philiprehberger-money 0.4.0

Precise monetary calculations using integer cents with currency support and formatting

philiprehberger-money

Precise monetary calculations using integer cents with currency support and formatting.

Installation

pip install philiprehberger-money

Usage

Creating Money

from philiprehberger_money import Money

price = Money.from_major(19.99, "USD")
free = Money.zero("EUR")

Arithmetic

from philiprehberger_money import Money

a = Money.from_major(10.00, "USD")
b = Money.from_major(3.50, "USD")

total = a + b          # $13.50
diff = a - b           # $6.50
doubled = a * 2        # $20.00
split = a.divide(3)    # $3.33 (rounded)
negated = -a           # -$10.00

Safe Currency Handling

from philiprehberger_money import Money, CurrencyMismatchError

usd = Money.from_major(10, "USD")
eur = Money.from_major(10, "EUR")

usd + eur  # raises CurrencyMismatchError

Allocation (Split Without Losing Cents)

from philiprehberger_money import Money

total = Money.from_major(100.00, "USD")

# Split 50/30/20
shares = total.allocate([50, 30, 20])
# [Money($50.00), Money($30.00), Money($20.00)]

# Handles remainders correctly
odd = Money.from_major(10.00, "USD")
thirds = odd.allocate([1, 1, 1])
# [Money($3.34), Money($3.33), Money($3.33)]

Denomination Rounding

from philiprehberger_money import Money

price = Money.from_major(1.23, "USD")

# Round to nearest 5 cents
rounded = price.round_to_nearest(5)
print(rounded.format(symbol="$"))  # "$1.25"

# Round to nearest 10 cents
rounded = price.round_to_nearest(10)
print(rounded.format(symbol="$"))  # "$1.20"

Currency Conversion

from philiprehberger_money import Money

usd = Money.from_major(100, "USD")

# Direct rate
eur = usd.convert("EUR", 0.92)
print(eur.format())  # "92.00 EUR"

# Using a rates dictionary
eur = usd.convert(to="EUR", rates={"USD/EUR": 0.92})

# Using a rate provider callable
def get_rate(from_currency: str, to_currency: str) -> float:
    return 0.92  # fetch from API, database, etc.

eur = usd.convert(to="EUR", rate_provider=get_rate)

Locale-Aware Formatting

from philiprehberger_money import Money

price = Money.from_major(1234.56, "USD")

print(price.format())                 # "1234.56 USD"
print(price.format(symbol="$"))       # "$1234.56"
print(price.format(locale="en_US"))   # "$1,234.56"
print(price.format(locale="de_DE"))   # "$1.234,56"

Rounding Modes

from philiprehberger_money import Money, RoundingMode, set_default_rounding_mode

# Per-instance rounding mode
m = Money(amount_cents=5, currency="USD", rounding_mode=RoundingMode.ROUND_HALF_EVEN)
result = m.divide(2)  # 2.5 -> 2 (banker's rounding)

# Change rounding mode on existing instance
m2 = m.with_rounding_mode(RoundingMode.ROUND_UP)

# Set global default (affects all instances without explicit mode)
set_default_rounding_mode(RoundingMode.ROUND_HALF_EVEN)

Comparisons

from philiprehberger_money import Money

a = Money.from_major(10, "USD")
b = Money.from_major(20, "USD")

a < b   # True
a == b  # False
a.is_positive()  # True
a.is_zero()      # False

Zero-Decimal Currencies

from philiprehberger_money import Money

yen = Money.from_major(1000, "JPY")
print(yen.format(symbol="\u00a5"))  # "\u00a51000"

Serialization

from philiprehberger_money import Money

m = Money.from_major(19.99, "USD")

d = m.to_dict()           # {"amount_cents": 1999, "currency": "USD"}
m2 = Money.from_dict(d)   # Money(19.99 USD)

API

Function / Class	Description
Money.from_major(amount, currency, *, rounding_mode=None)	Create from major units (dollars, euros, etc.)
Money.zero(currency, *, rounding_mode=None)	Create zero-value Money
Money.from_dict(data)	Create from dict
.add(other) / +	Add two Money values (same currency)
.subtract(other) / -	Subtract (same currency)
.multiply(factor) / *	Multiply by number
.divide(divisor)	Divide by number
.allocate(ratios)	Split into parts without losing cents
.round_to_nearest(step)	Round minor units to nearest multiple
.convert(to, rate=None, *, rates=None, rate_provider=None)	Convert to another currency using a rate, rates dict, or callable
.format(symbol=None, *, locale=None)	Format as string, optionally locale-aware
.with_rounding_mode(mode)	Return copy with specified rounding mode
.negate() / -m	Negate amount
.abs()	Absolute value
.is_zero() / .is_positive() / .is_negative()	Predicates
.to_dict()	Serialize to dict
.amount	Major unit value as float
.decimals	Currency decimal places
RoundingMode	Enum: ROUND_HALF_UP, ROUND_HALF_EVEN, ROUND_DOWN, ROUND_UP
set_default_rounding_mode(mode)	Set global default rounding mode
get_default_rounding_mode()	Get current global default rounding mode
CurrencyMismatchError	Raised on mixed-currency operations

Development

pip install -e .
python -m pytest tests/ -v

Support

If you find this package useful, consider giving it a star on GitHub — it helps motivate continued maintenance and development.

License

MIT