Re: sharing symbols

Definitely go for the module approach. Though not that short as I would prefer, the code below demonstrate how you could achieve the effect of "automatically" stuffing your constants into the list of exports of your module.

The code for finding the constant names in the symbol table is almost abstract and with a little effort could be migrated into a generic module, leaving your constant module lighter.

package MyConstants;

use strict;
use warnings;

require Exporter; # you may use other exporter modules
our @EXPORT; # empty by now

use constant FOO => 1;
use constant BOO => 2;
use constant BAR => 3;
# ...

#### here begins the code to find and populate the list of exports wit
+h constant names

our @GLOBAL_SYMBOLS; # these are not package constants, but Perl artif
+acts
BEGIN {
    @GLOBAL_SYMBOLS = qw(BEGIN EXPORT);
}

# $ans = is_constant($symbol_name);
#
# decides if a name is a package constant or not.
# Checks if it is all upper-case and not in @GLOBAL_SYMBOLS
sub is_constant {
    my $k = shift;
   return $k =~ /^[A-Z]+$/ 
       && !grep { $_ eq $k } @GLOBAL_SYMBOLS
}

# push_constants(\@export, @symbols)
#
# Push @symbol names into @export if they satisfy is_constant
sub push_constants {
    my $export_ref = shift;
    my @symbols = @_;
    for my $s (@_) {
        if ( is_constant($s) ) {
            #print "s: $s\n";
            push @$export_ref, $s
        }
    }
}

BEGIN {

    # iterate the package stash
    my @keys = do { no strict 'refs'; keys %{__PACKAGE__ . '::'} };
    push_constants(\@EXPORT, @keys);

}

print "export: @EXPORT\n";

#### here ends the code to find and populate the list of exports with 
+constant names

1;
[download]

Comment on Re: sharing symbols Download Code

Replies are listed 'Best First'.
Re^2: sharing symbols by bart (Canon) on Apr 13, 2007 at 11:42 UTC
`our @GLOBAL_SYMBOLS; # these are not package constants, but Perl artif +acts BEGIN { @GLOBAL_SYMBOLS = qw(BEGIN EXPORT); }` [download] `sub is_constant { my $k = shift; return $k =~ /^[A-Z]+$/ && !grep { $_ eq $k } @GLOBAL_SYMBOLS }` [download] Bah, use a hash, Luke! Use a hash! `our %GLOBAL_SYMBOL; # these are not package constants, but Perl artifa +cts BEGIN { %GLOBAL_SYMBOL = map { $_ => 1 } qw(BEGIN EXPORT ISA EXPORT_OK GLO +BAL_SYMBOL); }` [download] `sub is_constant { my $k = shift; return $k =~ /^[A-Z_0-9]+$/ && !$GLOBAL_SYMBOL{$k}; }` [download] BTW did you forget to exclude @GLOBAL_SYMBOLS, by any chance? And, why not use a lexical for it? BTW I think this functionality is generally interesting enough to deserve its own module on CPAN. Let's call it ExportAll, or something else like that. And, as the helper subs would reside in that module, they wouldn't be exported themselves. Update: Oh no, I see you only support only upper case letters only names (which would exclude @GLOBAL_SYMBOLS). Which seems too restrictive to my taste.	[reply] [d/l] [select]
Re^3: sharing symbols by ferreira (Chaplain) on Apr 13, 2007 at 19:42 UTC
Oh no, I see you only support only upper case letters only names (which would exclude @GLOBAL_SYMBOLS). Which seems too restrictive to my taste. Don't go down on me that fast. This restriction can be lifted very easily and that's why I kept `is_constant` separated from `push_constants`. If the role of `is_constant` is taken by a subroutine ref, the rest is generic enough. Here an implementation of that generic module whose idea you cherished for a moment: Read more... (2 kB) And then applying it to the original request of the OP: Read more... (491 Bytes) The user's code just says `use MyConstants;` [download] to import the constants into the current namespace. BTW I have not worried with `@GLOBAL_SYMBOLS` because it didn't match `/^[A-Z]+$/` which does not accept underlines. It was an oversight, but, because of this, it was not a problem. BTW you were right about using a hash. The grep was only for a quick-and-dirty solution.	[reply] [d/l] [select]


P is for Practical
	PerlMonks