Liquid for C#: High-Level Overview

Introduction

In the Liquid For C# series, I will be writing a C# interpretor for the Liquid templating language from scratch.

In this first post I define the project's scope and overall intention. Code does not factor into this stage at all, it's purely about the API's purpose, not it's implementation.

Broad Strokes

The first step in any project is to define what it will be doing at the highest level. Ideally, this should be expressible as a single sentence or a simple diagram.

This project's definition is deceptively simple: Template + Data = Output.

Armed with this very general definition, the next step is to break the overall process into broad, functionally cohesive chunks. I find that this is best achieved by running through potential use cases. The below is the outcome of that process.

It immediately jumps out at me that the Abstract Syntax Tree and steps that follow are implementation agnostic. This means that they are not specific to Liquid and, because of this, can be re-used in any templating language interpretor.

Defining Success

The question then becomes one of how to know when the project fulfils its purpose.

As the aim of this project is to provide a full C# implementation of Liquid's behaviour as it is currently implemented in Ruby, I will port all of the integration tests for Liquid to C# and follow a Test Driven Development approach. I will only consider the project to be a success when it passes all of the original tests.

What Next?

In bigger teams or projects its necessary to delve much deeper in the design phase, going as far as to define the interfaces for the API and how they plug together so that all involved parties can work independently without going off in completely different directions.

Since this is just me working on a hobby project, though, I'll instead be taking a very iterative approach and in the next post I'll be writing code!