How to create the pair without assembly in UniswapV2Factory

Question

I'm going to deploy the Uniswap contract on my customized Ethereum.

Could I replace fancy footwork in the factory by Solidity code?

I need to update this code assembly { pair := create2(0, add(bytecode, 32), mload(bytecode), salt)} into general solidity code.

I tried this, but not working well.

Stack Overflow questions can link external code for context, but the code you're directly asking about changing or fixing should always be in the question directly. — Peter Cordes, Mar 05 '22 at 11:59

score 1 · Accepted Answer · answered Mar 06 '22 at 22:04

1

I found the solution

bytes memory bytecode = type(UniswapV2Pair).creationCode;
bytes32 salt = keccak256(abi.encodePacked(token0, token1));
assembly {
  pair := create2(0, add(bytecode, 32), mload(bytecode), salt)
}

I updated above code into

UniswapV2Pair newPair = new UniswapV2Pair();
IUniswapV2Pair(pair).initialize(token0, token1);

answered Mar 06 '22 at 22:04

hobbydev

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I don't think you can calculate the pair address offchain without using `create2`. However, it seems like with Solidity version 0.8, you can do it without using assembly https://stackoverflow.com/questions/71121396/how-is-uniswap-assembly-create2-function-working – Relaxed Leaf Oct 01 '22 at 01:04

score 0 · Answer 2 · answered Mar 05 '22 at 12:08

Uniswap version 1 uses library contracts with hardcoded pair contract addresses.

First deploy the factory contract
Then call Factory.pairCodeHash - the hardcoded hex string of the init code
Replace the pair code hash in the source code, compile the rest of the contracts

More tips in this Python module.

How to create the pair without assembly in UniswapV2Factory

2 Answers2