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  • jquery drag and drop script and problem in reading json array

    - by Mac Taylor
    i made a script , exactly like wordpress widgets page and u can drag and drop objects this is my jquery script : <script type="text/javascript" >$(function(){ $('.widget') .each(function(){ $(this).hover(function(){ $(this).find('h4').addClass('collapse'); }, function(){ $(this).find('h4').removeClass('collapse'); }) .find('h4').hover(function(){ $(this).find('.in-widget-title').css('visibility', 'visible'); }, function(){ $(this).find('.in-widget-title').css('visibility', 'hidden'); }) .click(function(){ $(this).siblings('.widget-inside').toggle(); //Save state on change of collapse state of panel updateWidgetData(); }) .end() .find('.in-widget-title').css('visibility', 'hidden'); }); $('.column').sortable({ connectWith: '.column', handle: 'h4', cursor: 'move', placeholder: 'placeholder', forcePlaceholderSize: true, opacity: 0.4, start: function(event, ui){ //Firefox, Safari/Chrome fire click event after drag is complete, fix for that if($.browser.mozilla || $.browser.safari) $(ui.item).find('.widget-inside').toggle(); }, stop: function(event, ui){ ui.item.css({'top':'0','left':'0'}); //Opera fix if(!$.browser.mozilla && !$.browser.safari) updateWidgetData(); } }) .disableSelection(); }); function updateWidgetData(){ var items=[]; $('.column').each(function(){ var columnId=$(this).attr('id'); $('.widget', this).each(function(i){ var collapsed=0; if($(this).find('.widget-inside').css('display')=="none") collapsed=1; //Create Item object for current panel var item={ id: $(this).attr('id'), collapsed: collapsed, order : i, column: columnId }; //Push item object into items array items.push(item); }); }); //Assign items array to sortorder JSON variable var sortorder={ items: items }; //Pass sortorder variable to server using ajax to save state $.post("blocks.php"+"&order="+$.toJSON(sortorder), function(data){ $('#console').html(data).fadeIn("slow"); }); } </script> main part is saving object orders in table and this is my php part : function stripslashes_deep($value) { $value = is_array($value) ? array_map('stripslashes_deep', $value) : stripslashes($value); return $value; } $order = $_GET['order']; $order = sql_quote($order); if(empty($order)){ echo "Invalid data"; exit; } global $db,$prefix; if (get_magic_quotes_gpc()) { $_POST = array_map('stripslashes_deep', $_POST); $_GET = array_map('stripslashes_deep', $_GET); $_COOKIE = array_map('stripslashes_deep', $_COOKIE); $_REQUEST = array_map('stripslashes_deep', $_REQUEST); } $data=json_decode($order); foreach($newdata->items as $item) { //Extract column number for panel $col_id=preg_replace('/[^\d\s]/', '', $item->column); //Extract id of the panel $widget_id=preg_replace('/[^\d\s]/', '', $item->id); $sql="UPDATE blocks_tbl SET bposition='$col_id', weight='".$item->order."' WHERE id='".$widget_id."'"; mysql_query($sql) or die('Error updating widget DB'); } print_r($order); now forexample the output is this : items\":[{\"id\":\"item26\",\"collapsed\":1,\"order\":0,\"column\":\"c\"},{\"id\":\"item0\",\"collapsed\":1,\"order\":0,\"column\":\"i\"},{\"id\":\"item0\",\"collapsed\":1,\"order\":1,\"column\":\"i\"},{\"id\":\"item1\",\"collapsed\":1,\"order\":2,\"column\":\"i\"},{\"id\":\"item3\",\"collapsed\":1,\"order\":3,\"column\":\"i\"},{\"id\":\"item16\",\"collapsed\":1,\"order\":4,\"column\":\"i\"},{\"id\":\"item0\",\"collapsed\":1,\"order\":5,\"column\":\"i\"},{\"id\":\"item6\",\"collapsed\":1,\"order\":6,\"column\":\"i\"},{\"id\":\"item17\",\"collapsed\":1,\"order\":7,\"column\":\"i\"},{\"id\":\"item19\",\"collapsed\":1,\"order\":8,\"column\":\"i\"},{\"id\":\"item10\",\"collapsed\":1,\"order\":9,\"column\":\"i\"},{\"id\":\"item11\",\"collapsed\":1,\"order\":10,\"column\":\"i\"},{\"id\":\"item0\",\"collapsed\":1,\"order\":0,\"column\":\"l\"},{\"id\":\"item5\",\"collapsed\":1,\"order\":1,\"column\":\"l\"},{\"id\":\"item8\",\"collapsed\":1,\"order\":2,\"column\":\"l\"},{\"id\":\"item13\",\"collapsed\":1,\"order\":3,\"column\":\"l\"},{\"id\":\"item21\",\"collapsed\":1,\"order\":4,\"column\":\"l\"},{\"id\":\"item28\",\"collapsed\":1,\"order\":5,\"column\":\"l\"},{\"id\":\"item7\",\"collapsed\":1,\"order\":0,\"column\":\"r\"},{\"id\":\"item20\",\"collapsed\":1,\"order\":1,\"column\":\"r\"},{\"id\":\"item15\",\"collapsed\":1,\"order\":2,\"column\":\"r\"},{\"id\":\"item18\",\"collapsed\":1,\"order\":3,\"column\":\"r\"},{\"id\":\"item14\",\"collapsed\":1,\"order\":4,\"column\":\"r\"}]} question is how can i find out column_id or order im a little bit confused

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  • ASP.NET MVC Paging/Sorting/Filtering using the MVCContrib Grid and Pager

