Subject: Re: [Boost-bugs] [Boost C++ Libraries] #6126: Signed integer members of Boost.Fusion adapted ADTs are not output correctly with Boost.Spirit.Karma rules
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2012-02-02 01:03:20
#6126: Signed integer members of Boost.Fusion adapted ADTs are not output
correctly with Boost.Spirit.Karma rules
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Reporter: t0rt1e@⦠| Owner: hkaiser
Type: Bugs | Status: new
Milestone: To Be Determined | Component: spirit
Version: Boost 1.48.0 | Severity: Regression
Resolution: | Keywords: patch proposed, Boost.Spirit.Karma, Boost.Fusion, BOOST_FUSION_ADAPT_CLASS, BOOST_FUSION_ADAPT_ADT, short, int, long
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Comment (by bugs@â¦):
Thinking aloud:
I suppose the extract_from helper should just return the attribute proxy
by value.
I can see how that is undesirable for the general case (non-copyable or
copy-expensive attributes), but keep in mind that for adapted ADT's, the
`adt_attribute_proxy` instance can easily be returned by value while still
allowing the compiler to generate optimum code:
- RVO elides the copying,
- the caller can bind the temporary to a const& in case it needs to
access it twice (insert_int) and
- inlining does the rest
----
Of the wall: might this (the 'premature' decaying of the proxy to it's
exposed attribute type) have something to do with the special casing of
single-element-sequences in attribute extraction (decaying of a sequence
to it's single element)?
-- Ticket URL: <https://svn.boost.org/trac/boost/ticket/6126#comment:14> Boost C++ Libraries <http://www.boost.org/> Boost provides free peer-reviewed portable C++ source libraries.
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