ruby throws error for nil

Question

Given the following class:

require 'rubygems'
require 'oci8'

class DB
  attr_reader :handle
  def initialize(username, password, db)
    @handle = OCI8.new(username,password,db)
    #We show an error if we don't have a handle after we try to connect to the DB
    raise ArgumentError, "Database connection failed" if @handle.nil
  end
end
def main()
  myHandle=DB.new('myUser','myPass','myDB')
  myHandle.handle().exec('select count(*) from vcas.deviceentitlement where rownum <= 100')
end

main()

my script fails with error:

`initialize': undefined method `nil' for #<OCI8:USER> (NoMethodError)
    from /home/ndefontenay/Ruby/purge_entitlement/entitlement.rb:20:in `new'
    from /home/ndefontenay/Ruby/purge_entitlement/entitlement.rb:20:in `main'
    from /home/ndefontenay/Ruby/purge_entitlement/entitlement.rb:24

I thought nil was to check whether an object has been created properly, but it looks like it's trying to run a method called nil which doesn't exist. What's going on?

You have not written which file is `entitlement.rb`. And, since you are not showing the entire code, put the line numbers to the code so that it matches the description in the backtrace. — sawa, Aug 05 '13 at 17:21
And, do you think or do you not think that a method called `nil` exists? It sounds like both, which is contradiction. — sawa, Aug 05 '13 at 17:23

7stud · Accepted Answer · 2013-08-05T17:32:39.587

1

It's

@handle.nil?

llllllllllllllllllllll

See the dot? The dot means that what follows is a method call. The method's name is spelled nil?.

edited Aug 05 '13 at 17:32

answered Aug 05 '13 at 17:17

7stud

46,922
14
101
127

Thanks a lot. I totally missed the question mark. Just started learning ruby, a lot to go. Plenty of things are confusing me still. – Nicolas de Fontenay Aug 05 '13 at 17:36

score 0 · Answer 2 · answered Aug 05 '13 at 17:34

0

The proper method to check whether an object is nil is nil?

Methods with a question mark at the end of them return a boolean.

answered Aug 05 '13 at 17:34

ruby throws error for nil

2 Answers2