Re: attack of silly coding standard?

From:

James Kanze <james.kanze@gmail.com>

Newsgroups:

comp.lang.c++

Date:

Wed, 8 Dec 2010 03:18:33 -0800 (PST)

Message-ID:

<5e3646f3-f61a-4747-8da5-e4d326fd0f64@k14g2000pre.googlegroups.com>

On Dec 7, 8:24 pm, Paavo Helde <myfirstn...@osa.pri.ee> wrote:

Keith H Duggar <dug...@alum.mit.edu> wrote in news:e7c2f043-d750-49b2-
9f4e-f3815f6b1...@p8g2000vbs.googlegroups.com:

Let's bring some concreteness to the debate. Give me an example
from your /real world/ code of a function having at least several
interesting lines and multiple returns that you think is "better"
for having multiple returns.

My 2 cents (will be converted to 0.1278 cents soon):

        Exception RecoverExceptionInCatch() throw() {
                try {
                        throw;
                } catch(const Exception& e) {
                        return e;
                } catch(const std::exception& e) {
                        return Exception("EX12", e.what());
                } catch(const char* what) {
                        return Exception("EX14", what);
                } catch( ... ) {
                        return Exception("EX16", "Unknown error");
                }
        }

-- and --

bool IpAddress::IsIpv4MappedIpv6() const {
        const unsigned char ipv4_prefix[12] =
{0,0,0,0,0,0,0,0,0,0,255,255};
        return af_==AF_INET6 && memcmp(ip_, ipv4_prefix, 12)==0;
}

bool IpAddress::operator==(const IpAddress& b) const {
        if (af_==b.af_) {
                return memcmp(ip_, b.ip_, 16)==0;
        } else if (af_==AF_INET) {
                DEBUG_ASSERT(b.af_==AF_INET6);
                return b.IsIpv4MappedIpv6() && memcmp(ip_, b.ip_+12, 4)==0;
        } else {
                DEBUG_ASSERT(b.af_==AF_INET);
                DEBUG_ASSERT(af_==AF_INET6);
                return IsIpv4MappedIpv6() && memcmp(b.ip_, ip_+12, 4)==0;
        }
}

I'd consider both acceptable; in the second case, I would think
about putting each of the branches in a separate function, so
that the operator== would just consist of:
    return af_ == b.af_
        ? memcmp(ip_, b.ip_, 16) == 0
        : af_ == AF_INET
        ? compareMapped(ip_, b.ip_)
        : compareMapped(b.ip_, ip_);
or something like that. For the first, however, I really don't
see any better alternative (but you'll have to admit that it's
a very special case).

--
James Kanze