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Fluent Builder Pattern

Fluent Builder Pattern

Gamma Categorization: Creational Design Patten
Summary: Extension of the Builder Pattern, that allows us to chain the operation calls.

Problem examples

We want to chain the operation calls for convenience purposes.

Solution

The methods now return the class itself.

Sample Code

Plese refer to the Builder Pattern article for the complete code.

The main changes are made in the base abstract class of the ReportBuilder.

public abstract class ReportBuilder
{
    protected Report report;

    public ReportBuilder CreateReport()
    {
        report = new Report();
        return this;
    } 

    public ReportBuilder SetHeader(string header) 
    {
        report.Header = header;
        return this;
    } 

    public ReportBuilder AppendContentLine(string contentLine)
    {
        report.Content.Add(contentLine);
        return this;
    } 

    public ReportBuilder SetFooter(string footer)
    {
        report.Footer = footer;
        return this;
    } 

    public abstract string  DispatchReport();

    public void Clear() => report = new Report();
}

Usage 

The usage is now simplified as follows.

var textReportBuilder = new TextReportBuilder();

var report = textReportBuilder.CreateReport()
    .SetHeader($"Daily Report - {DateTime.UtcNow.ToString("dd/MM/yyyy")}")
    .AppendContentLine("14 Hot Meals")
    .AppendContentLine("22 Breakfasts")
    .SetFooter("Copyright - Cafe Shop")
    .DispatchReport();

System.Console.WriteLine(report);

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