Method Stereotypes

• All methods play a role or multiple roles in a class
• Identifying the role of a method helps with comprehension, but also with the original design
• A method has a primary role, with some methods a secondary role

Method Stereotype Taxonomy

• Detailed Explanation: Reverse Engineering Method Stereotypes (ICSM'06) by Dragan, N., Collard, M.L., Maletic, J.I.
• Updated Taxonomy: Automatic Identification of Class Stereotypes (ICSM'10) by Dragan, N., Collard, M.L., Maletic, J.I.
• Application: Automatically Redocumenting Source Code with Method and Class Stereotypes (DySDoc3'18) Guarnera, D., Collard, M.L., Dragan, N., Maletic, J.I., Newman, C., Decker, M.

Documentation

• Method stereotypes can be embedded in the source code as a comment
• documentation if the identification is manual
• redocumentation if the identification is automated
• Useful to be able to update in place

Taxonomy

• Accessors - Read access to the state of the object, both direct and derived
• Mutators - Write access to the state of the object
• Creational Methods - Create and manage the lifetime of objects
• Collaborational Methods - Work with objects of other classes
• Degenerate Methods - No access or changes to state

Accessors

Accessor::get

• Returns the value of a data member
• The purpose of the method is very simple and primitive
• Direct access to the value of the data member
• C++ Rules:
  • method is const
  • returns a data member
  • return type is primitive or container of a primitive

Accessor::predicate

• Returns a Boolean result computed from data members
• Result is not a direct data member, but a computation involving data members
• C++ Rules:
  • method is const
  • returns a Boolean value that is not a data member

Accessor::property

• Returns information based on data member values
• C++ Rules:
  • method is const
  • does not return a data member
  • return type is primitive or container of primitives
  • return type is not Boolean

Accessor::void-accessor

• Returns information about data members through a parameter

Mutators

Mutator::set

• Directly changes the value of a data member
• The parameter value is stored in the data member
• C++ Rules:
  • method is not const
  • return type is void or Boolean
  • only one data member is changed

Mutator::command

• Executes a complex change of the object’s state
• The change may involve several data members
• May change the data members either directly or indirectly with another mutator
• C++ Rules:
  • method is not const
  • return type is void or Boolean
  • complex change to the object’s state is performed, e.g., more than one data member is changed

Mutator::non-void-command

• Command which returns a value

Collaborational Methods

Collaborational::Collaborator

• Works on objects of classes different from itself
• C++ Rules:
  • returns void and at least one of the method’s parameters or local variables is an object
  • returns a parameter or local variable that is an object

Collaborational::Controller

• Works only on objects of classes different from itself

Creational Methods

Creational::factory

• Object creation method with the object returned to to the client

Degenerate Methods

Degenerate::incidental

• Does not read/change the object state, and no calls to other methods of the same class

Degenerate::stateless

• Does not read/change the object state, with one call to other methods of the same class

Degenerate::empty

• Method with no statements
• Typically part of an early implementation
• Maybe due to functionality moving elsewhere

Clear Design

• A method should have a single purpose, single responsibility issue
• Conversely, a method should have a single primary role, i.e., single role issue

Pop or Top vs. Pop and Top

Automated Detection

• Tool, stereocode, automatically redocuments source code with stereotypes
• XPath patterns with XPath extension functions
• Very scalable as it redocuments large systems in minutes