    - by rajbk
    This post walks you through creating a UI for paging, sorting and filtering a list of data items. It makes use of the excellent MVCContrib Grid and Pager Html UI helpers. A sample project is attached at the bottom. Our UI will eventually look like this. The application will make use of the Northwind database. The top portion of the page has a filter area region. The filter region is enclosed in a form tag. The select lists are wired up with jQuery to auto post back the form. The page has a pager region at the top and bottom of the product list. The product list has a link to display more details about a given product. The column headings are clickable for sorting and an icon shows the sort direction. Strongly Typed View Models The views are written to expect strongly typed objects. We suffix these strongly typed objects with ViewModel since they are designed specifically for passing data down to the view.  The following listing shows the ProductViewModel. This class will be used to hold information about a Product. We use attributes to specify if the property should be hidden and what its heading in the table should be. This metadata will be used by the MvcContrib Grid to render the table. Some of the properties are hidden from the UI ([ScaffoldColumn(false)) but are needed because we will be using those for filtering when writing our LINQ query. public ActionResult Index( string productName, int? supplierID, int? categoryID, GridSortOptions gridSortOptions, int? page) {   var productList = productRepository.GetProductsProjected();   // Set default sort column if (string.IsNullOrWhiteSpace(gridSortOptions.Column)) { gridSortOptions.Column = "ProductID"; }   // Filter on SupplierID if (supplierID.HasValue) { productList = productList.Where(a => a.SupplierID == supplierID); }   // Filter on CategoryID if (categoryID.HasValue) { productList = productList.Where(a => a.CategoryID == categoryID); }   // Filter on ProductName if (!string.IsNullOrWhiteSpace(productName)) { productList = productList.Where(a => a.ProductName.Contains(productName)); }   // Create all filter data and set current values if any // These values will be used to set the state of the select list and textbox // by sending it back to the view. var productFilterViewModel = new ProductFilterViewModel(); productFilterViewModel.SelectedCategoryID = categoryID ?? -1; productFilterViewModel.SelectedSupplierID = supplierID ?? -1; productFilterViewModel.Fill();   // Order and page the product list var productPagedList = productList .OrderBy(gridSortOptions.Column, gridSortOptions.Direction) .AsPagination(page ?? 1, 10);     var productListContainer = new ProductListContainerViewModel { ProductPagedList = productPagedList, ProductFilterViewModel = productFilterViewModel, GridSortOptions = gridSortOptions };   return View(productListContainer); } The following diagram shows the rest of the key ViewModels in our design. We have a container class called ProductListContainerViewModel which has nested classes. The ProductPagedList is of type IPagination<ProductViewModel>. The MvcContrib expects the IPagination<T> interface to determine the page number and page size of the collection we are working with. You convert any IEnumerable<T> into an IPagination<T> by calling the AsPagination extension method in the MvcContrib library. It also creates a paged set of type ProductViewModel. The ProductFilterViewModel class will hold information about the different select lists and the ProductName being searched on. It will also hold state of any previously selected item in the lists and the previous search criteria (you will recall that this type of state information was stored in Viewstate when working with WebForms). With MVC there is no state storage and so all state has to be fetched and passed back to the view. The GridSortOptions is a type defined in the MvcContrib library and is used by the Grid to determine the current column being sorted on and the current sort direction. The following shows the view and partial views used to render our UI. The Index view expects a type ProductListContainerViewModel which we described earlier. <%Html.RenderPartial("SearchFilters", Model.ProductFilterViewModel); %> <% Html.RenderPartial("Pager", Model.ProductPagedList); %> <% Html.RenderPartial("SearchResults", Model); %> <% Html.RenderPartial("Pager", Model.ProductPagedList); %> The View contains a partial view “SearchFilters” and passes it the ProductViewFilterContainer. The SearchFilter uses this Model to render all the search lists and textbox. The partial view “Pager” uses the ProductPageList which implements the interface IPagination. The “Pager” view contains the MvcContrib Pager helper used to render the paging information. This view is repeated twice since we want the pager UI to be available at the top and bottom of the product list. The Pager partial view is located in the Shared directory so that it can be reused across Views. The partial view “SearchResults” uses the ProductListContainer model. This partial view contains the MvcContrib Grid which needs both the ProdctPagedList and GridSortOptions to render itself. The Controller Action An example of a request like this: /Products?productName=test&supplierId=29&categoryId=4. The application receives this GET request and maps it to the Index method of the ProductController. Within the action we create an IQueryable<ProductViewModel> by calling the GetProductsProjected() method. /// <summary> /// This method takes in a filter list, paging/sort options and applies /// them to an IQueryable of type ProductViewModel /// </summary> /// <returns> /// The return object is a container that holds the sorted/paged list, /// state for the fiters and state about the current sorted column /// </returns> public ActionResult Index( string productName, int? supplierID, int? categoryID, GridSortOptions gridSortOptions, int? page) {   var productList = productRepository.GetProductsProjected();   // Set default sort column if (string.IsNullOrWhiteSpace(gridSortOptions.Column)) { gridSortOptions.Column = "ProductID"; }   // Filter on SupplierID if (supplierID.HasValue) { productList.Where(a => a.SupplierID == supplierID); }   // Filter on CategoryID if (categoryID.HasValue) { productList = productList.Where(a => a.CategoryID == categoryID); }   // Filter on ProductName if (!string.IsNullOrWhiteSpace(productName)) { productList = productList.Where(a => a.ProductName.Contains(productName)); }   // Create all filter data and set current values if any // These values will be used to set the state of the select list and textbox // by sending it back to the view. var productFilterViewModel = new ProductFilterViewModel(); productFilterViewModel.SelectedCategoryID = categoryID ?? -1; productFilterViewModel.SelectedSupplierID = supplierID ?? -1; productFilterViewModel.Fill();   // Order and page the product list var productPagedList = productList .OrderBy(gridSortOptions.Column, gridSortOptions.Direction) .AsPagination(page ?? 1, 10);     var productListContainer = new ProductListContainerViewModel { ProductPagedList = productPagedList, ProductFilterViewModel = productFilterViewModel, GridSortOptions = gridSortOptions };   return View(productListContainer); } The supplier, category and productname filters are applied to this IQueryable if any are present in the request. The ProductPagedList class is created by applying a sort order and calling the AsPagination method. Finally the ProductListContainerViewModel class is created and returned to the view. You have seen how to use strongly typed views with the MvcContrib Grid and Pager to render a clean lightweight UI with strongly typed views. You also saw how to use partial views to get data from the strongly typed model passed to it from the parent view. The code also shows you how to use jQuery to auto post back. The sample is attached below. Don’t forget to change your connection string to point to the server containing the Northwind database. NorthwindSales_MvcContrib.zip My name is Kobayashi. I work for Keyser Soze.

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  • PowerShell Script to Deploy Multiple VM on Azure in Parallel #azure #powershell

    - by Marco Russo (SQLBI)
    This blog is usually dedicated to Business Intelligence and SQL Server, but I didn’t found easily on the web simple PowerShell scripts to help me deploying a number of virtual machines on Azure that I use for testing and development. Since I need to deploy, start, stop and remove many virtual machines created from a common image I created (you know, Tabular is not part of the standard images provided by Microsoft…), I wanted to minimize the time required to execute every operation from my Windows Azure PowerShell console (but I suggest you using Windows PowerShell ISE), so I also wanted to fire the commands as soon as possible in parallel, without losing the result in the console. In order to execute multiple commands in parallel, I used the Start-Job cmdlet, and using Get-Job and Receive-Job I wait for job completion and display the messages generated during background command execution. This technique allows me to reduce execution time when I have to deploy, start, stop or remove virtual machines. Please note that a few operations on Azure acquire an exclusive lock and cannot be really executed in parallel, but only one part of their execution time is subject to this lock. Thus, you obtain a better response time also in these scenarios (this is the case of the provisioning of a new VM). Finally, when you remove the VMs you still have the disk containing the virtual machine to remove. This cannot be done just after the VM removal, because you have to wait that the removal operation is completed on Azure. So I wrote a script that you have to run a few minutes after VMs removal and delete disks (and VHD) no longer related to a VM. I just check that the disk were associated to the original image name used to provision the VMs (so I don’t remove other disks deployed by other batches that I might want to preserve). These examples are specific for my scenario, if you need more complex configurations you have to change and adapt the code. But if your need is to create multiple instances of the same VM running in a workgroup, these scripts should be good enough. I prepared the following PowerShell scripts: ProvisionVMs: Provision many VMs in parallel starting from the same image. It creates one service for each VM. RemoveVMs: Remove all the VMs in parallel – it also remove the service created for the VM StartVMs: Starts all the VMs in parallel StopVMs: Stops all the VMs in parallel RemoveOrphanDisks: Remove all the disks no longer used by any VMs. Run this script a few minutes after RemoveVMs script. ProvisionVMs # Name of subscription $SubscriptionName = "Copy the SubscriptionName property you get from Get-AzureSubscription"   # Name of storage account (where VMs will be deployed) $StorageAccount = "Copy the Label property you get from Get-AzureStorageAccount"   function ProvisionVM( [string]$VmName ) {     Start-Job -ArgumentList $VmName {         param($VmName) $Location = "Copy the Location property you get from Get-AzureStorageAccount" $InstanceSize = "A5" # You can use any other instance, such as Large, A6, and so on $AdminUsername = "UserName" # Write the name of the administrator account in the new VM $Password = "Password"      # Write the password of the administrator account in the new VM $Image = "Copy the ImageName property you get from Get-AzureVMImage" # You can list your own images using the following command: # Get-AzureVMImage | Where-Object {$_.PublisherName -eq "User" }         New-AzureVMConfig -Name $VmName -ImageName $Image -InstanceSize $InstanceSize |             Add-AzureProvisioningConfig -Windows -Password $Password -AdminUsername $AdminUsername|             New-AzureVM -Location $Location -ServiceName "$VmName" -Verbose     } }   # Set the proper storage - you might remove this line if you have only one storage in the subscription Set-AzureSubscription -SubscriptionName $SubscriptionName -CurrentStorageAccount $StorageAccount   # Select the subscription - this line is fundamental if you have access to multiple subscription # You might remove this line if you have only one subscription Select-AzureSubscription -SubscriptionName $SubscriptionName   # Every line in the following list provisions one VM using the name specified in the argument # You can change the number of lines - use a unique name for every VM - don't reuse names # already used in other VMs already deployed ProvisionVM "test10" ProvisionVM "test11" ProvisionVM "test12" ProvisionVM "test13" ProvisionVM "test14" ProvisionVM "test15" ProvisionVM "test16" ProvisionVM "test17" ProvisionVM "test18" ProvisionVM "test19" ProvisionVM "test20"   # Wait for all to complete While (Get-Job -State "Running") {     Get-Job -State "Completed" | Receive-Job     Start-Sleep 1 }   # Display output from all jobs Get-Job | Receive-Job   # Cleanup of jobs Remove-Job *   # Displays batch completed echo "Provisioning VM Completed" RemoveVMs # Name of subscription $SubscriptionName = "Copy the SubscriptionName property you get from Get-AzureSubscription"   function RemoveVM( [string]$VmName ) {     Start-Job -ArgumentList $VmName {         param($VmName)         Remove-AzureService -ServiceName $VmName -Force -Verbose     } }   # Select the subscription - this line is fundamental if you have access to multiple subscription # You might remove this line if you have only one subscription Select-AzureSubscription -SubscriptionName $SubscriptionName   # Every line in the following list remove one VM using the name specified in the argument # You can change the number of lines - use a unique name for every VM - don't reuse names # already used in other VMs already deployed RemoveVM "test10" RemoveVM "test11" RemoveVM "test12" RemoveVM "test13" RemoveVM "test14" RemoveVM "test15" RemoveVM "test16" RemoveVM "test17" RemoveVM "test18" RemoveVM "test19" RemoveVM "test20"   # Wait for all to complete While (Get-Job -State "Running") {     Get-Job -State "Completed" | Receive-Job     Start-Sleep 1 }   # Display output from all jobs Get-Job | Receive-Job   # Cleanup Remove-Job *   # Displays batch completed echo "Remove VM Completed" StartVMs # Name of subscription $SubscriptionName = "Copy the SubscriptionName property you get from Get-AzureSubscription"   function StartVM( [string]$VmName ) {     Start-Job -ArgumentList $VmName {         param($VmName)         Start-AzureVM -Name $VmName -ServiceName $VmName -Verbose     } }   # Select the subscription - this line is fundamental if you have access to multiple subscription # You might remove this line if you have only one subscription Select-AzureSubscription -SubscriptionName $SubscriptionName   # Every line in the following list starts one VM using the name specified in the argument # You can change the number of lines - use a unique name for every VM - don't reuse names # already used in other VMs already deployed StartVM "test10" StartVM "test11" StartVM "test11" StartVM "test12" StartVM "test13" StartVM "test14" StartVM "test15" StartVM "test16" StartVM "test17" StartVM "test18" StartVM "test19" StartVM "test20"   # Wait for all to complete While (Get-Job -State "Running") {     Get-Job -State "Completed" | Receive-Job     Start-Sleep 1 }   # Display output from all jobs Get-Job | Receive-Job   # Cleanup Remove-Job *   # Displays batch completed echo "Start VM Completed"   StopVMs # Name of subscription $SubscriptionName = "Copy the SubscriptionName property you get from Get-AzureSubscription"   function StopVM( [string]$VmName ) {     Start-Job -ArgumentList $VmName {         param($VmName)         Stop-AzureVM -Name $VmName -ServiceName $VmName -Verbose -Force     } }   # Select the subscription - this line is fundamental if you have access to multiple subscription # You might remove this line if you have only one subscription Select-AzureSubscription -SubscriptionName $SubscriptionName   # Every line in the following list stops one VM using the name specified in the argument # You can change the number of lines - use a unique name for every VM - don't reuse names # already used in other VMs already deployed StopVM "test10" StopVM "test11" StopVM "test12" StopVM "test13" StopVM "test14" StopVM "test15" StopVM "test16" StopVM "test17" StopVM "test18" StopVM "test19" StopVM "test20"   # Wait for all to complete While (Get-Job -State "Running") {     Get-Job -State "Completed" | Receive-Job     Start-Sleep 1 }   # Display output from all jobs Get-Job | Receive-Job   # Cleanup Remove-Job *   # Displays batch completed echo "Stop VM Completed" RemoveOrphanDisks $Image = "Copy the ImageName property you get from Get-AzureVMImage" # You can list your own images using the following command: # Get-AzureVMImage | Where-Object {$_.PublisherName -eq "User" }   # Remove all orphan disks coming from the image specified in $ImageName Get-AzureDisk |     Where-Object {$_.attachedto -eq $null -and $_.SourceImageName -eq $ImageName} |     Remove-AzureDisk -DeleteVHD -Verbose  

