C# 对象初始化可以简化

通过我的代码，我收到了3条信息，都说

对象初始化可以简化
，在我对知识（和OCD）日益增长的渴望中，我想“修复”我的代码，这样这些信息就不会出现。我知道我可以设置它，这样这些信息就不会出现，但我的脑海中仍然会有这样的想法：它们就在背景中，而不是坐在我身边。如果有人能指出如何“简化初始化”，那就太好了，这样我就可以提高自己的技能。如果需要更多的代码，让我知道，我可以添加它

1st:

TreeNode node = new TreeNode(drive.Substring(0, 1), driveImage, driveImage);//issue on this line
node.Tag = drive;

DirectoryInfo di = new DirectoryInfo(dir);
TreeNode node = new TreeNode(di.Name, 0, 1); //this line

OleDbCommand select = new OleDbCommand();//this line
select.Connection = cnDTC;
select.CommandText = string.Format("SELECT MAX(VERSION_NO) AS MAX_VERSION FROM ({0})", strSQL2);

var node = new TreeNode(drive.Substring(0, 1), driveImage, driveImage) {
    Tag = drive
};

OleDbCommand select = new OleDbCommand();//this line
select.Connection = cnDTC;
select.CommandText = string.Format("SELECT MAX(VERSION_NO) AS MAX_VERSION FROM ({0})",
      strSQL2);

var select = new OleDbCommand(
      String.Format("SELECT MAX(VERSION_NO) AS MAX_VERSION FROM ({0})", strSQL2), 
      cnDTC);

var select = new OleDbCommand($"SELECT MAX(VERSION_NO) AS MAX_VERSION FROM ({strSQL2})", 
      cnDTC);

第二名：

TreeNode node = new TreeNode(drive.Substring(0, 1), driveImage, driveImage);//issue on this line
node.Tag = drive;

DirectoryInfo di = new DirectoryInfo(dir);
TreeNode node = new TreeNode(di.Name, 0, 1); //this line

OleDbCommand select = new OleDbCommand();//this line
select.Connection = cnDTC;
select.CommandText = string.Format("SELECT MAX(VERSION_NO) AS MAX_VERSION FROM ({0})", strSQL2);

var node = new TreeNode(drive.Substring(0, 1), driveImage, driveImage) {
    Tag = drive
};

OleDbCommand select = new OleDbCommand();//this line
select.Connection = cnDTC;
select.CommandText = string.Format("SELECT MAX(VERSION_NO) AS MAX_VERSION FROM ({0})",
      strSQL2);

var select = new OleDbCommand(
      String.Format("SELECT MAX(VERSION_NO) AS MAX_VERSION FROM ({0})", strSQL2), 
      cnDTC);

var select = new OleDbCommand($"SELECT MAX(VERSION_NO) AS MAX_VERSION FROM ({strSQL2})", 
      cnDTC);

我怀疑treenodes是因为我给了他们相同的名字，但我试着改变了名字，但没什么不同

3rd:

TreeNode node = new TreeNode(drive.Substring(0, 1), driveImage, driveImage);//issue on this line
node.Tag = drive;

DirectoryInfo di = new DirectoryInfo(dir);
TreeNode node = new TreeNode(di.Name, 0, 1); //this line

OleDbCommand select = new OleDbCommand();//this line
select.Connection = cnDTC;
select.CommandText = string.Format("SELECT MAX(VERSION_NO) AS MAX_VERSION FROM ({0})", strSQL2);

var node = new TreeNode(drive.Substring(0, 1), driveImage, driveImage) {
    Tag = drive
};

OleDbCommand select = new OleDbCommand();//this line
select.Connection = cnDTC;
select.CommandText = string.Format("SELECT MAX(VERSION_NO) AS MAX_VERSION FROM ({0})",
      strSQL2);

var select = new OleDbCommand(
      String.Format("SELECT MAX(VERSION_NO) AS MAX_VERSION FROM ({0})", strSQL2), 
      cnDTC);

var select = new OleDbCommand($"SELECT MAX(VERSION_NO) AS MAX_VERSION FROM ({strSQL2})", 
      cnDTC);

编译器希望您使用以下语法：

var select = new OleDbCommand
{
   Connection = cnDTC,
   CommandText = string.Format("SELECT MAX(VERSION_NO) AS MAX_VERSION FROM ({0})", strSQL2)
};

这是您的第三个案例。
1st
之前：

TreeNode node = new TreeNode(drive.Substring(0, 1), driveImage, driveImage);
node.Tag = drive;

DirectoryInfo di = new DirectoryInfo(dir);
TreeNode node = new TreeNode(di.Name, 0, 1); //this line

