symbol tables and class data members

amazotron has asked for the wisdom of the Perl Monks concerning the following question:

Hi, all. I ran across some code in "Practical Perl Programming" that will solve several problems for me. I also am aware of the Alias module on CPAN, but wanted to see if I could get this working first. Below is a snippet.

package Foo;
use strict;

sub Test
{
    my @a = (1,2,3);
    my $aref = \@a;

    local (*aa) = $aref;
    
    push (@aa, 4); # line 11
    print "aa:",join(",",@aa),"\n"; # line 12
}

Test ();
[download]

Why must I qualify uses of aa as in Foo::aa? If I don't I get the error "Variable @aa not imported at xxx line yyy". By the way, having to qualify all the uses of aa is what I'm trying to avoid.

Comment on symbol tables and class data members Download Code

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Re: symbol tables and class data members by stephen (Priest) on May 06, 2002 at 18:32 UTC
You must qualify @aa because it's a package variable, and under 'use strict' you must qualify all package variables. If something is in the symbol table, it must be fully-qualified under strict unless you've declared it with 'our'. (Or use vars if you're not on the latest Perl.) It seems to me that what you want is a way of doing symbol-table hacking with lexical vars, and I'm afraid that that's not possible because lexical vars don't appear in the symbol table. I'd suggest declaring your vars with 'our'. stephen	[reply]
Re: Re: symbol tables and class data members by amazotron (Novice) on May 06, 2002 at 18:39 UTC
I guess I should explain that the package Foo is functioning as a class and Test as a method of that class. I was trying to find an easy way of converting existing package-oriented code into class-based code. That is, move globals to be data members and not have to struggle rewriting all the uses of those globals.	[reply]