将代码转换为.net 4.5 [英] Convert Code to .net 4.5

问题描述

这个空条件？运营商。我们如何将其转换回4.5代码

Having this null conditional ?. operator. How can we convert it back to 4.5 code

//How to convert this Function to .net 4.5 version..Code was shortend for clarity

return this.Children?.Count(f => f != null) > 0;

public ObservableCollection<DirectoryItemViewModel> Children {
 get
{
  return _Children;
}
            
set
{
  _Children = value;                
}
}

推荐答案

两个选项。

首先使用条件表达式执行相同的条件运算符行为：

First use a conditional expression doing the same conditional operator behavior:

return this.Children != null ? this.Children.Count(f=>f!=null) > 0 : false;

其次，保护您的Children属性不受null：

Second, protect your Children property against the null:

return this.Children.Count(f => f != null) > 0;

public ObservableCollection<DirectoryItemViewModel> Children {
 get
{
  return _Children ?? Enumerable.Empty<DirectoryItemViewModel>();
}
            
set
{
  _Children = value;                
}
}

Personaly，我更喜欢第二种，因为每次我需要Children属性时，我都不需要保护我的代码免受null 。

Personaly, I prefer the second because each time I need the Children property I don't need to protect my code against the null.

问候，

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