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Re: [Chicken-users] a couple of questions about foreign functions

From: Felix Winkelmann
Subject: Re: [Chicken-users] a couple of questions about foreign functions
Date: Thu, 22 Jan 2004 09:02:50 +0100
User-agent: Opera7.21/Win32 M2 build 3218

Am Wed, 21 Jan 2004 23:52:38 -0800 hat Valentyn Kamyshenko <address@hidden> geschrieben:

When this function returns, `buf' will point into a dead stack area,
so the data is likely to be corrupted after the return.

I suspected it!.

What makes the following code correct, then (have found it in runtime.c):


it looks like the vector is created on the stack, and then 'returned' to the continuation...

Indeed. But the invocation of the continuation (via `C_kontinue') does
*never* return, the data will remain on the stack and be collected
when a certain stack-limit is reached. C-code wrapped with ##core#primitive
invokes it's continuation (and thus the stack is not popped), but code
wrapped with foreign-[callback-]lambda will return normally, in C fashion.

If you mean error-routines that eventually invoke Scheme, then
you should use foreign-callback-lambda*. If you handle the
error in C (for example to display a message and exit), then
I see no problem.
I actually meant smth similar to ##sys#signal-hook (the hope was that there is C function that do the same).

Not directly. You will have to invoke a Scheme callback for this
(for example defined with `define-external'). But actually it would be
helpful to have a simple C API for raising errors. Thanks for the


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