RPN Calculator
10 Points
errors
try-rescue
Instructions
While working at Instruments of Texas, you are tasked to work on an experimental Reverse Polish Notation [RPN] calculator written in Elixir. Your team is having a problem with some operations raising errors and crashing the process. You have been tasked to write a function which wraps the operation function so that the errors can be handled more elegantly with idiomatic Elixir code.
1. Warn the team
Implement the function calculate!/2 to call the operation function with the stack as the only argument. The operation function is defined elsewhere, but you know that it can either complete successfully or raise an error.
stack = []
operation = fn _ -> :ok end
RPNCalculator.calculate!(stack, operation)
# => :ok
stack = []
operation = fn _ -> raise ArgumentError, "An error occurred" end
RPNCalculator.calculate!(stack, operation)
# => ** (ArgumentError) An error occurredFunction names that end in
!are a warning to programmers that this function may raise an error
2. Wrap the error
When doing more research you notice that many functions use atoms and tuples to indicate their success/failure. Implement calculate/2 using this strategy.
stack = []
operation = fn _ -> "operation completed" end
RPNCalculator.calculate(stack, operation)
# => {:ok, "operation completed"}
stack = []
operation = fn _ -> raise ArgumentError, "An error occurred" end
RPNCalculator.calculate(stack, operation)
# => :error3. Pass on the message
Some of the errors contain important information that your coworkers need to have to ensure the correct operation of the system. Implement calculate_verbose/2 to pass on the error message. The error is a struct that has a :message field.
stack = []
operation = fn _ -> "operation completed" end
RPNCalculator.calculate_verbose(stack, operation)
# => {:ok, "operation completed"}
stack = []
operation = fn _ -> raise ArgumentError, "An error occurred" end
RPNCalculator.calculate_verbose(stack, operation)
# => {:error, "An error occurred"}RPN Calculator
10 Points
errors
try-rescue
Instructions
While working at Instruments of Texas, you are tasked to work on an experimental Reverse Polish Notation [RPN] calculator written in Elixir. Your team is having a problem with some operations raising errors and crashing the process. You have been tasked to write a function which wraps the operation function so that the errors can be handled more elegantly with idiomatic Elixir code.
1. Warn the team
Implement the function calculate!/2 to call the operation function with the stack as the only argument. The operation function is defined elsewhere, but you know that it can either complete successfully or raise an error.
stack = []
operation = fn _ -> :ok end
RPNCalculator.calculate!(stack, operation)
# => :ok
stack = []
operation = fn _ -> raise ArgumentError, "An error occurred" end
RPNCalculator.calculate!(stack, operation)
# => ** (ArgumentError) An error occurredFunction names that end in
!are a warning to programmers that this function may raise an error
2. Wrap the error
When doing more research you notice that many functions use atoms and tuples to indicate their success/failure. Implement calculate/2 using this strategy.
stack = []
operation = fn _ -> "operation completed" end
RPNCalculator.calculate(stack, operation)
# => {:ok, "operation completed"}
stack = []
operation = fn _ -> raise ArgumentError, "An error occurred" end
RPNCalculator.calculate(stack, operation)
# => :error3. Pass on the message
Some of the errors contain important information that your coworkers need to have to ensure the correct operation of the system. Implement calculate_verbose/2 to pass on the error message. The error is a struct that has a :message field.
stack = []
operation = fn _ -> "operation completed" end
RPNCalculator.calculate_verbose(stack, operation)
# => {:ok, "operation completed"}
stack = []
operation = fn _ -> raise ArgumentError, "An error occurred" end
RPNCalculator.calculate_verbose(stack, operation)
# => {:error, "An error occurred"}