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Re: First look: Advanced Polymorphism whitepaper

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From:
chromatic
Date:
May 2, 2008 12:22
Subject:
Re: First look: Advanced Polymorphism whitepaper
Message ID:
200805021221.27740.chromatic@wgz.org
On Friday 02 May 2008 11:55:54 Larry Wall wrote:

> On Fri, May 02, 2008 at 11:15:34AM -0700, chromatic wrote:

> : All classes imply the existence of a role of the same name.

> If a role is derived from a class, it must of necessity be a snapshot
> of the class, because roles are immutable, while classes are not.

Agreed.

> The only interesting question in my mind is whether you can take
> another snapshot and override the previous one somehow, or whether
> such derived roles should version themselves so that the snapshots
> can be distinguished by longname.  Alternately, we make one snapshot
> when a class is first composed, and refuse to make any other snapshots
> for that name regardless of how the class under that name changes.

I'm not sure which is best.  Snapshotting at the time of first composition (or 
the first time someone says "Hey, I provide that other class's role!") seems 
right though.

-- c

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