googya

Rails 開發注意要點

About Ruby Syntax

• 編輯器設定 soft tab (space=2)，以 2 格空白符號做為程式內縮距離（不分語言）。
• 函式如果只有一個參數，就不強制打()
• 函式如果有二個以上的參數，通通都要有 ()
  • (避免發生奇怪的paser bug跟保持專案一致性)
• 字串限定用雙引號包覆
• 善用 "#{str1} #{str3} " 等字串改寫技巧取代不需要的字串加法。

googya

module ClassModule

#all successors excluding self
def successors(klass=self.name.to_s)
  descendants = []
  begin
    ObjectSpace.each_object(class << eval(klass);self;end) do |found|
      descendants << found
    end
  rescue Exception=>e

googya

#!/usr/bin/env ruby
# encoding: utf-8

# irb3 - Runs an IRB-esque prompt (but it's NOT really IRB!) over multiple
#        versions of Ruby at once (using RVM)
#        
#        By Peter Cooper, BSD licensed
#
#        Main dependency is term-ansicolor for each impl:
#          rvm exec gem install term-ansicolor

googya

after "deploy:symlink", "deploy:restart_workers"
after "deploy:restart_workers", "deploy:restart_scheduler"

##
# Rake helper task.
# http://pastie.org/255489
# http://geminstallthat.wordpress.com/2008/01/27/rake-tasks-through-capistrano/
# http://ananelson.com/said/on/2007/12/30/remote-rake-tasks-with-capistrano/
def run_remote_rake(rake_cmd)
  rake_args = ENV['RAKE_ARGS'].to_s.split(',')

googya

Site List

• http://www.salttiger.com/
• http://www.avaxsearch.com/
• http://it-ebooks.info/
• https://www.ebooks-it.net/
• http://www.pdfshu.org/

Image Site

googya

# Create your superuser
$ mongo
> use admin
> db.createUser({user:"someadmin",pwd:"secret", roles:[{role:"root",db:"admin"}]})
> exit

# Alias for convenience (optional and at your own risk)
$ echo 'alias mongo="mongo --port 27017 -u someadmin -p secret --authenticationDatabase admin"' >> ~/.bash_profile
$ source ~/.bash_profile

googya

(my response to https://twitter.com/apotonick/status/717105889845624832)

I haven't yet came across readily available resources for large-scale application architecture for Elixir apps. I found Programming Phoenix to be a good start for that though. And there's ~30 years of knowledge in the Erlang land :)

For web apps, I found the abstractions that Elixir/Phoenix provides to be really helpful. Indeed, the list below is somewhat ORM focused.

In the small, Ecto.Schema, Ecto.Query, Ecto.Changeset, and Phoenix.View allow me to build highly composable and side-effect free modules. I can have many schemas, changesets and queries all interacting with the same underlying DB table(s) if I want to. Most of the side-effects (through Ecto.Repo for DBs) are usually in the Phoenix.Controller (or other Plugs).

googya

Resources for Machine Learning in Ruby

Gems

• liblinear-ruby: Ruby interface to LIBLINEAR using SWIG

• classifier-reborn: Bayesian and LSI classification
  dependencies: GSL

googya

#!/bin/bash

# . script.sh     # identical to "source script.sh"
if [ $# -eq 0 ]
  then
    echo "No arguments supplied"
fi
if [ $# -eq 1 ]
then
	if [[ "$1" = "--set" ]]

googya

Latency numbers every programmer should know

L1 cache reference ......................... 0.5 ns
Branch mispredict ............................ 5 ns
L2 cache reference ........................... 7 ns
Mutex lock/unlock ........................... 25 ns
Main memory reference ...................... 100 ns             
Compress 1K bytes with Zippy ............. 3,000 ns  =   3 µs
Send 2K bytes over 1 Gbps network ....... 20,000 ns  =  20 µs
SSD random read ........................ 150,000 ns  = 150 µs

Read 1 MB sequentially from memory ..... 250,000 ns = 250 µs