Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!wuarchive!uwm.edu!ogicse!iwarp.intel.com!news
From: merlyn@iwarp.intel.com (Randal L. Schwartz)
Newsgroups: comp.lang.perl
Subject: Re: when is pass by reference necessary?
Message-ID: <1991Mar28.215043.5288@iwarp.intel.com>
Date: 28 Mar 91 21:50:43 GMT
References: <1991Mar28.053132.7061@yarra-glen.aaii.oz.au>
Sender: news@iwarp.intel.com
Reply-To: merlyn@iwarp.intel.com (Randal L. Schwartz)
Organization: Stonehenge; netaccess via Intel, Beaverton, Oregon, USA
Lines: 31
In-Reply-To: pem@yarra-glen.aaii.oz.au (Paul E. Maisano)

In article <1991Mar28.053132.7061@yarra-glen.aaii.oz.au>, pem@yarra-glen (Paul E. Maisano) writes:
| When I wrote this, I intended to pass the file handle as *X but I forgot
| the *. It still worked so I wondered if I was confused about why I thought
| the * was necessary. Is it necessary ? 

What's happening is that the 'X' is being passed as a literal string,
as if you had said

	&my_open("X", "file.dat");

and then in the assignment within the subroutine:

	local(*F, $name) = @_;

you are assigning:

	*F = "X";

which is the same as:

	*F = *X;

except that the "X" is looked up at runtime.  So, it is *safe* (at
least in this case... don't overgeneralize!), but *inefficient*.

print join(" ",("Perl","another","Just","hacker,")[2,1,0,3])
-- 
/=Randal L. Schwartz, Stonehenge Consulting Services (503)777-0095 ==========\
| on contract to Intel's iWarp project, Beaverton, Oregon, USA, Sol III      |
| merlyn@iwarp.intel.com ...!any-MX-mailer-like-uunet!iwarp.intel.com!merlyn |
\=Cute Quote: "Intel: putting the 'backward' in 'backward compatible'..."====/