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Re: Perl 5.16 and Beyond.

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From:
Abigail
Date:
September 13, 2011 06:21
Subject:
Re: Perl 5.16 and Beyond.
Message ID:
20110913132134.GF1811@almanda
On Tue, Sep 13, 2011 at 09:04:12AM -0400, David Golden wrote:
> On Tue, Sep 13, 2011 at 7:48 AM, Abigail <abigail@abigail.be> wrote:
> > In Jesse's scheme, from 5.16 onwards, this is going to mean "5.14
> > semantics".  But if this is run on 5.20, it shouldn't restrict itself
> > to patterns with 5.14 semantics. If it's run on 5.20, it should also
> > work on regexp constructs that were introduced in 5.18.
> 
> I'm very glad that Jesse put forth this ambitious vision, and at the
> same time, I worry that the devil is in the details and that we might
> find it hard to set expectations.  Here's another simple example
> inspired by yours:


Here's an even simpler example:


    use 5.18;
    sub mylc {
        lc $_ [0];
    }


Normally, I would document that as "mylc returns the lowercase of its
argument".

But that should now be documented as "mylc returns the 5.18 lowercase
version of its argument". After all, lc may change semantics in the
future. (Of course, I'm just using 'lc' as an example here; it could
be any other expression). And that would require people to not only
know the semantics of the version of Perl they are using - but also the
semantics of all versions since 5.14 up to the one they are working with.



Abigail

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