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• How to create dynamic textfield based on radio button's input

  - by qdog

  I am trying to get a form's textfield to dynamically appear based on a radio checkbox selection. For example, on my form...there is a radio button that ask "Do you want to enter your age?" with an option to check YES or NO. If the user check YES, a textfield dynamically appear after this so the the user can enter his or her age. If user check NO, then nothing happen. How do I begin to do something like this? Just looking for any feedback I can get. Thanks!

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• DrawString only works in top-left part of form vb.net

  - by WillumMaguire

  Here is my code Public Class Form1 Public MyFormObject As Graphics = Me.CreateGraphics Public objFont = New System.Drawing.Font("arial", 20) Public a, b As Integer Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click Randomize() For i = 1 To 10 a = CInt(Int(Rnd() * Me.Width)) b = CInt(Int(Rnd() * Me.Height)) MyFormObject.DrawString("text", objFont, System.Drawing.Brushes.Black, a, b) Next End Sub End Class As you can see, I have one button that draws the string "text" randomly in the form 10 times. My problem is that it will ONLY draw the string in the upper-left portion of the form, roughly 260x260 starting at 0,0. It literally cuts off the text if it goes beyond. Why is this? Shouldn't it work for the entire form?

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• .NET platform independant sync framework

  - by Quandary

  Question: I need to synchronize a few ActionScript files from my computer to a network share (backup). I saw a quick fix would be using Microsoft Sync Framework for this, and write a windows service. My problem is I also use Linux, and before I start with MS vendor lockin, is there any sync framework/library/whatever I could use that works accross platform? Or does the MS sync framework work on Linux, too? It is my understanding that it is a wrapper around some com objects, thus it wouldn't work. All I need is synchronizing files. So never mind the database part, although it would be nice to have it, too.

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• How to build a dynamic resize-able Flash player

  - by Leon

  Morning stackers! So my question today isn't dealing with any code, but how to go about this the correct way from the start. I have a video player built to a static size (max: 800x600) which I'll have to re-code every time I need it to be a different size. What I need it to do in the near future is dynamically resize itself and all the elements inside of it based on 1 width variable that it will received either from HTML or XML. Now to me there are 2 ways to go about this: Start with the smallest size possible and resize upwards, but I'm unsure of how the Flash movie will actually expand upwards as of right now. Or 2, start with the largest size possible (in this case 800x600) and size everything down. Step 1, I think seems to be the better way to go about this (ala YouTube style), but Step 2 also seems like it could be the easier way? A friend of mine mentioned that I should go with the larger size and have elements resize in each class, then fix to the upper left hand corner. However for the player to fit inside of certain div columns on sites, blogs whatever he said that there will have to be an HTML/CSS side of this... meaning that the div containing the resized flash player will have to cover up the areas of the Flash movie that are not to be shown? Is that possible to put a 800x600 flash movie into a div that smaller then 800 pixels wide? And cover it up with another div? Anyways, my mission is to be able to have a dynamically sized player like this: Thoughts? Recommendations? Best practices for this before I start?

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• VB.net save opened word document!

  - by comii

  Hi! I just trying to made word add-ins that gone save opened document.I made ribbon and button on it.Below is the that i use for saving word document on certain location: Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As Microsoft.Office.Tools.Ribbon.RibbonControlEventArgs) Handles Button1.Click Dim ThisApplication As Word.Application ThisApplication.ActiveDocument.SaveAs("C:\email") ThisApplication.Quit() ThisApplication= Nothing End Sub But when i click on this button i just made email.doc but that document does not contain any content of the opened document, it just made new doc file. What i am doing wrong? The event on this button need to just same as event on standard Word save button, so how i can do this?

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• How to generate <a> tag from input fields

  - by NonProgrammer

  Using ASP.Net (in C#), I need to generate a tag that contains person's name, address, etc. I have barely any experience with ASP.NET (or .NET languages) and I am given this assignment. Could someone please guide me to correct path please? Link should look like this: https://example.com/PRR/Info/Login.aspx?SupplierId=36&RegisteredUserLogin=T000001&Mode=RegisteredLoginless&RegisteredModeFunction=AutoShowTotals&RegisteredModeFunction=AutoShowTotals&PayerCountry=FI&[email protected]&ExternalOrderId=1000123&ServiceId=286&Amount286=5000.00&PayerInfo286=T000001|10000123|type1|m&SuccessReturnURL=http://success.html&FailureReturnURL=http://failure.html&SuccessCallbackURL=http://youpay.com/p247/success.html&FailureCallbackURL=http://yourfailure.html following components/fields needs to be sent to API in order to pre-populate information for users: FirstName, LastName, SupplierID = integer, Person's userlogin (Should increment by 1. Example: person 1 = t00001. Person2 = t00002, etc.), PayerCountry, Email, amount For some reason, my management thinks that this is something a non-technical person can do! Any help would be appreciated! Thanks!

