I don't think you can do it in one statement. You can do it in two statements though:

package November;
use base 'Juliet';
Juliet->VERSION(1.1);
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Excellent! -- thank you. I tried testing this, but couldn't get a version mis-match to cause a compile time error.

Then I decided to get into the debugger to have a better look at what was going on -- and the debugger issued the expected error right away. I'm not sure why, but I suspect it's the difference between what stage of the preparation the Perl internals got to in each situation. The debugger gets much closer to run-time, hence it triggered the error.

Alex / talexb / Toronto

Thanks PJ. We owe you so much. Groklaw -- RIP -- 2003 to 2013.

Yes, the two statements run at different times, as you found out:

package November;
use base 'Juliet';    # runs at compile time
Juliet->VERSION(1.1); # runs at runtime, after November.pm has been pa
+rsed completely
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This usually makes little difference as long as November.pm is its own file. If November.pm is loaded later, code from earlier modules will already have run by the time the ->VERSION() call is made.

This is definitely more elegant and shorter than my attempt here: Re: Using a base module with a required version.

use Juliet 1.1;
use base 'Juliet';
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But base has issues avoided by using parent.

use Juliet 1.1;
use parent 'Juliet';
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But I don't see the point of using either.

use Juliet 1.1;
our @ISA = 'Juliet';
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Saying it this way

use Juliet 1.1;
our @ISA = 'Juliet';
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actually makes the most sense to me -- but I'm uneasy about twiddling with @ISA since that's how Perl gets told about inheritance.

Hiding @ISA with your middle example

use Juliet 1.1;
use parent 'Juliet';
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is less alarming -- but it seems like it does the same thing.

Alex / talexb / Toronto

Thanks PJ. We owe you so much. Groklaw -- RIP -- 2003 to 2013.

I'm uneasy about twiddling with @ISA since that's how Perl gets told about inheritance.

I've very confused. Isn't that exactly what you want to do?

If not, you shouldn't be using base.pm or parent.pm or @ISA, just use Juliet 1.1;.

It doesn't appear as though that functionality is available in either base or parent. Here's a potential q&d workaround that may be sufficient if it turns out what you're trying to do isn't possible inherently:

use warnings;
use strict;

use version;

BEGIN {
    use base 'Mock::Sub';
    my $v = version->parse($Mock::Sub::VERSION);
    if ($v < version->parse(1.07)){
        die "Version '$v' of Mock::Sub isn't 1.07 or greater";
    }
}
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The output, first with version 1.06 of the distribution, then another run after updating the dist:

$ perl base.pl 
Version '1.06' of Mock::Sub isn't 1.07 or greater at base.pl line 10.
BEGIN failed--compilation aborted at base.pl line 12.

$ cpanm Mock::Sub
--> Working on Mock::Sub
Fetching http://www.cpan.org/authors/id/S/ST/STEVEB/Mock-Sub-1.09.tar.
+gz ... OK
Configuring Mock-Sub-1.09 ... OK
Building and testing Mock-Sub-1.09 ... OK
Successfully installed Mock-Sub-1.09 (upgraded from 1.06)
1 distribution installed

$ perl base.pl
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