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OK, so let's start with some actual BBS programming! I've chosen Crystal for this tutorial, so you'll need to install it. At the moment this is being written, the current version is 0.21.1. As the language is still in alpha, a lot may break until it reaches 1.0 (scheduled for later in 2017) and I'll try to keep this updated.

I won't cover installation, since the official docs are pretty good at that. You will need a macOS or Linux setup, either native or in a virtual machine.

Once you have it installed, it's time to get going. Crystal has a “skeleton” too built-in that creates an initial app and creates a local Git repository as well. Git is not part of the tutorial, but you should always keep your code in check with a source code management system, so have a look at it when you can.

To create the initial skeleton, type

crystal init app bbs

This will create the skeleton inside the bbs subfolder of the current directory. Jump into it and have a look around at the files created.

One thing the app creator leaves out is an easy way to compile the project - we can just type crystal build src/bbs.cr –release -o bbs_release every time we want to compile, but that would get old really quick. So instead we'll create a Makefile and use good old make to perform all these repetitive tasks on the project. Here's how it could look:

.PHONY: clean
 
run: bbs
	./bbs_release
clean:
	rm -f bbs_release
 
all: clean
	crystal build src/bbs.cr --release -o bbs_release
 
bbs:
	rm -f bbs_release
	crystal build src/bbs.cr --release -o bbs_release

Make is also out of scope for this tutorial, but it won't get more complicated than this. From now on, just type make in the project's root directory to erase the existing binary and compile a new one. If you type it now, you should see:

$ make
rm -f bbs_release
crystal build src/bbs.cr --release -o bbs_release
./bbs_release

That last line was our binary running, but of course it doesn't do anything yet!

Let's get the basics out of the way before we go into the meat of the problem. We want to store configuration settings, so let's do that first, and then move on to the main network loop.

Your src/bbs.cr file should look like this now:

require "./bbs/*"

module Bbs
  # TODO Put your code here
end

Change it to:

require "./bbs/*"

BBS::Main.new.go!

This will call a go! method on the BBS module's Main class. Let's create it, but on a separate file. Create a main.cr file inside the src/bbs/ directory with:

require "yaml"

module BBS
  class Main
    @config = YAML::Any

    def initialize
      load_config
    end

    def go!
      puts config.inspect
    end

    private getter :config

    private def load_config
      @config = YAML.parse(File.read("config.yml"))
    end
  end
end

This file will be required by src/bbs.cr (as mandated by its line 1) and will add the class to the BBS module. Let's create a basic config file as config.yml on the root directory of the project (more info on YAML here:

settings:
  port: 2023

If you type make now, you should see:

$ make
rm -f bbs_release
crystal build src/bbs.cr --release -o bbs_release
./bbs_release
{"settings" => {"port" => "2023"}}

Yay, we're live with the basics and our settings are being read! Let's recap for a bit, since this class introduces a few important concepts.

require "yaml"

This line requires in Crystal's built in YAML handling functions.