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  • Google Reader Play – Reading redefined

    - by samsudeen
    “Google Reader Play” is the new Web browsing feature launched by Google on Wednesday which allows users to browse and explore the content in Google reader  like a TV rather than the hierarchical tree view.  Google reader finds and displays the coolest things on the net using the same “Recommended Items”  feature in the Google Reader. if you are a Google user then it tries to filter the content based upon the “Items that several of your friends have shared” and “based upon your past reader History” “Google Reader Play” makes the personalization of content automation by allowing the users to mark , like and share items as shown below It also allows you to personalize the content by choosing the from the list of available categories The interface looks simple and and now users can feel reading news is like watching TV.This is what what  Google is saying about it In Google Reader Play, items are presented one at a time, and each item is big and full-screen. After you’ve read an item, just click the next arrow to move to the next one, or click any item on the filmstrip below to fast-forward. Join us on Facebook to read all our stories right inside your Facebook news feed.

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  • How To: Filter as you type RadGridView inside RadComboBox for WPF and Silverlight

    Ive made small example on how to place RadGridView inside editable RadComboBox and filter the grid items as you type in the combo:   The easiest way to place any UI element in RadComboBox is to create single RadComboBoxItem and define desired Template: <telerikInput:RadComboBox Text="{Binding Text, Mode=TwoWay}" IsEditable="True" Height="25" Width="200"> <telerikInput:RadComboBox.Items> <telerikInput:RadComboBoxItem> <telerikInput:RadComboBoxItem.Template> <ControlTemplate> <telerikGrid:RadGridView x:Name="RadGridView1" ShowGroupPanel="False" CanUserFreezeColumns="False" RowIndicatorVisibility="Collapsed" IsReadOnly="True" IsFilteringAllowed="False" ItemsSource="{Binding Items}" Width="200" Height="150" SelectedItem="{Binding SelectedItem, Mode=TwoWay}"> </telerikGrid:RadGridView> </ControlTemplate> </telerikInput:RadComboBoxItem.Template> </telerikInput:RadComboBoxItem> </telerikInput:RadComboBox.Items> </telerikInput:RadComboBox> Now you can create small view model and bind ...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Imperative vs. LINQ Performance on WP7

