A global using directive makes a namespace or type import available throughout every file in a C# project, reducing repetitive using declarations. The compiler can also supply common .NET namespaces through enabled implicit usings. section 2.5
Use global usings when a namespace appears across many classes:
- Place declarations such as global using Figgle; in a dedicated GlobalUsings.cs file. section 2.5
- Declare imports in the project file with an ItemGroup and Using Include entry. section 2.5
- Keep ordinary global usings distinct from global static usings, which expose static members without their containing type name. section 2.6
Listing 2.10 Global using in Project file
<Project Sdk="Microsoft.NET.Sdk">
<!-- ... -->
<ItemGroup>
<Using Include="Figgle" /> #1
</ItemGroup>
</Project>
The project-file form shows how a namespace becomes globally available without adding declarations to each source file. section 2.5
