1<br> nameif inside<br> security-level 100<br> ip address 192.168.110.254 255.255.255.0 <br> !<br> interface Vlan2<br> nameif outside<br> security-level 0<br> pppoe client vpdn group birdie<br> ip address removedIP 255.255.255.255 pppoe <br> !<br> interface Vlan3<br> no forward interface Vlan1<br> nameif home<br> security-level 50<br> ip address 192.168.7.1 255.255.255.0 <br> ! <br> interface Ethernet0/0<br> switchport access vlan 2<br> ! <br> interface Ethernet0/1<br> ! <br> interface Ethernet0/2<br> ! <br> interface Ethernet0/3<br> ! <br> interface Ethernet0/4<br> switchport access vlan 3<br> ! <br> interface Ethernet0/5<br> shutdown <br> ! <br> interface Ethernet0/6<br> shutdown <br> ! <br> interface Ethernet0/7<br> shutdown <br> ! <br> ftp mode passive<br> clock timezone EST -5<br> clock summer-time EDT recurring<br> access-list Outside-In extended permit icmp any any <br> access-list Outside-In extended permit tcp any any eq www <br> access-list Outside-In extended permit tcp any any eq https <br> access-list Outside-In extended permit tcp any any eq 5969 <br> access-list inside_nat0_outbound extended permit ip any 192.168.111.0 255.255.255.224 <br> access-list standardUser_splitTunnelAcl1 extended permit ip 192.168.111.0 255.255.255.0 any <br> access-list standardUser_splitTunnelAcl1 extended permit ip 192.168.110.0 255.255.255.0 <br>any access-list inside_in extended permit icmp any any <br> access-list inside_in extended permit ip any any <br> access-list home_in extended permit icmp any any <br> access-list home_in extended permit ip any any <br> pager lines 24<br> logging enable<br> logging asdm informational<br> mtu inside 1492<br> mtu outside 1492<br> mtu home 1500 <br> ip local pool vpnuser 192.168.111.5-192.168.111.20<br> icmp unreachable rate-limit 1 burst-size 1<br> asdm image disk0:/asdm-524.bin<br> no asdm history enable<br> arp timeout 14400<br> nat-control <br> global (outside) 1 interface<br> nat (inside) 0 access-list inside_nat0_outbound<br> nat (inside) 1 0.0.0.0 0.0.0.0<br> nat (home) 1 192.168.7.0 255.255.255.0<br> static (inside,outside) tcp interface https 192.168.110.6 https netmask 255.255.255.255 <br> static (inside,outside) tcp interface www 192.168.110.6 www netmask 255.255.255.255 <br> static (inside,outside) tcp interface 5969 192.168.110.12 5969 netmask 255.255.255.255 <br> static (inside,home) 192.168.110.0 192.168.110.0 netmask 255.255.255.0 <br> access-group inside_in in interface inside<br> access-group Outside-In in interface outside<br> access-group home_in in interface home<br> route outside 0.0.0.0 0.0.0.0 RemovedIP 1<br>

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  • There is no web named - Sharepoint Event Hander

