EXPORT_TAGS does not export a defined tag

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

I am trying to write a Perl module that exports a group of names and I can't seem to get it to work. It must be something obvious that I am not seeing.

This is my module in the file "tmod.pm" in the current directory:

package tmod;
use 5.20.0;
use strict;
use warnings;
require Exporter;
our @ISA = qw(Exporter);
our @EXPORT_OK = qw($v0 $v1 $v2);
our %EXPORT_TAGS = (tag_v0=>[qw($v0)]);
our $v0=0;
our $v1=1;
our $v2='';

1;
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And this is my test script:

use 5.20.0;
use strict;
use warnings;
use Carp;
use tmod qw(tag_v0);

say "done"; 
exit;
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The result is:

perl test_tmod.pl
"tag_v0" is not exported by the tmod module
Can't continue after import errors at test_tmod.pl line 5.
BEGIN failed--compilation aborted at test_tmod.pl line 5.
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I am running Citrus Perl 5.24.01 under Windows 10

All help will very much appreciated.

David

Comment on EXPORT_TAGS does not export a defined tag Select or Download Code

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Re: EXPORT_TAGS does not export a defined tag
by Athanasius (Archbishop) on Nov 30, 2017 at 03:38 UTC

Hello perlpipe,

When using a tag in a use directive, you have to prefix it with a colon:

use tmod qw( :tag_v0 );
#            ^
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See Exporter#Specialised-Import-Lists.

BTW, the Perl convention is to capitalise the first letter of a module name unless the module is functioning as a pragma. See perlmod#Perl-Modules.

Hope that helps,

Athanasius <°(((>< contra mundum Iustus alius egestas vitae, eros Piratica,

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Re^2: EXPORT_TAGS does not export a defined tag

by Anonymous Monk on Nov 30, 2017 at 15:28 UTC

Thanks everyone for your answers. I knew the answer was straight forward and I just couldn't see it.

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Re: EXPORT_TAGS does not export a defined tag
by huck (Prior) on Nov 30, 2017 at 03:39 UTC

I think you want

use tmod qw(:tag_v0);
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Specialised Import Lists

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Re: EXPORT_TAGS does not export a defined tag
by choroba (Cardinal) on Nov 30, 2017 at 08:36 UTC

What Not to Export

There's one more item to add to this list. Do not export variable names. Just because Exporter lets you do that, it does not mean you should.

($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,
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Re: EXPORT_TAGS does not export a defined tag
by beech (Parson) on Nov 30, 2017 at 03:43 UTC

You might also be interested in Problem with "use Exporter qw(import);"

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Re: EXPORT_TAGS does not export a defined tag
by stevieb (Canon) on Nov 30, 2017 at 04:22 UTC

Here's the repetitive way I've populated and offered things. This shows the usage.

I admit that it was the first time I've done anything regarding exporting items such as this in this way, so I'm just throwing it out there (feedback welcome :)

The other Monks have expressed exactly what the problem is here so I'll digress from that, but from you OP, feedback on what documentation may look like would be wonderful.

-stevieb

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