Specifications

Holds data related to Ethereum's technical specifications, serving as a reference point for Ethereum's rules and procedures obtained from the Ethereum execution specifications. The module is primarily used to enumerate and handle Ethereum's network upgrades or "hard forks" within the Ethereum Virtual Machine (EVM). These hard forks are referred to as SpecId in the code, representing different phases of Ethereum's development.

The SpecId enum assigns a unique numerical value and a unique string identifier to each Ethereum hard fork. These upgrades range from the earliest ones such as FRONTIER and HOMESTEAD, through to the most recent ones, including LONDON, MERGE, SHANGHAI, and LATEST.

The code also includes conversion methods such as try_from_u8() and from(). The former attempts to create a SpecId from a given u8 integer, while the latter creates a SpecId based on a string representing the name of the hard fork.

The enabled() method in SpecId is used to check if one spec is enabled on another, considering the order in which the hard forks were enacted.

The Spec trait is used to abstract the process of checking whether a given spec is enabled. It only has one method, enabled(), and a constant SPEC_ID.

The module then defines various Spec structs, each representing a different hard fork. These structs implement the Spec trait and each struct's SPEC_ID corresponds to the correct SpecId variant.

This module provides the necessary framework to handle and interact with the different Ethereum hard forks within the EVM, making it possible to handle transactions and contracts differently depending on which hard fork rules apply. It also simplifies the process of adapting to future hard forks by creating a new SpecId and corresponding Spec struct.