ObservableCollection 属性类 [英] ObservableCollection Property Class

问题描述

我在我的 MVVM 项目中多次重复这个属性.创建通用类或工厂来替换这些代码行的正确方法是什么?

I repeat this property in my MVVM project too many times to count. What would be the correct way to create a generic class or factory to replace these lines of code?

    ObservableCollection<Result> _resultCollection;
    public ObservableCollection<Result> ResultCollection
    {
        get
        {
            if (_resultCollection == null)
                _resultCollection = new ObservableCollection<Result>();
            return _resultCollection;
        }
        set
        {
            _resultCollection = value;
        }
    }

推荐答案

我知道这并不能完全回答您的问题，但我个人更喜欢在 Visual Studio 中使用录制的宏，它为我编写了所有内容.

I know this doesn't exactly answer your question, however personally I prefer to use a recorded macro in Visual Studio that writes all that for me.

我更喜欢使用它而不是通用类，因为它将所有相关代码保存在一个地方，并且很容易理解发生了什么.通常，我将所有私有字段放在类的顶部，并将所有公共属性隐藏在 #region 标记中，我一直折叠该标记，因此我不需要滚动浏览它们.

I prefer using this to a generic class as it keeps all the relevant code in one place, and it's easy to understand what is going on. Typically I put all my private Fields at the top of my class, and hide all the public Properties in a #region tag that I keep collapsed so I don't need to scroll through them.

在 VS 中创建宏相当容易:只需转到工具">宏">记录临时宏"，然后仅使用键盘执行所需的更改.一旦您的宏正常工作，只需将其保存为永久宏.如果你做得对，你可以用任何变量重新运行宏，它会以同样的方式构建它.

It's fairly easy to create a macro in VS: Simply go to Tools > Macros > Record Temporary Macro, then perform the changes you want using the keyboard only. Once you have the Macro working correctly, simply save it as a permanent macro. If you do it right, you can re-run the macro with any variable and it will build it out the same way.

创建宏时要记住的一些有用的键盘快捷键是:

Some useful keyboard shortcuts to remember when creating macros are:

• Ctrl+C/Ctrl+V 复制/粘贴
• Ctrl+Right/Ctrl+Left 移动一个词
• Home/End 移动到行首或行尾
• Shift 用于在移动光标时突出显示单词

• Ctrl+C/Ctrl+V to copy/paste
• Ctrl+Right/Ctrl+Left to move over a word
• Home/End to move to the beginning or end of a line
• Shift for highlighting words as you move the cursor

您可能还需要对 VB 宏代码进行一些小的修改，例如使用 .Replace() 将小写字母变为大写.

You may also need to do some minor modifications to the VB macro code, such as a .Replace() to turn lowercase letters to capitals.

这是我用来为 MVVM 构建所有公共属性的示例宏.它使用 PRISM 库，因此它使用语法 RaisePropertyChanged(() => this.SomeProperty);

Here's an example Macro I use to build out all my public Properties for MVVM. It uses the PRISM library, so it uses the syntax RaisePropertyChanged(() => this.SomeProperty);

Sub PRISM_BuildPropertyChanged_CursorAtDefaultAfterCtrlRE()
    DTE.ActiveDocument.Selection.LineDown(False, 2)
    DTE.ActiveDocument.Selection.WordLeft(True)
    DTE.ActiveDocument.Selection.Copy()
    DTE.ActiveDocument.Selection.LineDown(False, 3)
    DTE.ActiveDocument.Selection.EndOfLine()
    DTE.ActiveDocument.Selection.CharLeft()
    DTE.ActiveDocument.Selection.NewLine()
    DTE.ActiveDocument.Selection.Text = "RaisePropertyChanged(() => this."
    DTE.ActiveDocument.Selection.Paste()
    DTE.ActiveDocument.Selection.Text = ");"
    DTE.ActiveDocument.Selection.LineUp()
    DTE.ActiveDocument.Selection.StartOfLine(vsStartOfLineOptions.vsStartOfLineOptionsFirstText)
    DTE.ActiveDocument.Selection.CharRight(False, 4)
    DTE.ActiveDocument.Selection.NewLine()
    DTE.ActiveDocument.Selection.CharRight()
    DTE.ActiveDocument.Selection.NewLine()
    DTE.ActiveDocument.Selection.Text = "if (value != "
    DTE.ActiveDocument.Selection.WordRight(True)
    DTE.ActiveDocument.Selection.Copy()
    DTE.ActiveDocument.Selection.CharLeft()
    DTE.ActiveDocument.Selection.Paste()
    DTE.ActiveDocument.Selection.DeleteLeft()
    DTE.ActiveDocument.Selection.Text = ")"
    DTE.ActiveDocument.Selection.NewLine()
    DTE.ActiveDocument.Selection.Text = "{"
    DTE.ActiveDocument.Selection.LineDown()
    DTE.ActiveDocument.Selection.EndOfLine()
    DTE.ActiveDocument.Selection.NewLine()
    DTE.ActiveDocument.Selection.Text = "}"
End Sub

