I have a solution with ~40 projects, built during many years with wild usings that I wanted to clean up. The global usings feature, introduced in with C# 10.0 and .NET 6 (nov21) to simplify and reduce the repetition of commonly used namespaces throughout a project.
The question I have is, how do I ‘get’ the most commonly used namespaces and how do I do that at scale.
Getting an idea of what is ‘used’
This (LINQPad script) gives you an idea of the most commonly used ones, across your solution.
var solutionPath = @"path-to-solution";
var files = Directory.EnumerateFiles(solutionPath, "*.cs", SearchOption.AllDirectories);
var usingStatements = files
.SelectMany(file => File.ReadLines(file)
.Where(line => line.TrimStart().StartsWith("using "))
.Select(line => line.Trim()))
.GroupBy(usingLine => usingLine)
.Select(group => new { Using = group.Key, Count = group.Count() })
.OrderByDescending(x => x.Count);
usingStatements.Dump();
You will not be surprised with the results:
Generating GlobalUsings.cs
How do I now add a GlobalUsings.cs file to every one of these 40 projects, with the relevant usings?
- I define a variable
commonUsingswhich has the most reasonable candidates. - I scan every project directory and tally up the usings.
- The intersection between #1 and #2 I write to a GlobalUsings.cs file
- Done
var solutionPath = @"path-to-solution";
var globalUsingsFileName = "GlobalUsings.cs";
// Define the list of namespaces to intersect with (System, System.Linq)
var commonUsings = new[] { "using System;", "using System.Linq;", "using FluentAssertions;", "using Moq;", "using Xunit;", "using System.Collections.Generic;" };
// Find all directories with a `.csproj` file, assuming each project has one.
var projectDirectories = Directory.EnumerateFiles(solutionPath, "*.csproj", SearchOption.AllDirectories)
.Select(csprojPath => Path.GetDirectoryName(csprojPath))
.Distinct(); // Get unique project directories
foreach (var projectDirectory in projectDirectories)
{
// Get all C# files within the project directory
var csFiles = Directory.EnumerateFiles(projectDirectory, "*.cs", SearchOption.AllDirectories);
var usingStatements = csFiles
.SelectMany(file => File.ReadLines(file)
.Where(line => line.TrimStart().StartsWith("using "))
.Select(line => line.Trim()))
.GroupBy(usingLine => usingLine)
.Select(group => new { Using = group.Key, Count = group.Count() })
.OrderByDescending(x => x.Count)
.Where(u => u.Count > 1);
// Output the results for each project
Console.WriteLine($"Project: {Path.GetFileName(projectDirectory)}");
usingStatements.Dump();
// Find intersection of most used usings with the specified common usings
var intersectingUsings = usingStatements
.Select(u => u.Using)
.Intersect(commonUsings)
.ToList();
if (intersectingUsings.Any())
{
// Prepare the path for the GlobalUsings.cs file
var globalUsingsFilePath = Path.Combine(projectDirectory, globalUsingsFileName);
// Create or overwrite the GlobalUsings.cs file with the intersecting using statements
var globalUsingsContent = intersectingUsings
.Select(usingDirective => $"global {usingDirective}") // Convert to global using
.Aggregate((current, next) => current + Environment.NewLine + next); // Combine into one string
File.WriteAllText(globalUsingsFilePath, globalUsingsContent);
Console.WriteLine($"GlobalUsings.cs file created/updated for project {Path.GetFileName(projectDirectory)} with the following global usings:");
intersectingUsings.ForEach(Console.WriteLine);
}
}
Enjoy!
