Plugins

Implement the SquidStd plugin contract and have a plugin register its own services into the container.

What you'll build

A console app that defines a plugin implementing ISquidStdPlugin (SquidStd.Plugin.Abstractions), describes it with PluginMetadata, and calls Configure to register a service that the host then resolves.

Prerequisites

.NET 10 SDK
dotnet add package SquidStd.Plugin.Abstractions

Steps

1. Implement the plugin contract

A plugin exposes a PluginMetadata (its identity and dependencies) and a Configure method that registers its services, handlers, and integrations into the DryIoc container.


public interface IGreeter
{
    string Greet(string name);
}

public sealed class WeatherGreeter : IGreeter
{
    public string Greet(string name)
        => $"Hello {name}, the weather plugin is online.";
}

public sealed class WeatherPlugin : ISquidStdPlugin
{
    public PluginMetadata Metadata { get; } = new()
    {
        Id = "squidstd.weather",
        Name = "Weather Plugin",
        Version = new(1, 0, 0),
        Author = "SquidStd Samples",
        Description = "Registers a greeter service.",
        Dependencies = []
    };

    public void Configure(IContainer container, PluginContext context)
        => container.Register<IGreeter, WeatherGreeter>(Reuse.Singleton);
}

2. Describe, configure, and resolve

The host builds a PluginContext for boot-time data, invokes Configure on the plugin, and then resolves the services the plugin registered.


var bootstrap = SquidStdBootstrap.Create(
    new SquidStdOptions { ConfigName = "plugins-sample", RootDirectory = Directory.GetCurrentDirectory() }
);

var plugin = new WeatherPlugin();
Console.WriteLine($"Loading {plugin.Metadata.Name} v{plugin.Metadata.Version} by {plugin.Metadata.Author}");

bootstrap.UsePlugins(plugins => plugins.Add(plugin));

var greeter = bootstrap.Resolve<IGreeter>();
Console.WriteLine(greeter.Greet("squid"));

Run it

dotnet run --project samples/SquidStd.Samples.Plugins

Prints:

Loading Weather Plugin v1.0.0 by SquidStd Samples
Hello squid, the weather plugin is online.

How it works

ISquidStdPlugin is the contract a host loads: Metadata is the source of truth for plugin identity and load order (Dependencies), while Configure(IContainer, PluginContext) is called during container configuration so the plugin can register everything it contributes. PluginContext.Data carries host-supplied boot values into the plugin. A real host discovers plugin assemblies and calls Configure in dependency order; this sample wires one plugin by hand so the contract is fully runnable without external assemblies.

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