PrintMembersGenerator

A source generator that helps re-defining C# record's PrintMembers method to force include/exclude certain members.

This project is related to dotnet/csharplang#3925.

For more information about source generators, see Introducing C# source generators blog.

Overview

C# 9.0 introduced a new language feature called Records. A record is simply a reference type with some compiler-generated (synthesized) methods.

The interest of this project is on PrintMembers method, which the compiler uses when you call .ToString() on a record.

The compiler only includes all public non-override instance fields/properties in PrintMembers, and allows you to re-define PrintMembers if the provided implementation doesn't suite your need.

This source generator makes it easier to force-include or force-exclude certain record members in PrintMembers implementation through a provided attribute.

How to use

Add reference to the generator

Currently, this is not packed into a NuGet package. So you'll have to clone the source code, and add a reference to the PrintMembersSourceGenerators.csproj. The added reference should look like the following:

  <ItemGroup>
    <ProjectReference Include="PATH TO PrintMembersGenerator.csproj" 
                      OutputItemType="Analyzer"
                      ReferenceOutputAssembly="false" />
  </ItemGroup>

Use the attribute

First of all, here is the internal definition of the attribute:

namespace SourceGenerator
{
    [AttributeUsage(AttributeTargets.Field | AttributeTargets.Property, AllowMultiple = false, Inherited = false)]
    public sealed class PrintMembersAttribute : Attribute
    {
        public bool ShouldInclude { get; set; } = true;
    }
}

As you see, the attribute can only be applied to fields and properties.

To force-include a member in PrintMembers, you should either use [PrintMembers] or [PrintMembers(ShouldInclude = true)].
To force-exclude a member in PrintMembers, you should use [PrintMembers(ShouldInclude = false)].

Currently, positional record parameters are not supported. Support for them should be added soon through targeted attributes:

[property: PrintMembers(ShouldInclude = false)]

See this comment on dotnet/csharplang#3644.

Notes