ICurrency Interface

Definition

Namespace

Bodu.Financial.Currencies

Assembly

Bodu.Financial.dll

Package

Bodu.Financial 1.0.0

Source

ICurrency.cs

Identifies a currency at the type-system level, supplying the ISO 4217 code, minor-unit precision, and optional cash-rounding and historicity metadata used by Money<TCurrency>.

public interface ICurrency

Remarks

Implementations of ICurrency are tag types - they exist solely to parameterize Money<TCurrency> and carry the currency's static metadata. They are never instantiated; the shipped implementations declare a private constructor and expose only static members.

The interface relies on the C# 11 static-abstract-member feature, so members are accessed through the type itself ( USD.IsoCode, USD.MinorUnits) and via TCurrency.IsoCode from within generic code constrained by where TCurrency : ICurrency.

IsoCode and MinorUnits are required. The remaining members ( CashRoundingIncrement, IsHistoric, DemonetizedOn, SuccessorIsoCode) are static virtual with sensible defaults so existing custom implementations remain source-compatible - only the shipped Bodu.Financial.Currencies tags override the defaults to surface country-specific cash rounding or historic-currency metadata.

using Bodu.Financial;
using Bodu.Financial.Currencies;

// Metadata is read statically from the tag type - no instance is ever created.
string code = USD.IsoCode;        // "USD"
int minorUnits = USD.MinorUnits;  // 2
int numeric = USD.NumericCode;    // 840

// The same members are reachable through a generic constraint.
static string DescribeCurrency<TCurrency>() where TCurrency : ICurrency =>
    $"{TCurrency.IsoCode} ({TCurrency.MinorUnits} minor units)";

Properties

CashRoundingIncrement

Gets the smallest cash denomination of the currency, expressed in the major unit.

public static decimal CashRoundingIncrement { get; }

Property Value

decimal

The cash-rounding increment in the major unit (for example, 0.05m for CHF's five-rappen smallest circulating coin, 0.05m for AUD / CAD cash totals since smallest coins were withdrawn, or 1m for SEK / NOK / ISK), or 0m when the currency does not require special cash rounding beyond its MinorUnits precision.

Remarks

The default of 0m is interpreted by RoundToCash(MidpointRounding) as "no special cash rounding required", so the rounding becomes a no-op. Cash-rounding rules apply only to physical cash totals; electronic transactions retain the full MinorUnits precision.

DemonetizedOn

Gets the date the currency was withdrawn from circulation, if known.

public static DateOnly? DemonetizedOn { get; }

Property Value

DateOnly?

The demonetization date, or null when the currency is active or the date is unknown.

EnglishName

Gets the English-language name of the currency.

public static string EnglishName { get; }

Property Value

string

The currency's name in English, in singular form and Title Case (for example, "United States Dollar", "Euro", or "Australian Dollar"), or an empty string when no name is supplied.

Remarks

The English name is used by Money<TCurrency> formatting in the L specifier path ( "1,234.56 Australian Dollar") and is available through EnglishName on the runtime-tagged registry entry. The default is the empty string so existing ICurrency implementations remain source-compatible; when empty, the L specifier falls back to the ISO-substitution form rather than emitting a trailing space with no name.

IsHistoric

Gets a value indicating whether the currency has been demonetized and is no longer in active circulation.

public static bool IsHistoric { get; }

Property Value

bool

true when the currency is a historic predecessor (for example, the Euro-zone national currencies replaced in 2002, or ZWL since its 2024 demonetization); otherwise false.

Remarks

Historic currencies still participate fully in arithmetic and formatting so consumers can process legacy data; IsHistoric exists for filtering and reporting only.

IsoCode

Gets the ISO 4217 three-letter alphabetic code that identifies the currency.

public static abstract string IsoCode { get; }

Property Value

string

An uppercase three-letter currency code, such as "USD", "EUR", or "JPY".

MinorUnits

Gets the number of fractional digits in the currency's minor unit - the precision Money<TCurrency> rounds to on construction and formats by default.

public static abstract int MinorUnits { get; }

Property Value

int

The non-negative number of decimal places the currency uses; typically two (for USD, EUR, etc.), zero (for JPY, KRW, CLP), or three (for BHD, KWD, OMR).

NumericCode

Gets the ISO 4217 three-digit numeric code that identifies the currency.

public static int NumericCode { get; }

Property Value

int

The three-digit numeric code (for example, 840 for USD, 36 for AUD, 392 for JPY), or 0 when the currency is custom or the numeric code is unknown.

Remarks

The numeric code is the second public identifier defined by ISO 4217 and is widely used by payment formats (SWIFT MT messages, ISO 20022). The default of 0 keeps existing custom ICurrency implementations source-compatible; the shipped Bodu.Financial.Currencies tags override it with the canonical ISO numeric value.

SuccessorIsoCode

Gets the ISO 4217 alphabetic code of the currency that replaced this one, when applicable.

public static string? SuccessorIsoCode { get; }

Property Value

string

The three-letter ISO code of the successor currency (for example, "EUR" for the Euro-zone predecessor currencies), or null when there is no defined successor.

Applies to

Product	Versions
.NET	8, 10