Method: Weak::Map#initialize

Defined in:

lib/weak/map.rb

#initialize(default_value = UNDEFINED, &default_proc) ⇒ Map

Returns a new empty Weak::Map object.

The initial default value and initial default proc for the new hash depend on which form above was used.

If neither an default_value nor a block is given, initializes both the default value and the default proc to nil:

map = Weak::Map.new
map.default               # => nil
map.default_proc          # => nil

If a default_value is given but no block is given, initializes the default value to the given default_value and the default proc to nil:

map = Hash.new(false)
map.default               # => false
map.default_proc          # => nil

If a block is given but no default_value, stores the block as the default proc and sets the default value to nil:

map = Hash.new { |map, key| "Default value for #{key}" }
map.default              # => nil
map.default_proc.class   # => Proc
map[:nosuch]             # => "Default value for nosuch"

If both a block and a default_value are given, raises an ArgumentError

# File 'lib/weak/map.rb', line 316

def initialize(default_value = UNDEFINED, &default_proc)
  clear

  if UNDEFINED.equal?(default_value)
    @default_value = nil
    @default_proc = default_proc
  elsif block_given?
    raise ArgumentError, "wrong number of arguments (given 1, expected 0)"
  else
    @default_value = default_value
    @default_proc = nil
  end
end