ERC-7201 Storage Namespaces Explained ERC-7201 (formerly EIP-7201) is a standard for grouping storage variables together by a common identifier called a namespace, and also to document the group of variables via NatSpec annotation. The purpose of the standard is to simplify managing storage variables during upgrades. Namespaces Namespaces are a common approach in programming languages […]
Fixed Point Arithmetic in Solidity (Using Solady, Solmate, and ABDK as Examples) A fixed-point number is an integer that stores only the numerator of a fraction — while the denominator is implied. This type of arithmetic is not necessary in most programming languages because they have floating point numbers. It is necessary in Solidity because […]
The Transparent Upgradeable Proxy Pattern Explained in Detail The Transparent Upgradeable Proxy is a design pattern for upgrading a proxy while eliminating the possibility of a function selector clash. A functional Ethereum proxy needs at least the following two features: A storage slot holding the address of the implementation contract A mechanism for an admin […]
Understanding ABI encoding for function calls ABI encoding is the data format used for making function calls to smart contracts. It is also how smart contracts encode data when making calls to other smart contracts. This guide will show how to interpret ABI encoded data, how to compute the ABI encoding, and teach the relationship […]
Cross Program Invocation In Anchor Cross Program Invocation (CPI) is Solana’s terminology for a program calling the public function of another program. We’ve already done CPI before when we sent a transfer SOL transaction to the system program. Here is the relevant snippet by way of reminder: pub fn send_sol(ctx: Context<SendSol>, amount: u64) -> Result<()> […]
Nodelegatecall Explained The nodelegatecall modifier prevents delegatecalls from being sent to a contract. We will first show the mechanism for how to accomplish this then later discuss the motivation for why one might do this. Below, we’ve simplified the nodelegatecall modifier originally created by Uniswap V3’s noDelegateCall: contract NoDelegateCallExample { address immutable private originalAddress; constructor() […]
Reading Another Anchor Program’s Account Data On Chain In Solidity, reading another contract’s storage requires calling a view function or the storage variable being public. In Solana, an off-chain client can read a storage account directly. This tutorial shows how an on-chain Solana program can read the data in an account it does not own. […]
Delegatecall: The Detailed and Animated Guide This article explains how delegatecall works in detail. The Ethereum Virtual Machine (EVM) offers four opcodes for making calls between contracts: CALL (F1) CALLCODE (F2) STATICCALL (FA) and DELEGATECALL (F4). Notably, the CALLCODE opcode has been deprecated since Solidity v5, being replaced by DELEGATECALL. These opcodes have a direct […]
Low Level Call vs High Level Call in Solidity A contract in Solidity can call other contracts via two methods: through the contract interface, which is considered a high-level call, or by using the call method, which is a low-level approach. Despite both methods using the CALL opcode, Solidity handles them differently. In this article, we’ll compare […]