karmacoma-eth

// Reverse bytes received in calldata (abcd -> dcba)
// https://twitter.com/huff_language/status/1583894073487654913
// code length 206

/// @author Philippe Dumonet <philippe@dumo.net> -- https://twitter.com/real_philogy/status/1584304102418223104
/// @author karma (@0xkarmacoma) -- https://twitter.com/0xkarmacoma/status/1584239664310779904
/// @author kaden.eth (@0xKaden) -- https://twitter.com/0xKaden/status/1584280521089376256/
#define macro reverse_word() = takes(1) returns(1) {
  //               [x0]
  0x00ff00ff00ff00ff00ff00ff00ff00ff00ff00ff00ff00ff00ff00ff00ff00ff

karmacoma-eth

Sending Ether Cheat Sheet

TLDR

🥇 Instead of sending Ether, use the withdrawal pattern

🥈 If you really need to send Ether, use a safe wrapper like OpenZeppelin's Address.sendValue(addr, amount)

🥉 If you really need to send Ether without dependencies, use (bool success, ) = addr.call{value: amount}("")

hrkrshnn

Upgrade to at least 0.8.4

Using newer compiler versions and the optimizer gives gas optimizations and additional safety checks for free!

The advantages of versions 0.8.* over <0.8.0 are:

• Safemath by default from 0.8.0 (can be more gas efficient than some library based safemath).
• Low level inliner from 0.8.2, leads to cheaper runtime gas. Especially relevant when the contract has small functions. For

karmacoma-eth

# quine.etk
# ⬜ => ⬜
# A quine is a computer program which takes no input and produces a copy of its own source code as its only output.

# 0x80...f3 is the compiled code excluding the push16 instruction (from dup1 to return)
push16 0x8060801b17606f5953600152602136f3

                    # --- stack ---
dup1                # code code
push1 128           # 128 code code