    - by Roosh Malai
    I activated following code with feature (web level scope). Now when i add an item to any document library it should create a folder "". No folder is created and no error is given either. can anyone see what's is going on? I got the following from the log file. I found similar code all over google so I am kinda puzzled why is not working in my environment. Thanks using System; using System.Collections.Generic; using System.Text; using Microsoft.SharePoint; namespace AddaFolder { class clAddaFolder : SPItemEventReceiver { public override void ItemAdded(SPItemEventProperties properties) { base.ItemAdded(properties); using (SPSite currentSite = new SPSite(SPContext.Current.Site.Url)) using (SPWeb currentWeb = currentSite.OpenWeb(SPContext.Current.Web.Url)) { try { //SPListTemplateCollection coll = currentWeb.ListTemplates; //Get the current document library link SPList newList = currentWeb.GetList(SPContext.Current.Web.Url); //.Site.Url); //newList = currentWeb.Lists.Add("My TEST Folder",SPFileSystemObjectType.Folder); //newList.Lists.Items.Add("My TEST Folder", SPFileSystemObjectType.Folder); //newList.Update(); SPListItem newListItem; //newListItem = newList.Folders.Add("", SPFileSystemObjectType.Folder, "My Test Folder"); newListItem = newList.Folders.Add(newList.ToString(), SPFileSystemObjectType.Folder, "My Test Folder"); newListItem.Update(); } catch (SPException spEx) { throw spEx; } } } } } 04/03/2010 17:52:44.25 w3wp.exe (0x00C0) 0x0C88 Windows SharePoint Services General 8kh7 High There is no Web named "/sites/myDevSiteColl/myDevWeb/Shared Documents/Forms/AllItems.aspx". 04/03/2010 17:52:44.26 w3wp.exe (0x00C0) 0x0C88 Windows SharePoint Services General 8kh7 High There is no Web named "/sites/myDevSiteColl/myDevWeb/My TEST Doc Library/Forms/AllItems.aspx". 04/03/2010 17:52:44.27 w3wp.exe (0x00C0) 0x0C88 Windows SharePoint Services General 8kh7 High There is no Web named "/sites/myDevSiteColl/myDevWeb/Lists/Calendar/calendar.aspx". 04/03/2010 17:52:44.29 w3wp.exe (0x00C0) 0x0C88 Windows SharePoint Services General 8kh7 High There is no Web named "/sites/myDevSiteColl/myDevWeb/Lists/Tasks/AllItems.aspx". 04/03/2010 17:52:44.30 w3wp.exe (0x00C0) 0x0C88 Windows SharePoint Services General 8kh7 High There is no Web named "/sites/myDevSiteColl/myDevWeb/Lists/Team Discussion/AllItems.aspx". 04/03/2010 17:52:44.31 w3wp.exe (0x00C0) 0x0C88 Windows SharePoint Services General 8kh7 High There is no Web named "/sites/myDevSiteColl/myDevWeb/Shared Documents/Forms/AllItems.aspx". 04/03/2010 17:52:44.32 w3wp.exe (0x00C0) 0x0C88 Windows SharePoint Services General 8kh7 High There is no Web named "/sites/myDevSiteColl/myDevWeb/My TEST Doc Library/Forms/AllItems.aspx". 04/03/2010 17:52:44.34 w3wp.exe (0x00C0) 0x0C88 Windows SharePoint Services General 8kh7 High There is no Web named "/sites/myDevSiteColl/myDevWeb/Lists/Calendar/calendar.aspx". 04/03/2010 17:52:44.35 w3wp.exe (0x00C0) 0x0C88 Windows SharePoint Services General 8kh7 High There is no Web named "/sites/myDevSiteColl/myDevWeb/Lists/Tasks/AllItems.aspx". 04/03/2010 17:52:44.36 w3wp.exe (0x00C0) 0x0C88 Windows SharePoint Services General 8kh7 High There is no Web named "/sites/myDevSiteColl/myDevWeb/Lists/Team Discussion/AllItems.aspx". 04/03/2010 17:52:51.33 w3wp.exe (0x00C0) 0x0C88 Windows SharePoint Services General 8kh7 High There is no Web named "/sites/myDevSiteColl/myDevWeb/Shared Documents/Forms/AllItems.aspx". 