How To Write A Smart Contract

This talk covers writing an Ethereum smart contract in Solidity using developer-friendly tools. Followed by a workshop, where we learn, how to actually build a smart contract based dApp using the Truffle Framework, along with Ganache, Metamask and Web3.js.

Transcript

1. Usman Bashir Developer Circle Lead How To Write A Smart Contract
2. WHOAMI? • me@ usmanbashir.com • @ ubax • usmanbashir.com Who am I? Software Developer & Technology Consultant
3. What is Solidity?
4. Solidity high level JavaScript-like language compiles to Ethereum VM code
5. Solidity is a statically typed language
6. Data Types bool int / uint address bytes / string struct / enums / arrays
7. Arrays address[] public friends; address[5] internal bestFriends;
8. Structs struct Friend { address id; string name; uint8 age; bool bestFriend; }
9. Structs struct Friend { address id; string name; uint8 age; bool bestFriend; } Friend newFriend = Friend(0x00, “Name", 42, true);
10. Function Structure function (<parameter types>) {internal|external} [pure|constant|view|payable] [returns (<return types>)]
11. Function Types internal private public external
12. Internal (default) visible inside the contract context, including derived contracts
13. Private - only visible in the contract they are declared - and not in any derived contracts
14. Public can be called by you or anyone on the blockchain
15. External similar to public, but only someone from outside can call it
16. Function Types Cont’d pure view constant payable
17. Special Variable msg.sender address of the agent sending message
18. Trial by Fire
19. pragma solidity ^0.4.17; contract SimpleStorage { uint storedData; function set(uint _value) { storedData = _value; } function get() public view returns (uint) { return storedData; } }
20. pragma solidity ^0.4.17; contract SimpleStorage { uint storedData; function set(uint _value) { storedData = _value; } function get() public view returns (uint) { return storedData; } } Pragma instructions for compiler
21. pragma solidity ^0.4.17; contract SimpleStorage { uint storedData; function set(uint _value) { storedData = _value; } function get() public view returns (uint) { return storedData; } } Contract collection of code & data
22. pragma solidity ^0.4.17; contract SimpleStorage { uint storedData; function set(uint _value) { storedData = _value; } function get() public view returns (uint) { return storedData; } } State Variable
23. pragma solidity ^0.4.17; contract SimpleStorage { uint storedData; function set(uint _value) public { storedData = _value; } function get() public view returns (uint) { return storedData; } }
24. pragma solidity ^0.4.17; contract SimpleStorage { uint storedData; function set(uint _value) public { storedData = _value; } function get() public view returns (uint) { return storedData; } }
25. Developer Tools
26. Truffle http://truffleframework.com
27. Ganache http://truffleframework.com/ganache/
28. METAMASK https://metamask.io
29. Web3.js https://github.com/ethereum/web3.js/
30. EthFiddle https://ethfiddle.com
31. Usman Bashir Developer Circle Lead Workshop
32. Fill-In Code http://bit.ly/BlockSC
33. So... 1. Learn more & read Docs 2. Build dApps 3. … 4. Profit? What's Next?
34. So... Contact me! • @ ubax • me@ usmanbashir.com • usmanbashir.com Need MORE help?
35. Thank You