conditions_examples.rb

# As an exercise, come up with a ruby-way to specify 
# a set of search conditions for this SQL:

# simple or
# WHERE name = 'Dan' OR name = 'Paul'

# nested or, plus duplicating field names
# WHERE name = 'Paul' AND ( age < 18 OR age > 21 )

# not ( and don't say != )
# WHERE NOT name = 'Paul'

# Some of these might not work, I'm just brainstorming, and soliciting ideas

# prefix
Model.all(and(:name => "Paul", or(:age => lt(18), :age => gt(21))

# expressions
Model.all( c(:name => "Paul").and(c(:age => lt(18)).or(:age => gt(21))) )

# ambition-style
Model.all( name == "Paul" && ( age < 18 || age > 21 ) )

# Hashes. Assumes a plain hash is AND'ed
Model.all( :name => "Paul",
           :or => { :age => [lt(18), gt(21)] } )

# Custom parser
Model.all( " name = 'Paul' AND ( age < 18 OR age > 21 ) " )

# super-prefix
Model.all eq(:name, 'Paul').or(lt(:age, 18), gt(:age, 21))

# namelessjon 
Model.all( { :name => 'Paul' }, {:age => 21, :name => 'Joe'} )

# lisp-y afrench
Model.all( :conditions => [:and, [:eql, :name, 'Paul'], [:or, [:lt, :age, 18], [:gt, :age, 21]]] )

# EZ-Where style

Model.all( c { :name == "Dan" } | c { :name == "Paul" } )

Model.all( c { :name == "Paul" } + ( c { :age < 18 } | c { :age > 21 } ) )

Model.all( - c { :name == "Paul" } )

# Sam's Arrays:

Model.all( [ :name => 'Dan' ].or([:name => 'Paul']) )

Model.all( :name => 'Paul', [ :age => lt(18) ].or([ :age => gt(21) ]) )


# And for reference, here's how it will get represented internally.

Operation.new(:or, 
              Comparison.new(:eql, :name, "Dan"), 
              Comparison.new(:eql, :name, "Paul")
              )

Operation.new(:and,
              Comparison.new(:eql, :name, "Paul"),
              Operation.new(:or,
                            Comparison.new(:lt, :age, 18),
                            Comparison.new(:gt, :age, 21)
                            )
              )

Operation.new(:not,
              Comparison.new(:eql, :name, "Paul")
              )