From: Tom Cloyd <tomcloyd@...>
Date: 2009-01-21T11:34:16+09:00
Subject: Re: cannot get attr_accessor to work

Justin Collins wrote:
> Tom Cloyd wrote:
>> I've been staring at this for a couple of hours, and I cannot crack 
>> the nut. This SHOULD work, but I'm obviously screwing up. Just cannot 
>> see where. I'm carefully following several examples, but...I cannot 
>> get access to my instance variables.
>>
>> Here's a stripped down version of the code -
>>
>> # SetNet.rb
>>
>> def main
>>  # Set up logging
>>  run_log = Manage_log.new( 'logfile.txt' ).open
>>  log = run_log.log
>>  logging_now = run_log.lgg    # @logging_now = false
>>    # @log, @logging_now = manage_log( 'open' )
>> end
>>
>> # Creates program log file, setting default logging level of INFO. 
>> Current logging is appended to existing log content. Closes log when 
>> requested by user.
>>  #
>>  # * _op_ - Requested operation: _open_ or _close
>>  #
>> class Manage_log  attr_accessor :log, :lgg
>>  def initialize( logFileName )
>>    @logFileName = logFileName
>>  end
>>  def open    #create log file
>>    log_main = File.open( @logFileName, File::WRONLY | File::APPEND )
>>    @log = Logger.new( log_main )
>>    @log.datetime_format = "%Y-%m-%d %H:%M:%S"
>>    @lgg = true
>>
>>    # set logging level
>>    @log.level = Logger::INFO # I.e., only INFO level and above will 
>> be logged
>>    @log.info( '===== START logging' ) # just a program place indicator
>>    puts '> logging started, at INFO level'
>>  end
>>
>> end
>>
>> %w(rubygems ruby-debug readline strscan logger fileutils).each{ |lib| 
>> require lib }
>> Debugger.start
>> debugger # call to ruby-debug
>>
>> main
>>
>> ====
>>
>> Demonstration of the lack of access -
>>
>>> $ ruby setnet-x.rb
>>> setnet-x.rb:40
>>> main
>>> (rdb:1) b 4
>>> Breakpoint 1 file setnet-x.rb, line 4
>>> (rdb:1) c
>>> Breakpoint 1 at setnet-x.rb:4
>>> setnet-x.rb:4
>>> run_log = Manage_log.new( 'logfile.txt' ).open
>>> (rdb:1) n
>>> > logging started, at INFO level
>>> setnet-x.rb:5
>>> log = run_log.log
>>> (rdb:1) p run_log.log
>>> NoMethodError Exception: undefined method `log' for nil:NilClass
>>> (rdb:1)
>> I would truly appreciate someone's pointing out the problem here.
>>
>> Thanks!
>>
>> Tom
>>
>
>
> Take a look at ManageLog#open. The last expression is a call to puts, 
> which returns nil. You are setting the variable "run_log" to the 
> result of the call to open in the debugger, but that result is nil. 
> Then you try to call "log" on nil, thus the error.
>
> -Justin
>
>
Well, nuts. That's crystal clear. Man, it's tough being a Ruby amateur, 
when it 's not great fun, which it hasn't been for a couple of hours.

Thanks Justin. Much appreciated.

t.

-- 

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Tom Cloyd, MS MA, LMHC - Private practice Psychotherapist
Bellingham, Washington, U.S.A: (360) 920-1226
<< tc@tomcloyd.com >> (email)
<< TomCloyd.com >> (website) 
<< sleightmind.wordpress.com >> (mental health weblog)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~