Method: Object#then

Defined in:
object.c

#then {|x| ... } ⇒ Object #yield_self {|x| ... } ⇒ Object

Yields self to the block and returns the result of the block.

3.next.then {|x| x**x }.to_s             #=> "256"
"my string".yield_self {|s| s.upcase }   #=> "MY STRING"

Good usage for then is value piping in method chains:

require 'open-uri'
require 'json'

construct_url(arguments).
  then {|url| open(url).read }.
  then {|response| JSON.parse(response) }

When called without block, the method returns Enumerator, which can be used, for example, for conditional circuit-breaking:

# meets condition, no-op
1.then.detect(&:odd?)            # => 1
# does not meet condition, drop value
2.then.detect(&:odd?)            # => nil

Overloads:

  • #then {|x| ... } ⇒ Object

    Yields:

    • (x)

    Returns:

  • #yield_self {|x| ... } ⇒ Object

    Yields:

    • (x)

    Returns:



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# File 'object.c', line 598

static VALUE
rb_obj_yield_self(VALUE obj)
{
    RETURN_SIZED_ENUMERATOR(obj, 0, 0, rb_obj_size);
    return rb_yield_values2(1, &obj);
}