From: Daniel Gehriger (gehriger_at_[hidden])
Date: 2007-05-24 13:43:56
Eric Niebler wrote:
>
> This is by design. get_vector_float() returns a temporary object. You
> can't modify it.
> --snip--
>
Yes, shortly after my post I came to the same conclusion. Thank you for your
reply, though!
My I suggest an addition to BOOST_FOREACH ?
I happen to work with custom containers whose iterators are invalidated when
certain member functions are called on the contained objects. So I typically
use a loop pattern as follows:
-------------------
for (Coll::iterator it = col.begin(); it != col.end(); /* noop */)
{
Coll::value_type& o = *(it++);
o.destroy();
}
-------------------
I adapted the BOOST_FOREACH pattern to implement this pattern:
-------------------
#define FOREACH_PRE(VAR, COL)
\
BOOST_FOREACH_PREAMBLE()
\
if (boost::foreach_detail_::auto_any_t _foreach_col =
BOOST_FOREACH_CONTAIN(COL)) {} else \
if (boost::foreach_detail_::auto_any_t _foreach_cur =
BOOST_FOREACH_BEGIN(COL)) {} else \
if (boost::foreach_detail_::auto_any_t _foreach_end =
BOOST_FOREACH_END(COL)) {} else \
for (bool _foreach_continue = true;
\
_foreach_continue && !BOOST_FOREACH_DONE(COL);
\
/* noop */)
\
if (boost::foreach_detail_::set_false(_foreach_continue)) {} else
\
for (VAR = BOOST_FOREACH_DEREF(COL); !_foreach_continue;
_foreach_continue = true) \
if (BOOST_FOREACH_NEXT(COL), false) {} else
-------------------
Would you consider adding it to Boost ?
Regards,
Daniel Gehriger
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