问题

我只是想确保在C# 11.0 (.NET 7)中执行这个操作是有意义的：

if (filePath is null || String.IsNullOrWhiteSpace(filePath))
    return false;

我的想法是，IsNull... 使用了'=='运算符，而这个运算符可以被重载，而'is'则不行。

英文:

I just want to be sure that doing this makes sense in C# 11.0 (.NET 7):

if (filePath is null || String.IsNullOrWhiteSpace(filePath))
    return false;

My thought is that IsNull... uses '==' operator, that can be overloaded, while 'is' can not.

答案1

得分: 3

几乎可以肯定您的代码是多余的：如果filePath是string类型，则以下代码足够：

if (string.IsNullOrWhiteSpace(filePath)) {
  ...
}

"几乎"是用于处理filePath类型如下所示的特殊情况的情况：

public class MyPath {
  ...

  public static implicit operator string(MyPath value) {
    ...
  }
}

在这种情况下，您当前的代码双重检查是有意义的：

MyPath filePath = ...

if (filePath is null || string.IsNullOrWhiteSpace(filePath)) {
  ...
}

我们检查filePath是否为null，或者当它不为null时，其string表示是否为null或仅包含空格。

英文:

Almost certainly your code is redundant: if filePath is string then

if (string.IsNullOrWhiteSpace(filePath)) {
  ...
}

is enough. "Almost" is for exotic case when filePath is of type like this:

public class MyPath {
  ...

  public static implicit operator string(MyPath value) {
    ...
  }
}

In this case your current code with double check makes sense:

MyPath filePath = ...

if (filePath is null || string.IsNullOrWhiteSpace(filePath)) {
  ...
}

we check if filePath is null or when it's not null its string representation is null or consists of white spaces only.

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