我一直在阅读这篇关于闭包的文章,他们说:
所以我根据他们的代码做了一个例子,对我而言,闭包似乎就像常规的命名方法一样,也"无需担心地处理局部变量",其中"所有的管道都是自动的".
或者这个"局部变量的包装"解决了什么问题,使得闭包如此特殊/有趣/有用？
using System;
namespace TestingLambda2872
{
class Program
{
static void Main(string[] args)
{
Func<int, int> AddToIt = AddToItClosure();
Console.WriteLine("the result is {0}", AddToIt(3)); //returns 30
Console.ReadLine();
}
public static Func<int, int> AddToItClosure()
{
int a = 27;
Func<int, int> func = s => s + a;
return func;
}
}
}
所以这个问题的答案就是阅读Jon Skeet关于 Marc指出的闭包的文章.本文不仅展示了在C#中导致lambda表达式的演变,还展示了如何在Java中处理闭包,这是本主题的优秀读物.
在我的视图中,我有一个按钮.
当用户单击此按钮时,我希望ViewModel在数据库中保存TextBlock的上下文.
<StackPanel HorizontalAlignment="Left" VerticalAlignment="Top">
<TextBlock Text="{Binding FirstName}"/>
<TextBox Text="Save this text to the database."/>
<Button Content="Save" Command="{Binding SaveCommand}"/>
</StackPanel>
但是,在我的ViewModel中的DelegateCommand中,"Save()"方法不传递任何参数,那么如何从视图中获取数据呢？
#region DelegateCommand: Save
private DelegateCommand saveCommand;
public ICommand SaveCommand
{
get
{
if (saveCommand == null)
{
saveCommand = new DelegateCommand(Save, CanSave);
}
return saveCommand;
}
}
private void Save()
{
TextBox textBox = ......how do I get the value of the view's textbox from here?....
}
private bool CanSave()
{
return true;
}
#endregion
有没有人知道使用Prism的WPF代码示例,其中每个模块在另一个模块的菜单中将自己注册为menuitem？
(我目前有一个应用程序尝试使用EventAggregator执行此操作,因此一个模块侦听来自其他模块的已发布事件,这些模块需要在菜单中将其标题作为菜单项,但我遇到了订单问题加载和线程等我想找到一个使用经典Prism结构来做这个的例子.)
我在考虑这个问题:
Shell.xaml:
<DockPanel>
<TextBlock Text="Menu:" DockPanel.Dock="Top"/>
<Menu
Name="MenuRegion"
cal:RegionManager.RegionName="MenuRegion"
DockPanel.Dock="Top"/>
</DockPanel>
合同视图:
<UserControl x:Class="ContractModule.Views.AllContracts"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
<MenuItem Header="Contracts">
</MenuItem>
</UserControl>
客户观点:
<UserControl x:Class="CustomerModule.Views.CustomerView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
<MenuItem Header="Customers">
</MenuItem>
</UserControl>
但是要知道我已经完成了非Prism MVVM应用程序结构,并且Menus总是很好地绑定到ViewModel中的ObservableCollections,上面似乎打破了这个漂亮的模式.以上是在Prism中做到这一点的习惯方式吗？
在网页设计过程中进行颜色选择时,我使用免费的在线工具,如ColorSchemer,其中我:
这使我的设计看起来比我从色轮中自由选择颜色更好.
但除了这种简单的方法之外,使用这些工具制作更专业的色彩决策的最佳策略是什么？
在下面的例子中,我如何轻松转换eventScores为List<int>可以将其用作参数prettyPrint？
Console.WriteLine("Example of LINQ's Where:");
List<int> scores = new List<int> { 1,2,3,4,5,6,7,8 };
var evenScores = scores.Where(i => i % 2 == 0);
Action<List<int>, string> prettyPrint = (list, title) =>
{
Console.WriteLine("*** {0} ***", title);
list.ForEach(i => Console.WriteLine(i));
};
scores.ForEach(i => Console.WriteLine(i));
prettyPrint(scores, "The Scores:");
foreach (int score in evenScores) { Console.WriteLine(score); }
以下代码给出了这个错误:
无法从'System.Collections.Generic.List'转换为'System.Collections.Generic.List'.
如何向编译器指出Customer确实从对象继承？或者它只是不与泛型集合对象继承(发送List<string>获取相同的错误).
using System.Collections.Generic;
using System.Windows;
using System.Windows.Documents;
namespace TestControl3423
{
public partial class Window2 : Window
{
public Window2()
{
InitializeComponent();
List<Customer> customers = Customer.GetCustomers();
FillSmartGrid(customers);
//List<CorporateCustomer> corporateCustomers = CorporateCustomer.GetCorporateCustomers();
//FillSmartGrid(corporateCustomers);
}
public void FillSmartGrid(List<object> items)
{
//do reflection on items and display dynamically
}
}
public class Customer
{
public string FirstName { get; set; }
public string LastName { get; set; }
public string Street { get; set; }
public string Location { …在下面的XAML中,单词"Test" 水平居中但不垂直居中.
