Question

Can someone tell me why this method is always returning true, even when the string does not match the pattern? I’ve ran the regex through TextWrangler’s regex engine, and the pattern is correct. Thanks

def validatePEM pem
 if /^-{4}([-\s])BEGIN/.match(pem)
   print "validatePEM found a match\n"
   return true
 else
   return false
  end
end
@s = '---BEGIN RSA PRIVATE KEY-----'


if validatePEM @s
  print "VALID PEM FILE\n"
else
  print "INVALID PEM FILE\n"
end

Answer 1

Just as a FYI, there are several things done in “un-Ruby” ways.

I’d write:

def validatePEM pem
if /\A-{4}([-\s])BEGIN/.match(pem)
  print "validatePEM found a match\n"
  return true
else
  return false
  end
end
@s = '---BEGIN RSA PRIVATE KEY-----'


if validatePEM @s
  print "VALID PEM FILE\n"
else
  print "INVALID PEM FILE\n"
end

something like:

def validatePEM(pem)
  !!pem[/\A-{4}([\s-])BEGIN/]
end

@s = '---BEGIN RSA PRIVATE KEY-----'

puts '%s PEM FILE' % (validatePEM(@s) ? 'VALID' : 'INVALID')

The use of a ternary statement for printing is something that some might question when writing in Ruby, but the Ruby Style guide agrees that writing trivial conditional tests with ternary (?:) is OK.