Writing a Dollar Auction Contract

August 16, 2018 by Todd Proebsting

This post will implement a “dollar auction” contract for ERC20 tokens. It will be a modest change to the English auction contract.

Writing a Penny Auction Contract

August 8, 2018 by Todd Proebsting

This post will implement a bidding fee auction (aka “penny auction”) contract for ERC20 tokens. It will be a modest change to the English auction contract.

Contracts Calling Arbitrary Functions

August 2, 2018 by Steve Marx

Solidity offers convenient high-level syntax for calling functions in other contracts, but this high-level syntax is only available when the target contract’s interface is known at compile time. In this post, I’ll show how smart contracts can use low-level message passing to make arbitrary calls into other contracts. I’ll use this mechanism to enhance our trivial multisig wallet so that it can make function calls in addition to transferring ether.

Anatomy of Transaction Data

July 25, 2018 by Steve Marx

[This blog post explains how transaction data is used to invoke smart contracts in Ethereum, but it is not necessary for learning Solidity programming. We write it for those of you who would like a deeper understanding of what is going on when a transaction is sent to a smart contract.] In our previous post How Ethereum Transactions Work, we mentioned that the data field of a transaction encodes what (if any) smart contract function should be invoked. In this post, I’ll dive deeper into the specifics of the data field.

State Channels with Signing Keys

July 18, 2018 by Steve Marx

In this post, I’ll show how a temporary signing key can be used to improve the user experience of working with state channels.

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