News Monday, July 16

Unable to declare public mapping in Solidity

  • The problem here seems to be with the getters that are created when you declare the variables public, changing the visibility to internal cancels the error.
  • In this answer it is explained that passing nested arrays is the problem.
  • Note that in both cases adding a fix-length variable to the structs cancels the errors.

Tags:

Unable to declare public mapping in Solidity

How does EtherDelta migrates mapping?

  • I’m looking at EtherDelta contract, and — provided it had been migrated several times in the past and probably foresees future migrations — I’m confused as I don’t see any method by which the owner of the contract can migrate the data.
  • They must have a list of all the addresses in the mapping in order to migrate the data to a new version of the contract, don’t they?
  • Yet it is missing from the contract.

Tags:

How does EtherDelta migrates mapping?

What does it mean when a function is called in the head of constructor() function?

  • I’m reading through some smart contracts and I noticed functions being called in the head of the constructor function, like MarginAdmin() in the following example.
  • In this case, MarginAdmin is another solidity contract that is being imported into this file.
  • What does this mean when a function gets called like this in the head of constructor function?

Tags:

What does it mean when a function is called in the head of constructor() function?

In solidity smart contracts how do you access internal state variables declared in the constructor?

  • You should simply include those variables outside of the constructor function as a global variable for the contract.
  • Take a look at a pretty simple to understand, and very commonly used contract: you can see the variable lives outside the constructor function, and instead just gets set (rather than declared) within the constructor.
  • Would this pattern work for your scenario, or is there some specific need to initialize the variable as a part of the constructor function?

Tags:

In solidity smart contracts how do you access internal state variables declared in the constructor?

Truffle – Transfer leads to “Error: VM Exception while processing transaction: revert”

Tags:

Truffle – Transfer leads to “Error: VM Exception while processing transaction: revert”

Calling function from ERC721Token reverts

Tags:

Calling function from ERC721Token reverts

Data Blockchain ICO bench, DBC ICO, DBCC Coins

  • DataBlockChain.io is a revolutionary data platform that stands to disrupt the way that companies and individuals gather premium data.
  • The result is that clients can access specific data sets in a cost-effective and transparent way, collecting exactly what they need without paying for extraneous data.
  • Data is the backbone of the marketing boom, and DataBlockChain.io has the capability to be the category killer We will merge our own proprietary data with many of the world’s largest databases ranging from government data, industry specific data, voting records, business to business data, property data, credit bureau data,…
  • The level of access to quality data DataBlockChain.io offers has been cost prohibitive for most companies outside of the Fortune 500, but as a result of our platform, all participants will be able to obtain the exact, nuanced data they are seeking.
  • Because DataBlockChain.io removes the middlemen in the data industry that tend to drive prices up and cause inefficiencies, no order size will be too small to fulfill.

Tags:

Data Blockchain ICO bench, DBC ICO, DBCC Coins | DataBlockChain.io

Tags:

Tags:

eStories

Tags:

eStories

Top Solidity Courses

Getting Started with Ethereum Solidity Development (6,530 students enrolled)

By Sebastien Arbogast

  • Understand the basic philosophy behind the blockchain and distributed/decentralized applications
  • The basics of how a blockchain generally works, just enough to be able to use it as a development platform
  • Develop a distributed application, from creating a blank project to deploying it in production all the way through writing smart contracts, unit testing them, and creating a user interface for them
  • How to combine the right tools to put together a consistent development environment
  • The fundamentals of the Solidity smart contract language
  • How to use the Truffle build and testing framework
  • How to deploy a decentralized app to various Ethereum instances (testrpc, private chain, test chain, main net)

Learn more.

Ethereum Blockchain Developer: Build Projects Using Solidity (10,937 students enrolled)

By Ravinder Deol

  • Be Proficient In Solidity Programming By Building Projects In This Course.
  • Understand Blockchain Technology At A Theoretical And Practical Level.
  • Be Aware On A Practical Level Of How Smart Contracts Operate.
  • Be Able To Work With The Ethereum’s Major Core Development Tools.
  • Understand The Core Development Functions Of Ethereum.
  • Understand What Decentralisation Is As We’re Working With This Technology.
  • Be Able To Explain The Structure Of A Solidity Clearly Through Practical Examples.
  • Understand How To Use Web3 In Conjunction With The Project We’re Creating.
  • Be Proficient In Advanced Development With Truffle And Ethereum Studio.
  • Complete A Final Assignment Which Consists Of An Ethereum Blockchain Based Curriculum Vitae.

Learn more.

Ethereum : Decentralized Application Design & Development (9,794 students enrolled)

By Rajeev Sakhuja

  • Leverage the Ethereum tools/software such as Wallet, Geth, MetaMask, Remix, TruffleV4, Ganache….
  • Create an ERC20 Compliant token to launch an Initial Coin Offering (ICO)
  • Setup Private Blockchain Network
  • Develop Smart contracts in Solidity using multiple tools such as Web3/Ganache/TruffleV4/Mocha framework
  • Comfortably describe how Ethereum Blockchain works | Ethers, Gas, POW, POS, Nodes …
  • Describe how the Blockchain technologies work | Distributed Ledgers, Consensus, Mining ….
  • Develop UI/front end for Decentralized Application in HTML/CSS/Javascript using web3 libraries
  • Develop end to end Decentralized Applications (DAPP) on Ethereum platform
  • Setup private Ethereum networks for development & experimentation
  • Identify and use the right design patterns for developing smart contracts
  • Architect, Design & Build real use cases on Ethereum platform

Learn more.

The Complete Ethereum Course: Get .001 Ether In Your Wallet (4,273 students enrolled)

By Ravinder Deol

  • Understand how Ethereum, the emerging cryptocurrency works, and get involved with it practically as well as learning the theoretical side of the cryptocurrency.
  • Realise how becoming an early adopter of Ethereum gives you the best chance to capitalize on its rise, as many would have missed the meteoric rise of Bitcoin.
  • Undertake your first ever Ethereum transaction by receiving .001 Ether from me for completing this course, I will of course walk you through how to setup your wallet.

Learn more.

Compile Your First Ethereum Smart Contract With Solidity (245 students enrolled)

By Will Bunker

  • Compile a basic smart contract
  • Set a private blockchain for testing
  • Deploy smart contract to blockchain
  • Call the functions on smart contract.

Learn more.

Learn Solidity: Programming Language for Smart Contracts (3,153 students enrolled)

By Toshendra Sharma

  • Develop Ethereum Smart Contracts using Solidity
  • Understand the basics & advance features of Solidity & Ethereum Virtual Machine
  • Develop their own decentralized blockchain applications

Learn more.





Source link https://jsnews.io/solidity/ethereum-solidity-contractdevelopment-mapping-much-more/

LEAVE A REPLY

Please enter your comment!
Please enter your name here