/ Ruby on Rails
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method

returning

v3.0.9 - Show latest stable - Class: Object
returning(value)
public

Returns value after yielding value to the block. This simplifies the process of constructing an object, performing work on the object, and then returning the object from a method. It is a Ruby-ized realization of the K combinator, courtesy of Mikael Brockman.

Examples

# Without returning
def foo
  values = []
  values << "bar"
  values << "baz"
  return values
end

foo # => ['bar', 'baz']

# returning with a local variable
def foo
  returning values = [] do
    values << 'bar'
    values << 'baz'
  end
end

foo # => ['bar', 'baz']

# returning with a block argument
def foo
  returning [] do |values|
    values << 'bar'
    values << 'baz'
  end
end

foo # => ['bar', 'baz']

2Notes

Watch out for syntax errors

Mange · Jan 8, 20095 thanks

Watch out when you are using +returning+ with hashes. If you would write code like def foo(bars) returning {} do |map| bars.each { |bar| map[bar.first] = bar } end end you will get a syntax error since it looks like you tried to supply two blocks! Instead you should write it with parenthesis around the hash: def foo(bars) returning({}) do |map| bars.each { |bar| map[bar.first] = bar } end end

Replacement

kamilio · Jul 23, 2012

==== Replacement

# Method using returning can replaced
def foo
returning Hash.new do |h|
  h[:foo] = "bar"
end
end

# By method using tap  
def foo
Hash.new.tap do |h|
  h[:foo] = "bar"
end
end