From: Steve Tu <lists@...>
Date: 2013-02-01T20:36:59+09:00
Subject: Novice: self, @self.respond_to? and dynamically built methods

I have been plodding through a Ruby tutorial and came across the
'require'
and 'load' methods(?). Prior to that, all of the tutorial examples I
played with had been bolted into one file. I had added in a 'zenity'
based menu option to drive the selection of the tutorial subjects.
Now I have split each of the tutorial subjects into separate files that
get 'loaded' or 'required'. The 'main' section is then just a  call to
the zenity menu driver, and calls to the respective methods.

All works fine...apart from...

I had an old tutorial module that looked at the passing of arguments
into Ruby from the command line. This example did little more than split
the arguments into the argument type and value and then displayed them.
I thought it would be nice then to revisit this and make the argument
type the name of a tutorial 'method' and the argument value any value
required by that tutorial method.

This seemed relatively straight forward, so I could now call my Ruby
module as:
./ptutorial.rb -s"HASHES" -o"1"

From my driver menu, I could then select the argument tutorial - and it
would split the two arguments into a variable containing a method name
(by downcasing and appending _test to the -s argument) and option
variable.

Now, to stop a call to a non existent method, I wanted to see if the
built method variable existed as a method.

What I thought I could then do, was to see if 'self' responded to the
method by using:
if self.respond_to?(method)

but it seems that 'self' does not respond to that method - although if I
call self.send(method, option) it appears to work fine (even though if I
look at the methods that self/@self supports via the methods method,
none of my 'local' tutorial methods appear).

I thought that it may be down to use of 'self' as opposed to '@self' but
both fail on the respond_to?, and seem to process the method ok on the
send.

What I want is to dynamically build a method name, then see if the
object (in this case 'self' or the current module) supports that method
and if so to then execute that method with any optional arguments.

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