Archives

Ruby Tips and Tricks

Generate random numbers within a given range

irb(main):019:0> rand(10..20)
=> 12
irb(main):020:0> rand(10...20) # works with exclusive range
=> 16

Dump your object using awesome_print

# Install the gem first
gem install awesome_print

irb(main):001:0> require 'ap'
=> true
irb(main):002:0> ap :a => 1, :b => 'greg', :c => [1,2,3]
{
    :a => 1,
    :b => "greg",
    :c => [
        [0] 1,
        [1] 2,
        [2] 3
    ]
}
=> {:a=>1, :b=>"greg", :c=>[1, 2, 3]}

Concatenating strings

irb(main):005:0> "abc" + "def"
=> "abcdef"
irb(main):006:0> "abc".concat("def")
=> "abcdef"
irb(main):007:0> x = "abc" "def"
=> "abcdef"

Include modules in a single line

class MyClass
  include Module1, Module2, Module3
  # However, the modules are included in reverse order. Confusing eh!
end

Instance variable interpolation

irb(main):008:0> @name = "greg"
=> "greg"
irb(main):009:0> "my name is #{@name}"
=> "my name is greg"
irb(main):010:0> "my name is #@name"
=> "my name is greg"

I still prefer the curly braces.

Syntax checking

$ ruby -c facu.rb 
facu.rb:12: syntax error, unexpected keyword_end, expecting $end

Zipping arrays

irb(main):027:0> names = %w(fred jess john)
=> ["fred", "jess", "john"]
irb(main):028:0> ages = [38, 47,91]
=> [38, 47, 91]
irb(main):029:0> locations = %w(spain france usa)
=> ["spain", "france", "usa"]
irb(main):030:0> names.zip(ages)
=> [["fred", 38], ["jess", 47], ["john", 91]]
irb(main):031:0> names.zip(ages, locations)
=> [["fred", 38, "spain"], ["jess", 47, "france"], ["john", 91, "usa"]]

Range into arrays

irb(main):034:0> (10..20).to_a  # what I used to do
=> [10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20]
irb(main):035:0> [*10..20]
=> [10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20]

Using parameter as default value

irb(main):047:0> def method(a, b=a); "#{a} #{b}"; end
=> nil
irb(main):048:0> method 1
=> "1 1"
irb(main):049:0> method 1, 2
=> "1 2"

Put regex match in a variable

irb(main):058:0> s = "Greg Moreno"
=> "Greg Moreno"
irb(main):059:0> /(?<first>\w+) (?<second>\w+)/ =~ s
=> 0
irb(main):060:0> first
=> "Greg"
irb(main):061:0> second
=> "Moreno"
09 Feb 2012