Tirsvad
6d99810e30
MIL-003 Console interface. - Add calculator() with recursive restart: y continues with the result, n starts a new calculation, q quits - Show one ASCII title at start: a calculator with the lettering to its right - Re-prompt on invalid numbers, operations and answers; restart on division by zero - Add __main__.py for python -m calc and the calc console script - Add interface tests with input() fed through monkeypatch Closes #22 Closes #23 Closes #24 Closes #25 Task: MIL-003#1 Task: MIL-003#2 Task: MIL-003#3 Task: MIL-003#4
113 lines
3.1 KiB
Python
113 lines
3.1 KiB
Python
"""!
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@file calculator.py
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@brief The interactive console calculator.
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"""
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from calc.constants import (
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ANSWER_CONTINUE,
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ANSWER_NEW,
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ANSWER_QUIT,
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ASCII_TITLE,
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MESSAGE_DIVIDE_BY_ZERO,
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MESSAGE_GOODBYE,
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MESSAGE_INVALID_ANSWER,
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MESSAGE_INVALID_NUMBER,
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MESSAGE_INVALID_OPERATION,
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PROMPT_AGAIN,
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PROMPT_FIRST_NUMBER,
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PROMPT_NEXT_NUMBER,
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PROMPT_OPERATION,
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)
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from calc.operations import OPERATIONS
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def format_number(value: float) -> str:
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"""!
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@brief Format a number without a trailing ".0" for whole values.
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@param value The number to format.
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@return The text to show the user.
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"""
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return str(int(value)) if value.is_integer() else str(value)
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def read_number(prompt: str) -> float:
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"""!
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@brief Ask for a number until the user types a valid one.
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@param prompt The text shown to the user.
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@return The number typed by the user.
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"""
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while True:
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try:
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return float(input(prompt))
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except ValueError:
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print(MESSAGE_INVALID_NUMBER)
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def read_operation() -> str:
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"""!
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@brief Show the available operations and ask for one until it is valid.
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@return The symbol of the chosen operation, a key of OPERATIONS.
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"""
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for symbol in OPERATIONS:
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print(symbol)
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while True:
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symbol = input(PROMPT_OPERATION).strip()
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if symbol in OPERATIONS:
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return symbol
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print(MESSAGE_INVALID_OPERATION)
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def read_answer(result: float) -> str:
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"""!
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@brief Ask whether to continue with the result, start anew or quit.
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@param result The result of the last calculation.
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@return One of ANSWER_CONTINUE, ANSWER_NEW or ANSWER_QUIT.
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"""
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while True:
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answer = input(PROMPT_AGAIN.format(result=format_number(result)))
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answer = answer.strip().lower()
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if answer in (ANSWER_CONTINUE, ANSWER_NEW, ANSWER_QUIT):
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return answer
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print(MESSAGE_INVALID_ANSWER)
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def calculator() -> None:
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"""!
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@brief Run one calculation session.
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The user may continue with the previous result. Starting a new
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calculation calls this function again (recursion), which gives a clean
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restart. A division by zero also restarts the calculator.
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"""
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num1 = read_number(PROMPT_FIRST_NUMBER)
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while True:
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symbol = read_operation()
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num2 = read_number(PROMPT_NEXT_NUMBER)
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try:
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result = OPERATIONS[symbol](num1, num2)
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except ZeroDivisionError:
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print(MESSAGE_DIVIDE_BY_ZERO)
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calculator()
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return
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print(
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f"{format_number(num1)} {symbol} {format_number(num2)} "
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f"= {format_number(result)}"
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)
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answer = read_answer(result)
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if answer == ANSWER_CONTINUE:
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num1 = result
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elif answer == ANSWER_NEW:
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calculator()
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return
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else:
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print(MESSAGE_GOODBYE)
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return
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def main() -> None:
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"""!
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@brief Program entry point: show the ASCII title and start the calculator.
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"""
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print(ASCII_TITLE)
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calculator()
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