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Jim Melton
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 Posted: Fri Feb 27, 2004 6:16 pm Post subject: RTTI lifetimes |
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Is this safe?
template<class T>
class AClass
{
std::type_info const& getType() const { return typeid(T); }
};
The question was raised internally about returning a reference to (what
appears to be) a temporary. Yet intuition says that the RTTI stuff is not
actually constructed in response to a typeid statement.
Is there a lifetime issue here?
--
<disclaimer>
Opinions posted are those of the author.
My company doesn't pay me enough to speak for them.
</disclaimer>
--
Jim Melton
Software Architect, Fusion Programs
Lockheed Martin IS&S
(303) 971-3846
[ See http://www.gotw.ca/resources/clcm.htm for info about ]
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kanze@gabi-soft.fr
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| Posted: Mon Mar 01, 2004 12:30 pm Post subject: Re: RTTI lifetimes |
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Jim Melton <jim.melton (AT) lmco (DOT) com> wrote
| Quote: | Is this safe?
template
class AClass
{
std::type_info const& getType() const { return typeid(T); }
};
The question was raised internally about returning a reference to
(what appears to be) a temporary. Yet intuition says that the RTTI
stuff is not actually constructed in response to a typeid statement.
|
Typically it isn't, but the standard does allow lazy construction
(something like a singleton, for example). However, §5.2.8/1: "The
result of a typeid expression is an lvalue [...]. The lifetime of the
object referred to by the lvalue extends to the end of the programm."
| Quote: | Is there a lifetime issue here?
|
There shouldn't be, except maybe in some cases with dynamically linked
objects. (The standard doesn't say anything about dynamic linking, but
I wouldn't be surprised that if you unload the object containing the
class, the type_info describing it disappear as well.)
--
James Kanze GABI Software mailto:kanze (AT) gabi-soft (DOT) fr
Conseils en informatique orientée objet/ http://www.gabi-soft.fr
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