Discussion of engineering best practices, design patterns and security for smart contracts
please share your views
Thanks
Does anybody have some insight about the question asked here: https://ethereum.stackexchange.com/questions/52258/what-are-good-specific-reasons-the-onerc721received-function-returns-a-magic-val
@mudgen_twitter Sorry, would love to help but that is way beyond me at the moment.
Hello everyone,just created a lottery game as smart contract ,can you give me some advice ? see more http://luckyyou.io
@adhikarideepak depends on your use, with some applications it makes sense to store data with a database & call the required functions from the smart contracts with an API like web3 or ethersjs. But if you are looking to bypass SQL/NoSQL databases check IPFS. Storage in blockchain is still a big issue though.
@cryptogee I don't know what you mean, but your best bet is probably to read the inheritance section: https://solidity.readthedocs.io/en/latest/contracts.html#inheritance
the 'super' keyword might be relevant to you
the 'super' keyword might be relevant to you
can anyone help to get some simple tutorials for smart contract with front-end and database DAPP ?
Hello. I just wrote a blog post of auditing my own smart contract. Hope this is helpful to the audience here https://medium.com/@makoto_inoue/self-audit-a-new-bug-and-call-for-community-auditing-of-blockparty-e774a8596496
```var gas = await commitFunction.EstimateGasAsync(platformAccount.Address, new Nethereum.Hex.HexTypes.HexBigInteger(15000), new HexBigInteger(Nethereum.Util.UnitConversion.Convert.ToWei(0)), id.HexToByteArray()).ConfigureAwait(false);```
It work fine at last week, but this week it works error, it so confuse to me.
I am trying ethereum-login example from https://auth0.com/blog/an-introduction-to-ethereum-and-smart-contracts-part-2/
After doing all steps successfull when I try to execute contract , there is error TypeError: LoginContract.LoginAttempt is not a function
Contract is unable to find its method , what can be possible mistake here ...
or can some body give me some example about new web3.eth.Contract(jsonInterface[, address][, options])
I have a requirement where we need to save data(pdf) to blockchain so that any third party can access and view it later by the block address. I can't store the hash of the data on blockchain as the third party does not have access to the original document to verify the hash of the data. Is it feasible?
@array-addu I often see people store data on IPFS and then hashes in the blockchain. But I'm not completely clear on what the problem is. Do you just need data storage? IPFS, Swarm and other solutions exist for that. Or are you trying to restrict access by some permissions or authorization
I need Help to implement whitelist addresses contract in my existing smartcontract
anyone can help me ?
Anyone familiar here with inline assembly? I've tried like everywhere.
I'm trying to make a low level dispatcher. What is different from existing implementations is that I Need to load in a struct from storage to pass as a param to the library I'm delegating to. I'd also need to split the calldata and put that storage struct in between.
Here's the issue on github: ethereum/solidity#4854
Any help gets huge kudos in my extensive blogpost on smart contract architecture :)
You might ask ,why don't you just write functions that delegate to the library directly without assembly? Because that doesn't save any gas despite many people thinking it does. Making this issue work would reduce deployment gas cost of instances delegating to the logic of the library by more than half. This has enormous positive implications for example identity, where it becomes way cheaper than the current price of 0.30$ to deploy the uPort contract.
@kyriediculous the best resource I know of is the solidity documentation.
You might find this bytes library a useful resource: https://github.com/0xProject/0x-monorepo/blob/development/packages/contracts/src/2.0.0/utils/LibBytes/LibBytes.sol
You might find this bytes library a useful resource: https://github.com/0xProject/0x-monorepo/blob/development/packages/contracts/src/2.0.0/utils/LibBytes/LibBytes.sol
@Amol_Sharma_twitter checkout this channel : https://www.youtube.com/channel/UCb3Rrg2t4PZ59Sna497DUZA?sub_confirmation=1
Can I ask a question about Crowdsale Contract?
Aside Oracle can there be another approach to it ?
