Path: utzoo!news-server.csri.toronto.edu!rutgers!sun-barr!cs.utexas.edu!uunet!pdn!tscs!tct!chip
From: chip@tct.uucp (Chip Salzenberg)
Newsgroups: comp.lang.perl
Subject: Re: Why...
Message-ID: <27D7FB2E.472@tct.uucp>
Date: 8 Mar 91 20:59:26 GMT
References: <124891@uunet.UU.NET>
Organization: Teltronics/TCT, Sarasota, FL
Lines: 24

According to rbj@uunet.UU.NET (Root Boy Jim):
>...do shmread & shmwrite exist? Was it too much trouble to
>	create a variable whose size and location were fixed?
>
>...given that we really do want shmread & shmwrite, why is the
>	shared memory region repeatedly attached to & from?
>	Does perl open & close files between I/O :-)

I did the System V IPC support, so let me answer.

The reason was... laziness and impatience!  (How appropriate for
hacking Perl features...)

I needed support for System V IPC, but I didn't need speed.  I didn't
(and still don't) understand Perl's internals well enough to hack in
fixed-location and fixed-size variables.  Ergo, shmread/shmwrite.

As for the attach/detach, that's necessary to allow removed shared
memory segments to disappear -- if you keep a segment attached, it
will never disappear.
-- 
Chip Salzenberg at Teltronics/TCT     <chip@tct.uucp>, <uunet!pdn!tct!chip>
 "Most of my code is written by myself.  That is why so little gets done."
                 -- Herman "HLLs will never fly" Rubin