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• Dynamic change .click value Jquery IE issue.

  - by user326100

  Hello guys.. it's i first time i'm asking here. Sorry if the answer is available already. I have a very small jQuery script that canges the paramether for onclick attr on a DIV. IT works like as right and left arrows for some content in the middle. BAsically i set the onclick="foo(1)" then when get clicked sld change the value 1 to 2, and keep changing everytime i click. on jQuery functio i'm using: $("#v_arrow_r").attr('onclick','').unbind().click(newclick_next); it works like a charm on FF and Chrome, but does not work on IE !!!! Argh... here the the code: if (start == 24) { var a = 0; var b = 0; } else { var a = start-6; var b = start+6; } next = "home_featured_videos(" + b + ");"; newclick_next = eval("(function(){"+next+"});"); prev = "home_featured_videos(" + a + ");"; newclick_prev = eval("(function(){"+prev+"});"); $('#video-module').css('background',''); $('#video-module').html(response); $("#v_arrow_l").attr('onclick','').unbind().click(newclick_prev); $("#v_arrow_r").attr('onclick','').unbind().click(newclick_next); The html: //CONTENT So like i said.. i define the attr onclick when page open. It work well on IE. but when i click the arrow and call the function the oncli is set to null and i add the function to .click. IE stop working. the click is dead. If anybody have idea why this is happening. Thanx in advance. Kind Regards Varois

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• How to use JQuery to remove dynamic content?

  - by ed.talmadge

  I have an html page that is generated by a CMS. I cannot modify the page, but can add JavaScript. Each time the page loads, a JavaScript function (that I cannot modify) dynamically inserts a paragraph onto the page. How can I use JQuery to .remove() that paragraph whenever it is loaded? For example, when the page first loads, it look like this (blank): <div></div> Then, a few seconds later, a JavaScript function (that I have no control over) adds a paragraph to the page. The page then looks like this: <div><p id="foo">bar</p></div> How can I use JQuery to remove the paragraph with id=foo each time it is dynamically loaded onto the page?

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• Making dynamic images have static filenames

  - by michaeltk

  My website currently has various links to a php script that generates the images dynamically. For example, the link may say "img source="/dynamic_images.php?type=pie-chart&color=red" Obviously, this is not great for SEO. I'd like to somehow make the filenames of these links appear to be static, and use a solution (like Mod-Rewrite) to ensure that the images can still be dynamically created. I suppose I could have something like "img src="average-profits-in-scuba-diving-industry.png?type=pie-chart&color=red" (and use Mod-Rewrite to take care of changing the filename prefix to dynamic_images.php), but I'm afraid that the search engines would shy away from the querystring on the end of the image filename. Any solutions? Thanks in advance.

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• .Net Linq - Doing a operation on the subset

  - by Melursus

  I need to have the following : (name1 + "a") + (name2 + "a") + ... Dim separator() As String = {"|"} myString.Split(separator, StringSplitOptions.None).SomeLinq(...) I don't know what to add at the end to add an "a" to each element...

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• Drupal Webform textfield dynamic growing list

  - by Bob Crowley

  Just curious... I have a project where people can input their cooking recipes. I would like to build a webform that will have a textfield and when it is filled in a new textfield appears below. A "growing textfield list". Let me try to show it here: Ingredient #1 _________________________________ [add] When you type and ingredient click "add" you then are going to see: Ingredient #1 Potatoes_________________________ Ingredient #2 _________________________________ [add] Sorry for not knowing the proper markup. However if anyone knows: a) the proper term for this ( I call a growing textfield list )? b) how to do it with webform in drupal?

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• How to bind a label inside a gridview to another table?

