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4e907d9662
- Document XRP/MPT and IOU short-circuit behaviour in STAmount::isZeroAtScale - Disambiguate duplicate "Cover precision guard: Deposit" testcase names in LoanBroker_test - Extend testIsZeroAtScale with half-ULP boundary, large-magnitude gap, and negative-value cases - Tighten ASSERT in canApplyToBrokerCover to compare full assets (covers MPT, not just issuer)
protocol
Classes and functions for handling data and values associated with the XRP Ledger protocol.
Serialized Objects
Objects transmitted over the network must be serialized into a canonical format. The prefix "ST" refers to classes that deal with the serialized format.
The term "Tx" or "tx" is an abbreviation for "Transaction", a commonly occurring object type.
Optional Fields
Our serialized fields have some "type magic" to make optional fields easier to read:
- The operation
x[sfFoo]means "return the value of 'Foo' if it exists, or the default value if it doesn't." - The operation
x[~sfFoo]means "return the value of 'Foo' if it exists, or nothing if it doesn't." This usage of the tilde/bitwise NOT operator is not standard outside of thexrpldcodebase.- As a consequence of this,
x[~sfFoo] = y[~sfFoo]assigns the value of Foo from y to x, including omitting Foo from x if it doesn't exist in y.
- As a consequence of this,
Typically, for things that are guaranteed to exist, you use
x[sfFoo] and avoid having to deal with a container that may
or may not hold a value. For things not guaranteed to exist,
you use x[~sfFoo] because you want such a container. It
avoids having to look something up twice, once just to see if
it exists and a second time to get/set its value.
(Real example)
The source of this "type magic" is in SField.h.