This is the final part of the Lottery Smart Contract series that I started 2 weeks ago. You are read part 1 here and part 2 here. In this final part I will be walking through the codes of the Lottery Smart Contract to explain what some of the more important lines of codes do. 

The Codes

This is part 2 of the "Lottery as a Smart Contract" series. In part 1, I described the business logic behind the Lottery Smart Contract. Here, I will demonstrate how this contract is executed. To run this, you will need:

Writing a lottery contract is a great way to learn important Smart Contract concepts such as State, Event and Visibility. In this 3 part series, I will describe the logic and codes behind a Lottery Smart Contract. In developing my Lottery Contract, I used Oraclize, a data carrier service that executes external JSON web services.

Motivation

This is a continuation of Part 1 where I described how Safe Remote Purchase works. In this blog post, I will document the process of executing the Safe Remote Purchase Smart Contract using Remix Solidity IDE and MetaMask, running on a Google Chrome browser.

MetaMask

An area of Smart Contract development that has consistently intrigued me is its real world usage to disintermediate the middleman. There's one gem of a Smart Contract that achieves this in the Solidity documentation called Safe Remote Purchase.  This is the first blog post of a 2-parter where I will document how to execute Safe Remote Purchase using a combination of Remix and MetaMask.

(Updated, 29th May 2018: I have written an update to this article. Consider reading Ethereum Geth Syncing 101 in 2018 instead)

I run geth on my cloud server to sync with the Ethereum Blockchain. I start geth whenever I code and it goes into a round of resynchronization with the Blockchain. This takes anything from minutes (that's if the last time I code is yesterday), or hours (if the last time I did this was months ago). 

This is a continuation of the Going Dutch Smart Contract project that I started on 2nd Sep 2017. It has been a month, which is probably the equivalent of a year if you count in blockchain-time. Geth has gone from 1.6.7 to 1.7.2 and after upgrading my setup, I had to let it run overnight (in fast mode!) to sync my node to the block again.

Objective

My buddy, Mark and I have been hanging out on supper dates for the past 18 years. Sometimes he pays first and I forget to pay him back. The reverse happens at other times. We don't trust each other to maintain an Excel file to capture the records. I mean, look, what if Mark doctors the Excel file when I am not looking. This is obviously a great candidate for blockchain - now our records becomes immutable and the history of our misspending are forever etched in the blockchain.

Objectives

Mahesh Murthy has an amazing tutorial to setup an Ethereum environment to develop Truffle Dapps on the Ethereum blockchain. You can read it here. Part 1 of the tutorial explains the architecture of the Ethereum platforms and lets you execute a smart contract via a simple web page that runs locally. The blockchain runs locally using testrpc.