Re: export constants from package

[drieux]

On Wednesday, Nov 19, 2003, at 06:38 US/Pacific, Haim Ashkenazi wrote:

Hi

I'm writing a module to serve a script I'm writing and I was wondering 
if
it's possible to add a constant to the @EXPORT array. I prefer not to 
use
variables because these settings shouldn't be changed, but I want every
script that uses this module to be able to access these constants.

I read somewhere that you can declare your constants like this:
*BLAH = \"blah blah";
and then export $BLAH.
I tested it and it works, but I wanted to know if that's a good way of 
doing
it, or there's a better one in terms of speed and memory usage.
well first off do you mean

	use constant MY_CONSTANT => 82 ; # capitalizing them can help ID them.

{ cf. perldoc constant }

which is how I put them into a production perl module.

Then think in terms of whether you want to have them
always exported, eg @EXPORT, or can you 'bundle' them
in %EXPORT_TAGS eg:
        our %EXPORT_TAGS = ( 'all' => [ qw( .... ) ],
                'constants' => [ qw(....) ],
                ....
                );
This way if some of the constants natively cluster with
some of the functions, then you can think in terms of
and code the 'traditional' form of
        bail_out($thing,$poo,$err_num)
                if( my_got_error($that_return) == MY_CONSTANT );
which while 'traumatizing' some of the "c-coders" could
be 'repositioned' for them as
        if( my_got_error($that_return) == MY_CONSTANT ) {
                bail_out($thing,$poo,$err_num);
        }
Is that the sort of idea that you are looking at?
or would the 'accessor' method be more interesting?
	sub get_my_constant { MY_CONSTANT ; }

so that you could have

        if ( $obj->my_got_error($that_return) == $obj->get_my_constant() ) {
                bail_out($thing,$poo,$err_num);
        }
HTH.

ciao
drieux
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