编写MVVM样板代码的更好方法? [英] A better way to write MVVM boilerplate code?

问题描述

我最近发现自己编写了许多样板MVVM代码，并且想知道是否有一种花哨的方法可以解决所有这些问题?我已经使用了实现INotifyPropertyChanged的ViewModelBase类，但是并不能解决必须编写所有访问器代码等问题.也许通过编写执行此操作的自定义属性或通过模板系统来实现?

I have found myself recently writing a lot of boilerplate MVVM code and wonder if there is a fancy way to get around writing it all? I already use a ViewModelBase class that implements INotifyPropertyChanged but that doesnt solve the problem of having to write all the accessor code etc. Perhaps by writing a custom attribute that does this, or via a templating system?

public MyClass : ViewModelBase
{
    private int someVariable;

    public int SomeVariable
    {
        get
        {
            return this.someVariable;
        }

        set
        {
            this.someVariable = value;
            this.NotifyPropertyChanged("SomeVariable");
        }
    }
}

推荐答案

我有一个代码段，可用于创建视图模型属性.这个特定的代码段使用了其他评论者所暗示的Expression<Func<T>>表示法.

I have a snippet that i use to create my view model properties. This particular snippet uses the Expression<Func<T>> notation that other commenters have hinted upon.

<?xml version="1.0" encoding="utf-8"?>
<CodeSnippets xmlns="http://schemas.microsoft.com/VisualStudio/2005/CodeSnippet">
  <CodeSnippet Format="1.0.0">
    <Header>
      <SnippetTypes>
        <SnippetType>Expansion</SnippetType>
      </SnippetTypes>
      <Title>View Model Property</Title>
      <Description>
          Declares a property and member suitable for Viewmodel implementation.
      </Description>
      <HelpUrl>
      </HelpUrl>
      <Shortcut>propvm</Shortcut>
    </Header>
    <Snippet>
      <Declarations>
        <Literal Editable="true">
          <ID>propname</ID>
          <ToolTip>Property Name</ToolTip>
          <Default>Name</Default>
          <Function>
          </Function>
        </Literal>
        <Literal Editable="true">
          <ID>type</ID>
          <ToolTip>Property type.</ToolTip>
          <Default>Type</Default>
          <Function>
          </Function>
        </Literal>
        <Literal Editable="true">
          <ID>init</ID>
          <ToolTip>Member initialisation</ToolTip>
          <Default>null</Default>
          <Function>
          </Function>
        </Literal>
      </Declarations>
      <Code Language="csharp" Kind="type decl"><![CDATA[public $type$ $propname$
{
    get { return m_$propname$; }
    set 
    { 
        m_$propname$ = value;
        base.OnPropertyChanged(() => $propname$);
    }
} $type$ m_$propname$ = default($type$);$end$]]></Code>
    </Snippet>
  </CodeSnippet>
</CodeSnippets>

注意对base.PropertyChanged()的呼叫.我有一个ViewModelBase类来为我做繁重的属性通知和验证.

Note the call to base.PropertyChanged(). I have a ViewModelBase class to do the heavy lifting of property notification and validation for me.

用法是这样

1. 键入propvm
2. 打 TAB 两次
3. 填写突出显示的字段，然后按Tab键翻到下一个！

1. Type propvm
2. Hit TAB twice
3. Fill in the highlighted field and press tab to flip to the next one!

演练:创建代码段

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