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From: talmage@luvthang.UUCP (David W. Talmage)
Newsgroups: comp.lang.icon
Subject: Idol gotcha:  mixing procedures and methods
Message-ID: <9105312217.AA02235@luvthang.UUCP>
Date: 31 May 91 22:17:07 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Distribution: inet
Organization: The Internet
Lines: 40

Boy, do I feel dumb!  Here's a "gotcha" for those of us who work with
Idol, Clint Jeffery's neato object-oriented language derived from Icon.

In Idol, you can have both procedures and methods in a class
definition.  Procedures become part of the global name space while
methods stay local to the objects of their class.  Because procedures
are in the global space, they have no concept of the variable "self",
which all methods may use to access the instance variables of their
class.  Procedures which try to dereference self invoke a run-time
error: "record expected".

This sample should illustrate the problem:

class DoNuthin(theFrobotz, theZimZam)
method asString()
  return "theFrobotz= " || self.theFrobotz || " theZimZam= " || self.theZimZam 
end

procedure printThem()
  write( self.theFrobotz )
  write( self.theZimZam )
end

initially
  printThem()
end

procedure main()
local aDoNuthin

  aDoNuthin := DoNuthin( "David", "Talmage" )
  write( aDoNuthin$asString() )

end

I don't want to tell you how long it took me to figure that one out.

-----------------------------------------------------------------------------
David W. Talmage (talmage@luvthang.aquin.ori-cal.com)
"I need fifty dollars to make you hollar.  I get paid to run this luvthang."