shortcuts_and_symbols.rb

str = "It's not too scary when you realize that everything is an object"

str.size # => 64
str.class # => String

str = "and you call methods on them"

str.reverse # => "meht no sdohtem llac uoy dna"

# EVERYTHING is an object

3.class # => Fixnum
nil.class # => NilClass
true.class # => TrueClass
/^regexps\stoo!$/.class # => Regexp

# EVERYTHING has methods

str.nil? # => false
[].empty? # => true
1 + 1 # => 2
1.+(1) # => 2

# Methods are chainable

str.upcase.reverse # => "MEHT NO SDOHTEM LLAC UOY DNA"

# Symbols aren't scary either, they are objects similar to strings

:foo.class # => Symbol
:foo.to_s # => "foo"
"foo".to_sym # => :foo

# But they are different, two identical strings will have different object ids, two identical symbols will have the same
"foo".object_id == "foo".object_id # => false
:foo.object_id == :foo.object_id # => true

# Symbols are handy for hash keys, among other things:

bar = { 'name' => "Tamal", 'status' => "Poopin'" }
bar['status'] # => "Poopin'"

baz = { :name => "Tamal", :status => "Poopin'" }
bar[:status] # => "Poopin'"

# Some methods allow you to iterate over the contents with blocks

ary = [1,2,3]
i = 0
while i < ary.size
  puts ary[i]
  i += 1
end
# >> 1
# >> 2
# >> 3

[1,2,3].each { |i| puts i }
# >> 1
# >> 2
# >> 3

# Some iterators let you modify the contents and return a new value

ary = [1,2,3]
new_ary = []
i = 0
while i < ary.size
  new_ary << ary[i] * 100
  i += 1
end
new_ary # => [100, 200, 300]

[1,2,3].map { |number| number * 100 } # => [100, 200, 300]

# Blocks can use curly braces or do..end

[1,2,3].map do |number|
  number * 100
end # => [100, 200, 300]