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ConsenSys/smart-contract-best-practices

Discussion of engineering best practices, design patterns and security for smart contracts

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Foluso

@foogunlana

@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

Wappnet Systems

@WappnetS_twitter

Hello Everyone

I need Help to implement whitelist addresses contract in my existing smartcontract

anyone can help me ?

Yasin Shuman

@yshuman1

hey all, is there a channel dedicated to testing contracts?

Maurelian

@maurelian

@yshuman1 not to my knowledge, but consensys/truffle will probably discuss testing a fair bit

Nico Vergauwen

@kyriediculous

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.

Maurelian

@maurelian

@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

Anubhav Gupta

@array-addu

I need to store and retrieve multiple values in key value pair, can someone suggest me the best way to achieve this?

Amol🕶

@Amol_Sharma_twitter

Hi I am new here, anyone has a "best practices for smart contract" link/URL/document?

ThisIsCodeXpert

@ThisIsCodeXpert

@Amol_Sharma_twitter checkout this channel : https://www.youtube.com/channel/UCb3Rrg2t4PZ59Sna497DUZA?sub_confirmation=1

Amol🕶

@Amol_Sharma_twitter

Thanks @ThisIsCodeXpert

Devashish Tomar

@dev1644

Hi There,

Can I ask a question about Crowdsale Contract?

Devashish Tomar

@dev1644

How can I link the price of a token to a fiat Currency in Smart Contract.

Aside Oracle can there be another approach to it ?

Shashikant Soni

@shashiks

@dev1644 Since fiat prices are not available on Blockchains. Your best option is an oracle. No I haven't heard of any alternate approach around this

Devashish Tomar

@dev1644

Ok , I knew about oracle approach , want to know if there any other way to do this. Anyways Thanks Bro.

ArsenKulikov

@ArsenKulikov

Hello, Guys! I'm trying to deploy my contracts in mainnet using truffle and infura ws. With ropsten testnet it works perfect, but i had many issues, trying to deploy in mainnet. Finally, after many fixes, all my migrations successfully ended. But last running migrations end on 'Saving successful migration to network...' . Aaaand - nothing. I see it in my console about few hours and nothing happens. Can someone help me, what is this can be?

SatoshiSon

@Thirdwizard

Hi, can someone same me a sample of how to build ERC20 Token with function:
Lock Airdrop Distribution till after Token Sale and Distribute Automatically to members, Distribute Token to Investors automatically, Only Core Investors are required to sell tokens on the first seven (7) days
after listing of Token on Exchange market.
Reserved Tokens locked for 6 Months. Lock Team Member tokens for 12 Months.
Presale and Crowdsale Tokens are distributed automatically to buyers ETH Address,
and locked till After Token sale and 7 days after listing on Exchange Market. Token Sale Prices: $0.001, $0.005, $0.01, $0.05, $0.05
Unsold tokens to be burnt, after crowdsale. If tokens allocated to a particular tier are not exhausted in sales, it should be rolled over progressively to the next tier.

Thanks for the Help

Amol🕶

@Amol_Sharma_twitter

Hi, I am using web3j to deploy contract. Does anyone know how to listen to events on the deployed contract using Infura?

Ankit

@a4nkit_twitter

Hello, can anyone give working issue permission for https://github.com/ConsenSys/smart-contract-best-practices/blob/master/docs/about/contributing.md

also, while deploying on local this time I am getting TypeError: unhashable type: 'dict' error

this was not coming in my previous system. I am the only one who is facing the issue or its for most of us.

@maurelian ??

Ayush Gupta

@ayushgupta0610_twitter

Has anyone able to come up with a solution for EIP170??

Maurelian

@maurelian

@a4nkit_twitter Do you have python 3.6+?

