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|
module Hashie
module Extensions
# SRP: This extension will fail an error whenever a key is accessed
# that does not exist in the hash.
#
# EXAMPLE:
#
# class StrictKeyAccessHash < Hash
# include Hashie::Extensions::StrictKeyAccess
# end
#
# >> hash = StrictKeyAccessHash[foo: "bar"]
# => {:foo=>"bar"}
# >> hash[:foo]
# => "bar"
# >> hash[:cow]
# KeyError: key not found: :cow
#
# NOTE: For googlers coming from Python to Ruby, this extension makes a Hash
# behave more like a "Dictionary".
#
module StrictKeyAccess
class DefaultError < StandardError
def initialize
super('Setting or using a default with Hashie::Extensions::StrictKeyAccess'\
' does not make sense'
)
end
end
# NOTE: Defaults don't make any sense with a StrictKeyAccess.
# NOTE: When key lookup fails a KeyError is raised.
#
# Normal:
#
# >> a = Hash.new(123)
# => {}
# >> a["noes"]
# => 123
#
# With StrictKeyAccess:
#
# >> a = StrictKeyAccessHash.new(123)
# => {}
# >> a["noes"]
# KeyError: key not found: "noes"
#
def [](key)
fetch(key)
end
def default(_ = nil)
raise DefaultError
end
def default=(_)
raise DefaultError
end
def default_proc
raise DefaultError
end
def default_proc=(_)
raise DefaultError
end
def key(value)
super.tap do |result|
if result.nil? && (!key?(result) || self[result] != value)
raise KeyError, "key not found with value of #{value.inspect}"
end
end
end
end
end
end
|
