Table of Contents

Introduction

What is Rez?

Rez consists of two main parts:

  • A specification for a simple templating language
  • A library implementing the parsing and resolving of Rez template text in .NET applications

Rez takes heavy inspiration from Mustache, a popular templating language used in many web applications.

One of the key reasons for creating Rez instead of using an existing solution was the need for terse, nestable tokens that are still easy to read.

A 10-second example

var resolver = new Resolver();
resolver.AddSource(new ResolverSource(new Dictionary<string, string> { { "name", "World" } }));

var greeting = resolver.Resolve("Hello, {name}!");

// greeting: "Hello, World!"

Key features

  • Terse, readable syntax — variables are written as {name} and functions as {name(args)}
  • Nesting — placeholders can be nested (e.g., {variable{number}}) and are resolved inside-out, left-to-right
  • Recursion — resolved values may themselves contain placeholders, which are resolved in turn (with a hard limit of 4096 recursions to prevent infinite loops)
  • Escaping — braces can be escaped with a backslash (\{notAVariable\}) to exclude them from resolution
  • Pluggable sources — variables and functions are supplied by any number of IResolverSource implementations, queried in order with first-match-wins semantics
  • Graceful fallback — placeholders that cannot be resolved are left in the output unchanged
  • High performance — the resolution pipeline operates on pooled buffers and spans to minimize allocations
  • Configuration integration — the optional Invex.Rez.Configuration package resolves templates inside Microsoft.Extensions.Configuration values transparently

Packages

Package Description
Invex.Rez The core templating library: resolver, sources, and store
Invex.Rez.Configuration Integration with Microsoft.Extensions.Configuration and dependency injection

Both packages target net10.0, net9.0, net8.0, and netstandard2.0.

Where did the name come from?

The name Rez is a play on the word "res" (short for "resolution"), which is the process of resolving a template. The name was chosen as it is short and memorable and is not too similar to other names in the .NET ecosystem.

Where to go next

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