[BEANUTILS-335] Provide support for "fluid" beans

• Type: New Feature
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Fix Version/s: 2.0.0-M2
• Component/s: Bean / Property Utils
• Assignee: Unassigned
• Reporter: Daniel Fabulich
• Created: 12/Feb/09 00:33
• Updated: 2 days ago 14:06

Description

The attached patch allows users to easily define what I'm calling a "fluid" bean (though there might be a better name for it).

The idea here is to write a bean that doesn't follow the standard JavaBean convention. Specifically, a "fluid" bean's setters return "this," so you can "chain" calls to the setters, and the getters and setters don't start with "get/set" but are just the name of the property. For example:

public class Employee extends AbstractFluidBean {
  private String firstName, lastName;
  public String firstName() { return firstName; }
  public Employee firstName(String firstName) {
    this.firstName = firstName;
    return this;
  }
  public String lastName() { return lastName; }
  public Employee lastName(String lastName) {
    this.lastName = lastName;
    return this;
  }
}

Fluid beans have some limitations: you can't use indexed or mapped properties with a fluid bean (because there's no way to disambiguate an indexed getter from a simple setter). I think that's OK because indexed properties are a bit silly. (Why not just return a List or a Map?)

But I think they have substantial readability advantages. With a fluid bean, you can write code like this:

HumanResources.hire(new Employee().firstName("Dan").lastName("Fabulich"));

For an example of fluid chained setters in the wild, see (for example) Effective Java Second Edition by Joshua Bloch. In Item 2 "Consider a builder when faced with many constructor parameters" Bloch defines a fluid bean with chained setters, so you can use it like this:

NutritionFacts cocoCola = new NutritionFacts.Builder(240, 8)
  .calories(100).sodium(35).carbohydrate(27).build();