Meziantou.Framework

Introduction

edit

Meziantou.Framework.CodeDom builds C# source code from objects instead of strings. You create a tree of code objects (a compilation unit, its namespaces, types, members, statements and expressions) and the library writes the C# code, with the indentation, the braces, the parentheses and the escaping done for you:

var unit = new CompilationUnit();
unit.AddUsing("System");

var ns = unit.AddNamespace("Demo");
var type = ns.AddType(new ClassDeclaration("Greeter")
{
    Modifiers = Modifiers.Public,
});

var method = type.AddMember(new MethodDeclaration("GetMessage")
{
    Modifiers = Modifiers.Public | Modifiers.Static,
    ReturnType = typeof(string),
});

var nameArgument = method.AddArgument("name", typeof(string));
method.Statements = new ReturnStatement(Expression.Add("Hello ", nameArgument, "!"));

var generatedCode = unit.ToCsharpString();

generatedCode contains:

using System;

namespace Demo
{
    public class Greeter
    {
        public static string GetMessage(string name)
        {
            return (("Hello " + name) + "!");
        }
    }
}

It is a modern replacement for System.CodeDom, which has not evolved for years, focused on C#: records, nullable reference types, async and await, nameof, generic constraints such as unmanaged...

Use it in code generators, scaffolding tools, source generators or build tasks that write C# files: the code is easier to compose and to refactor than string concatenation, and the output is always well formed.

Principles

  • A tree of objects. Every element is a CodeObject with a Parent. Adding an object to a collection or assigning it to a property attaches it to the tree.
  • Conversions keep the code short. A Type, a string, a number, a bool or an enum converts to the matching type reference or literal, and a member declaration or an argument to a reference to it.
  • The output is explicit. Binary expressions are parenthesized, and the types that are not C# keywords are written with their full name and global::, so the meaning of the generated code does not depend on operator precedence or on the using directives of the file.
  • No compilation. The library writes source code; it does not check that the code compiles.

Next steps