Re: subclassing Logging

On Apr 30, 2010, at 11:23 PM, [e-mail] wrote:

> Tim,
>=20
> I am trying to subclass the logging module to have a consistent setup =
for my classes. They all log to the same rolling file.  I seem to get =
two different errors.
>=20
> Error one:
> require 'fileutils'
> require 'logging'
>=20
> module MyLogger
> class Log < Logging::Logger
>  def initialize(config)  # config not used in test but will be.
>    super("reader")
>    Logging.appenders.stdout(:level =3D> :debug)
>    file_path =3D  "./reader.log"
>    Logging.appenders.rolling_file(
>    "readerlog",
>    :filename =3D> file_path,
>    :age =3D> :daily,
>    :layout =3D> Logging.layouts.json)
>    add_appenders('stdout','readerlog')
>  end
> end
> end
>=20

Take a look at this example logging configuration. It walks though the =
concept of logger hierarchies in the logging framework.

http://github.com/TwP/logging/blob/master/examples/hierarchies.rb

This, I believe, is what you are trying to accomplish. You should not =
have to subclass the Logging:Logger. Take a look at the other example =
files in that "examples" folder; they walk through in code some of the =
concepts behind the logging framework.

Logging.appenders.stdout(
  'stdout',
  :layout =3D> Logging.layouts.pattern
)

Logging.appenders.rolling_file(
  'readerlog',
  :filename =3D> './reader.log',
  :age =3D> :daily,
  :layout =3D> Logging.layouts.json
)

logger =3D Logging.logger['YourModule']
logger.appenders =3D ['stdout', 'readerlog']
logger.level =3D :info


In the above snippet of code, I created two appenders. The first is =
named "stdout" and will use a pattern based layout to write log messages =
to STDOUT. The second is named "readerlog" and will use a JSON layout to =
write log messages to a file called "reader.log".

I then created a new logger instance, added the two appenders by name, =
and then set the log level to 'info'.

Now you can create nested loggers that will use the same appenders and =
have the same default log level.


another_logger =3D Logging.logger['YourModule::Another']
yet_another_logger =3D Logging.logger['YourModule::Another::Yet']


> with this in a larger program or by it self I get:
>=20
> NoMethodError: undefined method `synchronize' for nil:NilClass
>        from =
/usr/local/ruby/lib/ruby/gems/1.8/gems/logging-1.4.1/lib/logging/logger.rb=
:51:in `new'
>        from (irb):2
> irb command is  l =3D  MyLogger::Log.new('test')
>=20
> If I remove the parameter from the initialize, I can make it work =
standalone.
>=20
> I tried using rspec in the larger app and just the test for log fails =
the same with the parameter.  I take it off and the init passes but the =
actual log does not return.
>=20

The Logging framework has built in support for rspec. It can be =
configured to log all messages to a StringIO instance during tests. You =
can then read out your log messages from the StringIO and make sure the =
right messages are making it into the log.

In your spec_helper file ....


require 'spec/logging_helper'

Spec::Runner.configure do |config|
  include Spec::LoggingHelper
  config.capture_log_messages
end


And in your actual specs ...


it 'logs a message on error' do
  @foo.error_method
  @log_output.readline.should =3D=3D 'This is your error message'
end


I hope all this helps.

Blessings,
TwP


PS  I cc'd the ruby-talk mailing list so this information can be found =
by others.


> describe MyLogger::Log do
>  it "should initialize" do
>    l =3D MyLogger::Log.new()
>    l.class.should =3D=3D MyLogger::Log
>  end
> end
>=20
> describe MyLogger::Log do
>  before :each do
>    @log =3D MyLogger::Log.new
>  end
>=20
>  it "should log a debug" do
>    @log.info "Rspec debug".should =3D=3D true
>  end
>=20
> end
>=20
> the @log.info fails with:
> 'MyLogger::Log should log a debug' FAILED
> expected: true,
>     got: "Rspec debug" (using =3D=3D)
>=20
>=20
> I can use any help you can give.
>=20
> Don French