04/03/2010 17:52:51.34 w3wp.exe (0x00C0) 0x0C88 Windows SharePoint Services General 8kh7 High There is no Web named "/sites/myDevSiteColl/myDevWeb/My TEST Doc Library/Forms/AllItems.aspx". 04/03/2010 17:52:51.35 w3wp.exe (0x00C0) 0x0C88 Windows SharePoint Services General 8kh7 High There is no Web named "/sites/myDevSiteColl/myDevWeb/Lists/Calendar/calendar.aspx". 04/03/2010 17:52:51.37 w3wp.exe (0x00C0) 0x0C88 Windows SharePoint Services General 8kh7 High There is no Web named "/sites/myDevSiteColl/myDevWeb/Lists/Tasks/AllItems.aspx". 04/03/2010 17:52:51.38 w3wp.exe (0x00C0) 0x0C88 Windows SharePoint Services General 8kh7 High There is no Web named "/sites/myDevSiteColl/myDevWeb/Lists/Team Discussion/AllItems.aspx". 04/03/2010 17:52:51.39 w3wp.exe (0x00C0) 0x0C88 Windows SharePoint Services General 8kh7 High There is no Web named "/sites/myDevSiteColl/myDevWeb/Shared Documents/Forms/AllItems.aspx". 04/03/2010 17:52:51.40 w3wp.exe (0x00C0) 0x0C88 Windows SharePoint Services General 8kh7 High There is no Web named "/sites/myDevSiteColl/myDevWeb/My TEST Doc Library/Forms/AllItems.aspx". 04/03/2010 17:52:51.41 w3wp.exe (0x00C0) 0x0C88 Windows SharePoint Services General 8kh7 High There is no Web named "/sites/myDevSiteColl/myDevWeb/Lists/Calendar/calendar.aspx". 04/03/2010 17:52:51.43 w3wp.exe (0x00C0) 0x0C88 Windows SharePoint Services General 8kh7 High There is no Web named "/sites/myDevSiteColl/myDevWeb/Lists/Tasks/AllItems.aspx". 04/03/2010 17:52:51.44 w3wp.exe (0x00C0) 0x0C88 Windows SharePoint Services General 8kh7 High There is no Web named "/sites/myDevSiteColl/myDevWeb/Lists/Team Discussion/AllItems.aspx". 04/03/2010 17:53:02.69 w3wp.exe (0x00C0) 0x0C88 Windows SharePoint Services General 8kh7 High There is no Web named "/sites/myDevSiteColl/myDevWeb/Shared Documents/Forms/AllItems.aspx". 04/03/2010 17:53:02.71 w3wp.exe (0x00C0) 0x0C88 Windows SharePoint Services General 8kh7 High There is no Web named "/sites/myDevSiteColl/myDevWeb/My TEST Doc Library/Forms/AllItems.aspx". 04/03/2010 17:53:02.72 w3wp.exe (0x00C0) 0x0C88 Windows SharePoint Services General 8kh7 High There is no Web named "/sites/myDevSiteColl/myDevWeb/Lists/Calendar/calendar.aspx". 04/03/2010 17:53:02.73 w3wp.exe (0x00C0) 0x0C88 Windows SharePoint Services General 8kh7 High There is no Web named "/sites/myDevSiteColl/myDevWeb/Lists/Tasks/AllItems.aspx". 04/03/2010 17:53:02.74 w3wp.exe (0x00C0) 0x0C88 Windows SharePoint Services General 8kh7 High There is no Web named "/sites/myDevSiteColl/myDevWeb/Lists/Team Discussion/AllItems.aspx". 04/03/2010 17:53:02.75 w3wp.exe (0x00C0) 0x0C88 Windows SharePoint Services General 8kh7 High There is no Web named "/sites/myDevSiteColl/myDevWeb/Shared Documents/Forms/AllItems.aspx". 04/03/2010 17:53:02.76 w3wp.exe (0x00C0) 0x0C88 Windows SharePoint Services General 8kh7 High There is no Web named "/sites/myDevSiteColl/myDevWeb/My TEST Doc Library/Forms/AllItems.aspx". 04/03/2010 17:53:02.77 w3wp.exe (0x00C0) 0x0C88 Windows SharePoint Services General 8kh7 High There is no Web named "/sites/myDevSiteColl/myDevWeb/Lists/Calendar/calendar.aspx". 04/03/2010 17:53:02.78 w3wp.exe (0x00C0) 0x0C88 Windows SharePoint Services General 8kh7 High There is no Web named "/sites/myDevSiteColl/myDevWeb/Lists/Tasks/AllItems.aspx". 04/03/2010 17:53:02.79 w3wp.exe (0x00C0) 0x0C88 Windows SharePoint Services General 8kh7 High There is no Web named "/sites/myDevSiteColl/myDevWeb/Lists/Team Discussion/AllItems.aspx".

