NH.Plumber.Core 1.1.2

What is Plumber?

Plumber consists of a pipeline that can be used to add steps to it and execute them. Each step can modify the context and pass it to the next step. Plumber consists of a Promise class that can be used to create a promise that can be resolved or rejected at a later time.

Pipeline

Plumber contains a very lightweight pipeline that allow us to add each step of a logic to it and later we can Execute these steps. Each step can either be a Func<TContext, Func<TContext,Task>, Task> or an object implementing the IPipeLineStep<TContext> interface.

Context

Each pipeline should have a context that will be passed to each step of the pipeline. This context can be anything. Each step can modify the context and pass it to the next step.

Next Step

Each step will receive the next step of the pipeline and will be able to call it when it is ready. A Step can also decide to not call the next step and stop the pipeline.

Example

     [Fact]
    public async Task FibonacciTest()
    {
        var fibonacciStep = new Func<List<int>, Func<List<int>, Task>, Task>(async (context, next) =>
        {
            if (context.Count == 0)
                context.Add(1);
            else if (context.Count == 1)
                context.Add(1);
            else
                context.Add(context[context.Count - 1] + context[context.Count - 2]);
            await next(context);
        });

        var pipeline = new PipeLine<List<int>>();
        Enumerable.Range(0, 10).ToList().ForEach(i => pipeline.AddNextStep(fibonacciStep));
        var context = new List<int>();
        await pipeline.ExecuteAsync(context);

        Assert.Equal(new[] { 1, 1, 2, 3, 5, 8, 13, 21, 34, 55 }, context.ToArray());
    }

Promise

Plumber contains a Promise class that can be used to create a promise that can be resolved or rejected at a later time. A Promise can have a context that will be passed to the resolve or reject methods.

Example

    [Fact]
    public async Task PromiseTest()
    {
        
        var promise = new Promise<StringBuilder>(async  sb => {
                sb.Append("Hello");
                await Task.Delay(1000);
                });
        
        promise.Then(async sb => {
            sb.Append(" World!");
            await Task.Delay(1000);
        });

        var sb = new StringBuilder();
        var state = await promise.ResolveAsync(sb);
        Assert.Equal("Hello World!", sb.ToString());
        Assert.Equal(PromiseState.Resolved, state);
    }