    - by Bil Simser
    Jesse Liberty had a nice post presenting the concepts around imperative, LINQ and fluent programming to populate a listbox. Check out the post as it’s a great example of some foundational things every .NET programmer should know. I was more interested in what the IL code that would be generated from imperative vs. LINQ was like and what the performance numbers are and how they differ. The code at the instruction level is interesting but not surprising. The imperative example with it’s creating lists and loops weighs in at about 60 instructions. .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; } 1: .method private hidebysig instance void ImperativeMethod() cil managed 2: { 3: .maxstack 3 4: .locals init ( 5: [0] class [mscorlib]System.Collections.Generic.IEnumerable`1<int32> someData, 6: [1] class [mscorlib]System.Collections.Generic.List`1<int32> inLoop, 7: [2] int32 n, 8: [3] class [mscorlib]System.Collections.Generic.IEnumerator`1<int32> CS$5$0000, 9: [4] bool CS$4$0001) 10: L_0000: nop 11: L_0001: ldc.i4.1 12: L_0002: ldc.i4.s 50 13: L_0004: call class [mscorlib]System.Collections.Generic.IEnumerable`1<int32> [System.Core]System.Linq.Enumerable::Range(int32, int32) 14: L_0009: stloc.0 15: L_000a: newobj instance void [mscorlib]System.Collections.Generic.List`1<int32>::.ctor() 16: L_000f: stloc.1 17: L_0010: nop 18: L_0011: ldloc.0 19: L_0012: callvirt instance class [mscorlib]System.Collections.Generic.IEnumerator`1<!0> [mscorlib]System.Collections.Generic.IEnumerable`1<int32>::GetEnumerator() 20: L_0017: stloc.3 21: L_0018: br.s L_003a 22: L_001a: ldloc.3 23: L_001b: callvirt instance !0 [mscorlib]System.Collections.Generic.IEnumerator`1<int32>::get_Current() 24: L_0020: stloc.2 25: L_0021: nop 26: L_0022: ldloc.2 27: L_0023: ldc.i4.5 28: L_0024: cgt 29: L_0026: ldc.i4.0 30: L_0027: ceq 31: L_0029: stloc.s CS$4$0001 32: L_002b: ldloc.s CS$4$0001 33: L_002d: brtrue.s L_0039 34: L_002f: ldloc.1 35: L_0030: ldloc.2 36: L_0031: ldloc.2 37: L_0032: mul 38: L_0033: callvirt instance void [mscorlib]System.Collections.Generic.List`1<int32>::Add(!0) 39: L_0038: nop 40: L_0039: nop 41: L_003a: ldloc.3 42: L_003b: callvirt instance bool [mscorlib]System.Collections.IEnumerator::MoveNext() 43: L_0040: stloc.s CS$4$0001 44: L_0042: ldloc.s CS$4$0001 45: L_0044: brtrue.s L_001a 46: L_0046: leave.s L_005a 47: L_0048: ldloc.3 48: L_0049: ldnull 49: L_004a: ceq 50: L_004c: stloc.s CS$4$0001 51: L_004e: ldloc.s CS$4$0001 52: L_0050: brtrue.s L_0059 53: L_0052: ldloc.3 54: L_0053: callvirt instance void [mscorlib]System.IDisposable::Dispose() 55: L_0058: nop 56: L_0059: endfinally 57: L_005a: nop 58: L_005b: ldarg.0 59: L_005c: ldfld class [System.Windows]System.Windows.Controls.ListBox PerfTest.MainPage::LB1 60: L_0061: ldloc.1 61: L_0062: callvirt instance void [System.Windows]System.Windows.Controls.ItemsControl::set_ItemsSource(class [mscorlib]System.Collections.IEnumerable) 62: L_0067: nop 63: L_0068: ret 64: .try L_0018 to L_0048 finally handler L_0048 to L_005a 65: } 66:   67: Compare that to the IL generated for the LINQ version which has about half of the instructions and just gets the job done, no fluff. .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } 1: .method private hidebysig instance void LINQMethod() cil managed 2: { 3: .maxstack 4 4: .locals init ( 5: [0] class [mscorlib]System.Collections.Generic.IEnumerable`1<int32> someData, 6: [1] class [mscorlib]System.Collections.Generic.IEnumerable`1<int32> queryResult) 7: L_0000: nop 8: L_0001: ldc.i4.1 9: L_0002: ldc.i4.s 50 10: L_0004: call class [mscorlib]System.Collections.Generic.IEnumerable`1<int32> [System.Core]System.Linq.Enumerable::Range(int32, int32) 11: L_0009: stloc.0 12: L_000a: ldloc.0 13: L_000b: ldsfld class [System.Core]System.Func`2<int32, bool> PerfTest.MainPage::CS$<>9__CachedAnonymousMethodDelegate6 14: L_0010: brtrue.s L_0025 15: L_0012: ldnull 16: L_0013: ldftn bool PerfTest.MainPage::<LINQProgramming>b__4(int32) 17: L_0019: newobj instance void [System.Core]System.Func`2<int32, bool>::.ctor(object, native int) 18: L_001e: stsfld class [System.Core]System.Func`2<int32, bool> PerfTest.MainPage::CS$<>9__CachedAnonymousMethodDelegate6 19: L_0023: br.s L_0025 20: L_0025: ldsfld class [System.Core]System.Func`2<int32, bool> PerfTest.MainPage::CS$<>9__CachedAnonymousMethodDelegate6 21: L_002a: call class [mscorlib]System.Collections.Generic.IEnumerable`1<!!0> [System.Core]System.Linq.Enumerable::Where<int32>(class [mscorlib]System.Collections.Generic.IEnumerable`1<!!0>, class [System.Core]System.Func`2<!!0, bool>) 22: L_002f: ldsfld class [System.Core]System.Func`2<int32, int32> PerfTest.MainPage::CS$<>9__CachedAnonymousMethodDelegate7 23: L_0034: brtrue.s L_0049 24: L_0036: ldnull 25: L_0037: ldftn int32 PerfTest.MainPage::<LINQProgramming>b__5(int32) 26: L_003d: newobj instance void [System.Core]System.Func`2<int32, int32>::.ctor(object, native int) 27: L_0042: stsfld class [System.Core]System.Func`2<int32, int32> PerfTest.MainPage::CS$<>9__CachedAnonymousMethodDelegate7 28: L_0047: br.s L_0049 29: L_0049: ldsfld class [System.Core]System.Func`2<int32, int32> PerfTest.MainPage::CS$<>9__CachedAnonymousMethodDelegate7 30: L_004e: call class [mscorlib]System.Collections.Generic.IEnumerable`1<!!1> [System.Core]System.Linq.Enumerable::Select<int32, int32>(class [mscorlib]System.Collections.Generic.IEnumerable`1<!!0>, class [System.Core]System.Func`2<!!0, !!1>) 31: L_0053: stloc.1 32: L_0054: ldarg.0 33: L_0055: ldfld class [System.Windows]System.Windows.Controls.ListBox PerfTest.MainPage::LB2 34: L_005a: ldloc.1 35: L_005b: callvirt instance void [System.Windows]System.Windows.Controls.ItemsControl::set_ItemsSource(class [mscorlib]System.Collections.IEnumerable) 36: L_0060: nop 37: L_0061: ret 38: } Again, not surprising here but a good indicator that you should consider using LINQ where possible. In fact if you have ReSharper installed you’ll see a squiggly (technical term) in the imperative code that says “Hey Dude, I can convert this to LINQ if you want to be c00L!” (or something like that, it’s the 2010 geek version of Clippy). What about the fluent version? As Jon correctly pointed out in the comments, when you compare the IL for the LINQ code and the IL for the fluent code it’s the same. LINQ and the fluent interface are just syntactical sugar so you decide what you’re most comfortable with. At the end of the day they’re both the same. Now onto the numbers. Again I expected the imperative version to be better performing than the LINQ version (before I saw the IL that was generated). Call it womanly instinct. A gut feel. Whatever. Some of the numbers are interesting though. For Jesse’s example of 50 items, the numbers were interesting. The imperative sample clocked in at 7ms while the LINQ version completed in 4. As the number of items went up, the elapsed time didn’t necessarily climb exponentially. At 500 items they were pretty much the same and the results were similar up to about 50,000 items. After that I tried 500,000 items where the gap widened but not by much (2.2 seconds for imperative, 2.3 for LINQ). It wasn’t until I tried 5,000,000 items where things were noticeable. Imperative filled the list in 20 seconds while LINQ took 8 seconds longer (although personally I wouldn’t suggest you put 5 million items in a list unless you want your users showing up at your door with torches and pitchforks). Here’s the table with the full results. Method/Items 50 500 5,000 50,000 500,000 5,000,000 Imperative 7ms 7ms 38ms 223ms 2230ms 20974ms LINQ/Fluent 4ms 6ms 41ms 240ms 2310ms 28731ms Like I said, at the end of the day it’s not a huge difference and you really don’t want your users waiting around for 30 seconds on a mobile device filling lists. In fact if Windows Phone 7 detects you’re taking more than 10 seconds to do any one thing, it considers the app hung and shuts it down. The results here are for Windows Phone 7 but frankly they're the same for desktop and web apps so feel free to apply it generally. From a programming perspective, choose what you like. Some LINQ statements can get pretty hairy so I usually fall back with my simple mind and write it imperatively. If you really want to impress your friends, write it old school then let ReSharper do the hard work for! Happy programming!

