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Re: scm_init_guile when null threads
From: |
Oleg Parashchenko |
Subject: |
Re: scm_init_guile when null threads |
Date: |
Sun, 2 Apr 2006 19:29:23 +0400 |
Hello Ken,
On Sun, 2 Apr 2006 00:50:20 -0500
Ken Raeburn <address@hidden> wrote:
...
>
> You call scm_with_guile, and give it a function to call that
> manipulates Guile objects or calls Guile functions; it causes the
> thread to enter "guile mode", calls the function, leaves "guile mode"
> and returns to the caller. (You can also pass a pointer to whatever
> associated data you want, so you don't have to make your function
> rely on global variables.)
Thank you for explaining the interface.
>
> Since it controls entry and exit to your function, its ability to
> figure out where the "guile part" of the stack of that thread (needed
> for garbage collection) starts is much greater than with
> scm_init_guile. If you use scm_init_guile, it needs to figure out
> where the thread's stack's base is (yes, this may be easier on some
> platforms when configured for null threads), because under that
> interface, you could pop back up a few stack frames before invoking
> some Guile routines and storing objects into stack slots. Using
> scm_with_guile, your automatic variables with SCM objects won't get
> stored on the "wrong" side of the stack pointer that scm_with_guile
> has recorded.
I have two questions about scm_with_guile related to initialization and
nesting.
I have impression that before using Guile, one has to initialize Guile
using scm_init_gsubr(), scm_init_procprop() etc, but scm_with_guile
doesn't do it. Am I wrong?
Now about nesting. Let's suppose my program switches to Guile using
scm_with_guile (stack base "A"). Guile runs, at some moments executes
an extension function, and switches back to the program. The code needs
some Guile and calls scm_with_guile again (stack base "B"). The question:
does garbage collector work correctly, not missing the Scheme values
between "A" and "B"?
>
> Ken
--
Oleg Parashchenko olpa@ http://xmlhack.ru/ XML news in Russian
http://uucode.com/blog/ Generative Programming, XML, TeX, Scheme