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Contents
#--
# StaticHash
#
# Copyright (c) 2005 Thomas Sawyer
#
# Ported from Gavin Kistner's WriteOnceHash in basiclibrary.rb
# Copyright (c) 2004 Gavin Kistner
#
# Reuse License
#
# It is covered under the license viewable at
# http://phrogz.net/JS/_ReuseLicense.txt
# Reuse or modification is free provided you abide by the terms of that
# license. (Including the first two lines above in your source code
# usually satisfies the conditions.)
#
# ==========================================================================
# Revision History
# ==========================================================================
#
# 2004-06-01 Trans * Ported to Calibre
#
# ==========================================================================
#++
#:title: StaticHash
#
# A Hash object which raises an error if any
# previously-defined key attempts to be set again.
#
# == Synopsis
#
# foo = Hash::Static.new
# foo['name'] = 'Tom' #=> 'Tom'
# foo['age'] = 30 #=> 30
# foo['name'] = 'Bob'
#
# _produces_
#
# Error: StaticHash has value for key 'name' in object:
# {"name"=>"Tom", "age"=>30} (RuntimeError)
#
# == Author(s)
#
# * Gavin Kistner
#
class StaticHash < Hash
# Set a value for a key;
# raises an error if that key already exists with a different value.
def []=(key,val)
if self.has_key?(key) && self[key]!=val
raise ArgumentError, "StaticHash already has value for key '#{key.to_s}'"
end
super
end
end
# _____ _
# |_ _|__ ___| |_
# | |/ _ \/ __| __|
# | | __/\__ \ |_
# |_|\___||___/\__|
#
=begin testing
require 'test/unit'
class TC_StaticHash < Test::Unit::TestCase
def setup
@sh1 = StaticHash.new
end
def test_assign
@sh1["x"] = 1
assert_raises( ArgumentError ){ @sh1["x"] = 2 }
end
end
=end
Version data entries
7 entries across 7 versions & 1 rubygems