Le 07/09/2011 15:29, Lasse Reichstein a écrit :
On Wed, Sep 7, 2011 at 2:07 PM, David Bruant <[email protected]
<mailto:[email protected]>> wrote:
If this is really considered, the problem to solve is to express
an infinite set with a finite representation. RegExps may be a
solution. One big question is on RegExp expressivity: Can any
infinite string set be expressed with (a finite number of) JS
RegExps?
Nope. Any finite set of RegExps can be combined into a single RegExp,
so the language they recognize is still regular (or what the class of
languages recognized by JS RegExps really is, since it's bigger than
the regular languages, but doesn't include all context free langauges).
Very true. I had a doubt on whether RegExp were purely limited to
regular languages. I have never really taken the time to check whether
RegExps were just providing sugar for regular languages matching or if
they were going further than that. But hopefully, you're right.
As for proxies with arbitrarily many properties, I don't think there's
a way to prevent it (it's the catch-all effect).
Extensible proxies are not a problem. Non-extensible proxies are if the
specs asks for non-extensible objects (then proxies) to have a finite
set of properties. Current design and prototype implementation [1] seem
to go in the direction of non-extensible proxies having a finite set of
properties even though still "catching all". See L.262-273 where is
defined this.fixedProps which is a regular object (finite number of
properties).
David
[1]
http://code.google.com/p/es-lab/source/browse/trunk/src/proxies/FixedTrappingProxy.js
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