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  • NSFileManager - Copying Files at Startup

    - by David Schiefer
    Hi, I need to copy a few sample files from my app's resource folder and place them in my app's document folder. I came up with the attached code, it compiles fine but it doesn't work. All the directories I refer to do exist. I'm not quite sure what I am doing wrong, could someone point me in the right direction please? NSFileManager*manager = [NSFileManager defaultManager]; NSString*dirToCopyTo = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents"]; NSString*path = [[NSBundle mainBundle] resourcePath]; NSString*dirToCopyFrom = [path stringByAppendingPathComponent:@"Samples"]; NSError*error; NSArray*files = [manager contentsOfDirectoryAtPath:dirToCopyTo error:nil]; for (NSString *file in files) { [manager copyItemAtPath:[dirToCopyFrom stringByAppendingPathComponent:file] toPath:dirToCopyTo error:&error]; if (error) { NSLog(@"%@",[error localizedDescription]); } }

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  • Sharepoint and encryption

    - by YeomansLeo
    I'm currently setting up WSS 3.0 at my work, and I'm in the finance section of it. My question is, is there a possibility to encrypt and decrypt lists? And I mean entire lists, because the document libraries will have different types of files in it, from Word to Invoices in InfoPath. I know there is a solution in CodePlex called CryptoCollaboration, but whenever I deploy the solution in SharePoint I get a server error. Any alternatives? Or maybe you could fix the codeplex solution, that would be great! Thanks in advance!

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  • iPhone - how to store documents consisting of multiple images?

    - by Joe Strout
    My iPhone (actually, iPad) app creates documents that consist of several images, plus a bit of metadata. What's the best practice for storing these sorts of documents on disk? I see two main options: Create a folder for each document, and store my images as separate PNG files within the folder (plus another little file for the metadata). Create a single file which contains all images and metadata. But I'm not sure how to easily do option 2. I think I can convert my images in PNG format to/from NSData, but then what? I'm still a newbie at Cocoa, but I believe I saw something about stuffing mixed data into some NSSomethingOrOther and having this write itself out to disk, and read itself back in later. Does this ring a bell with anyone? And, will it work with large binary blobs of data like my images? Or would you recommend I simply go with option 1?

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  • Is there a way to disable the hardware on/off switch for the Wireless interface?