有了它，我就可以写我的私有定义了，比如

With it, I can write my private definition, such as

private ObservableCollection<SomeObject> _someCollection;

点击Ctrl+R、E来构建公共属性定义

Hit Ctrl+R, E to build the public property definition

private ObservableCollection<SomeObject> _someCollection;

public ObservableCollection<SomeObject> SomeCollection
{
    get { return _someCollection; }
    set { _someCollection = value; }
}

然后运行我的宏来构建属性更改通知

Then run my Macro to build out the Property Change notification

public ObservableCollection<SomeObject> SomeCollection
{
    get { return _someCollection; }
    set 
    {
        if (value != _someCollection)
        {
            _someCollection = value;
            RaisePropertyChanged(() => this.SomeCollection);
        }
    }
}

(默认情况下，Ctrl+R、E 将光标放在私有字段定义的末尾，因此这是运行此命令时光标需要位于的位置宏)

(By default, Ctrl+R, E puts the cursor at the end of the private field definition, so that is where the cursor needs to be when running this macro)

我还有另一个旧宏，它添加代码来检查值是否为空，如果是，则将其设置为对象的新实例，但我从未使用过它，因为我更喜欢在构造函数而不是在属性定义中.

I also have another old macro that adds code that checks if the value is null, and if so sets it to a new instance of the object, but its one I never used much since I prefer to set my default definitions in the Constructor instead of in the Property definition.

如果需要，它看起来像这样(注意宏名称 - 在运行此宏之前，您需要突出显示公共属性名称):

If you want it, it looks like this (note the Macro name - You need to highlight the public property name prior to running this macro):

Sub CreatePublicGet_NoNull_HightlightPropertyNameFirst()
    DTE.ActiveDocument.Selection.CharLeft(False, 2)
    DTE.ActiveDocument.Selection.StartOfLine(vsStartOfLineOptions.vsStartOfLineOptionsFirstText, True)
    DTE.ActiveDocument.Selection.WordRight(True)
    DTE.ActiveDocument.Selection.Copy()
    DTE.ActiveDocument.Selection.LineDown(False, 2)
    DTE.ActiveDocument.Selection.StartOfLine(vsStartOfLineOptions.vsStartOfLineOptionsFirstText)
    DTE.ActiveDocument.Selection.CharRight(False, 4)
    DTE.ActiveDocument.Selection.NewLine()
    DTE.ActiveDocument.Selection.CharRight()
    DTE.ActiveDocument.Selection.NewLine()
    DTE.ActiveDocument.Selection.EndOfLine()
    DTE.ActiveDocument.Selection.CharLeft()
    DTE.ActiveDocument.Selection.NewLine()
    DTE.ActiveDocument.Selection.LineUp(False, 2)
    DTE.ActiveDocument.Selection.EndOfLine()
    DTE.ActiveDocument.Selection.NewLine()
    DTE.ActiveDocument.Selection.Paste()
    DTE.ActiveDocument.Selection.Text = "();"
    DTE.ActiveDocument.Selection.LineDown()
    DTE.ActiveDocument.Selection.WordLeft(True)
    DTE.ActiveDocument.Selection.CharLeft()
    DTE.ActiveDocument.Selection.WordLeft(True)
    DTE.ActiveDocument.Selection.Copy()
    DTE.ActiveDocument.Selection.LineUp(False, 2)
    DTE.ActiveDocument.Selection.NewLine()
    DTE.ActiveDocument.Selection.Text = "if ("
    DTE.ActiveDocument.Selection.Paste()
    DTE.ActiveDocument.Selection.Text = " == null)"
    DTE.ActiveDocument.Selection.NewLine()
    DTE.ActiveDocument.Selection.Text = "{"
    DTE.ActiveDocument.Selection.LineDown()
    DTE.ActiveDocument.Selection.StartOfLine(vsStartOfLineOptions.vsStartOfLineOptionsFirstText)
    DTE.ActiveDocument.Selection.EndOfLine()
    DTE.ActiveDocument.Selection.NewLine()
    DTE.ActiveDocument.Selection.Text = "}"
    DTE.ActiveDocument.Selection.LineUp()
    DTE.ActiveDocument.Selection.StartOfLine(vsStartOfLineOptions.vsStartOfLineOptionsFirstText)
    DTE.ActiveDocument.Selection.Paste()
    DTE.ActiveDocument.Selection.Text = " = new "
    DTE.ActiveDocument.Selection.Collapse()
    DTE.ActiveDocument.Selection.EndOfLine()
    DTE.ActiveDocument.Selection.LineDown(False, 4)
    DTE.ActiveDocument.Selection.EndOfLine()
    DTE.ActiveDocument.Selection.LineUp(True)
    DTE.ActiveDocument.Selection.Delete()
End Sub

导致代码如下所示:

public ObservableCollection<SomeObject> SomeCollection
{
    get 
    {
        if (_someCollection == null)
        {
            _someCollection = new ObservableCollection<SomeObject>();
        }
        return _someCollection; 
    }
}

这篇关于ObservableCollection 属性类的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！