  - by Kolten

  I have a very standard Gridview, with Edit and Delete buttons auto-generated. It is bound to a tableadapter which is linked to my "RelationshipTypes" table. dbo.RelationshipTypes: ID, Name, OriginConfigTypeID, DestinationConfigTypeID I wish to use a label that will pull the name from the ConfigTypes table, using the "OriginConfigTypeID" and "DestinationTypeID" as the link. dbo.ConfigTypes: ID, Name My problem is, I can't automatically generate Edit and Delete buttons using an Inner Join in my dataset. Or can I? FOllowing is my code: <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" AutoGenerateDeleteButton="True" AutoGenerateEditButton="True" CssClass="TableList" DataKeyNames="ID" DataSourceID="dsRelationShipTypes1"> <Columns> <asp:BoundField DataField="ID" HeaderText="ID" InsertVisible="False" ReadOnly="True" SortExpression="ID" Visible=False/> <asp:TemplateField HeaderText="Origin" SortExpression="OriginCIType_ID"> <EditItemTemplate> &nbsp;<asp:DropDownList Enabled=true ID="DropDownList2" runat="server" DataSourceID="dsCIType1" DataTextField="Name" DataValueField="ID" SelectedValue='<%# Bind("OriginCIType_ID") %>'> </asp:DropDownList> </EditItemTemplate> <ItemTemplate> &nbsp; <asp:Label ID="Label2" runat="server" Text='<%# Bind("OriginCIType_ID") %>'></asp:Label> </ItemTemplate> </asp:TemplateField> <asp:TemplateField HeaderText="Name" SortExpression="Name"> <EditItemTemplate> <asp:TextBox ID="TextBox3" runat="server" Text='<%# Bind("Name") %>'></asp:TextBox> </EditItemTemplate> <ItemTemplate> <asp:Label ID="Label3" runat="server" Text='<%# Bind("Name") %>'></asp:Label> </ItemTemplate> </asp:TemplateField> <asp:TemplateField HeaderText="Destination" SortExpression="DestinationCIType_ID"> <EditItemTemplate> <asp:DropDownList ID="DropDownList3" runat="server" DataSourceID="dsCIType1" DataTextField="Name" DataValueField="ID" SelectedValue='<%# Bind("DestinationCIType_ID") %>'> </asp:DropDownList> </EditItemTemplate> <ItemTemplate> <asp:Label ID="Label1" runat="server" Text='<%# Bind("DestinationCIType_ID") %>'></asp:Label> </ItemTemplate> </asp:TemplateField> </Columns> </asp:GridView> So I did try to create my own edit and delete buttons, but kept receiving the error "cannot find update method" or something similar. Do I have to manually code the delete and update methods in my code-behind?

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• Problem using GDI+ with multiple threads (VB.NET)

  - by Joe B

  I think it would be best if I just copy and pasted the code (it's very trivial). Private Sub Main() Handles MyBase.Shown timer.Interval = 10 timer.Enabled = True End Sub Private Sub Form1_Paint(ByVal sender As System.Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles MyBase.Paint e.Graphics.DrawImage(image, 0, 0) End Sub Private Sub tick() Handles timer.Elapsed Using g = Graphics.FromImage(image) g.Clear(Color.Transparent) g.DrawLine(Pens.Red, 0 + i, 0 + i, Me.Width - i, Me.Height - i) End Using Me.Invalidate() End Sub An exception, "The object is currently in use elsewhere", is raised during the tick event. Could someone tell me why this happens and how to solve it? Thanks.

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• Dynamic columns in C# rdlc report

  - by Mugume David

  Suppose I have a report that lists employees (as rows) with their respective taxes charged (in columns). It is possible for a new tax to come up. Since my rdlc report file is currently designed (from XML of-course) to statically generate the coulumns. A future shift in events will need me to alter the rdlc file and add in a new column. how can i do this dynamically. I intend to avoid opening the rdlc file and adding XML code.