    - by avee
    I have an HP 520 and is running the latest Ubuntu 11.10. The hardware works fine with Ubuntu with one exception: The device has a hardware switch for turning the wifi on and off. Every time the wi-fi is disabled through the hardware switch, I am unable to bring it on again. The message on the networking popup would be device not ready. What I am looking for is a way to disable the hardware switch altogether so that when users accidentally press the button, the wifi would not be disabled. There is no setting to disable the switch in the BIOS. Hardware info from lspci -nn: 00:00.0 Host bridge [0600]: Intel Corporation Mobile 945GME Express Memory Controller Hub [8086:27ac] (rev 03) 00:02.0 VGA compatible controller [0300]: Intel Corporation Mobile 945GME Express Integrated Graphics Controller [8086:27ae] (rev 03) 00:02.1 Display controller [0380]: Intel Corporation Mobile 945GM/GMS/GME, 943/940GML Express Integrated Graphics Controller [8086:27a6] (rev 03) 00:1b.0 Audio device [0403]: Intel Corporation N10/ICH 7 Family High Definition Audio Controller [8086:27d8] (rev 01) 00:1c.0 PCI bridge [0604]: Intel Corporation N10/ICH 7 Family PCI Express Port 1 [8086:27d0] (rev 01) 00:1c.1 PCI bridge [0604]: Intel Corporation N10/ICH 7 Family PCI Express Port 2 [8086:27d2] (rev 01) 00:1d.0 USB Controller [0c03]: Intel Corporation N10/ICH 7 Family USB UHCI Controller #1 [8086:27c8] (rev 01) 00:1d.7 USB Controller [0c03]: Intel Corporation N10/ICH 7 Family USB2 EHCI Controller [8086:27cc] (rev 01) 00:1e.0 PCI bridge [0604]: Intel Corporation 82801 Mobile PCI Bridge [8086:2448] (rev e1) 00:1f.0 ISA bridge [0601]: Intel Corporation 82801GBM (ICH7-M) LPC Interface Bridge [8086:27b9] (rev 01) 00:1f.2 IDE interface [0101]: Intel Corporation 82801GBM/GHM (ICH7 Family) SATA IDE Controller [8086:27c4] (rev 01) 02:06.0 CardBus bridge [0607]: ENE Technology Inc CB1410 Cardbus Controller [1524:1410] (rev 01) 02:08.0 Ethernet controller [0200]: Intel Corporation 82562ET/EZ/GT/GZ - PRO/100 VE (LOM) Ethernet Controller Mobile [8086:1068] (rev 01) 10:00.0 Network controller [0280]: Intel Corporation PRO/Wireless 3945ABG [Golan] Network Connection [8086:4222] (rev 02) The output from lsmod | grep iwl: iwl3945 73329 0 iwl_legacy 71499 1 iwl3945 mac80211 272785 2 iwl3945,iwl_legacy cfg80211 172392 3 iwl3945,iwl_legacy,mac80211

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  • C#: Handling Notifications: inheritance, events, or delegates?

