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Re: Gets vertical skylines from grob stencils (issue 5626052)

From: David Kastrup
Subject: Re: Gets vertical skylines from grob stencils (issue 5626052)
Date: Sun, 19 Feb 2012 09:01:03 +0100
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/24.0.92 (gnu/linux)

"address@hidden" <address@hidden> writes:

> Here's what does:
> ----) Moving things to C++
> There's still a lot of scheme code in (scm_foo,
> scm_bar, etc.).

scm_xxx is not slow per se (the interpreter is more a cause for Scheme
slowness than the primitives).  However, Scheme data structures like
alists are often not really access-friendly.

> I don't know if this could be the reason for the slowdown.  The
> problem is that it's hard to get around this, as all of the data is
> stored in Scheme structures.

Depends on the kind of structure.  For one thing, it appears to me that
transform matrices should be smobified so that they don't get packed and
unpacked all the time but are basically transparently passed around in
Scheme and appear as a native type.  For most operations on them, you
should have a ly:xxx procedure that does not even bother unpacking
individual elements.

David Kastrup

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