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• Rails - Dynamic name routes namespace

  - by Kuro

  Hi, Using Rails 2.3, I'm trying to configure my routes but I uncounter some difficulties. I would like to have something like : http:// mydomain.com/mycontroller/myaction/myid That should respond with controllers in :front namespace http:// mydomain.com/aname/mycontroller/myaction/mydi That should respond with controllers in :custom namespace I try something like this, but I'm totaly wrong : map.namespace :front, :path_prefix => "" do |f| f.root :controller => :home, :action => :index f.resources :home ... end map.namespace :custom, :path_prefix => "" do |m| m.root :controller => :home, :action => :index m.resources :home ... m.match ':sub_url/site/:controller/:action/:id' m.match ':sub_url/site/:controller/:action/:id' m.match ':sub_url/site/:controller/:action/:id.:format' m.match ':sub_url/site/:controller/:action.:format' end I put matching instruction in custom namespace but I'm not sure it's the right place for it. I think I really don't get the way to customize fields in url matching and I don't know how to find documentation about Rails 2.3, most of my research drove me to Rails 3 doc about the topic... Somebody to help me ?

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• ExtJS (4.0) dynamic / lazy loading

  - by Paul

  Given a border layout with a west (navigation) and a center region. Let say I click on topic A in the west region, I want to replace (replace as in 'delete last topic') the center region with 'extjs' program code named topic_a.js I succeed in loading with this code: dynamicPanel = new Ext.Component({ loader: { url: '/www/file.htm', renderer: 'html', autoLoad: true, scripts: true } }); var oMainContainer = Ext.getCmp('maincontainer'); oMainContainer.show(); oMainContainer.add(dynamicPanel); But calling this the second time 'adds' things up in the center region and of course fails short in 'deleting', what would be a good approach?

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• how to create a dynamic class at runtime in Java

  - by Mrityunjay

  hi, is it possible to create a new java file from existing java file after changing some of its attributes at runtime?? Suppose i have a java file pubic class Student{ private int rollNo; private String name; // getters and setters // constructor } is it possible to create something like this, provided that rollNo is key element for the table.. public class Student { private StudentKey key; private String name; //getters and setters //constructor } public class StudentKey { private int rollNo; // getters and setters // construcotors } please help..

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• Start Line with (New... in VB.net

  - by pedro_cesar

  Hello; Why can't I start a line using a parenthesis followed by the keyword new?? For example: (New <custom_obj>).foo(var) In that case is obvious that I'm trying to avoid creating a named instance of the the <custom_obj> because I know that I'll only be using it at that sentence. Note that actually creating a named instance is not a problem for me... I just wanna know the reason why this is not possible.

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• Multiple versions of .NET

  - by grawity

  In my WinXP box, I have these "programs" installed: Microsoft .NET Framework 1.1 Microsoft .NET Framework 2.0 SP2 Microsoft .NET Framework 3.0 SP2 Microsoft .NET Framework 3.5 SP1 Do I need all four versions? Can software compiled on .NET 1.1 run on a 3.5 runtime?

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• C++ dynamic array sizing problem

  - by Peter

  The basic pseudo code looks like this: void myFunction() { int size = 10; int * MyArray; MyArray = new int[size]; cout << size << endl; cout << sizeof(MyArray) << endl; } The first cout returns 10, as expected, while the second cout returns 4. Anyone have an explanation?

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• Dynamic SQL and Funtions

  - by Unlimited071

  Hi all, is there any way of accomplishing something like the following: CREATE FUNCTION GetQtyFromID ( @oricod varchar(15), @ccocod varchar(15), @ocmnum int, @oinnum int, @acmnum int, @acttip char(2), @unisim varchar(15) ) AS BEGIN DECLARE @Result decimal(18,8) DECLARE @SQLString nvarchar(max); DECLARE @ParmDefinition nvarchar(max); --I need to execute a query stored in a cell which returns the calculated qty. --i.e of AcuQry: select @cant = sum(smt) from table where oricod = @oricod and ... SELECT @SQLString = AcuQry FROM OinActUni WHERE (OriCod = @oricod) AND (ActTipCod = @acttip) AND (UniSim = @unisim) AND (AcuEst > 0) SET @ParmDefinition = N' @oricod varchar(15), @ccocod varchar(15), @ocmnum int, @oinnum int, @acmnum int, @cant decimal(18,8) output'; EXECUTE sp_executesql @SQLString, @ParmDefinition, @oricod = @oricod, @ccocod = @ccocod, @ocmnum = @ocmnum, @oinnum = @oinnum, @acmnum = @acmnum, @cant = @result OUTPUT; RETURN @Result END The problem with this approach is that it is prohibited to execute sp_excutesql in a function... What I need is to do something like: select id, getQtyFromID(id) as qty from table The main idea is to execute a query stored in a table cell, this is because the qty of something depends on it's unit. the unit can be days or it can be metric tons, so there is no relation between the units, therefore the need of a specific query for each unit.

