rippled/include/xrpl/ledger/helpers

Ledger Entry Helpers (entries/)

Overview

This folder contains helper classes and free functions for working with Serialized Ledger Entries (SLEs). Its centerpiece is SLEBase.h, which defines two base classes — ReadOnlySLE and WritableSLE — that provide a type-safe, context-aware wrapper around the raw std::shared_ptr<SLE> used throughout the rest of the codebase.

The Problem: Untyped SLE Access

Historically, ledger entries are passed around as bare std::shared_ptr<SLE> (or std::shared_ptr<SLE const>). This has several drawbacks:

1. No compile-time entry-type safety. Any code holding an std::shared_ptr<SLE> can read or write any field on any ledger entry type. Nothing prevents you from calling sle->getFieldU32(sfOwnerCount) on an Offer SLE, even though Offers don't have that field.

2. No read/write distinction. A function that only needs to read an entry still receives a mutable std::shared_ptr<SLE>, making it easy to accidentally mutate state. Conversely, a function that must write has no way to express that requirement in its signature.

3. No association with the view. The SLE and the ReadView / ApplyView it came from travel as separate arguments, so callers must manually keep them in sync and remember to call view.update(sle) after mutations.

The Solution: SLEBase.h

SLEBase.h introduces two base classes that pair an SLE with its view context and enforce read/write semantics at compile time.

ReadOnlySLE bundles a std::shared_ptr<SLE const> with the ReadView it was read from. It provides existence checks and const-only access to the underlying entry. Derived classes add domain-specific read-only accessors (e.g. AccountRoot::isGlobalFrozen()).

WritableSLE bundles a mutable std::shared_ptr<SLE> with the ApplyView used for writes. It provides helpers to insert, update, and erase the entry in the view, keeping the SLE and its view in sync automatically.

Dual-Inheritance Pattern

Concrete writable wrappers inherit from both the read-only wrapper and WritableSLE:

WritableAccountRoot
  ├── AccountRoot   (extends ReadOnlySLE)  — read-only domain methods
  └── WritableSLE                          — write capabilities

This lets a writable wrapper reuse all read-only domain logic from its parent while gaining mutation and persistence operations from WritableSLE.

Migration Status

This migration is still in progress and is still in the early stages. New code should prefer the wrapper style where possible; existing free functions will be migrated incrementally.