damien-roche

A Primer on Ruby Method Lookup

Method lookup is a simple affair in most languages without multiple inheritance. You start from the receiver and move up the ancestors chain until you locate the method. Because Ruby allows you to mix in modules and extend singleton classes at runtime, this is an entirely different affair.

I will not build contrived code to exemplify the more complicated aspects of Ruby method lookup, as this will only serve to confuse the matter.

When you pass a message to an object, here is how Ruby finds what method to call:

1. Look within singleton class

jirutka

#!/bin/sh
#
# The MIT License
#
# Copyright 2014-2017 Jakub Jirutka <[email protected]>.
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

brunopgalvao

<%= form_for @person do |f| %>
  <%= f.label :first_name, "First Name" %>:
  <%= f.text_field :first_name, list: 'first-name' %>
  <datalist id="first-name">
    <% Person.all.each do |person| %>
      <option value="<%= person.first_name %>"></option>
    <% end %>
  </datalist>
  <%= f.submit %>
<% end %>

hopsoft

# lib/tasks/db.rake
namespace :db do

  desc "Dumps the database to db/APP_NAME.dump"
  task :dump => :environment do
    cmd = nil
    with_config do |app, host, db, user|
      cmd = "pg_dump --host #{host} --username #{user} --verbose --clean --no-owner --no-acl --format=c #{db} > #{Rails.root}/db/#{app}.dump"
    end
    puts cmd

alexpchin

Alex's Rails Cheat Sheet

I think the most confusing thing that I have found about Ruby on Rails so far has been the transition from (trying to) write code myself to the use of the fabled "Rails Magic". So, to help my own understanding of a few core Ruby on Rails concepts, I have decided to write something on what I think is a CRITICAL topic... the idea of Convention over Configuration and why (in my mind) it is the most important thing that helps Rails become magic!

(This may be a topic that we cover in more detail in class but as I said, I'm writing this for my own understanding... I hope it helps someone else understand things too... Perhaps you can give me a hand when I'm crying next week!)

##Convention over configuration ###What does this "actually" mean...

DanHerbert

OBSOLETE

This entire guide is based on an old version of Homebrew/Node and no longer applies. It was only ever intended to fix a specific error message which has since been fixed. I've kept it here for historical purposes, but it should no longer be used. Homebrew maintainers have fixed things and the options mentioned don't exist and won't work.

I still believe it is better to manually install npm separately since having a generic package manager maintain another package manager is a bad idea, but the instructions below don't explain how to do that.

Fixing npm On Mac OS X for Homebrew Users

Installing node through Homebrew can cause problems with npm for globally installed packages. To fix it quickly, use the solution below. An explanation is also included at the end of this document.

davinmsu

  def self.dedupe
    # find all models and group them on keys which should be common
    grouped = all.group_by{|model| [model.title,model.info,model.address,model.phone] }
    grouped.values.each do |duplicates|
      # the first one we want to keep right?
      first_one = duplicates.shift # or pop for last one
      # if there are any more left, they are duplicates
      # so delete all of them
      duplicates.each{|double| double.destroy} # duplicates can now be destroyed
    end

andelf

extern mod sync;

// str op trait
use std::str::StrSlice;
// for tcp listen
use std::io::{TcpListener, TcpStream};
use std::io::net::ip::SocketAddr;
// for trait
use std::io::{Listener, Writer, Acceptor, Buffer};
// for spawn

wen-long

##ss-redir 的 iptables 配置(透明代理)

透明代理指对客户端透明，客户端不需要进行任何设置就使用了网管设置的代理规则

创建 /etc/ss-redir.json 本地监听 7777 运行ss-redir -v -c /etc/ss-redir.json

iptables -t nat -N SHADOWSOCKS
# 在 nat 表中创建新链
iptables -t nat -A SHADOWSOCKS -p tcp --dport 23596 -j RETURN
# 23596 是 ss 代理服务器的端口，即远程 shadowsocks 服务器提供服务的端口，如果你有多个 ip 可用,但端口一致，就设置这个

chanks

Turning PostgreSQL into a queue serving 10,000 jobs per second

RDBMS-based job queues have been criticized recently for being unable to handle heavy loads. And they deserve it, to some extent, because the queries used to safely lock a job have been pretty hairy. SELECT FOR UPDATE followed by an UPDATE works fine at first, but then you add more workers, and each is trying to SELECT FOR UPDATE the same row (and maybe throwing NOWAIT in there, then catching the errors and retrying), and things slow down.

On top of that, they have to actually update the row to mark it as locked, so the rest of your workers are sitting there waiting while one of them propagates its lock to disk (and the disks of however many servers you're replicating to). QueueClassic got some mileage out of the novel idea of randomly picking a row near the front of the queue to lock, but I can't still seem to get more than an an extra few hundred jobs per second out of it under heavy load.

So, many developers have started going straight t