Introducing C# 10: File-scoped namespaces

Introduction

C# is still evolving and C# 10 proposes a new feature : file_scoped namespaces. As its name suggests, the namespace declared in a file (without braces, but whose instruction ends with a semicolon) will apply to all elements declared in the same file. It’s practical, no more need for indentation since the opening and closing braces of the namespace disappear. There is still a limitation, only one namespace can be declared in the file, otherwise you will get a compiler error.

Example

The following code shows what is a file-scoped namespace:

The following below is illegal:

The compiler will throw the following error:

Error CS8955 Source file can not contain both file-scoped and normal namespace declarations.

The following below is also illegal:

The compiler will throw the following error:

Error CS8954 Source file can only contain one file-scoped namespace declaration.