Object-Oriented – Term for Accessor Method Returning Boolean

object-orientedterminology

I seem to recall that there is a specific term for an accessor method that returns a Boolean value but it escapes me. For example: typical methods such as:

class Example {
    bool isDirty();
    bool hasChildren();
    bool isValid(SomeType obj);
};

I will also settle for such a term as applied to a non-member functions.

Best Answer

A function from some type T to Boolean is usually called a predicate, and if you want to make clear that it is a method of an object, i.e. that it takes the implicit this argument in addition to its other arguments, then you could call it a predicate method. If it takes no other arguments except the implicit this argument, then you can call it a predicate property.

See for example Predicate<T> in .NET and e.g. javax.sql.rowset.Predicate or com.google.common.base.Predicate in Java.

Related Solutions

PHP – Advantages of Multiple Methods Over Switch

A switch is considered not OOP because often polymorphism can do the trick.

In your case, an OOP implementation could be this:

class Oop 
{
  protected $goer;

  public function __construct($goer)
  {
    $this->goer = $goer;
  }

  public function go()
  {
    return $this->goer->go();
  }
}

class Goer
{
  public function go()
  {
    //...
  }
}

class GoerA extends Goer
{
  public function go()
  {
    //...
  }
}

class GoerB extends Goer
{
  public function go()
  {
    //...
  }
}

class GoerC extends Goer
{
  public function go()
  {
    //...
  }
}


$oop = new Oop(new GoerB());
$oop->go();

C++ – Talking About Methods vs Member Functions

Why don't you include an explanation (very much like you did in your question) in the introductory part of the documentation, e.g. a Conventions section? Then you could explain that the term "method", as used in your documentation, is meant in the generic sense of method (Java), member function (C++), ... since the documentation applies to all implementations.

Best Answer

Related Solutions

PHP – Advantages of Multiple Methods Over Switch

C++ – Talking About Methods vs Member Functions

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