boram / calculator

CLI RPN Calculator

Usage

cd into this project and run the binary:

$ ./bin/calculator

To exit, type q or CTRL+D.

Overview

Calculator is composed of:

• Calculator::CLI
• Calculator::Processor

Calculator::CLI

Calculator::CLI owns the REPL.

When exceptions are raised in Calculator::Processor, they are rescued here and written to stdout.

Calculator::Processor

Calculator::Processor owns the core calculator functionality. Numbers are pushed on to an internal stack and evaluated when an arithmetic operator (+, -, *, /) is encountered.

Input values are validated here to be arithmetic operators or numbers.

Exceptions raised here bubble up to the CLI.

Future Improvements

1. Specs have many opportunities for DRYing up.
2. Specs spawn this in a separate process so that input and output can be tested directly. However, this means that async issues can mean these tests are potentially brittle. Perhaps, we should look at non-async testing strategies.
3. Fix divide by zero errors in some scenarios where they are not handled. This means there might also be an opportunity for normalizing some logic.