Module design_pattern_examples_rust::handlerchain

The HandlerChain design pattern example module

Example of using the “Handle Chain” or “Chain of Responsibility” design pattern.

The Handler Chain pattern is used to support a dynamic list of handlers that are passed the same arguments. It is kind of the inverse of the Visitor pattern, where the Visitor pattern is a handler that is passed to all objects in a list, while the Handler Chain pattern is an object passed to handlers in a list.

In this exercise, multiple rectangular regions called MessageWindows embody the handlers and the HandlerChain object passes message objects to each MessageWindow until the message is handled.

Accessed through the handlerchain_exercise() function.

Modules

• handlerchain_handlerchain
  Contains the HandlerChain struct that manages all windows represented by the IMessageHandler trait.
• handlerchain_imessagehandler_trait
  Contains the IMessageHandler trait.
• handlerchain_message
  Contains the Message and MessagePosition structs, along with the MessageType enumeration, which are the foundation of the “Handler Chain” design pattern example.
• handlerchain_messagewindow
  Contains the WindowRectangle struct and the MessageWindow struct.

Functions

• _handlerchain_construct_window_chain 🔒
  Helper method to construct a list of windows. Messages will be passed to these windows via the HandlerChain object.
• handlerchain_exercise
  Example of using the “Handle Chain” or “Chain of Responsibility” design pattern.