NAME
arrayfields.rb
URIS
http://www.codeforpeople.com/lib/ruby/
http://rubyforge.org/projects/codeforpeople/
SYNOPSIS
require ‘arrayfields’
a = Arrayfields.new :k, :v, :a, :b
p a[:k] #=> :v
p a[:a] #=> :b
p a.fields #=> [:k, :a]
p a.values #=> [:v, :b]
p a #=> [:v, :b]
p a.to_hash #=> {:k => :v, :a => :b}
p a.pairs #=> [[:k, :v], [:a, :b]]
a[:foo] = :bar
p a[:foo] #=> :bar
p a.fields #=> [:k, :a, :foo]
AND
require 'arrayfields'
fields = 'name', 'age'
a = [ 'zaphod', 42 ]
a.fields = fields
a['name'] #=> 'zaphod'
a[:name ] #=> 'zaphod'
a.indices 'name', 'age' #=> [ 'zaphod', 42 ]
DESCRIPTION
allow keyword access to array instances. arrayfields works by
adding only a
few methods to arrays, namely #fields= and fields, but the
#fields= method is
hooked to extend an array on a per object basis. in otherwords
only those
arrays whose fields are set will have auto-magical keyword access
bestowed on
them - all other arrays remain unaffected. arrays with keyword
access require
much less memory when compared to hashes/objects and yet still
provide fast
lookup and preserve data order.
LIST OF OVERRIDDEN METHODS
Array#[]
Array#slice
Array#[]=
Array#at
Array#delete_at
Array#fill
Array#values_at
Array#indices
Array#indexes
Array#slice!
LIST OF HASH-LIKE METHODS
Array#each_with_field
Array#each_pair
Array#each_key
Array#each_value
Array#fetch
Array#has_key?
Array#member?
Array#key?
Array#has_value?
Array#value?
Array#keys
Array#store
Array#values
Array#to_hash
Array#to_h
Array#update
Array#replace
Array#invert
Array#pairs
LIST OF ADDED Array METHODS
Array#fields=
Array#fields
LIST OF ADDED Array CLASS METHODS
Array.fields/Array.struct
SAMPLES
<========< sample/a.rb >========>
~ > cat sample/a.rb
require 'arrayfields'
#
# the class Array has only a few added method, one is for
setting the fields,
# when the fields are set for an array THIS INSTANCE ONLY will
be modified to
# allow keyword access. other arrays will not be affected!
#
a = [0,1,2]
fields = [‘zero’, ‘one’, ‘two’]
a.fields = fields # ONLY the Array ‘a’ is
affected!
#
# keyword access is now allowed for many methods
#
p a[‘zero’] #=> 0
p a[‘one’] #=> 1
p a[‘two’] #=> 2
p a.at(‘one’) #=> 1
p a.values_at(‘zero’, ‘two’) #=> [0, 2]
#
# assigmnet is allowed
#
a[‘zero’] = 42
p a[‘zero’] #=> 0
a[‘zero’] = 0
#
# assignment to non-fields results in the element being appended
and the field
# being added for future use (also appended)
#
p(a.fields.join(‘,’)) #=> “zero, one, two”
p a[‘three’] #=> nil
a[‘three’] = 3
p(a.fields.join(‘,’)) #=> “zero, one, two, three”
p a[‘three’] #=> 3
#
# other detructive methods are also keyword enabled
#
a.fill 42, ‘zero’, len = a.size
p(a.values_at(a.fields)) #=> [42, 42, 42, 42]
a.replace [0,1,2,3]
a.slice! 'two', 2
p a #=> [0,1]
~ > ruby sample/a.rb
0
1
2
1
[0, 2]
42
"zero,one,two"
nil
"zero,one,two,three"
3
[42, 42, 42, 42]
[0, 1]
<========< sample/b.rb >========>
~ > cat sample/b.rb
require 'arrayfields'
#
# the struct class factory method can be used in much the same
way as ruby’s
# own struct generators and is useful when the fields for a set
of arrays is
# known apriori
#
c = Array.struct :a, :b, :c # class generator
a = c.new [42, nil, nil]
a[:c] = 42
p a #=> [42, nil, 42]
#
# of course we can append too
#
a[:d] = 42.0
p a[:d] #=> 42.0
p a #=> [42, nil, 42, 42.0]
~ > ruby sample/b.rb
[42, nil, 42]
42.0
[42, nil, 42, 42.0]
<========< sample/c.rb >========>
~ > cat sample/c.rb
require 'arrayfields'
#
# the Array.fields methods generates an insance with those fields
#
a = Array.fields :a, :b, :c
a[:a] = a[:c] = 42
p a #=> [42, nil, 42]
p a.fields #=> [:a, :b, :c]
p a.values #=> [42, nil, 42]
~ > ruby sample/c.rb
[42, nil, 42]
[:a, :b, :c]
[42, nil, 42]
<========< sample/d.rb >========>
~ > cat sample/d.rb
require 'arrayfields'
#
# the Arrayfields.new method is a contruct that takes evenly
numbered pairs of
# arbitrary objects and builds up and fielded array
#
a = Arrayfields.new :key, :value, :a, :b
p a.fields #=> [:key, :a]
p a.values #=> [:value, :b]
#
# you can use a hash - but of course the ordering gets lost in
the initial
# hash creation. aka the order of fields get horked by the
unorderedness if
# the hash iteration. it’s okay for some purposed though
#
a = Arrayfields.new :key => :value, :a => :b
p a.fields #=> [:key, :a]
p a.values #=> [:value, :b]
#
# lists of pairs get flattened - the result simply has to be
evenly numbered
#
a = Arrayfields.new [[:key, :value], [:a, :b]]
p a.fields #=> [:key, :a]
p a.values #=> [:value, :b]
p a.pairs #=>
[[:key, :value], [:a, :b]]
~ > ruby sample/d.rb
[:key, :a]
[:value, :b]
[:key, :a]
[:value, :b]
[:key, :a]
[:value, :b]
[[:key, :value], [:a, :b]]
<========< sample/e.rb >========>
~ > cat sample/e.rb
require 'arrayfields'
Entry = Array.struct :path, :stat
entry = Entry[ File.basename(__FILE__), File.stat(__FILE__) ]
p entry[:path] #=> "e.rb"
p entry.path #=> "e.rb"
entry.path = 'foo'
p entry[:path] #=> "foo"
p entry.path #=> "foo"
entry.path 'bar' # getter acts as setter without args
p entry['path'] #=> "bar"
p entry.path #=> "bar"
~ > ruby sample/e.rb
"e.rb"
"e.rb"
"foo"
"foo"
"bar"
"bar"
AUTHOR
[email protected]
HISTORY
4.3.0:
- a dup like method, named ‘copy’ and based on clone, is added
to Arrayfields objects
4.2.0:
- a dup impl apparently caused some confusion with both rake and
rails, so
this release undoes that impl and should be considered a
critical bugfix
release
enjoy.
