From: Dave Thomas <Dave@...>
Date: 2001-02-20T02:02:28+09:00
Subject: [ruby-talk:11119] Re: Auto-magically determine your class/method in Ruby

Bryan Zarnett <bryan_zarnett@yahoo.ca> writes:

> Is their a way to auto-magically determine the class
> and method that called an operation in another class.
> For example, I have a logger class that would like to
> embed in the output line the Class and operation that
> logged a message. I don't want to have to pass this
> information as an argument if I have to.

This is Ruby. Of _course_ there is... :)

Here's the logging stuff. I made a global function called log, and
encapsulated the actual logging within a class Logger. The global
function picks up the value of 'self', and passes it, along with the
args, to the real logger function. There, we get the name of self's
class, and use the caller function to get the file name, line number
and method name of the invocation of 'log'.

     def log(*args)
       Logger.log(self, *args)
     end

     class Logger
       def Logger.log(fromObject, *args)
         fromClass = fromObject.class.to_s
         fileEtc = caller(2)[0]
         txt = args.shift
         printf "Class #{fromClass}[#{fromObject.id}] (#{fileEtc}): #{txt}\n", *args
       end
     end

     # Let's test this

     class Dave
       def doSomething
         log("Fortran code is %s", "A")
       end
     end

     log("Toplevel")

     Dave.new.doSomething

#=>
     Class Object[537712200] (t.rb:23): Toplevel
     Class Dave[537684200] (t.rb:19:in `doSomething'): Fortran code is A



Regards


Dave