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  • Ubuntu One file sync error: SSL Handshake

    - by Jay Ó Broin
    Ubuntu One repeatedly tries to sync my files but keeps disconnecting before anything is uploaded. Here are some of the messages from syncdaemon.log: 2012-01-08 12:12:34,068 - ubuntuone.SyncDaemon.ActionQueue - INFO - Connection started to host fs-2.ubuntuone.com, port 443. 2012-01-08 12:12:34,256 - ubuntuone.SyncDaemon.ActionQueue - INFO - Connection made. 2012-01-08 12:12:34,257 - ubuntuone.SyncDaemon.StorageClient - INFO - Connection made. 2012-01-08 12:13:08,832 - ubuntuone.SyncDaemon.StorageClient - INFO - Connection lost, reason: [Failure instance: Traceback (failure with no frames): <class 'OpenSSL.SSL.Error'>: [('SSL routines', 'SSL23_READ', 'ssl handshake failure')]]. 2012-01-08 12:13:08,833 - ubuntuone.SyncDaemon.ActionQueue - INFO - The request 'protocol_version' failed with the error: [('SSL routines', 'SSL23_READ', 'ssl handshake failure')] 2012-01-08 12:13:08,844 - ubuntuone.SyncDaemon.ActionQueue - WARNING - Connection lost: [('SSL routines', 'SSL23_READ', 'ssl handshake failure')] 2012-01-08 12:13:38,550 - ubuntuone.SyncDaemon.Main - NOTE - ---- MARK (state: <State: 'WAITING' (queues WORKING connection 'With User With Network')>; queue: 1378; hash: 0) ---- 2012-01-08 12:15:08,870 - ubuntuone.SyncDaemon.ActionQueue - INFO - Connection started to host fs-2.ubuntuone.com, port 443. 2012-01-08 12:15:09,033 - ubuntuone.SyncDaemon.ActionQueue - INFO - Connection made. 2012-01-08 12:15:09,034 - ubuntuone.SyncDaemon.StorageClient - INFO - Connection made. 2012-01-08 12:15:33,676 - ubuntuone.SyncDaemon.StorageClient - INFO - Connection lost, reason: [Failure instance: Traceback (failure with no frames): <class 'OpenSSL.SSL.Error'>: [('SSL routines', 'SSL23_READ', 'ssl handshake failure')]]. 2012-01-08 12:15:33,677 - ubuntuone.SyncDaemon.ActionQueue - INFO - The request 'protocol_version' failed with the error: [('SSL routines', 'SSL23_READ', 'ssl handshake failure')] 2012-01-08 12:15:33,692 - ubuntuone.SyncDaemon.ActionQueue - WARNING - Connection lost: [('SSL routines', 'SSL23_READ', 'ssl handshake failure')] 2012-01-08 12:15:38,551 - ubuntuone.SyncDaemon.Main - NOTE - ---- MARK (state: <State: 'WAITING' (queues WORKING connection 'With User With Network')>; queue: 1378; hash: 0) ---- I'm using Ubuntu 11.10.

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  • Creating an email notification system based on polling database rows

    - by Ashish Sharma
    I have to design an email notification system based on the following requirements: The email notifications would be created based on polling rows in a Mysql 5.5 DB table when they are in a particular 'Completed' state. The email notification should be sent out in no more than 5 minutes from the time the row was created in the DB table (At the time of DB table row creation the state of the row might not be 'Completed'). Once 5 minutes for the DB table row expire in reaching the 'Completed' state, separate email notification need to be sent (basically telling the user that the original email notification would be delayed) and then sending the email notification as and when the row state reaches to being 'Completed'. The rest of the system requirements are : Adding relevant checks to monitor the whole system via MBeans interface. The system should be scalable so that if the rate of DB table rows creation increases so does the Email notification system be able to ramp up. So I request suggestions on following lines: What approach should I take in solving the problem described from a programming/Design pattern point of view? Suggestion for any third party plugin/software that can be used to solve the problem described? Points to take care regarding scalability and monitoring the health of the system? Java is the language of preference but I am open to using off the shelf components that can be interfaced with Java language or provide standard ports for communication. Currently I do have an in house grown system (written in Java) that is catering to the specified requirements, but it's now crumbling under increased load and now I want to give the problem a fresh look. thanks in advance Ashish

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  • DENY select on sys.dm_db_index_physical_stats

    - by steveh99999
    Technorati Tags: security,DMV,permission,sys.dm_db_index_physical_stats I recently saw an interesting blog article by Paul Randal about the performance overhead of querying the sys.dm_db_index_physical_stats. So I was thinking, would it be possible to let non-sysadmin users query DMVs on a SQL server but stop them querying this I/O intensive DMV ? Yes it is, here’s how… 1. Create a new login for test purposes, with permissions to access AdventureWorks database only … CREATE LOGIN [test] WITH PASSWORD='xxxx', DEFAULT_DATABASE=[AdventureWorks] GO USE [AdventureWorks] GO CREATE USER [test] FOR LOGIN [test] WITH DEFAULT_SCHEMA=[dbo] GO 2.login as user test and issue command SELECT  * FROM sys.dm_db_index_physical_stats(DB_ID('AdventureWorks'),NULL,NULL,NULL,'DETAILED') gets error :-  Msg 297, Level 16, State 12, Line 1 The user does not have permission to perform this action. 3.As a sysadmin, issue command :- USE AdventureWorks GRANT VIEW DATABASE STATE TO [test] or GRANT VIEW SERVER STATE TO [test] if all databases can be queried via DMV. 4. Try again as user test to issue command SELECT * FROM sys.dm_db_index_physical_stats(DB_ID('AdventureWorks '),NULL,NULL,NULL,'DETAILED') -- now produces valid results from the DMV.. 5 now create the test user in master database, public role only USE master CREATE USER [test] FOR LOGIN [test] 6 issue command :- USE master DENY SELECT ON sys.dm_db_index_physical_stats TO [test] 7 Now go back to AdventureWorks using test login and try SELECT * FROM sys.dm_db_index_physical_stats(DB_ID('AdventureWorks’),NULL,NULL,NULL,’DETAILED') Now gets error... Msg 229, Level 14, State 5, Line 1 The SELECT permission was denied on the object 'dm_db_index_physical_stats', database 'mssqlsystemresource', schema 'sys'. but the user is still able to query all other non-IO-intensive DMVs. If the user attempts to view the index physical stats via a builtin management studio report  – see recent blog post by Pinal Dave they get an error also

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  • storing map template in database

    - by Timigen
    I am working on an application that displays choropleth maps. These maps are of all different types, some display state by county, country by state/province, or world by country. How should I handle storing the map information in the database? My Thoughts: I won't need to do queries to find POI inside a region, so I don't think there is a need to use spatial datatypes. I am considering storing a map as a geoJSON object (I am using JS mapping library that accepts geoJSON). The only issue is what if I want a map of the US northeast. Then I would have geoJSON for the US and a separate one for the US northeast, which would be redundant. Would it make sense to have a shape database where I had each state then when I needed a map of the US I could query for each state, and when I needed a map of the US Northeast I could again query for what I need? Note: I am not concerned with storing the data for each region, just the region itself. I will query for the data on the fly for the specific region.

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  • Handling DataGrid.SelectedItems in an MVVM-friendly manner

    - by Laurent Bugnion
    An interesting question from one of the MVVM Light users today: Is there an MVVM-friendly way to get a DataGrid’s SelectedItems into the ViewModel? The issue there is as old as the DataGrid (that’s not very old but still): SelectedItem (singular) is a DependencyProperty and can be databound to a property in the ViewModel. SelectedItems (plural) is not a DependencyProperty. Thankfully the answer is very simple: Use EventToCommand to call a Command in the ViewModel, and pass the SelectedItems collection as parameter. For example, if the command in the ViewModel is declared as follows:public RelayCommand<IList> SelectionChangedCommand { get; private set; }and (in the MainViewModel constructor):SelectionChangedCommand = new RelayCommand<IList>( items => { if (items == null) { NumberOfItemsSelected = 0; return; } NumberOfItemsSelected = items.Count; }); Then the XAML markup becomes:<sdk:DataGrid x:Name="MyDataGrid" ItemsSource="{Binding Items}"> <i:Interaction.Triggers> <i:EventTrigger EventName="SelectionChanged"> <cmd:EventToCommand Command="{Binding SelectionChangedCommand}" CommandParameter="{Binding SelectedItems, ElementName=MyDataGrid}" /> </i:EventTrigger> </i:Interaction.Triggers> </sdk:DataGrid> I slapped a quick sample and published it here (VS2010, SL4 but the concept works in SL3 and WPF too). Cheers! Laurent Laurent Bugnion (GalaSoft) Subscribe | Twitter | Facebook | Flickr | LinkedIn

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  • Consistency of an object

    - by Stefano Borini
    I tend to keep my objects consistent during their lifetime. In some cases, setting up an object requires multiple calls to different routines. For example, a connection object may operate in this way: Connection c = new Connection(); c.setHost("http://whatever") c.setPort(8080) c.connect() please note this is just a stupid example to let you understand the point. In between calls to setHost and setPort the object is inconsistent, because the Port has not been specified yet, so this code would crash Connection c = new Connection(); c.setHost("http://whatever") c.connect() Meaning that it's a requisite for connect() to have previous calls to both setHost and setPort, otherwise it won't be able to operate as its state is inconsistent. You may fix the issue with a default value, but there may be cases where no sensible default may be devised. We assume in the later example that there's no default for the port, and therefore a call to c.connect() without first calling both setHost and setPort will be an inconsistent state of the object. This, to me, points at an incorrect interface design, but I may be wrong, so I want to hear your opinion. Do you organize your interface so that the object is always in a consistent (i.e. workable) state both before and after the call ? Edit: Please don't try to solve the problem I gave above. I know how to solve that. My question is much broader in sense. I am looking for a design principle, officially or informally stated, regarding consistency of object state between calls.

