1.1 KiB
DECISIONS (append-only)
lex phase
Token as dataclass: Used @dataclass for Token to get __eq__ for free, enabling assertIn and assertEqual in tests.
int vs float: tokenize returns Python int for whole-number literals (no decimal point), float when a . is present. This matches the plan's wording "numeric value (int or float)".
EOF value: Set EOF token value to None (no meaningful payload).
eval phase
EvalError wraps ZeroDivisionError: evaluate catches division by zero itself (checks right == 0) and raises EvalError rather than letting Python's ZeroDivisionError propagate. This is the public API contract: callers catch EvalError.
D3 formatting rule in fmt_result: Placed in calc/evaluator.py so it's importable and testable from calc/test_evaluator.py. Rule: isinstance(v, float) and v.is_integer() → str(int(v)), else str(v). Python's / always returns float, so 4/2 = 2.0; fmt_result converts to "2".
CLI at repo root as calc.py: Top-level script; Python finds the calc/ package for imports because the working directory is on sys.path when running python calc.py.