之后：

TreeNode node = new TreeNode(drive.Substring(0, 1), driveImage, driveImage);//issue on this line
node.Tag = drive;

DirectoryInfo di = new DirectoryInfo(dir);
TreeNode node = new TreeNode(di.Name, 0, 1); //this line

OleDbCommand select = new OleDbCommand();//this line
select.Connection = cnDTC;
select.CommandText = string.Format("SELECT MAX(VERSION_NO) AS MAX_VERSION FROM ({0})", strSQL2);

var node = new TreeNode(drive.Substring(0, 1), driveImage, driveImage) {
    Tag = drive
};

OleDbCommand select = new OleDbCommand();//this line
select.Connection = cnDTC;
select.CommandText = string.Format("SELECT MAX(VERSION_NO) AS MAX_VERSION FROM ({0})",
      strSQL2);

var select = new OleDbCommand(
      String.Format("SELECT MAX(VERSION_NO) AS MAX_VERSION FROM ({0})", strSQL2), 
      cnDTC);

var select = new OleDbCommand($"SELECT MAX(VERSION_NO) AS MAX_VERSION FROM ({strSQL2})", 
      cnDTC);

第二名
之前：

TreeNode node = new TreeNode(drive.Substring(0, 1), driveImage, driveImage);
node.Tag = drive;

DirectoryInfo di = new DirectoryInfo(dir);
TreeNode node = new TreeNode(di.Name, 0, 1); //this line

之后：

var node = new TreeNode((new DirectoryInfo(dir)).Name, 0, 1);

3rd
之前：

TreeNode node = new TreeNode(drive.Substring(0, 1), driveImage, driveImage);//issue on this line
node.Tag = drive;

DirectoryInfo di = new DirectoryInfo(dir);
TreeNode node = new TreeNode(di.Name, 0, 1); //this line

OleDbCommand select = new OleDbCommand();//this line
select.Connection = cnDTC;
select.CommandText = string.Format("SELECT MAX(VERSION_NO) AS MAX_VERSION FROM ({0})", strSQL2);

var node = new TreeNode(drive.Substring(0, 1), driveImage, driveImage) {
    Tag = drive
};

OleDbCommand select = new OleDbCommand();//this line
select.Connection = cnDTC;
select.CommandText = string.Format("SELECT MAX(VERSION_NO) AS MAX_VERSION FROM ({0})",
      strSQL2);

var select = new OleDbCommand(
      String.Format("SELECT MAX(VERSION_NO) AS MAX_VERSION FROM ({0})", strSQL2), 
      cnDTC);

var select = new OleDbCommand($"SELECT MAX(VERSION_NO) AS MAX_VERSION FROM ({strSQL2})", 
      cnDTC);

之后：

TreeNode node = new TreeNode(drive.Substring(0, 1), driveImage, driveImage);//issue on this line
node.Tag = drive;

DirectoryInfo di = new DirectoryInfo(dir);
TreeNode node = new TreeNode(di.Name, 0, 1); //this line

OleDbCommand select = new OleDbCommand();//this line
select.Connection = cnDTC;
select.CommandText = string.Format("SELECT MAX(VERSION_NO) AS MAX_VERSION FROM ({0})", strSQL2);

var node = new TreeNode(drive.Substring(0, 1), driveImage, driveImage) {
    Tag = drive
};

OleDbCommand select = new OleDbCommand();//this line
select.Connection = cnDTC;
select.CommandText = string.Format("SELECT MAX(VERSION_NO) AS MAX_VERSION FROM ({0})",
      strSQL2);

var select = new OleDbCommand(
      String.Format("SELECT MAX(VERSION_NO) AS MAX_VERSION FROM ({0})", strSQL2), 
      cnDTC);

var select = new OleDbCommand($"SELECT MAX(VERSION_NO) AS MAX_VERSION FROM ({strSQL2})", 
      cnDTC);

3rd（带字符串插值）：

TreeNode node = new TreeNode(drive.Substring(0, 1), driveImage, driveImage);//issue on this line
node.Tag = drive;

DirectoryInfo di = new DirectoryInfo(dir);
TreeNode node = new TreeNode(di.Name, 0, 1); //this line

OleDbCommand select = new OleDbCommand();//this line
select.Connection = cnDTC;
select.CommandText = string.Format("SELECT MAX(VERSION_NO) AS MAX_VERSION FROM ({0})", strSQL2);

var node = new TreeNode(drive.Substring(0, 1), driveImage, driveImage) {
    Tag = drive
};