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  • What are the consequences of immutable classes with references to mutable classes?

    - by glenviewjeff
    I've recently begun adopting the best practice of designing my classes to be immutable per Effective Java [Bloch2008]. I have a series of interrelated questions about degrees of mutability and their consequences. I have run into situations where a (Java) class I implemented is only "internally immutable" because it uses references to other mutable classes. In this case, the class under development appears from the external environment to have state. Do any of the benefits (see below) of immutable classes hold true even by only "internally immutable" classes? Is there an accepted term for the aforementioned "internal mutability"? Wikipedia's immutable object page uses the unsourced term "deep immutability" to describe an object whose references are also immutable. Is the distinction between mutability and side-effect-ness/state important? Josh Bloch lists the following benefits of immutable classes: are simple to construct, test, and use are automatically thread-safe and have no synchronization issues do not need a copy constructor do not need an implementation of clone allow hashCode to use lazy initialization, and to cache its return value do not need to be copied defensively when used as a field make good Map keys and Set elements (these objects must not change state while in the collection) have their class invariant established once upon construction, and it never needs to be checked again always have "failure atomicity" (a term used by Joshua Bloch) : if an immutable object throws an exception, it's never left in an undesirable or indeterminate state

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  • When are Getters and Setters Justified

    - by Winston Ewert
    Getters and setters are often criticized as being not proper OO. On the other hand most OO code I've seen has extensive getters and setters. When are getters and setters justified? Do you try to avoid using them? Are they overused in general? If your favorite language has properties (mine does) then such things are also considered getters and setters for this question. They are same thing from an OO methodology perspective. They just have nicer syntax. Sources for Getter/Setter Criticism (some taken from comments to give them better visibility): http://www.javaworld.com/javaworld/jw-09-2003/jw-0905-toolbox.html http://typicalprogrammer.com/?p=23 http://c2.com/cgi/wiki?AccessorsAreEvil http://www.darronschall.com/weblog/2005/03/no-brain-getter-and-setters.cfm http://www.adam-bien.com/roller/abien/entry/encapsulation_violation_with_getters_and To state the criticism simply: Getters and Setters allow you to manipulate the internal state of objects from outside of the object. This violates encapsulation. Only the object itself should care about its internal state. And an example Procedural version of code. struct Fridge { int cheese; } void go_shopping(Fridge fridge) { fridge.cheese += 5; } Mutator version of code: class Fridge { int cheese; void set_cheese(int _cheese) { cheese = _cheese; } int get_cheese() { return cheese; } } void go_shopping(Fridge fridge) { fridge.set_cheese(fridge.get_cheese() + 5); } The getters and setters made the code much more complicated without affording proper encapsulation. Because the internal state is accessible to other objects we don't gain a whole lot by adding these getters and setters. The question has been previously discussed on Stack Overflow: http://stackoverflow.com/questions/565095/java-are-getters-and-setters-evil http://stackoverflow.com/questions/996179

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  • Netbook performs hard shutdown without warning on low battery power

    - by Steve Kroon
    My Asus EEE netbook performs a hard shutdown when it reaches low battery power, without giving any warning - i.e. the power just goes off, without any shutdown process. I can't find anything in the syslog, and no error messages are printed before it happens. I've had this problem on previous (K)Ubuntu versions, and hoped updating to Ubuntu Precise would help resolve the issue, but it hasn't. The option in the Power application for "when power is critically low" is currently blank - the only options are a (grayed-out) hibernate and "Power off". I have re-installed indicator-power to no effect. The time remaining reported by acpi is unstable, as is the time remaining reported by gnome-power-statistics. (For example, running acpi twice in succession, I got 2h16min, and then 3h21min remaining. These sorts of jumps in the remaining time are also in the gnome-power-statistics graphs.) It might be possible to write a script to give me advance warning (as per @RanRag's comment below), but I would prefer to isolate why I don't get a critical battery notification from the system before this happens, so that I can take action as appropriate (suspend/shutdown/plug in power) when I get a notification. Some additional information on the battery: kroon@minia:~$ upower -i /org/freedesktop/UPower/devices/battery_BAT0 native-path: /sys/devices/LNXSYSTM:00/device:00/PNP0A08:00/PNP0C0A:00/power_supply/BAT0 vendor: ASUS model: 1005P power supply: yes updated: Fri Aug 17 07:31:23 2012 (9 seconds ago) has history: yes has statistics: yes battery present: yes rechargeable: yes state: charging energy: 33.966 Wh energy-empty: 0 Wh energy-full: 34.9272 Wh energy-full-design: 47.52 Wh energy-rate: 3.7692 W voltage: 12.61 V time to full: 15.3 minutes percentage: 97.248% capacity: 73.5% technology: lithium-ion History (charge): 1345181483 97.248 charging 1345181453 97.155 charging 1345181423 97.062 charging 1345181393 96.970 charging History (rate): 1345181483 3.769 charging 1345181453 3.899 charging 1345181423 4.061 charging 1345181393 4.201 charging kroon@minia:~$ cat /proc/acpi/battery/BAT0/state present: yes capacity state: ok charging state: charging present rate: 332 mA remaining capacity: 3149 mAh present voltage: 12612 mV kroon@minia:~$ cat /proc/acpi/battery/BAT0/info present: yes design capacity: 4400 mAh last full capacity: 3209 mAh battery technology: rechargeable design voltage: 10800 mV design capacity warning: 10 mAh design capacity low: 5 mAh cycle count: 0 capacity granularity 1: 44 mAh capacity granularity 2: 44 mAh model number: 1005P serial number: battery type: LION OEM info: ASUS

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  • Implementing game rules in a tactical battle board game

    - by Setzer22
    I'm trying to create a game similar to what one would find in a typical D&D board game combat. For mor examples you could think of games like Advance Wars, Fire Emblem or Disgaea. I should say that I'm using design by component so far, but I can't find a nice way to fit components into the part I want to ask. I'm struggling right now with the "game rules" logic. That is, the code that displays the menu, allows the player to select units, and command them, then tells the unit game objects what to do given the player input. The best way I could thing of handling this was using a big state machine, so everything that could be done in a "turn" is handled by this state machine, and the update code of this state machine does different things depending on the state. This approach, though, leads to a large amount of code (anything not model-related) to go into a big class. Of course I can subdivide this big class into more classes, but it doesn't feel modular and upgradable enough. I'd like to know of better systems to handle this in order to be able to upgrade the game with new rules without having a monstruous if/else chain (or switch / case, for that matter). So, any ideas? I'd also like to ask that if you recommend me a specific design pattern to also provide some kind of example or further explanation and not stick to "Yeah you should use MVC and it'll work".

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  • storing data for maps database

    - by Timigen
    I am working on an application that displays choropleth maps. These maps are of all different types, some display state by county, country by state/province, or world by country. How should I handle storing the map information in the database? My Thoughts: I won't need to do queries to find POI inside a region, so I don't think there is a need to use spatial datatypes. I am considering storing a map as a geoJSON object (I am using JS mapping library that accepts geoJSON). The only issue is what if I want a map of the US northeast. Then I would have geoJSON for the US and a separate one for the US northeast, which would be redundant. Would it make sense to have a shape database where I had each state then when I needed a map of the US I could query for each state, and when I needed a map of the US Northeast I could again query for what I need? Note: I am not concerned with storing the data for each region, just the region itself. I will query for the data on the fly for the specific region.