如何让它垂直居中？
<Window x:Class="TestVerticalAlign2343.Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
WindowStartupLocation="CenterScreen"
Title="Window1" Height="768" Width="1024">
<DockPanel LastChildFill="True">
<Slider x:Name="TheSlider"
DockPanel.Dock="Left"
Orientation="Vertical"
HorizontalAlignment="Center"
HorizontalContentAlignment="Center"
Minimum="0"
Maximum="10"
Cursor="Hand"
Value="{Binding CurrentSliderValue}"
IsDirectionReversed="True"
IsSnapToTickEnabled="True"
Margin="10 10 0 10"/>
<Border DockPanel.Dock="Right" Background="Beige"
Padding="10"
Margin="10"
CornerRadius="5">
<StackPanel Height="700">
<TextBlock
Text="Test"
HorizontalAlignment="Center"
VerticalAlignment="Center"
FontSize="200" x:Name="TheNumber"/>
</StackPanel>
</Border>
</DockPanel>
</Window>
在下面的示例代码中,我收到此错误:
Element TestSerializeDictionary123.Customer.CustomProperties vom Typ System.Collections.Generic.Dictionary`2 [[System.String,mscorlib,Version = 2.0.0.0,Culture = neutral,PublicKeyToken = b77a5c561934e089],[System.Object,mscorlib,Version = 2.0 .0.0,Culture = neutral,PublicKeyToken = b77a5c561934e089]]无法序列化,因为它实现了IDictionary.
当我取出Dictionary属性时,它工作正常.
如何使用字典属性序列化此Customer对象？或者我可以使用哪种替换类型的Dictionary可序列化？
using System;
using System.Collections.Generic;
using System.Xml.Serialization;
using System.IO;
using System.Xml;
using System.Text;
namespace TestSerializeDictionary123
{
public class Program
{
static void Main(string[] args)
{
List<Customer> customers = Customer.GetCustomers();
Console.WriteLine("--- Serializing ------------------");
foreach (var customer in customers)
{
Console.WriteLine("Serializing " + customer.GetFullName() + "...");
string xml = XmlHelpers.SerializeObject<Customer>(customer);
Console.WriteLine(xml);
Console.WriteLine("Deserializing ...");
Customer customer2 = XmlHelpers.DeserializeObject<Customer>(xml); …这有效:
XAML:
<Window x:Class="Test239992.Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="Window1" Height="300" Width="300">
<StackPanel>
<TextBlock Tag="1" Text="Customers" MouseDown="Handle_Click"/>
<TextBlock Tag="2" Text="Appointments" MouseDown="Handle_Click"/>
</StackPanel>
</Window>
代码背后:
using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;
namespace Test239992
{
public partial class Window1 : Window
{
public Window1()
{
InitializeComponent();
}
private void Handle_Click(object sender, MouseButtonEventArgs e)
{
int id = Int32.Parse(((TextBlock)sender).Tag.ToString());
MessageBox.Show("you chose id " + id.ToString());
}
}
}
但是我如何将MouseDown事件放在一个样式中,这给了我错误 "无法在类型'System.Windows.Controls.TextBlock'上找到样式属性'MouseDown'":
<Window x:Class="Test239992.Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="Window1" Height="300" Width="300">
<Window.Resources>
<Style TargetType="{x:Type TextBlock}" …WPF应用程序中的以下代码创建一个超链接,其外观和行为类似于超链接,但在单击时不执行任何操作.
我需要更改什么,以便当我单击它时,它会打开默认浏览器并转到指定的URL？
替代文字http://www.deviantsart.com/upload/4fbnq2.png
XAML:
<Window x:Class="TestLink238492.Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="Window1" Height="300" Width="300">
<StackPanel Margin="10">
<ContentControl x:Name="MainArea"/>
</StackPanel>
</Window>
代码背后:
using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
namespace TestLink238492
{
public partial class Window1 : Window
{
public Window1()
{
InitializeComponent();
FlowDocumentScrollViewer fdsv = new FlowDocumentScrollViewer();
FlowDocument doc = new FlowDocument();
fdsv.Document = doc;
fdsv.VerticalScrollBarVisibility = ScrollBarVisibility.Hidden;
doc.PagePadding = new Thickness(0);
Paragraph paragraph = new Paragraph();
doc.Blocks.Add(paragraph);
Run run = new Run("this is flow document …c# ×6
wpf ×4
action ×1
bootstrapper ×1
closures ×1
colors ×1
containers ×1
css ×1
dictionary ×1
flowdocument ×1
func ×1
generics ×1
html ×1
hyperlink ×1
layout ×1
linq ×1
mvvm ×1
prism ×1
stackpanel ×1
styles ×1
xaml ×1