Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!usc!samsung!uunet!lupine!rfg
From: rfg@NCD.COM (Ron Guilmette)
Newsgroups: comp.lang.c++
Subject: Re: C++ and UNIX Signals.
Message-ID: <1224@lupine.NCD.COM>
Date: 18 Aug 90 06:03:01 GMT
References: <1699@dinl.mmc.UUCP>
Organization: Network Computing Devices, Inc., Mt. View, CA
Lines: 29

In article <1699@dinl.mmc.UUCP> noren@dinl.UUCP (Charles Noren) writes:
>
>How reentrant is C++ code? ...
...
>Probably the real danger of C++ and signals is the ignorance
>that new C++ coders (like myself) of what C++ really does with
>things and inadvertantly writing non-reentrant code.  To help
>dispell this ignorance, I'll start a top 10 (20? 30?) list of
>coding techniques that makes your code NON-reentrant:
>
>1.  Put read/write static variables inside your C++ functions
>    (especially handy when called from signal handlers).

Just to clarify a bit, I believe that this could be restated as:

	Performing any operation on a variable (whose lifetime is the
	same as that of the entire program) which modifies that variable
	will tend to make your code non-reentrant.
	
You mentioned one category of "permanent lifetime" variables (i.e.
local variables declared as storage class `static') but there is also
the category of all file-scope (global) variables to consider.

This general rule applies to other languages as well (e.g. `C').
-- 

// Ron Guilmette  -  C++ Entomologist
// Internet: rfg@ncd.com      uucp: ...uunet!lupine!rfg
// Motto:  If it sticks, force it.  If it breaks, it needed replacing anyway.