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  • Oct 10 2017 22:42
    @jpitts banned @etherchamp1_twitter
  • Jun 05 2016 10:33
    @chriseth banned @adamskee
okay, how do I get this address in my solidity contract?
like, is there any way i can get that address using an inbuilt function?
Not quite sure what you mean, are you trying to get the owner of another contract in your contract?
2 replies
George Carder

(also asked in compiler channel and they referred me here)

  • in assembly what is the storage location of return data?

  • put directly.. given the example below, what is location?

thanks in advance


... in contract

modifier defer(... args ..) {
  // want to use assembly here to access return data of modified function
  // so I imagine it'd be like
  bytes memory returnPtr;
  assembly {
    returnPtr := mload(location)
   <Type> returnData;
   (returnData) = abi.decode(returnPtr, <Type>);

function someFunction() defer(..args..) {
  if (monday) {
    return 42;
  } else if (tuesday) {
    return 32;
  return 123;
Yo hey guys, im having a dumb problem probably, i cant assign a value to a key in a mapping, if i do it thru a function it works but if i want to do it as the result of an if confitional it just returns 0

Hey masters. Is this $$ a special keyword of solidity ?

  function setContract(CoreContracts name, address contractAddress) public {
        require(msg.sender == DIRECTORY, $$(ErrorCode(UNAUTHORIZED_CALLER)));  <- this is the line with the "$$"
        contracts[uint256(name)] = contractAddress;

Found in this contract

Oh nvm. Just found out the answer... is a command for solpp, a solidity pre-processor

HI, please ask a question, my project directory structure is like this, now I need to upload the source code to https://etherscan.io

But https://etherscan.io doesn't seem to support source code validation for this structure, it only supports single file source code and multiple file source code in the same directory, and my source code is multiple files in different directories.

Do you have any solution to this problem?

Here you can only select multiple files in the same directory at once
do unused arguments end up in the transaction log?
I basically want an additional piece of data to operate on externally of contract. I know I could use an event for this, but wondering if I could just add an extra arg as a cheaper alternative?
hello everyone , im newly intrested with smart contracts , i got a theorical question ( not coding or development help ) anyone can help me to understand something i dont know about smart chains
which is the ethereum space?
João Vitor Ianuci
Hello guys, I'm new on solidity contracts - I have a problem doing a contract with mint number of 20K unique nfts, How I can check that an ipfs metadata already minted, there a way without a large loop?
Moody Salem
hey yall... is the solidity baked in safemath the cheapest implementation?
1 reply
i'm finding switching from our implementation to the builtin makes operations more gas expensive
in addition, it added 500 bytes of bytecode
Merouane B.
Hi, i’m looking to batch mint NFTs with the optimal gas fees, NFTs have single copy of each. Should I use ERC 721 or 1155 to do so ?
what did you ure before?
Richard Zhang
Hi guys, do you consider scaling contracts to multiple contracts (maybe Factory design)? I'm worried that storing data on 1 contract will be costly
Perelyn Sama
Hey does anyone have a way to create a react dapp? I tried the truffle react box but I'm getting some errors
Nikolay Toplev
Hi, everyone. I would be grateful for who can help me with triggering function call in solidity per block on binance smart chain. Thank you in advance.
Code Chef
Does anyone know how to trigger function calls per block in solidity?
2 replies
Nikolay Toplev
Could you offer me a link to show how to do that?
2 replies
hello can someone help me understand why i cant withdraw my token
even tho the solidity code looks safe
tried all slippage
Jonathan Gros-Dubois
Does Ethereum support adding custom data to transactions?
If so, how many bytes in a transaction?

Yes, you can include it on the “data” field of the transaction. I’m not sure of the number of the bytes but the limit is probably not a problem, unless you’re trying to share something huuuge like video or image content. Don’t do that on Ethereum, use IPFS for that.

See this SO question, and you need to add the “data” field to the transaction



Have you heard about the upcoming Bitcoin Bankathon? It's an international hackathon with five challenges to tackle real world problems by building decentralized financial applications. It lasts from November 19th till December 8th and contains a total of 250,000USD-equivalent prizes. If you want to sign up for it, please visit the website: https://bitcoin-alliance.org/

You can build with any language that compiles to the EVM. This includes Solidity, Julia, and new or experimental programming languages such as Vyper.


First of all, thank you Vitalik Buterin !

@Perelyn-sama i would define a dApp, decentralized Application, by now and here, you just need one Component as a smartContract.

To really understand, what a smartContract is, we’ll need some good „openMic“-Sessions, or some defining content.. leacked


Hi Guys
For following contract, if I change B, would it change bytecode of contract ?
I was assuming that due to treeShaking it should not
but when I changed B, bytecode also changed
Can you please explain ?
bytes32 constant a = bytes32(hex"1e8e1b45c8500eaae36dbdda78698134042397867d83fedc92005af7c108c793");
bytes32 constant b = bytes32(hex"9723a2a3c9b49f62a314da557d9f0e080f0af927614758f525c253a9cfd1597a");

library Lib {
    function aaa() internal pure returns (bytes32) {
        return a;

    function bbb() internal pure returns (bytes32) {
        return b;

contract HelloWorld {
    function fn() external pure returns (bytes32) {
        return Lib.aaa();
Hi there!!
I asked question on OZ forum but nobody knows...
Is there somebody brave enough who would like to check it and perhaps collaborate?
I'm sure it will also help lots of devs in the future...
Víctor Hernández

Hey! I know this is specfic for solidity-devs, but maybe someone with more experience can help me. It's about some tools, mostly about hardhat and the compiler.

1. When i specified the compiler in hardhat.config. Is there any way to override an entire folder? I have one folder that have to be compiled with 0.6.12 and 1000 optimizer runs, and another with 0.6.12 but with 200 optimizer runs. In short: Can i do this with the entire folder? Or some ideas? lmao. I do not want to add every contract as override but if it the only way, ok(i already asked on Hardhat Discord yesterday)

2. Which values in the hardhat compiler we can say are default? I mean: i created the Input JSON description with Solt, and i copy the same settings that the I/O JSON in hardhat.config. The problem comes when i get a different bytecode compiling from the Solidity file with hardhat, and compiling with solc --standard-json (using the same version with hardhat btw). It's no problem with the "metadata hash" at the end of the bytecode - actually, i get the same metadata hash . It's really different on several points along the bytecode. These contracts are using abiEncoderV2 too. This problem doesnt happen with all the contracts. I not checked the bytecode from each contract, but until now - i see this difference only on the contracts with AbiEncodeV2. So, idk if Hardhat add some setting that are not "default". Could be that the reason that i get different bytecode? Or something else?

I really know that could be dense all these questions, but i really spend full time with my own research and still getting different bytecode with those contracts with AbiEncodeV2.

Thanks for any answer :)

Anique Hashmani
anyone here to help ?
can anyone help me with solidity willing to pay Good amount.
Hi, everyone.
I am a senior solidity developer, do you need any help?
Ridoy Khan Rana
This message was deleted
1 reply
Only three days left till the start of the Bitcoin Bankathon!
ReLliM nIvEk
Hello.i.have a.private question about deploying on smart contracts ds feel more comfortable if I spoke in private if possible for legal purposes