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I sent Ron the following two files to Ron a couple of days ago, and
received a nice reply.
This quick-and-dirty implementation only uses an Array to store
objects. Ron pointed out that it will be much more interesting if the
objects were stored in files, perhaps mapping objects to things like
fixed-length records.
Jim
--
Jim Menard, (e-mail address removed), (e-mail address removed)
http://www.io.com/~jimm
"Any sufficiently complicated C or Fortran program contains an ad hoc
informally-specified bug-ridden slow implementation of half of Common Lisp.=
"
-- Greenspun's Tenth Rule of Programming
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#
http://www.xprogramming.com/xpmag/xstSomeThoughts.htm
require 'delegate'
class Object
# Return true if self's instance variables match
def xst_match(restrict_query_obj)
restrict_query_obj.instance_variables.each { | name |
restrict_value = restrict_query_obj.instance_variable_get(name)
return false if restrict_value != nil &&
!(restrict_value === self.instance_variable_get(name))
}
return true
end
end
class RecordSet < DelegateClass(Array)
def initialize(array=[])
super(array)
end
def restrict(*restrictions)
return select { | item |
restrictions.detect { | restriction | item.xst_match(restriction) }
}
end
end
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#!/usr/bin/env ruby
require 'test/unit'
require 'test/unit/ui/console/testrunner' # Only required on Windows
require 'record_set'
# For testing: a class with a few attributes.
class Something
attr_accessor :name, :email, :age # Not required for XST to work
def initialize(name=nil, email=nil, age=nil)
@name, @email, @age = name, email, age
end
def to_s
"name = #@name, age = #@age, email = #@email"
end
end
class RecordSetTest < Test::Unit::TestCase
def setup
@rs = RecordSet.new
@rs << (
@jimmy = Something.new('Jimmy Neutron', '(e-mail address removed)', 12))
@rs << Something.new('Spongebob Squarepants')
@rs << Something.new(nil, '(e-mail address removed)', 22)
end
def test_match_self
@rs.each { | obj | assert obj.xst_match(obj) }
end
def test_match_nil
assert nil.xst_match(nil)
assert @jimmy.xst_match(nil)
end
def test_not_match_nil
assert !nil.xst_match(
@jimmy)
end
def test_match
assert_equal 'Jimmy Neutron', @jimmy.name
assert @jimmy.xst_match(Something.new) # All nil values
assert @jimmy.xst_match(Something.new('Jimmy Neutron'))
assert @jimmy.xst_match(Something.new(nil, '(e-mail address removed)'))
assert @jimmy.xst_match(Something.new(nil, nil, 12))
assert @jimmy.xst_match(Something.new('Jimmy Neutron',
'(e-mail address removed)'))
assert @jimmy.xst_match(Something.new('Jimmy Neutron',
'(e-mail address removed)', 12))
assert @jimmy.xst_match(Something.new(nil, '(e-mail address removed)', 12))
assert @jimmy.xst_match(Something.new('Jimmy Neutron', nil, 12))
end
def test_not_match
assert
[email protected]_match(Something.new('Jimmy Neutron', nil, 99))
assert
[email protected]_match(Something.new('Jimmy Neutron',
'(e-mail address removed)', 99))
assert
[email protected]_match(Something.new(/N..tron/, nil, 99))
end
def test_regex_match
assert @jimmy.xst_match(Something.new(/N..tron/))
end
def test_simple_restrict
found = @rs.restrict(Something.new('Jimmy Neutron'))
assert_not_nil found
assert_equal 1, found.length
assert_equal 'Jimmy Neutron', found[0].name
end
def test_restrict_array
found = @rs.restrict(Something.new('Jimmy Neutron'),
Something.new(nil, '(e-mail address removed)'))
assert_not_nil found
assert_equal 2, found.length
# These tests rely upon the ordering of the records in the record set
assert_equal 'Jimmy Neutron', found[0].name
assert_equal '(e-mail address removed)', found[1].email
end
def test_regex_restrict
found = @rs.restrict(Something.new(/Ne..ron/))
assert_not_nil found
assert_equal 1, found.length
assert_equal 'Jimmy Neutron', found[0].name
end
def test_regex_array_restrict
found = @rs.restrict(Something.new(/Ne..ron/),
Something.new(nil, '(e-mail address removed)'))
assert_not_nil found
assert_equal 2, found.length
# These tests rely upon the ordering of the records in the record set
assert_equal 'Jimmy Neutron', found[0].name
assert_equal '(e-mail address removed)', found[1].email
end
def test_length
assert_equal 3, @rs.length
end
end
# This is required on Windows; not on *nix
if __FILE__ == $0
Test::Unit::UI::Console::TestRunner.run(RecordSetTest)
end
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