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Re: How and when to use GCPRO?

From: Stefan Monnier
Subject: Re: How and when to use GCPRO?
Date: Mon, 27 Dec 2010 21:17:42 -0500
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/24.0.50 (gnu/linux)

>>>> Actually, both Fcar and Fcdr can GC (by signalling an error which
>>>> triggers the debugger).
>>> But the debugger will not return.
>> Oh, right,
> Discussions like this worry me. What if the function is later changed to
> call something that can GC? What if it's used in some new context? If
> it's not utterly performance-critical code, isn't it better to be safe
> than sorry and GCPRO anyway? It's not as if it's an expensive operation.
> Premature optimization is the root of all evil, after all.

On most platforms, GCPRO is a no-op, and on those where it's not, it's
never been a major performance issue, AFAIK.  The problem is just that
it makes the code that much more verbose and painful to


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