    - by James Michael Hare
    Often times as developers we have to design a class where we get notification when certain things happen. In older object-oriented code this would often be implemented by overriding methods -- with events, delegates, and interfaces, however, we have far more elegant options. So, when should you use each of these methods and what are their strengths and weaknesses? Now, for the purposes of this article when I say notification, I'm just talking about ways for a class to let a user know that something has occurred. This can be through any programmatic means such as inheritance, events, delegates, etc. So let's build some context. I'm sitting here thinking about a provider neutral messaging layer for the place I work, and I got to the point where I needed to design the message subscriber which will receive messages from the message bus. Basically, what we want is to be able to create a message listener and have it be called whenever a new message arrives. Now, back before the flood we would have done this via inheritance and an abstract class: 1:  2: // using inheritance - omitting argument null checks and halt logic 3: public abstract class MessageListener 4: { 5: private ISubscriber _subscriber; 6: private bool _isHalted = false; 7: private Thread _messageThread; 8:  9: // assign the subscriber and start the messaging loop 10: public MessageListener(ISubscriber subscriber) 11: { 12: _subscriber = subscriber; 13: _messageThread = new Thread(MessageLoop); 14: _messageThread.Start(); 15: } 16:  17: // user will override this to process their messages 18: protected abstract void OnMessageReceived(Message msg); 19:  20: // handle the looping in the thread 21: private void MessageLoop() 22: { 23: while(!_isHalted) 24: { 25: // as long as processing, wait 1 second for message 26: Message msg = _subscriber.Receive(TimeSpan.FromSeconds(1)); 27: if(msg != null) 28: { 29: OnMessageReceived(msg); 30: } 31: } 32: } 33: ... 34: } It seems so odd to write this kind of code now. Does it feel odd to you? Maybe it's just because I've gotten so used to delegation that I really don't like the feel of this. To me it is akin to saying that if I want to drive my car I need to derive a new instance of it just to put myself in the driver's seat. And yet, unquestionably, five years ago I would have probably written the code as you see above. To me, inheritance is a flawed approach for notifications due to several reasons: Inheritance is one of the HIGHEST forms of coupling. You can't seal the listener class because it depends on sub-classing to work. Because C# does not allow multiple-inheritance, I've spent my one inheritance implementing this class. Every time you need to listen to a bus, you have to derive a class which leads to lots of trivial sub-classes. The act of consuming a message should be a separate responsibility than the act of listening for a message (SRP). Inheritance is such a strong statement (this IS-A that) that it should only be used in building type hierarchies and not for overriding use-specific behaviors and notifications. Chances are, if a class needs to be inherited to be used, it most likely is not designed as well as it could be in today's modern programming languages. So lets look at the other tools available to us for getting notified instead. Here's a few other choices to consider. Have the listener expose a MessageReceived event. Have the listener accept a new IMessageHandler interface instance. Have the listener accept an Action<Message> delegate. Really, all of these are different forms of delegation. Now, .NET events are a bit heavier than the other types of delegates in terms of run-time execution, but they are a great way to allow others using your class to subscribe to your events: 1: // using event - ommiting argument null checks and halt logic 2: public sealed class MessageListener 3: { 4: private ISubscriber _subscriber; 5: private bool _isHalted = false; 6: private Thread _messageThread; 7:  8: // assign the subscriber and start the messaging loop 9: public MessageListener(ISubscriber subscriber) 10: { 11: _subscriber = subscriber; 12: _messageThread = new Thread(MessageLoop); 13: _messageThread.Start(); 14: } 15:  16: // user will override this to process their messages 17: public event Action<Message> MessageReceived; 18:  19: // handle the looping in the thread 20: private void MessageLoop() 21: { 22: while(!_isHalted) 23: { 24: // as long as processing, wait 1 second for message 25: Message msg = _subscriber.Receive(TimeSpan.FromSeconds(1)); 26: if(msg != null && MessageReceived != null) 27: { 28: MessageReceived(msg); 29: } 30: } 31: } 32: } Note, now we can seal the class to avoid changes and the user just needs to provide a message handling method: 1: theListener.MessageReceived += CustomReceiveMethod; However, personally I don't think events hold up as well in this case because events are largely optional. To me, what is the point of a listener if you create one with no event listeners? So in my mind, use events when handling the notification is optional. So how about the delegation via interface? I personally like this method quite a bit. Basically what it does is similar to inheritance method mentioned first, but better because it makes it easy to split the part of the class that doesn't change (the base listener behavior) from the part that does change (the user-specified action after receiving a message). So assuming we had an interface like: 1: public interface IMessageHandler 2: { 3: void OnMessageReceived(Message receivedMessage); 4: } Our listener would look like this: 1: // using delegation via interface - omitting argument null checks and halt logic 2: public sealed class MessageListener 3: { 4: private ISubscriber _subscriber; 5: private IMessageHandler _handler; 6: private bool _isHalted = false; 7: private Thread _messageThread; 8:  9: // assign the subscriber and start the messaging loop 10: public MessageListener(ISubscriber subscriber, IMessageHandler handler) 11: { 12: _subscriber = subscriber; 13: _handler = handler; 14: _messageThread = new Thread(MessageLoop); 15: _messageThread.Start(); 16: } 17:  18: // handle the looping in the thread 19: private void MessageLoop() 20: { 21: while(!