From: Wejn <lists+rubytalk@...>
Date: 2002-10-17T05:47:09+09:00
Subject: Plugin autoregistration (inherited method call)

Hi,
  i'm trying to write some kind of plugin system for my project ... and
i really would like to make plugin developer's life easier ... so i decided
to carry most of the work in my classes... the problem is i'm unable to
get it to work properly :(

My original idea was to register 'transports' this way:

# --- begin -----------------------------------------------------------------
class Transport
  @@transports = {}
  def Transport.add(addr, tgt)
    @@transports[addr] = tgt
  end
  def Transport.registered_transports
    ar = []
    @@transports.each_key { |x| ar << x }
    ar
  end
end

class TCPTransport < Transport
  Transport.add('tcp', self)
end

puts "Registered transports: " + Transport.registered_transports.join(', ')
# ---  end  -----------------------------------------------------------------

which works perfectly ... but ... you MUST call
"Transport.add('tcp', self)", which is (imho) pretty ugly.
I tried to rewrite it this way:

# --- begin -----------------------------------------------------------------
class Transport
  @@transports = {}
  def Transport.registered_transports
    ar = []
    @@transports.each_key { |x| ar << x }
    ar
  end
  def Transport.inherited(sub)
    @@transports[sub.new.proto_id] = sub
  end
end

class TCPTransport < Transport
  def proto_id
    'tcp'
  end
end

puts "Registered transports: " + Transport.registered_transports.join(', ')
# ---  end  -----------------------------------------------------------------

but it just doesn't work ... :(
Neither does "@@transports[sub.proto_id] = sub" -- but I can't figure out why.

Did I overlooked something (or is there any (better) way)?

Thanks in advance,
                     W.

PS: I'm still using Ruby 1.6 ... but if there's 1.7 way only ...
    i'll switch :)
-- 
              Wejn <lists+rubytalk(at)box.cz>
(svamberk.net's Linux section, fi.muni.cz student, linuxfan)
>>>         Bored?  Want hours of entertainment?         <<<
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