[`var is] an implicitly typed local variable declaration …

它更进一步：

A local variable declarator in an implicitly typed local variable
declaration is subject to the following restrictions:

• The declarator must include an initializer.
• The initializer must be an expression.
• The initializer expression must have a compile-time type which cannot
  be the null type.
• The local variable declaration cannot include
  multiple declarators.
• The initializer cannot refer to the declared variable itself

所以不,你不能这样做.此外,我建议不要考虑全局变量.

语言不支持全局变量.您可以在公共静态字段中找到替代方法,但这会泄漏对象状态并破坏封装.