API Reference

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---

WhittakerTech::Midas (module)

Constants

Constant	Value
ROUNDING_POLICIES	{ round:, ceil:, floor:, bankers: } — lambdas
DEFAULT_ROUNDING_POLICY	:round

Module methods

Method	Returns	Notes
table_name(name)	String	Resolves fully-qualified table name
table_namespace=	—	Sets PostgreSQL schema namespace
currency_directions	Hash	Per-currency direction map (:ltr / :rtl)
currency_direction_for(code)	Symbol	Returns :ltr or :rtl for a currency code

---

Coin

Class methods

Method	Returns	Notes
Coin.value(currency_minor, currency_code)	Coin	Lowest-level factory (requires Integer)
Coin.zero(currency_code)	Coin	Zero-valued Coin
Coin.parse(value, currency_code: nil)	Coin	Coerces Money / Numeric / String

Instance methods — accessors

Method	Returns	Notes
amount	Money	Projection (memoized). Not the source of truth.
amount=(value)	—	Accepts Money or Numeric (minor units)
currency_code	String	ISO 4217 code (3 letters, uppercase)
currency_minor	Integer	Raw minor units (cents, pence, etc.)
minor	Integer	Alias for currency_minor
fractional	Integer	Alias for currency_minor
currency	String	Alias for currency_code
decimals	Integer	Decimal places defined by the currency
scale	Integer	10 ** decimals
major	BigDecimal	Major-unit value. Not payable money.

Instance methods — behaviour

Method	Returns	Notes
format(to: nil)	String	Delegates to Money#format
present(pattern, **opts)	String	Token-based formatting; see Presenter
allocate(per:, rounding_policy: :round)	Allocation	Returns per-unit value object

---

Coin::Arithmetic

Mixed into Coin. All operations return new frozen Coins.

Method	Returns	Raises
==(other)	Boolean	—
eql?(other)	Boolean	—
hash	Integer	—
+(other)	Coin	TypeError, ArgumentError (currency mismatch)
-(other)	Coin	TypeError, ArgumentError
*(integer)	Coin	TypeError (non-Integer)
%(integer)	Coin	TypeError, ZeroDivisionError
negate	Coin	—
-@	Coin	—
divide(divisor, rounding_policy: :round)	Coin	TypeError, ZeroDivisionError
divide_round(divisor)	Coin	Generated shorthand
divide_ceil(divisor)	Coin	Generated shorthand
divide_floor(divisor)	Coin	Generated shorthand
divide_bankers(divisor)	Coin	Generated shorthand

---

Coin::Allocation

Method	Returns	Notes
coin	Coin	The source Coin (frozen)
divisor / per	Numeric	Number of units
rounding_policy	Symbol	e.g. :round, :ceil
value	Coin	Per-unit Coin
price(qty: 1)	Coin	Total for N units
currency_code	String	Delegated from coin
decimals	Integer	Delegated from coin
scale	Integer	Delegated from coin
zero?	Boolean	Delegated from coin
positive?	Boolean	Delegated from coin
negative?	Boolean	Delegated from coin

---

Coin::Presenter

TOKEN_MAP

{ '%' => :token_percent, 't' => :token_total, 'm' => :token_minor,
  'M' => :token_major,   'c' => :token_currency_code,
  's' => :token_currency_symbol, 'n' => :token_number_only,
  'u' => :token_units,   'p' => :token_per_exact, '~' => :token_approx }

Class methods

Method	Returns	Notes
format(coin, pattern, **)	String	Main entry point
build_context(coin, **opts)	Context	Assembles rendering struct
scan(pattern, ctx)	String	Tokenises and expands pattern

Options for present / format

Option	Type	Default	Token
approx:	Boolean	false	%~
units:	String	nil (renders empty)	%u
per_exact:	String	nil (renders empty)	%p
currency_dir:	Symbol	From Midas.currency_direction_for	all

---

Coin::Parser

Method	Returns	Raises
parse(value, currency_code: nil)	Coin	TypeError, ArgumentError

Input coercion rules:

Input	Behaviour
Coin	Returned unchanged
Money	Wraps money.cents + money.currency.iso_code
Numeric	Major units; scaled to minor. Requires currency_code.
String	Strips non-numeric chars. Requires currency_code or embedded symbol.

---

Coin::Bidi

Method / Constant	Notes
LRI = "\u2066"	Left-to-Right Isolate mark
RLI = "\u2067"	Right-to-Left Isolate mark
PDI = "\u2069"	Pop Directional Isolate mark (closes span)
bidi_isolate(text, dir:)	Wraps text; dir: is :ltr, :rtl, or nil
bidi_isolate_number(text)	Shorthand for LTR isolation of numeric strings
bidi_currency_dir(currency_code)	Reads from Midas.currency_directions

---

Bankable

Class methods (in ActiveRecord model)

Method	Notes
has_coin(name, dependent: :destroy)	Declares a single monetary attribute
has_coins(*names, dependent: :destroy)	Declares multiple at once

Generated instance methods (for has_coin :price)

Method	Returns	Notes
price	Coin?	Returns the persisted Coin or nil
price_coin	Coin?	The has_one association
price_amount	Money?	coin.amount or nil
price_format	String?	Formatted string or nil
set_price(amount:, currency_code:)	Coin	Creates or updates the Coin
midas_coins	Relation	All coins on this resource

set_* amount coercion

Input type	Treated as
Money	Minor units from money.cents
Integer	Already minor units
Float / Numeric	Major units × 10 ** decimals_for(currency)

---

FormHelper

Method	Returns	Notes
midas_currency_field(form, attribute, currency_code:, **opts)	String (HTML)	Renders display + hidden fields

Options:

Option	Type	Notes
currency_code:	String	Required. ISO 4217 code.
label:	String	Field label text
decimals:	Integer	Decimal places override (default: 2)
input_html:	Hash	Passed to the visible display input
wrapper_html:	Hash	Passed to the wrapper <div>