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Re: When to choose defsubst
From: |
Stefan Monnier |
Subject: |
Re: When to choose defsubst |
Date: |
Mon, 02 Apr 2007 13:31:23 -0400 |
User-agent: |
Gnus/5.11 (Gnus v5.11) Emacs/22.0.96 (gnu/linux) |
> I tried to find an easy answer but failed miserably at it :/
> So my question is this: when/why should I use a defsubst ?
Never.
Stefan
PS: `defsubst' is like `defun' except it additionally tells the
byte-compiler that this function should be inlined at every call site.
In some rare cases, it can make a noticeable performance difference,
but these are very rare, so you should only do that after noticing an
actual performance problem and finding out where time is spent (with
elp, typically).
The reason not to use `defsubst' is that it does not behave well w.r.t
debug/advice/trace/...