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Re: [ #70622] Versions Disappear

John Peacock
September 9, 2011 03:54
Re: [ #70622] Versions Disappear
Message ID:
On 09/07/2011 07:05 AM, Nicholas Clark wrote:
> But what this means is that on any *previous* major release, any module
> can load and as a side effect change core semantics everywhere.
> Effectively, loading behaves like upgrading perl to a different
> major version. At runtime. From any module's code.

Loading in any release of Perl prior to 5.10.0 changes one 
and only one global behavior, and it is one that MUST be changed in 
order for version objects to function.  This isn't a high level argument 
about purity of code or what can or cannot be changed by aftermarket 
CPAN modules.  This is cold hard fact.

The existing UNIVERSAL::VERSION code in any release of Perl prior to 
5.9.whatever (when was imported into the core) has no idea 
how to handle version objects.  From 5.6.0 onwards, there was some 
somewhat hacky code to try and compare v-strings, but otherwise 
UNIVERSAL::VERSION _only_ understood floating point numbers (or things 
that looked like numbers).  That completely defeats the purpose of 
having standard parsing and comparison logic for version objects completely.

I am increasingly regretting agreeing to make the change to; 
so much so that I am thinking of just changing it back on CPAN and 
letting the argument about what to do about blead go on without me.  If 
you want the contents of Package's $VERSION scalar, get it via 
$Package::VERSION.  If, however, you want what is equivalent to what 
that version will actually be used for comparison purpose, call the 
function Package->VERSION, which should return the stringified version 
object that would have been used has you issued Package->VERSION(0).

And still, no on has fixed base's idiotic behavior.

I have to go drive my daughter to school.  Have fun storming the castle 
in my absence...

John Perl Programming lists via nntp and http.
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