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Is there a way to directly be able to retrieve CHAIN_ID information about the executing chain from a smart contract?

I know that for any chain that has EIP-155 implemented, CHAIN_IDs are retrievable from the v component of a signature but would require the passing of one for extraction.

Since CHAIN_ID is information about the chain I suspect that there should be a way to access this. Is there a way for Solidity to directly get this information?

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    Alternative: Because you are deploying the contract on a different chain you can give the chain id as a constructor parameter. – Mikko Ohtamaa Aug 17 '18 at 14:40
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As of version 0.5.12, Solidity includes an assembly function chainid() that provides access to the new CHAINID opcode:

function getChainID() external view returns (uint256) {
    uint256 id;
    assembly {
        id := chainid()
    }
    return id;
}

To use it, ensure you set the compiler's EVM version to Istanbul with the --evm-version istanbul flag.

Related documentation: Solidity Assembly - v0.5.12

0

There isn't as of yet, but Istanbul (the upcoming hardfork) includes eip-1344, which includes a CHAINID opcode that pushes the chain id to the stack. I assume Solidity will add block.chainId or something similar, or at least add it to Solidity Assembly so that libraries can access it.

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