_isHalted) 22: { 23: // as long as processing, wait 1 second for message 24: Message msg = _subscriber.Receive(TimeSpan.FromSeconds(1)); 25: if(msg != null) 26: { 27: _handler.OnMessageReceived(msg); 28: } 29: } 30: } 31: } And they would call it by creating a class that implements IMessageHandler and pass that instance into the constructor of the listener. I like that this alleviates the issues of inheritance and essentially forces you to provide a handler (as opposed to events) on construction. Well, this is good, but personally I think we could go one step further. While I like this better than events or inheritance, it still forces you to implement a specific method name. What if that name collides? Furthermore if you have lots of these you end up either with large classes inheriting multiple interfaces to implement one method, or lots of small classes. Also, if you had one class that wanted to manage messages from two different subscribers differently, it wouldn't be able to because the interface can't be overloaded. This brings me to using delegates directly. In general, every time I think about creating an interface for something, and if that interface contains only one method, I start thinking a delegate is a better approach. Now, that said delegates don't accomplish everything an interface can. Obviously having the interface allows you to refer to the classes that implement the interface which can be very handy. In this case, though, really all you want is a method to handle the messages. So let's look at a method delegate: 1: // using delegation via delegate - omitting argument null checks and halt logic 2: public sealed class MessageListener 3: { 4: private ISubscriber _subscriber; 5: private Action<Message> _handler; 6: private bool _isHalted = false; 7: private Thread _messageThread; 8:  9: // assign the subscriber and start the messaging loop 10: public MessageListener(ISubscriber subscriber, Action<Message> handler) 11: { 12: _subscriber = subscriber; 13: _handler = handler; 14: _messageThread = new Thread(MessageLoop); 15: _messageThread.Start(); 16: } 17:  18: // handle the looping in the thread 19: private void MessageLoop() 20: { 21: while(!_isHalted) 22: { 23: // as long as processing, wait 1 second for message 24: Message msg = _subscriber.Receive(TimeSpan.FromSeconds(1)); 25: if(msg != null) 26: { 27: _handler(msg); 28: } 29: } 30: } 31: } Here the MessageListener now takes an Action<Message>.  For those of you unfamiliar with the pre-defined delegate types in .NET, that is a method with the signature: void SomeMethodName(Message). The great thing about delegates is it gives you a lot of power. You could create an anonymous delegate, a lambda, or specify any other method as long as it satisfies the Action<Message> signature. This way, you don't need to define an arbitrary helper class or name the method a specific thing. Incidentally, we could combine both the interface and delegate approach to allow maximum flexibility. Doing this, the user could either pass in a delegate, or specify a delegate interface: 1: // using delegation - give users choice of interface or delegate 2: public sealed class MessageListener 3: { 4: private ISubscriber _subscriber; 5: private Action<Message> _handler; 6: private bool _isHalted = false; 7: private Thread _messageThread; 8:  9: // assign the subscriber and start the messaging loop 10: public MessageListener(ISubscriber subscriber, Action<Message> handler) 11: { 12: _subscriber = subscriber; 13: _handler = handler; 14: _messageThread = new Thread(MessageLoop); 15: _messageThread.Start(); 16: } 17:  18: // passes the interface method as a delegate using method group 19: public MessageListener(ISubscriber subscriber, IMessageHandler handler) 20: : this(subscriber, handler.OnMessageReceived) 21: { 22: } 23:  24: // handle the looping in the thread 25: private void MessageLoop() 26: { 27: while(!_isHalted) 28: { 29: // as long as processing, wait 1 second for message 30: Message msg = _subscriber.Receive(TimeSpan.FromSeconds(1)); 31: if(msg != null) 32: { 33: _handler(msg); 34: } 35: } 36: } 37: } } This is the method I tend to prefer because it allows the user of the class to choose which method works best for them. You may be curious about the actual performance of these different methods. 1: Enter iterations: 2: 1000000 3:  4: Inheritance took 4 ms. 5: Events took 7 ms. 6: Interface delegation took 4 ms. 7: Lambda delegate took 5 ms. Before you get too caught up in the numbers, however, keep in mind that this is performance over over 1,000,000 iterations. Since they are all < 10 ms which boils down to fractions of a micro-second per iteration so really any of them are a fine choice performance wise. As such, I think the choice of what to do really boils down to what you're trying to do. Here's my guidelines: Inheritance should be used only when defining a collection of related types with implementation specific behaviors, it should not be used as a hook for users to add their own functionality. Events should be used when subscription is optional or multi-cast is desired. Interface delegation should be used when you wish to refer to implementing classes by the interface type or if the type requires several methods to be implemented. Delegate method delegation should be used when you only need to provide one method and do not need to refer to implementers by the interface name.

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