Jeffrey Anthony

@jeffanthony

@ayushgupta0610_twitter "The solution is to put a hard cap on the size of an object that can be saved to the blockchain, and do so non-disruptively by setting the cap at a value slightly higher than what is feasible with current gas limits." master/EIPS/eip-170.md

fdervillez

@fdervillez

Hello. I am new comer here and stuck by an issue when trying to create a contract. Hope I could get some help here. I have a public function inside a main contract that keeps on leading "truffle migrate" to "out of gas" error when I turn it public. This function only creates a new child contract with something like "p = new contract(...)". As long as I keep it internal / private, it works fine and does the job within the main contract constructor. However when I want to call it publicly it fails from the migration step... Any idea? I tried to upper the gas limit but it seems to be endless... Thanks a lot...

Nico Vergauwen

@kyriediculous

Have you tried supplying the transaction with a gas amount of lets say

2 million?

Juan Castellon

@Juan-cc

@fdervillez it could be possible that you are getting gas issues changing the function visibility. Check this out: https://medium.com/@gus_tavo_guim/public-vs-external-functions-in-solidity-b46bcf0ba3ac

fdervillez

@fdervillez

Thanks a lot for the advise. Actually I changed the code structure and now it seems to work fine. May be it was related to function visibility indeed. Thanks again.

Isaque Daniel

@Isaquedanielre

Hello, I'm Isaque, leading a team to build a P2P crypto AgriFintech in South America, and we are looking for people interested in participate of the project.

Our project is a decentralized investment platform which connects farmers (which ones out of the credit and bank system) to investors (individual or institutional) using the Ethereum platform, smart contracts and web applications.

All the solicitation of loams will be analysed and validated using our data science engine already developed (which uses a combination of satellite images, wheatear forecast, crops informations and parameters and so on).

We are looking forward developers who knows solidity, web3, truffle, javascript, react.js.

Any interested people can send the CV and Portfolio to fewnickels@fewnickels.com

Thanks!

Justin Reid

@JusMReid

Getting these errors while tryting to npm install dependencies for my contract. Any help? Thanks

MSBuild: error

Oluwafemi E. Akinde

@SirPhemmiey

@Isaquedanielre is remote option available?

Isaque Daniel

@Isaquedanielre

@SirPhemmiey Hi, we are finishing the first round with the people, because we cannot to hire so much people at this time. If you interest send your CV, and we keep talking. best

ganeshdipdumbare

@ganeshdipdumbare

Hello, I am getting 0x after compiling smart contract using truffle
Is anybody having any idea

Siddharth Bhalla

@bhalla98

Hi, how do we handle indexed parameters in the constructor of Crowdsale contract?

Oluwafemi E. Akinde

@SirPhemmiey

@Isaquedanielre Okay, thanks. I have just done that

Anton

@AntonCorbijn

Here, did anyone experienced to get keccak hash of array type with web3 soliditySha3?
Please let me know if it is possible to calculate for array types with web3 soliditySha3.

Anubhav Gupta

@array-addu

Can someone suggest me how to use estimateGas for function calls like below:

await (MyContract.methods.addDoc(id,sha256hash).send({from: coinbase[0],gas: 1000000})

rushabh parmar

@parmarrushabh

hello everyone
any go developer who wants to work as a freelancer please fill free to contact me

Retrofred

@retrofred1_twitter

looking to implement smart contracts to IOT devices, any experienced devs with this?

rushabh parmar

@parmarrushabh

vikramvaishnav

@vikramvaishnav

Hello, I am new to dapp. I am trying to create my first dapp through truffle pet-shop but i got error in testing contract please help.
Here is Error
TypeError: Member "adopt" not found or not visible after argument-dependent lookup in type(contract Adoption).
uint returnPetId=Adoption.adopt(expectedPetId);
^------------^
Thanks in Advance

Brian Liotti

@bliotti

@vikramvaishnav add your first test function after the expectedPetID and expectedAdopter declarations

Shivam Srivastava

@shivam3746

Hey can anyone help me in writing javascript tests for my smart contract

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