OleDbCommand select = new OleDbCommand();//this line
select.Connection = cnDTC;
select.CommandText = string.Format("SELECT MAX(VERSION_NO) AS MAX_VERSION FROM ({0})",
      strSQL2);

var select = new OleDbCommand(
      String.Format("SELECT MAX(VERSION_NO) AS MAX_VERSION FROM ({0})", strSQL2), 
      cnDTC);

var select = new OleDbCommand($"SELECT MAX(VERSION_NO) AS MAX_VERSION FROM ({strSQL2})", 
      cnDTC);

顺便说一句：每当出现此类消息时，请尝试将光标放在该行上，然后按Ctrl+。（或单击出现的灯泡）-打开“快速修复/快速重构”

进一步阅读（这真的不是邪恶的我对这段代码也有类似的问题：

        Customer oCust = new Customer();
        oCust.Address = txtAddress.Text;
        oCust.City = txtCity.Text;
        oCust.State = txtState.Text;

        Customer oCust = new Customer()
        {
           Address = txtAddress.Text,
           City = txtCity.Text,
           State = txtState.Text
        };

用这个密码解决了这个问题：

        Customer oCust = new Customer();
        oCust.Address = txtAddress.Text;
        oCust.City = txtCity.Text;
        oCust.State = txtState.Text;

        Customer oCust = new Customer()
        {
           Address = txtAddress.Text,
           City = txtCity.Text,
           State = txtState.Text
        };

所以…关闭警告信息（IDE0017）（在VS 2017/2019中）：

单击工具选项卡。然后转到选项…

然后|文本编辑器| C#|代码样式|常规|

在“表达首选项”下，将“首选对象初始值设定项”更改为“否”

或者，您可以将首选项保留为是，并将严重性从警告更改为
建议

现在它将在错误列表中显示为一条消息。
虽然前面的所有建议都很好，但我会添加第三种方法。关闭这些警告并忽略它们。虽然我欣赏微软的试图让每个人都高效、整洁地编码，在我看来，这不是一个好建议，它实际上会产生难以阅读和编辑的代码

首先，这实质上将对象初始化转换为一行代码，任何错误都会这样报告。如果将20位数据加载到对象中，则会在第一行显示错误，而不会告诉您哪个属性出错。调试将不会有帮助，因为您将整个代码块显示为er罗

其次，如果将来需要扩展代码并为特定属性添加额外的代码，那么现在需要在单独的代码中执行。这会增加碎片并分离相关的代码位（可能有争议）

这两个问题看起来都很小，但警告提示了一个解决方案，这也是一个很小的问题。为了将您的初始化括起来，您使您的代码更难调试和修改。在我看来，这是一个糟糕的权衡

您可以通过右键单击警告并选择“抑制”来禁用警告，或转到工具>选项>文本编辑器>C#>代码样式>常规>首选对象初始值设定项>并将警告设置为无，或将首选项设置为否。
我喜欢，但我觉得似乎有一些更大的想法需要讨论

<>从我的经验来看，VisualStudio提供的重构建议是没有帮助的。我认为更大的问题是代码设计是否正确。在面向对象的编程中，一个接一个地设置属性<强> 5 < /强>违反封装。这个想法是，对象应该总是在有效的ST中。在任何成员被访问/调用后ate，直到对象被销毁。在这种情况下，设置每个属性后，状态应有效。适当的封装将导致软件应用程序的整体改进，因为您正在增强其内聚性

对象初始化可以简化
消息可能有助于在违反封装的情况下检测代码中可以使用的点：


抽象工厂模式
构建器模式
工厂方法模式
原型模式

这使我们能够解决tonyenkiducx提出的问题：

TreeNode node = new TreeNode(drive.Substring(0, 1), driveImage, driveImage);
node.Tag = drive;

DirectoryInfo di = new DirectoryInfo(dir);
TreeNode node = new TreeNode(di.Name, 0, 1); //this line

首先，这实质上是将对象初始化转换为一行代码，任何错误都会这样报告。如果将20位数据加载到对象中，则会在第一行显示错误，而不会告诉您哪个属性出错。调试不会有帮助，因为您会将整个代码块显示为错误r

其次，如果将来需要扩展代码并为特定属性添加额外的代码，那么现在需要在单独的代码中执行。这会增加碎片并分离相关的代码位（可能有争议）

这样，而不是在对象被消费的点内联实例化，这是VisualStudio经常建议的，我建议您考虑使用创建模式。这可能不会删除简化消息，但此时，您已经仔细考虑了消息标志并可以安全地抑制它。
谢谢，但我不在这里。为什么
var
比实际给出它的类型更简单，因为据我所知
var
用于不同的类型？不，绝对不是，请继续阅读链接文章，它只是一个“快捷方式”。（试着将鼠标指针放在var声明上，这将给出准确的推断类型。var！=variant！！！！：）顺便说一句，您正在使用string.Format打开sql注入的应用程序。^^^>这只是我，还是其中的一些人