kylefox

class AddRecordUuidToActiveStorageAttachments < ActiveRecord::Migration[5.2]
  def change
    # After applying this migration, you'll need to manually go through your
    # attachments and populate the new `record_uuid` column.
    # If you're unable to do this, you'll probably have to delete all your attachments.
    # You've pretty much got useless garbage data if that's the case :(
    add_column :active_storage_attachments, :record_uuid, :uuid
  end
end

stefaneng

echo '[{"key": 1}, {"key": 2}, {"key": 1}]' | jq 'group_by (.key)[] | {key: .[0].key, length: length}'

joepie91

Your blockchain must have all of the following properties:

• It's a merkle tree, or a construct with equivalent properties.
• There is no single point of trust or authority; nodes are operated by different parties.
• Multiple 'forks' of the blockchain may exist - that is, nodes may disagree on what the full sequence of blocks looks like.
• In the case of such a fork, there must exist a deterministic consensus algorithm of some sort to decide what the "real" blockchain looks like (ie. which fork is "correct").
• The consensus algorithm must be executable with only the information contained in the blockchain (or its forks), and no external input (eg. no decisionmaking from a centralized 'trust node').

If your blockchain is missing any of the above properties, it is not a blockchain, it is just a ledger.

joshdover

Idiomatic React Testing Patterns

Testing React components seems simple at first. Then you need to test something that isn't a pure interaction and things seem to break down. These 4 patterns should help you write readable, flexible tests for the type of component you are testing.

Setup

I recommend doing all setup in the most functional way possible. If you can avoid it, don't set variables in a beforeEach. This will help ensure tests are isolated and make things a bit easier to reason about. I use a pattern that gives great defaults for each test example but allows every example to override props when needed:

paragonie-scott

Hello software developers,

Please check your code to ensure you're not making one of the following mistakes related to cryptography.

I. General Mistakes

• Writing your own home-grown cryptography primitives (For example: Mifare Classic)
  • Exception: For the sake of learning, but don't deploy it in production.
• Using a fast hash function (e.g. MD5, SHA256) for storing passwords. Use bcrypt instead.
• Not using a cryptographically secure random number generator

obstschale

Octave CheatSheet

GNU Octave is a high-level interpreted language, primarily intended for numerical computations.
(via GNU Octave)

Hint: I also mad an octave docset for Dash: https://github.com/obstschale/octave-docset

Basics

toolmantim

# A simple Makefile alternative to using Grunt for your static asset compilation
#
## Usage
#
#   $ npm install
#
# And then you can run various commands:
#
#   $ make            # compile files that need compiling
#   $ make clean all  # remove target files and recompile from scratch

focusaurus

const express = require("express");
const router = express.Router();

router.get('/', function (req, res) {
  res.send("This is the '/' route in ep_app");
});

module.exports = router;

teropa

Tutorials

• The best tutorials are in the introductory books. See below.
• Getting Started with Clojure - A detailed tutorial on getting a modern (as of Jan 2013) Clojure workflow going.
  • Emacs Live is a nice development environment based on Emacs.
• Understanding The Clojure Development Ecosystem
• Clojure Docs Site is a community-driven doc site with good tutorials, and reference material going somewhat deeper than individual API docs.
• Functional Programming for the Rest of Us is a classic introduction to functional thinking
• [A comprehensive article on namespaces and different ways of requiring them](http://blog.8thlight.com/colin-jones/2010/12/05/clojure-libs-and-namespaces-require-use-import-and-ns.

jashkenas

# MAC manipulators
alias random_mac='sudo ifconfig en0 ether `openssl rand -hex 6 | sed "s/\(..\)/\1:/g; s/.$//"`'
alias restore_mac='sudo ifconfig en0 ether YOUR_ORIGINAL_MAC_ADDRESS_GOES_HERE'