Path: utzoo!utgpu!news-server.csri.toronto.edu!bonnie.concordia.ca!uunet!etnibsd!vsh
From: vsh@etnibsd.UUCP (Steve Harris)
Newsgroups: comp.lang.perl
Subject: Re: While learning PERL... a suggestion
Summary: So, is this how the symbol table works?
Keywords: perl file learn suggest
Message-ID: <1204@etnibsd.UUCP>
Date: 24 Jan 91 22:31:00 GMT
References: <1991Jan19.003519.23569@ux1.cso.uiuc.edu> <1991Jan24.100539.20366@iwarp.intel.com>
Organization: Eaton Corp, Semiconductor Equipment Div., Beverly, MA
Lines: 38

In article <1991Jan24.100539.20366@iwarp.intel.com>, merlyn@iwarp.intel.com (Randal L. Schwartz) writes:
> 
> I hope Larry will forgive me for the following.  It's probably close
> enough for jazz, but Larry will cringe at the description.
> 
> Think of *FOO as the internal representation of the symbol "FOO" in
> the program, in *whatever* form it is used: &FOO, $FOO, %FOO, @FOO,
> and FOO as a filehandle.  When you say *BAR = *FOO, you are really
> saying that BAR can be used anywhere that FOO can be used with
> identical results.  It doesn't matter if there's an intermediate step:
> you could say $a = *FOO then *BAR = $a.
> 
> So assigning something to *BAR _must_ affect all object with a BAR as
> their name.  It's dangerous... it's not just for filehandles.

Okay, is this paraphrase correct?

Perl keeps a symbol table containing all the symbols (names) in your
perl program.  However, each entry in the symbol table **MAY** refer to
a scalar, an array, a filehandle, a subroutine, etc., depending on
context.

Presumably, the symbol table entry for "FOO" has a pointer to a struct
containing (pointers to) all the possible instances of the symbol.

When you say *BAR = *FOO, you're creating a symbol table entry "BAR"
which points to the same struct as the symbol table entry "FOO".  So
that a reference to $BAR is exactly the same as a reference to $FOO,
ditto for @FOO and @BAR, etc.


	FOO ----+	    ->	scalar
		 \	    ->	array
		  -> struct ->	associative array
		 /	    ->	subroutine
	BAR ----+	    ->	filehandle
-- 
Steve Harris - Eaton Corp. - Beverly, MA - uunet!etnibsd!vsh