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From: lawrence@APS.Atex.Kodak.COM (Scott Lawrence)
Newsgroups: comp.lang.perl
Subject: Re: A question on associative arrays
Message-ID: <LAWRENCE.91May31113043@adastra.APS.Atex.Kodak.COM>
Date: 31 May 91 16:30:43 GMT
References: <PRZEMEK.91May30164101@rrdstrad.nist.gov> <1991May30.205555.14490@convex.com>
	<1991May31.011755.4305@eng.umd.edu>
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Organization: Advanced Publishing Systems, Atex Inc. A Kodak company
Lines: 59
In-Reply-To: ziegast@eng.umd.edu's message of 31 May 91 01: 17:55 GMT

In article <1991May31.011755.4305@eng.umd.edu> ziegast@eng.umd.edu (Eric W. Ziegast) writes:

Eric>    I gave it a few tests of wort-case scenarios...

Eric>    1. Null assignment (an assignment nonetheless)
Eric>            $assoc{''}='';
Eric>            print %assoc ? "true" : "false";
Eric>       Results in true.

Eric>    2. Defining the assoc as a local
Eric>            sub foo {
Eric>                    local(%assoc);
Eric>                    print %assoc ? "true" : "false";
Eric>            }
Eric>            &foo
Eric>       Results in false.

Eric>    3. A new dbm file
Eric>            dbmopen(%assoc,"newdbmfile",0600);
Eric>            print %assoc ? "true" : "false";
Eric>       Results in false.

Eric>    I performed these tests with Perl 3.0 (41) on a SunOS 4.1 system.
Eric>    I believe ndbm was compiled into our perl.  Just FYI.
Eric>    Eric Ziegast

I got the same results with 4.03 on SunOS 4.1, and was prompted to check
on the behaviour of `defined' in those same cases.  The interesting one
turned out to be case 2, in which local( %assoc2 ) does not cause
defined( %assoc2 ) to return true.

===========

$assoc1{''}='';
print "Case 1 ", ( defined(  %assoc1 )? "defined" : "undefined" ), "\n";

Case 1 defined <<<<<< makes sense

======
sub case2
{
local( %assoc2 );
print "Case 2 ", (defined(%assoc2)? "defined" : "undefined" ), "\n";
}
&case2;

Case 2 undefined 

======

dbmopen( %assoc3, "/tmp/testdbmfile", 0777);
print "Case 3 ", (defined(%assoc3)? "defined" : "undefined" ), "\n";

Case 3 defined
======
--
Scott Lawrence       <lawrence@APS.Atex.Kodak.COM>   Voice: {US} 508-670-4023
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