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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: Performance of access type : a tiny mistake in the WikiBook ?
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Date: Thu, 8 Oct 2009 11:11:42 +0200
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Date: 2009-10-08T11:11:42+02:00
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On Wed, 7 Oct 2009 17:48:56 -0700 (PDT), Yannick Duch�ne Hibou57 wrote:

> I understand what you mean about testing, but I am mainly looking for
> average answers.

The average answer is that any static constraint known to hold must be
specified.

Rationale: this weakens the precondition, which the compiler should
otherwise check dynamically, i.e. possibly generate some additional code.

For non-static constraints the rule is opposite, because it strengthens the
precondition.

So:

in before in out
constant before <nothing>
pool specific before general access

But:

not null vs. <nothing> depends on the where that constraint was put
subtype vs. type, ditto
specific type vs. class, ditto

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de