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• Dynamic programming Approach- Knapsack Puzzle

  - by idalsin

  I'm trying to solve the Knapsack problem with the dynamical programming(DP) approach, with Python 3.x. My TA pointed us towards this code for a head start. I've tried to implement it, as below: def take_input(infile): f_open = open(infile, 'r') lines = [] for line in f_open: lines.append(line.strip()) f_open.close() return lines def create_list(jewel_lines): #turns the jewels into a list of lists jewels_list = [] for x in jewel_lines: weight = x.split()[0] value = x.split()[1] jewels_list.append((int(value), int(weight))) jewels_list = sorted(jewels_list, key = lambda x : (-x[0], x[1])) return jewels_list def dynamic_grab(items, max_weight): table = [[0 for weight in range(max_weight+1)] for j in range(len(items)+1)] for j in range(1,len(items)+1): val= items[j-1][0] wt= items[j-1][1] for weight in range(1, max_weight+1): if wt > weight: table[j][weight] = table[j-1][weight] else: table[j][weight] = max(table[j-1][weight],table[j-1][weight-wt] + val) result = [] weight = max_weight for j in range(len(items),0,-1): was_added = table[j][weight] != table[j-1][weight] if was_added: val = items[j-1][0] wt = items[j-1][1] result.append(items[j-1]) weight -= wt return result def totalvalue(comb): #total of a combo of items totwt = totval = 0 for val, wt in comb: totwt += wt totval += val return (totval, -totwt) if totwt <= max_weight else (0,0) #required setup of variables infile = "JT_test1.txt" given_input = take_input(infile) max_weight = int(given_input[0]) given_input.pop(0) jewels_list = create_list(given_input) #test lines print(jewels_list) print(greedy_grab(jewels_list, max_weight)) bagged = dynamic_grab(jewels_list, max_weight) print(totalvalue(bagged)) The sample case is below. It is in the format line[0] = bag_max, line[1:] is in form(weight, value): 575 125 3000 50 100 500 6000 25 30 I'm confused as to the logic of this code in that it returns me a tuple and I'm not sure what the output tuple represents. I've been looking at this for a while and just don't understand what the code is pointing me at. Any help would be appreciated.

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• Does LearnDevNow offers a useful subscription for .NET related training : with video and text reference material?

  - by user766926

  Does LearnDevNow offers a useful subscription for .NET video and text reference training material or to learn .NET? I could not find a review of www.learnnowonline.com/learndevnow I've been doing research about places that offer .NET / ASP.NET / C# / LINQ / SQL / JQuery video training that provide excellent material for developers. Kind of like a Lynda.com for back end development. However, I have not find one place that offers quality material that is easily accessible for the user, and that is priced competitive. This is what I'm looking for: Online Video tutorials with free future updates (videos that can be accessed on any device ie: android portable devices, mac / ipad, linux machines) Printable courseware (ie PDFs so that you can take notes, print if necessary, and read in a tablet in case you don;t have internet access) labs, and easy to access code Pre/Post Assessments/Exams for each training to keep track of your progress and what you have learned/skills. (Appdev used to offer this but it was way too expensive (thousands for each training ie 1k for each. I paid about five thousand at Appdev, and now I regret that purchase), and after a few years/months the training became obsolete - outdated) I looked at learnnowonline.com/learndevnow but it seems that their courseware / text reference material can only be accessed online, and don't know if their videos work in all mobile devices, and browsers (Safari, Chrome, IE, Opera, Firefox) Also, it seems Appdev not longer exist and now is called " AppDev is now LearnNowPlus : www.learnnowonline.com/appdev That site not longer offers prices. I tried to find reviews but could not find any. Does anyone know, or can share a review about some of these type of online training service providers? I would appreciate your feedback on this, and if you can share your past experiences with their service or similar/better services that would even be better. Thanks.

