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From: dvdeug@x8b4e53cd.dhcp.okstate.edu (David Starner)
Subject: Re: How to implement a continue statement in Ada?
Date: 2000/02/09
Message-ID: <87s8s3$aai1@news.cis.okstate.edu>#1/1
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References: <87pgm3$o3p$1@nnrp1.deja.com> <87pmrq$9ae1@news.cis.okstate.edu>
 <m3ya8v1g93.fsf@skinner.demon.co.uk>
Organization: Oklahoma State University
User-Agent: slrn/0.9.6.2 (Linux)
Reply-To: dstarner98@aasaa.ofe.org
Newsgroups: comp.lang.ada
Date: 2000-02-09T00:00:00+00:00
List-Id: <comp.lang.ada>

On 08 Feb 2000 22:28:08 +0000, Aidan Skinner <aidan@skinner.demon.co.uk> wrote:
>dvdeug@x8b4e53cd.dhcp.okstate.edu (David Starner) writes:
>
>> I disagree with that rule. The goto statement is the most
>> powerful control structure, and judiciously used, is 
>> very useful. My most recent use of a goto was to emulate
>> tail recursion. Does that mean that Ada needs a tail
>
>I would expect this case to be picked up by the compiler, without the
>need for an explicit goto. Was there a reason why the appropriate
>section of code couldn't be put into a (possibly nested) procedure and 
>recurse itself?

The code was part of a lexer, and looked like

function lexer return token is begin
<<label>>
-- Bookkeeping
if char(1) = '*' then
-- Deal with it
elsif char(1) = ''' then
...
elsif char (1) = '(' and char (2) = '*' then
   -- Eat the comment
   either goto label or return lexer;
elsif char (1) =  '%' then
...

GNAT didn't recognize it as tail recursion, so the non-recursive
version performed better with certain (pathological) code. I'd
be surprised to find that any Ada compiler did much better on
tail recursion than GNAT, as it's not important for most Ada
programs.

-- 
David Starner - dstarner98@aasaa.ofe.org
Only a nerd would worry about wrong parentheses with
square brackets. But that's what mathematicians are.
   -- Dr. Burchard, math professor at OSU