Another way: 
package MyAgent;

use parent 'LWP::UserAgent';
BEGIN {LWP::UserAgent->VERSION(6.39)}

[download]

But that's a little fragile; someone may refactor and forget to keep the BEGIN block after the call to parent causing things blow up. Sometimes code becomes complex, masking simple mistakes. I would prefer a solution that doesn't require the user to maintain several steps to set up inheritance while assuring minimal versions for parent classes.

I only now noticed this and must ask: how does this scenario cause things to blow up? Someone moving the BEGIN to before use parent? Even the most basic tests should catch that immediately.

TIMTOWDI:

use LWP::UserAgent 6.39;
use parent 'LWP::UserAgent';

[download]

That makes an extra require but perl will check %INC, see that LWP::UserAgent has already been loaded, and proceed quickly. Normal style is that object-oriented modules export nothing, so the implicit ->import call should be harmless.

I believe that parent::versioned is the kind of feature that really does belong in the core or not at all — the TIMTOWDIs for it are just too simple to justify another dependency from CPAN for serious work, and it is the kind of feature that non-serious work does not care about.

In reply to Re: parent::versioned supports minimum version specification in parent classes by jcb
in thread parent::versioned supports minimum version specification in parent classes by davido

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