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• C# 5 Async, Part 3: Preparing Existing code For Await

  - by Reed

  While the Visual Studio Async CTP provides a fantastic model for asynchronous programming, it requires code to be implemented in terms of Task and Task<T>.  The CTP adds support for Task-based asynchrony to the .NET Framework methods, and promises to have these implemented directly in the framework in the future.  However, existing code outside the framework will need to be converted to using the Task class prior to being usable via the CTP. Wrapping existing asynchronous code into a Task or Task<T> is, thankfully, fairly straightforward.  There are two main approaches to this. Code written using the Asynchronous Programming Model (APM) is very easy to convert to using Task<T>.  The TaskFactory class provides the tools to directly convert APM code into a method returning a Task<T>.  This is done via the FromAsync method.  This method takes the BeginOperation and EndOperation methods, as well as any parameters and state objects as arguments, and returns a Task<T> directly. For example, we could easily convert the WebRequest BeginGetResponse and EndGetResponse methods into a method which returns a Task<WebResponse> via: Task<WebResponse> task = Task.Factory .FromAsync<WebResponse>( request.BeginGetResponse, request.EndGetResponse, null); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Event-based Asynchronous Pattern (EAP) code can also be wrapped into a Task<T>, though this requires a bit more effort than the one line of code above.  This is handled via the TaskCompletionSource<T> class.  MSDN provides a detailed example of using this to wrap an EAP operation into a method returning Task<T>.  It demonstrates handling cancellation and exception handling as well as the basic operation of the asynchronous method itself. The basic form of this operation is typically: Task<YourResult> GetResultAsync() { var tcs = new TaskCompletionSource<YourResult>(); // Handle the event, and setup the task results... this.GetResultCompleted += (o,e) => { if (e.Error != null) tcs.TrySetException(e.Error); else if (e.Cancelled) tcs.TrySetCanceled(); else tcs.TrySetResult(e.Result); }; // Call the asynchronous method this.GetResult(); // Return the task from the TaskCompletionSource return tcs.Task; } We can easily use these methods to wrap our own code into a method that returns a Task<T>.  Existing libraries which cannot be edited can be extended via Extension methods.  The CTP uses this technique to add appropriate methods throughout the framework. The suggested naming for these methods is to define these methods as “Task<YourResult> YourClass.YourOperationAsync(…)”.  However, this naming often conflicts with the default naming of the EAP.  If this is the case, the CTP has standardized on using “Task<YourResult> YourClass.YourOperationTaskAsync(…)”. Once we’ve wrapped all of our existing code into operations that return Task<T>, we can begin investigating how the Async CTP can be used with our own code.

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• ConcurrentDictionary<TKey,TValue> used with Lazy<T>

  - by Reed

  In a recent thread on the MSDN forum for the TPL, Stephen Toub suggested mixing ConcurrentDictionary<T,U> with Lazy<T>.  This provides a fantastic model for creating a thread safe dictionary of values where the construction of the value type is expensive.  This is an incredibly useful pattern for many operations, such as value caches. The ConcurrentDictionary<TKey, TValue> class was added in .NET 4, and provides a thread-safe, lock free collection of key value pairs.  While this is a fantastic replacement for Dictionary<TKey, TValue>, it has a potential flaw when used with values where construction of the value class is expensive. The typical way this is used is to call a method such as GetOrAdd to fetch or add a value to the dictionary.  It handles all of the thread safety for you, but as a result, if two threads call this simultaneously, two instances of TValue can easily be constructed. If TValue is very expensive to construct, or worse, has side effects if constructed too often, this is less than desirable.  While you can easily work around this with locking, Stephen Toub provided a very clever alternative – using Lazy<TValue> as the value in the dictionary instead. This looks like the following.  Instead of calling: MyValue value = dictionary.GetOrAdd( key, () => new MyValue(key)); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } We would instead use a ConcurrentDictionary<TKey, Lazy<TValue>>, and write: MyValue value = dictionary.GetOrAdd( key, () => new Lazy<MyValue>( () => new MyValue(key))) .Value; This simple change dramatically changes how the operation works.  Now, if two threads call this simultaneously, instead of constructing two MyValue instances, we construct two Lazy<MyValue> instances. However, the Lazy<T> class is very cheap to construct.  Unlike “MyValue”, we can safely afford to construct this twice and “throw away” one of the instances. We then call Lazy<T>.Value at the end to fetch our “MyValue” instance.  At this point, GetOrAdd will always return the same instance of Lazy<MyValue>.  Since Lazy<T> doesn’t construct the MyValue instance until requested, the actual MyClass instance returned is only constructed once.

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