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Re: safe_call1 considered harmful

From: Kenichi Handa
Subject: Re: safe_call1 considered harmful
Date: Sun, 30 Jul 2006 18:18:48 +0900
User-agent: SEMI/1.14.3 (Ushinoya) FLIM/1.14.2 (Yagi-Nishiguchi) APEL/10.2 Emacs/22.0.50 (i686-pc-linux-gnu) MULE/5.0 (SAKAKI)

In article <address@hidden>, Richard Stallman <address@hidden> writes:

>     find-operation-coding-system calls a registered function
>     with a single argument; a list of arguments given to
>     find-operation-coding-system.  So, appending an extra
>     argument at the tail of the list is fairly safe.

> It might seem that way; but what happens if we change the calling
> convention of one of the operations, giving it an additional argument?
> That may be necessary some day.  I prefer the current convention.

We can change tar-mode/arc-mode/jka-compr to call
find-operation-coding-system with full number of arguments
plus the extra argument BUFFER.  Then, a function called
from find-operation-coding-system can check if the number of
arguments is greater than the normal number (which can be
checked by subr-arity).  If it is greater, the function can
know that the last argument is BUFFER.  By that way, the
function doesn't break even if we add a new argument to

Kenichi Handa

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