cratis-csharp-standards

Key rules (quick reference)

• Use C# 13 features always — records, primary constructors, pattern matching
• var over explicit types — the right side already tells you the type
• File-scoped namespace declarations — one less indentation level
• using directives: alphabetically sorted, single-line, unused ones removed
• No regions — if a file needs them, it needs refactoring
• No postfixes: no Async, Impl, Service, Manager, Handler on class names
• No Exception suffix on exception types — AuthorNotFound not AuthorNotFoundException
• Never use built-in exceptions — always create custom exception types
• record for events, commands, read models, concepts — value equality for free
• Primary constructors for all types — eliminates field boilerplate
• is null / is not null — never == null / != null
• Blank line before opening { of every code block
• Final return on its own line
• Private fields: _camelCase with underscore prefix
• Interfaces: I prefix (IMyService)
• No [EventType] arguments — the type name is the event identifier
• [Command] records define Handle() directly — no separate handler classes

---

Formatting

// File-scoped namespace (no extra indent)
namespace MyApp.Authors.Registration;

// Alphabetically sorted using directives
using Cratis.Arc.Commands;
using Cratis.Chronicle.Events;
using Microsoft.Extensions.Logging;

// Blank line before { of every block
if (condition)
{
    DoSomething();
}

// Expression-bodied for simple members
public string FullName => $"{FirstName} {LastName}";

// Final return on its own line
public string GetName()
{
    var result = BuildName();

    return result;
}

---

Naming

Artifact	Convention	Example
Type / method / public member	PascalCase	RegisterAuthor, AuthorId
Private field	_camelCase	_eventLog
Local variable	camelCase	authorId
Interface	I prefix	IEventLog
Exception type	No Exception suffix	AuthorNotFound
Feature folder	Pluralized domain noun	Authors/
Concept file	Concept name	AuthorId.cs