The SystemA design pattern is one of the recommended ways to implement the system layers that a program relies on and provides an elegant way to initialize those layers from within the shunting block.
Conventions:
- SystemA - both the name of the design pattern and a way to emphasize that the system interface should be both abstracted away from the heart of the program and be well-defined
- SystemB - the implementation of the system interface that allows the program to run in the browser
- SystemC - the implementation of the system interface that allows the program to run in the terminal as a command-line application
The idea is that executing the shunting block will result in one of SystemB or SystemC being instantiated, which the heart of the program can rely on as a capabilities provider.