Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.csd.uwm.edu!bionet!ames!uhccux!munnari.oz.au!mimir!hugin!augean!mpope
From: mpope@augean.OZ (Michael T Pope)
Newsgroups: comp.lang.c++
Subject: Re: scope of FOR
Summary: Save the classic |for|
Message-ID: <573@augean.OZ>
Date: 23 Aug 89 13:08:05 GMT
References: <1807@hcr.UUCP> <9803@alice.UUCP>
Reply-To: mpope@augean.OZ (Michael T Pope)
Organization: U.of.Adelaide, E&E Engineering
Lines: 39

In article <9803@alice.UUCP> ark@alice.UUCP (Andrew Koenig) writes:
>In article <1807@hcr.UUCP>, ron@hcr.UUCP (Ron Irvine) writes:
>
>> This would let programmers localize the extent of the declared
>> variable to the FOR statement.  Bjarne could you please fix this.
>
>Sorry, it's too late.
>
>While working on 2.0 we seriously considered fixing it --
>until we discovered how much existing code it would break.

Thankyou.  I would have been bitten hard by that.  However, in what
way would one "fix" it?  Surely one does not want to replace the
simplicity of---

  for (<foo>;<bar>;<baz>) <rubbish>  

---being equivalent to---

  <foo>;
  for (;<bar>;<baz>) <rubbish>

---with some new special case behaviour?  

Is there currently anywhere in the language where scope is
defined by anything other than {}s and explicit declaration keywords?
(Well... ignoring file boundaries and function declarations:-)
If not, now is a bad time to start.

Admittedly the for(<decl>...) syntax could be criticized as
potentially misleading, but since the scope of those declarations can
be restricted trivially by wrapping the whole |for| in an extra pair
of {}s the idea looks like mere syntactic sugar to me.

Please dont break |for|.  If restricted scope loop variables
are really desirable, better to invent a new keyword/syntax.

Cheers,
Mike Pope