Common Ruby Idioms

Question

One thing I love about ruby is that mostly it is a very readable language (which is great for self-documenting code)

However, inspired by this question: Ruby Code ex

Answer 1

method missing magick

class Dummy  
  def method_missing(m, *args, &block)  
    "You just called method with name #{m} and arguments- #{args}"  
  end  
end

Dummy.new.anything(10, 20)
=> "You just called method with name anything and arguments- [10, 20]"

if you call methods that not exists in ruby objects, ruby interpreter will call method called 'method_missing' if its defined, you could user this for some tricks, like writing api wrappers, or dsl, where you don;t know all methods and parameters names

Answer 2

You can deepcopy with Marshaling object easily. - taken from The Ruby Programming Language

def deepcopy(o)
  Marshal.load(Marshal.dump(o))
end

Note that files and I/O streams, as well as Method and Binding objects, are too dynamic to be marshaled; there would be no reliable way to restore their state.

Answer 3

By the way, from the referenced question

a ||= b 

is equivalent to

if a == nil   
  a = b 
end

That's subtly incorrect, and is a source of bugs in newcomers' Ruby applications.

Since both (and only) nil and false evaluate to a boolean false, a ||= b is actually (almost*) equivalent to:

if a == nil || a == false
  a = b
end

Or, to rewrite it with another Ruby idiom:

a = b unless a

(*Since every statement has a value, these are not technically equivalent to a ||= b. But if you're not relying on the value of the statement, you won't see a difference.)

Answer 4

Nice question!

As I think the more intuitive & faster the code is, a better software we’re building. I will show you how I express my thoughts using Ruby in little snippets of code. Read more here

Map

We can use map method in different ways:

user_ids = users.map { |user| user.id }

Or:

user_ids = users.map(&:id)

Sample

We can use rand method:

[1, 2, 3][rand(3)]

Shuffle:

[1, 2, 3].shuffle.first

And the idiomatic, simple and easiest way... sample!

[1, 2, 3].sample

Double Pipe Equals / Memoization

As you said in the description, we can use memoization:

some_variable ||= 10
puts some_variable # => 10

some_variable ||= 99
puts some_variable # => 10

Static Method / Class Method

I like to use class methods, I feel it is a really idiomatic way to create & use classes:

GetSearchResult.call(params)

Simple. Beautiful. Intuitive. What happens in the background?

class GetSearchResult
  def self.call(params)
    new(params).call
  end

  def initialize(params)
    @params = params
  end

  def call
    # ... your code here ...
  end
end

For more info to write idiomatic Ruby code, read here

Answer 5

I like this:

str = "Something evil this way comes!"
regexp = /(\w[aeiou])/

str[regexp, 1] # <- This

Which is (roughly) equivalent to:

str_match = str.match(regexp)
str_match[1] unless str_match.nil?

Or at least that's what I've used to replace such blocks.

Answer 6

I like how If-then-elses or case-when could be shortened because they return a value:

if test>0
  result = "positive"
elsif test==0
  result = "zero"
else
  result = "negative"
end

could be rewriten

result = if test>0
  "positive"
elsif test==0
  "zero"
else
  "negative"
end

The same could be applied to case-when:

result = case test
when test>0 ; "positive"
when test==0 ; "zero"
else "negative"
end