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  • How to fix a dpkg broken by the Brother MFC-7340 deb driver

    - by Roman A. Taycher
    I'm getting an apt-get error that says E: The package brmfc7340lpr needs to be reinstalled, but I can't find an archive for it. (the brmfc7340lpr is a printer driver) its a local deb file, doing an dpkg or apt-get purge doesn't work, neither does apt-get install -f How do I reinstall a package from a local deb file? P.S. box-name% sudo apt-get upgrade [sudo] password for username: Reading package lists... Done Building dependency tree Reading state information... Done E: The package brmfc7340lpr needs to be reinstalled, but I can't find an archive for it. box-name% sudo apt-get purge brmfc7340lpr Reading package lists... Done Building dependency tree Reading state information... Done E: The package brmfc7340lpr needs to be reinstalled, but I can't find an archive for it. box-name% sudo dpkg --purge brmfc7340lpr dpkg: error processing brmfc7340lpr (--purge): Package is in a very bad inconsistent state - you should reinstall it before attempting a removal. Errors were encountered while processing: brmfc7340lpr box-name% sudo dpkg --install brmfc7340lpr-2.0.2-1.i386.deb Selecting previously deselected package brmfc7340lpr. (Reading database ... 725204 files and directories currently installed.) Preparing to replace brmfc7340lpr 2.0.2-1 (using .../brmfc7340lpr-2.0.2-1.i386.deb) ... Unpacking replacement brmfc7340lpr ... start: Unknown job: lpd dpkg: warning: subprocess old post-removal script returned error exit status 1 dpkg - trying script from the new package instead ... start: Unknown job: lpd dpkg: error processing brmfc7340lpr-2.0.2-1.i386.deb (--install): subprocess new post-removal script returned error exit status 1 start: Unknown job: lpd dpkg: error while cleaning up: subprocess new post-removal script returned error exit status 1 Errors were encountered while processing: brmfc7340lpr-2.0.2-1.i386.deb box-name% sudo apt-get install -f Reading package lists... Done Building dependency tree Reading state information... Done E: The package brmfc7340lpr needs to be reinstalled, but I can't find an archive for it. box-name%

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  • In Scrum, should you split up the backlog in a functional backlog and a technical backlog or not?

    - by Patrick
    In our Scrum teams we use a backlog, which mostly contains functional topics, but also sometimes contains technical topics. The advantage of having 1 backlog is that it becomes easy to choose the topics for the next sprint, but I have some questions: First, to me it seems more logical to have a separate technical backlog, where developers themselves can add pure technical items, like: we could improve performance in this method, this class lacks some technical documentation, ... By having one backlog, all developers always have to pass via the product owner to have their topics added to the backlog, which seems additional, unnecessary work for the product owner. Second, if you have a product owner that only focuses on the pure-functional items, the pure-technical items (like missing technical documentation, code that erodes and should be refactored, classes that always give problems during debugging because they don't have a stable foundation and should be refactored, ...) always end up at the end of the list because "they don't serve the customer directly". By having a separate technical backlog, and time reserved in every sprint for these pure technical items, we can improve the applications functionally, but also keep them healthy inside. What is the best approach? One backlog or two?

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  • Why unhandled exceptions are useful

    - by Simon Cooper
    It’s the bane of most programmers’ lives – an unhandled exception causes your application or webapp to crash, an ugly dialog gets displayed to the user, and they come complaining to you. Then, somehow, you need to figure out what went wrong. Hopefully, you’ve got a log file, or some other way of reporting unhandled exceptions (obligatory employer plug: SmartAssembly reports an application’s unhandled exceptions straight to you, along with the entire state of the stack and variables at that point). If not, you have to try and replicate it yourself, or do some psychic debugging to try and figure out what’s wrong. However, it’s good that the program crashed. Or, more precisely, it is correct behaviour. An unhandled exception in your application means that, somewhere in your code, there is an assumption that you made that is actually invalid. Coding assumptions Let me explain a bit more. Every method, every line of code you write, depends on implicit assumptions that you have made. Take this following simple method, that copies a collection to an array and includes an item if it isn’t in the collection already, using a supplied IEqualityComparer: public static T[] ToArrayWithItem( ICollection<T> coll, T obj, IEqualityComparer<T> comparer) { // check if the object is in collection already // using the supplied comparer foreach (var item in coll) { if (comparer.Equals(item, obj)) { // it's in the collection already // simply copy the collection to an array // and return it T[] array = new T[coll.Count]; coll.CopyTo(array, 0); return array; } } // not in the collection // copy coll to an array, and add obj to it // then return it T[] array = new T[coll.Count+1]; coll.CopyTo(array, 0); array[array.Length-1] = obj; return array; } What’s all the assumptions made by this fairly simple bit of code? coll is never null comparer is never null coll.CopyTo(array, 0) will copy all the items in the collection into the array, in the order defined for the collection, starting at the first item in the array. The enumerator for coll returns all the items in the collection, in the order defined for the collection comparer.Equals returns true if the items are equal (for whatever definition of ‘equal’ the comparer uses), false otherwise comparer.Equals, coll.CopyTo, and the coll enumerator will never throw an exception or hang for any possible input and any possible values of T coll will have less than 4 billion items in it (this is a built-in limit of the CLR) array won’t be more than 2GB, both on 32 and 64-bit systems, for any possible values of T (again, a limit of the CLR) There are no threads that will modify coll while this method is running and, more esoterically: The C# compiler will compile this code to IL according to the C# specification The CLR and JIT compiler will produce machine code to execute the IL on the user’s computer The computer will execute the machine code correctly That’s a lot of assumptions. Now, it could be that all these assumptions are valid for the situations this method is called. But if this does crash out with an exception, or crash later on, then that shows one of the assumptions has been invalidated somehow. An unhandled exception shows that your code is running in a situation which you did not anticipate, and there is something about how your code runs that you do not understand. Debugging the problem is the process of learning more about the new situation and how your code interacts with it. When you understand the problem, the solution is (usually) obvious. The solution may be a one-line fix, the rewrite of a method or class, or a large-scale refactoring of the codebase, but whatever it is, the fix for the crash will incorporate the new information you’ve gained about your own code, along with the modified assumptions. When code is running with an assumption or invariant it depended on broken, then the result is ‘undefined behaviour’. Anything can happen, up to and including formatting the entire disk or making the user’s computer sentient and start doing a good impression of Skynet. You might think that those can’t happen, but at Halting problem levels of generality, as soon as an assumption the code depended on is broken, the program can do anything. That is why it’s important to fail-fast and stop the program as soon as an invariant is broken, to minimise the damage that is done. What does this mean in practice? To start with, document and check your assumptions. As with most things, there is a level of judgement required. How you check and document your assumptions depends on how the code is used (that’s some more assumptions you’ve made), how likely it is a method will be passed invalid arguments or called in an invalid state, how likely it is the assumptions will be broken, how expensive it is to check the assumptions, and how bad things are likely to get if the assumptions are broken. Now, some assumptions you can assume unless proven otherwise. You can safely assume the C# compiler, CLR, and computer all run the method correctly, unless you have evidence of a compiler, CLR or processor bug. You can also assume that interface implementations work the way you expect them to; implementing an interface is more than simply declaring methods with certain signatures in your type. The behaviour of those methods, and how they work, is part of the interface contract as well. For example, for members of a public API, it is very important to document your assumptions and check your state before running the bulk of the method, throwing ArgumentException, ArgumentNullException, InvalidOperationException, or another exception type as appropriate if the input or state is wrong. For internal and private methods, it is less important. If a private method expects collection items in a certain order, then you don’t necessarily need to explicitly check it in code, but you can add comments or documentation specifying what state you expect the collection to be in at a certain point. That way, anyone debugging your code can immediately see what’s wrong if this does ever become an issue. You can also use DEBUG preprocessor blocks and Debug.Assert to document and check your assumptions without incurring a performance hit in release builds. On my coding soapbox… A few pet peeves of mine around assumptions. Firstly, catch-all try blocks: try { ... } catch { } A catch-all hides exceptions generated by broken assumptions, and lets the program carry on in an unknown state. Later, an exception is likely to be generated due to further broken assumptions due to the unknown state, causing difficulties when debugging as the catch-all has hidden the original problem. It’s much better to let the program crash straight away, so you know where the problem is. You should only use a catch-all if you are sure that any exception generated in the try block is safe to ignore. That’s a pretty big ask! Secondly, using as when you should be casting. Doing this: (obj as IFoo).Method(); or this: IFoo foo = obj as IFoo; ... foo.Method(); when you should be doing this: ((IFoo)obj).Method(); or this: IFoo foo = (IFoo)obj; ... foo.Method(); There’s an assumption here that obj will always implement IFoo. If it doesn’t, then by using as instead of a cast you’ve turned an obvious InvalidCastException at the point of the cast that will probably tell you what type obj actually is, into a non-obvious NullReferenceException at some later point that gives you no information at all. If you believe obj is always an IFoo, then say so in code! Let it fail-fast if not, then it’s far easier to figure out what’s wrong. Thirdly, document your assumptions. If an algorithm depends on a non-trivial relationship between several objects or variables, then say so. A single-line comment will do. Don’t leave it up to whoever’s debugging your code after you to figure it out. Conclusion It’s better to crash out and fail-fast when an assumption is broken. If it doesn’t, then there’s likely to be further crashes along the way that hide the original problem. Or, even worse, your program will be running in an undefined state, where anything can happen. Unhandled exceptions aren’t good per-se, but they give you some very useful information about your code that you didn’t know before. And that can only be a good thing.

