關於 where to start coding ，我們在網路上蒐集到這些相關的討論、資訊與評價

【跟著AIT一起學程式設計】
隨著人們日益習慣線上互動，對程式設計人員的需求也越來越大。程式開發設計也正在向你招手等著你來學習， 如果你不知道從哪裡開始，不如花幾分鐘時間在我們的 Python 影片中學習一些技巧吧！這次的課程將介紹Python的「小烏龜」繪圖功能，藉此畫出不同形狀和圖案。在這段影片中大家將學習如何使用「小烏龜」來繪製基本形狀和如何加上簡單的程式來更改畫筆和畫布的背景顏色。大家快跟著影片一起動手畫畫看吧！ #PythonForBeginners #Python

* AIT程式語言課程是因應新冠疫情而推出的線上活動之一。

Learning Python with AIT
As the world is day by day becoming more used to virtual interactions, there’s a growing need for adept programmers. How about you? Is coding calling your name? Maybe you don’t know where to start learning? Take a few minutes and learn some tricks in Python. Today we introduce the role of “turtle” in Python, which is the pen that draws different shapes and patterns. In this video, you’ll get to see how “turtle” can be used to draw basic shapes, and how to enter codes to change the background color of your canvas. Please click to watch and learn!

*The series of Python classes is part of AIT's online learning resources.

Look at these kids learning how to code (talking to computers to tell them what to do)! Heard about this and thought it was fantastic!! Since 2017, Google has been running Code in the Community, offering free coding classes to about 2300 children from low-income families. No one should be left behind by technology. Over the next three years, about another 6700 students will benefit from this programme.
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So, if your child likes games, maybe they can learn coding and make their own game, or app, they can learn how to programme a robot, it’s a great place to start exploring what they can create with technology and very importantly, to start exploring where their creativity and persistence can take them! You can sign up in the link in my bio, applications close 14 jan!

📜 [專欄新文章] Solidity Weekly #17
✍️ mingderwang
📥 歡迎投稿： https://medium.com/taipei-ethereum-meetup #徵技術分享文 #使用心得 #教學文 #medium

token special issue

ERC827 的資安問題探討

警告: ERC827 規格還在討論中, 且已經發現容易造成資安問題. 本文僅供技術探討參考, 請勿 prod 使用! (若錯誤使用造成任何損失, 個人與專欄皆無法負擔賠償責任)

Why ERC827 can make you vulnerable to reentrancy attacks — and how to prevent them

上面連結文章, 介紹 ERC827 寫法不對, 有可能造成 Reentrancy 攻擊.

ERC827 是一種 ERC20 的擴充, 它是希望 ERC20 介面以外, 再增加 approveAndCall(), transferAndCall(), 以及transferFromAndCall()三種介面. 讓該合約在呼叫相對應 ERC20 的 approve(), transfer() 或 transferFrom() 功能之後, 能順便再呼叫 _to 參數的另一個合約地址 with _data 參數. 以 transferAndCall 為例, 定義如下: (截圖來自 ERC827 規格)

規格裡已經強調不可以搭配 fallback functions 使用, 所以使用時要替別注記!!!

ltdr: 為何 ERC827 有問題, 我還要介紹呢? 因為它讓不用 Ether 也能交易變成可能 (在這篇文章裡有介紹 Do not pay transaction fees in Ethereum), 裡面的 Feeless (警告: 沒有 reentery 保護, 有資安問題, 勿用), 就是使用了 ERC827 協定, 但 Save on fees, lose your tokens (ChainSecurity 的 CTO, https://medium.com/@HRitzdorf) 就馬上給他打臉.

雖然有問題, 但 OpenZeppelin 還是有 implement, 且加上嚴重警告, 希望它能繼續改良, 用大眾的力量來解決這個問題. 也讓 ERC20 能更 powerful, 且更為廣泛使用.

後記:

由於內容挑選不易, 造成出刊頻率不一, 雖然叫 “Solidity Weekly” 週刊, 但偶而會變成 bi-weekly, 深感抱歉. 我知道台灣非常多人在寫 Smart Contracts, 使用 Solidity 或寫 DApps 經驗都比我豐富, 希望大家能共同編輯 “Solidity Weekly”. 讓出刊頻率能像 blockchain 一樣(每個 block 挖到的平均速度是 14秒), 我們平均每一個禮拜一期. 只要是跟 Smart Contract 相關, 都歡迎加入”Taipei Ethereum Meetup” 編輯群, 我們可以自由加 Solidity Weekly #{issue++}. 我們沒有主編, 不必審核 (只內容要不要太離譜就好). (期待, 有人自告奮勇寫下一 期的 Solidity Weekly #18)

BTW, 我們的 Taipei Ethereum Meetup 專欄文章, 雖然以中文為主, 但已經發現有外國文章(The Best Way to Start Coding in Solidity) refer 到我們的文章, https://medium.com/…/ethereum-dapp-tutorial-push-button-cae… , 非常難得, 深感欣慰. 大家的努力, 世界都在看!

Solidity Weekly #17 was originally published in Taipei Ethereum Meetup on Medium, where people are continuing the conversation by highlighting and responding to this story.

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