[boost] Re: ENFORCE
Gennaro Prota wrote: On Thu, 8 May 2003 15:06:02 +0300, John Torjo [EMAIL PROTECTED] wrote: Unfortunately, we can't use the do-while(0) idiom, since we don't know when while(0) will be ;-) Oops, no. That's not the problem. The problem is that I read Daniel's reply out of context and too absent-mindedly :-) I thought it was something like if (false) ; else whereas he is really testing for a condition if(expr)... However, if you are going to abort at the end (or throw, but I don't want to enter in this matter) you can simply replace 'if' with 'while': But that does not give you any benefit at all, does it? The do-while-idiom is very different from the while-version you suggest. It's IMHO the only idiom that forces the user to add a semicolon, but we actually don't want to do that here. The user should be allowed to add (i) or other stuff. I think that the 'if' (or 'while', but that's not a difference) is the best we can do here. Regards, Daniel -- Daniel Frey aixigo AG - financial training, research and technology Schloß-Rahe-Straße 15, 52072 Aachen, Germany fon: +49 (0)241 936737-42, fax: +49 (0)241 936737-99 eMail: [EMAIL PROTECTED], web: http://www.aixigo.de ___ Unsubscribe other changes: http://lists.boost.org/mailman/listinfo.cgi/boost
Re: [boost] Re: ENFORCE
Gennaro Prota wrote:
Just that Borland won't warn on BOOST_INVARIANT(false). Admittedly
not a big one :-)
This warning can be configured away simply by purposely accessing a non-constant
variable or calling an inline function:
inline bool force_non_constant() { return true; }
if (force_non_constant(), expr) else ...
Regards,
Paul Mensonides
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[boost] Re: ENFORCE
David Abrahams [EMAIL PROTECTED] wrote in message news:[EMAIL PROTECTED] Andrei Alexandrescu [EMAIL PROTECTED] writes: By the way, I believe what would be more interesting for Boost is the recent article (http://www.cuj.com/experts/2106/alexandr.htm), written by Petru Marginean and myself. (Warning - the article has recently been updated.) We have good experience in reducing source code size by using enforcements. There are a number of interesting techniques used out there, and I believe ENFORCE would be quite useful as a Boost library. I browsed the article (I confess to not having read everything, so please correct any misapprehensions). My sense is that the technique is oriented towards detecting programmer errors and responding via an exception. No. Andrei ___ Unsubscribe other changes: http://lists.boost.org/mailman/listinfo.cgi/boost
[boost] Re: ENFORCE
David Abrahams wrote: Andrei Alexandrescu [EMAIL PROTECTED] writes: By the way, I believe what would be more interesting for Boost is the recent article (http://www.cuj.com/experts/2106/alexandr.htm), written by Petru Marginean and myself. (Warning - the article has recently been updated.) We have good experience in reducing source code size by using enforcements. There are a number of interesting techniques used out there, and I believe ENFORCE would be quite useful as a Boost library. I browsed the article (I confess to not having read everything, so please correct any misapprehensions). My sense is that the technique is oriented towards detecting programmer errors and responding via an exception. I don't think ENFORCE is oriented toward that at all. There's no orientation involved other than to throw an exception based on a condition. I agree with you that direct programming errors should generally not throw exceptions but should ASSERT so that the programmer can fix the error. However I don't think ENFORCE has anything to do with this debate about when to ASSERT and when to throw exceptions. Perhaps the examples give the impression which you have, but I think the problem is just choosing better examples in which one would want to throw an exception and not a technical issue as to the benefits of using ENFORCE in order to simplify exception throwing. ___ Unsubscribe other changes: http://lists.boost.org/mailman/listinfo.cgi/boost
Re: [boost] Re: ENFORCE
Andrei Alexandrescu [EMAIL PROTECTED] writes: I browsed the article (I confess to not having read everything, so please correct any misapprehensions). My sense is that the technique is oriented towards detecting programmer errors and responding via an exception. No. Please correct my misapprehension then. I did go back and read more carefully without getting a different impression. -- Dave Abrahams Boost Consulting www.boost-consulting.com ___ Unsubscribe other changes: http://lists.boost.org/mailman/listinfo.cgi/boost
Re: [boost] Re: ENFORCE
Edward Diener [EMAIL PROTECTED] writes: I browsed the article (I confess to not having read everything, so please correct any misapprehensions). My sense is that the technique is oriented towards detecting programmer errors and responding via an exception. I don't think ENFORCE is oriented toward that at all. There's no orientation involved other than to throw an exception based on a condition. I agree with you that direct programming errors should generally not throw exceptions but should ASSERT so that the programmer can fix the error. However I don't think ENFORCE has anything to do with this debate about when to ASSERT and when to throw exceptions. Perhaps the examples give the impression which you have I think so. but I think the problem is just choosing better examples in which one would want to throw an exception and not a technical issue as to the benefits of using ENFORCE in order to simplify exception throwing. Can you show me a better example? This is not a challenge. Really, if this ENFORCE idea is a useful one I want to understand it. -- Dave Abrahams Boost Consulting www.boost-consulting.com ___ Unsubscribe other changes: http://lists.boost.org/mailman/listinfo.cgi/boost
Re: [boost] Re: ENFORCE
From: David Abrahams [EMAIL PROTECTED]
Edward Diener [EMAIL PROTECTED] writes:
I browsed the article (I confess to not having read everything, so
please correct any misapprehensions). My sense is that the technique
is oriented towards detecting programmer errors and responding via an
exception.
I don't think ENFORCE is oriented toward that at all. There's no
orientation
involved other than to throw an exception based on a condition. I agree
with
you that direct programming errors should generally not throw exceptions
but
should ASSERT so that the programmer can fix the error. However I don't
think ENFORCE has anything to do with this debate about when to ASSERT
and
when to throw exceptions. Perhaps the examples give the impression which
you
have
I think so.
but I think the problem is just choosing better examples in which
one would want to throw an exception and not a technical issue as to
the benefits of using ENFORCE in order to simplify exception
throwing.
Can you show me a better example? This is not a challenge. Really,
if this ENFORCE idea is a useful one I want to understand it.
I think something like:
templateclass T
inline T Enforce( T obj, const char* msg ) {
assert( !!obj, msg );
return obj;
}
(also it's const equivalent...not shown)
now you can do the same sort of thing as mentioned in the article
Enforce(cout) Enforce(MakeWidget())-ToString();
I would think that the compiler could optimize away the Enforce calls with
NDEBUG defined, but when not defined it will catch NULL derefs as the author
intended.
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