export constants nicely from perl module...

[Michael G Schwern]

On Fri, Feb 06, 2004 at 06:49:53AM -0500, Wesley Darlington wrote:
> I resent having to give the name of each constant twice. (I'm going to
> call this 'syntactic soot' - better descriptions welcome!)
> 
> I'm wondering if there's a better way. Perhaps something like...
> 
> -----8<-----8<-----8<-----8<-----8<-----8<-----8<-----
> package Widget::Config;
> use base 'Exporter::Constants';
> 
> econst widget_dir => '/usr/local/widget/conf';
> econst max_widgets => 42;
> -----8<-----8<-----8<-----8<-----8<-----8<-----8<-----
> 
> ...but as long as its syntactically reasonably sweet, I don't mind
> what it looks like. There will be lots of constants.

Remember, constants are just subroutines with a prototype of ().

Also, constants have to be declared at compile time in order to be constant, 
but compile time is relative.  So...

sub econst {
	my($name, $value) = @_;
	my $caller = caller;
	*{$name} = sub () { $value };
	push @{$caller.'::EXPORT'}, $name;
}


-- 
Michael G Schwern        schwern at pobox.com  http://www.pobox.com/~schwern/
It's Flypaper Licking time!