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  • What data to send when tracking clicks with Google Analytics events (and how)?

    - by user359650
    When tracking clicks on links, there are 3 items I'm interested in: link location in the page by grabbing the id of the closest parent: to see influence of location on click-through link text: to see influence of text on click-through link href attribute value: to see where people go when leaving my website The problem when using Google Analytics to track those clicks is that events only have 3 available text fields, one of which being the category, which if you use to store one of the above items will create a mess in your Event reporting because you will have as many categories as item values. Therefore if you assign a predefined value to the category (e.g. clicks), then you're left with only 2 event fields (action, label) to store 3 items (location, text, href). That in itself isn't the end of the world because you can concatenate 2 items into 1 event field, then use the reporting or the API to filter things out. Accordingly what I plan on doing is this: category: clicks action: {location_on_page} ¦ {text} label: {href} where {__} are variable values related to the clicked links With this I can easily create some reports directly via the GUI: downloads: include only events where label ends with .pdf click outs to particular domains: include only events where label contains domain And for more complex tasks I need to export the data (or use the API): influence of location on clicks: for each location in the design, count number of events that have that location in the action, then corroborate with pageviews of the corresponding pages. Whilst this looks good I'm wondering if there is a better approach, hence the following questions: Q1: Can you foresee any particular issues with this particular setup (e.g. things I won't be able to report on)? Q2: Can you think of other data that would be interesting to include in the event?

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  • Software design of a browser-based strategic MMO game

    - by Mehran
    I wonder if there are any known tested software designs for Travian-like browser-based strategic MMO games? I mean how would they implement the server of such games or what is stored in database and what is stored in RAM? Is the state of the world stored in one piece or is it distributed among a number of storage? Does anyone know a resource to study the problems and solutions of creating such games? [UPDATE] Suggested in comments, I'm going to give an example how would I design such a project. Even though I'm not sure if I'm proposing the right one. Having stored the world state in a MongoDB, I would implement an event collection in which all the changes to the world will register. Changes that are meant to happen in the future will come with an action date set to the future and those that are to be carried out immediately will be set to now. Having this datastore as the central point of the system, players will issue their actions as events inserted in datastore. At the other end of the system, I'll have a constant-running software taking out events out of the datastore which are due to be carried out and not done yet. Executing an event means apply some update on the world's state and thus the datastore. As scalable as this design sounds, I'm not sure if it will be worth implementing. For one, it is pointless to cache the datastore as most of updates happen once without any follow ups. For instance if you have the growth of resources in your game, you'll be updating the whole world state periodically in which case, having incorporated a cache, you are keeping the whole world in RAM (which most likely is impossible). So can someone come up with a better design?

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  • Producer-consumer pattern with consumer restrictions

    - by Dan
    I have a processing problem that I am thinking is a classic producer-consumer problem with the two added wrinkles that there may be a variable number of producers and there is the restriction that no more than one item per producer may be consumed at any one time. I will generally have 50-100 producers and as many consumers as CPU cores on the server. I want to maximize the throughput of the consumers while ensuring that there are never more than one work item in process from any single producer. This is more complicated than the classic producer-consumer problem which I think assumes a single producer and no restriction on which work items may be in progress at any one time. I think the problem of multiple producers is relatively easily solved by enqueuing all work items on a single work queue protected by a critical section. I think the restriction on simultaneously processing work items from any single producer is harder because I cannot think of any solution that does not require each consumer to notify some kind of work dispatcher that a particular work item has been completed so as to lift the restriction on work items from that producer. In other words, if Consumer2 has just completed WorkItem42 from Producer53, there needs to be some kind of callback or notification from Consumer2 to a work dispatcher to allow the work dispatcher to release the next work item from Producer53 to the next available consumer (whether Consumer2 or otherwise). Am I overlooking something simple here? Is there a known pattern for this problem? I would appreciate any pointers.

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  • Use Your Android Phone to Comparison Shop: 4 Scanner Apps Reviewed

    - by Jason Fitzpatrick
    A smart phone in your pocket is great for on the go news, web browsing, and—of course—mobile gaming. It’s also fantastic for comparison shopping. Today we take a look at four Android scanners and price comparison engines. It’s quite a neat time to be a consumer. Historically if you wanted to do serious price comparisons you had to haul yourself around town, gather flyers from the newspapers, and otherwise invest way too much energy into potential savings that might not even break into double digits. Now you can comparison shop with an ease that borders on magic: by simply pulling out your smart phone and scanning the barcode or typing in the name of the item you wish to compare. Today we’re taking a look at some of the more popular and powerful barcode scanners and price comparison engines available for the Android platform. Before we get to that, a word on our methodology. To test the barcode scanners and the resulting search results we wandered around and rounded up some relatively random items from around the How-To Geek offices. This included a children’s graphic novel, a Wii game, a board game, a pack of razors, a box of tea, and a bottle of nail polish. It’s a decent spread of consumer items that covers several genres. For each application we scanned all the items, looked for the best price at the time, and noted any other relevant benefits of using one scanner over another. It’s worth noting that our primary focus was on the speed and ease of use. You may find that certain scanners have specific features that best suit your needs. What we focused on was how fast you could scan, compare prices, and purchase items if you desired. Since all the scanners are free-as-in-beer, feel free to download them all and run your own tests to confirm our conclusions. Use Your Android Phone to Comparison Shop: 4 Scanner Apps Reviewed How to Run Android Apps on Your Desktop the Easy Way HTG Explains: Do You Really Need to Defrag Your PC?

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  • Turn-based Client-Server Card Game - Unicast (TCP) or Multicast (UDP)

    - by LDM91
    I am currently planning to make a card game project where the clients will communicate with the server in a turn-based and synchronous manner using messages sent over sockets. The problem I have is how to handle the following scenario: (Client takes it turn and sends its action to server) Client sends a message telling the server its move for the turn (e.g. plays the card 5 from its hand which needs to placed onto the table) Server receives messages and updates game state (server will hold all game state). Server iterates through a list of connected clients and sends a message to tell of them change in state Clients all refresh to display the state This is all based on using TCP, and looking at it now it seems a bit like the Observer pattern. The reason this seems to be an issue to me is this message doesn't seem to be point-to-point like the others as I want to send it to all the clients, and doesn't seem very efficient sending the same message in that way. I was thinking about using multicasting with UDP as then I could send the message to all the clients, however wouldn't this mean that the clients would in theory be able to message each other? There is of course the synchronous aspect as well, though this could be put on top of the UDP I guess. Basically, I would like to know what would be good practice as this project is really all about learning, and even though it won't be big enough to encounter performance issues from this I would like to consider them anyway. However, please note I am not interested in using message oriented middleware as a solution (I have experience with using MOM and I'm interested in considering other options excluding MOM if TCP sockets is a bad idea!).

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