A module is a colletction of items:

• functions
• structs
• traits

What does the bond mean? Somehow it can be translated as building up a strong binding relationship with a PoS network. If you want to put your tokens “at stake”, you must bond them first. But what does the bond actually do? What’s the difference between substrate and darwinia-network?

Account abstractions for bond – Stash and Controller

• Stash Key: The Stash account is meant to hold large amounts of funds. Its private key should be as secure as possible in a cold wallet.

• Controller Key: The Controller account signals choices on behalf of the Stash account, like payout preferences, but should only hold a minimal amount of funds to pay transaction fees. Its private key should be secure as it can affect validator settings, but will be used somewhat regularly for validator maintenance.

这几天在写Darwinia的eth-backing模块的测试，遇到不少问题，写个记录。

概述

eth-backing模块的主要负责以太坊的跨链功能，darwinia跨链的思路大致如下：
我在以太坊上建立相应的智能合约，以太坊上的token和darwinia上的token应该是可以1:1兑换的。一笔钱当然不能花两次，所以以太坊上的钱转移到darwinia上时，以太坊上的token就应该被销毁。所以总体逻辑应该是:

• 1. 以太坊上销毁这笔token

About closure

Closure in Rust, also called lamba expressions or lambdas, are functions that can capture the enclosing environment.

Some characterisitics of closures include:

• using || instead of () around input variables.
• optional body delimination {} for a single expression (mandatory otherwise).

This article is about setting up an environment for enbedded Linux application development for loongson. The resulting environment enables cross-platform application development for Loongson mipsel-based SOMs/COMs using Ubuntu18.04 for application development.

Communicate with loongson development board using USB cable

The first thing we need to do is communicating with hardware using USB cable.The boards are equipped with PL2303-based device. To be able to talk to an application, our machine must have appropriate PL2303 drivers. Fortunately, Ubuntu18.04 is default equipped with the PL2030 drivers(we could use lsmod | grep pl2303 to check it). The only thing necessary is to check whether the Ubuntu machine can communicate over USB with the attached loongson development board.

To do this:

• Connect the PC via an USB cable to the USB UART port of the loongson development board.

Runtime

The Runtime is block execution logic of a blockchain, sometimes referred to as the state transition function STF. In Substrate, this is stored on-chain in an implementation-neutal(语言无关的), machine-executable(机器可执行的) format as a WebAssembly binary.

Other system

• Ethereum(human-readable format)
• Bitcoin(not at all)

Rust by examples notes about primitives.

Primitives

Rust provides access to a wide variety of primitives.

scalar Types

• signed integers: i8, i16, i32, i64 and isize(pointer size)
• unsigned integers: u8, u16, u32, u64 and usize(pointer size)

Some notes with Rust by example about formatting.

Formatted print

Printing is handle by a series of macros defined in std::fmt some of which include:

• format!: write formatted text to String
• print!: print fotmatted text to the console(io::stdout)