Tough to debug. Variables work in irb but the method fails.

Question

I discovered a bug that without a trailing number [0-9], my method will fail. Therefore I used a quick gsub to insert that number.

I'm working with this method:

  def initialize(speciate)
     y = speciate.gsub(/$/, '1')
     x = y.scan(/[A-za-z]*\d+/)
     @chem_species = x.map { |chem| chem.scan(/[A-Z][^A-Z]*/) }.flatten
  end

When I test the variables in irb: (It works)

ruby-head > speciate = "NaCl"
 => "NaCl" 
ruby-head > y = speciate.gsub(/$/, '1')
 => "NaCl1" 
ruby-head > x = y.scan(/[A-za-z]*\d+/)
 => ["NaCl1"] 
ruby-head > @chem_species = x.map { |chem| chem.scan(/[A-Z][^A-Z]*/) }.flatten
 => ["Na", "Cl1"] 

When I run the Method in irb: (It fails)

ruby-head > x = Chemical.new("NaCl")
 => #<Chemical:0x0000010084d0b8 @chem_species=[]> 
x = Chemical.new("H2SO4")
 => #<Chemical:0x000001008467e0 @chem_species=["H2", "S", "O4"]> 

Thank you in Advance!

Answer 1

Since chemical symbols are always one uppercase letter, followed by zero or more lowercase letters, why not:

molecule = 'NaCl'
molecule.scan(/[A-Z][a-z]*[0-9]*/)
=> ["Na", "Cl"]

molecule = 'H2SO4'
molecule.scan(/[A-Z][a-z]*[0-9]*/)
=> ["H2", "S", "O4"]

molecule = 'Na2S'
molecule.scan(/[A-Z][a-z]*[0-9]*/)
=> ["Na2", "S"]

molecule = 'H'
molecule.scan(/[A-Z][a-z]*[0-9]*/)
=> ["H"]