TIL

Today I used Ruby’s Kernel::abort for the first time. It’s one of those incredibly useful methods I can’t believe I’ve never seen before. Observe: # abort.rb {1} def no_message abort end def message abort('Process terminated') end $ irb 2.2.2 :001 > require './abort' => true 2.2.2 :002 > no_message $ irb {1} 2.2.2 :001 > require './abort' => true 2.2.2 :002 > message Process terminated $ Use it to bail from a script. ...

Today I learned that I have thirty-nine Postgres databases on my computer, after running this command inside psql: \l ; Each one is small, but I don’t like to carrying around old data. I ended up dropping nine of them, with: drop database foo_development; For a lighter storage and cognitive load.

This week I learned that attr_reader is more performant than a simple getter method. Here’s a gist from five years ago where Aaron Patterson explains: https://gist.github.com/pjb3/629716 I ran that same benchmarking script today on Ruby 2.2.3. The gap has narrowed, but still exists: ruby-2.2.3 Rehearsal ----------------------------------------------- method 0.070000 0.000000 0.070000 ( 0.074840) attr_reader 0.050000 0.000000 0.050000 ( 0.052603) -------------------------------------- total: 0.120000sec user system total real method 0.070000 0.000000 0.070000 ( 0.072229) attr_reader 0.050000 0.000000 0.050000 ( 0.053374) I like attr_reader because it’s a Ruby convention and is one line instead of three. Now, I also like its performance relative to a getter. ...

I like to read commit logs. Today I wanted to see the first commit on a project. Here’s what I used: git rev-list --max-parents=0 HEAD Show me the commits that led to HEAD in reverse chronological order; then limit that list to the commits with no parent. Here’s a small modification, to show the entire commit rather than the SHA alone: git show $(git rev-list --max-parents=0 HEAD)

Today I found a useful method in ActiveRecord, restore_attributes. This method restores attributes on a dirty model. Use it when you are hacking in the Rails console and want to quickly return to a clean slate. Dirty the record: [1] pry(main)> p = Post.first Post Load (0.4ms) SELECT "posts".* FROM "posts" ORDER BY "posts"."id" ASC LIMIT 1 => #<Post:0x007f8462b09eb8 id: 106, title: "Hello World!", created_at: Sun, 09 Feb 2014 17:15:01 CST -06:00, url_slug: "hello-world"> [2] pry(main)> p.url_slug = 'foobar' => "foobar" [3] pry(main)> p.created_at = Time.now => 2015-10-13 11:41:37 -0500 [4] pry(main)> p => #<Post:0x007f8462b09eb8 id: 106, title: "Hello World!", created_at: Tue, 13 Oct 2015 11:41:37 CDT -05:00, url_slug: "foobar"> And restore: ...

I’m a huge fan of Vim buffers. I try to have my buffer list roughly mirror the files I am currently holding in my brain. The BufExplorer Vim plugin helps, and is included in the Hashrocket Dotmatrix. Today I learned to use the command \bs, which opens a colorful buffer list that you can navigate with Vim directions. https://github.com/jlanzarotta/bufexplorer

The rails generate (g) command is useful for quickly creating the building blocks of a Rails app. Until you misspell or otherwise mess up a command: % rails g model blurg_post invoke active_record create db/migrate/20151006162244_create_blurg_posts.rb create app/models/blurg_post.rb invoke rspec create spec/models/blurg_post_spec.rb ‘Blurg post’? I meant ‘blog post’. Luckily, we can remove those auto-generated files as fast as we created them, with destroy (d). % rails d model blurg_post invoke active_record remove db/migrate/20151006162244_create_blurg_posts.rb remove app/models/blurg_post.rb invoke rspec remove spec/models/blurg_post_spec.rb http://edgeguides.rubyonrails.org/command_line.html#rails-destroy

At the end of each day, I try to record what I did, to jog my memory during the next morning’s standup. This is a helpful aid: git log --since="24 hours ago" I SSH into my work machine and run this in my project’s root directory. Combined with an alias from the Hashrocket Dotmatrix, glg (git log --graph --oneline --decorate --color --all), I get a terse summary of the day’s work, ready to be pasted into your note-taking or project management tool of choice: ...

It’s important to fetch Ruby environmental variables rather than directly referencing them. This code depends on ‘secret_key’: key = ENV['secret_key'] When ‘secret_key’ is not set, ‘key’ will be assigned nil, which is an object. Later, a call to key.upcase will produce a NoMethodError, because Ruby doesn’t know how to uppercase nil. This is better: key = ENV.fetch('secret_key') Now, when ‘secret_key’ is not set, KeyError will be raised. The code fails fast. fetch takes a second argument as a default, which means you can even prevent KeyError entirely, if you choose. ...

‘Random’ numbers in Go don’t always seem random. This is because the rand package defaults to a seed of 1. That’s great if you need a bunch of random numbers at the start of your program. Not great if you expect a different outcome each time you run the program. A solution is to seed rand with Unix time. Try it in the init() function: package main import ( "math/rand" "time" ) func init() { rand.Seed(time.Now().UTC().UnixNano()) } ...