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John Grabner
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 Posted: Tue Sep 27, 2005 8:23 am Post subject: STL typedefs and incomplete types |
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Given the following is it expected to compile. I need to use the
iterator definition in the actual definition of incomplete.
#include <map>
class incomplete;
typedef std::map<incomplete, int> myMap;
typedef myMap::iterator myMapIter;
John.
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Maxim Yegorushkin
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| Posted: Tue Sep 27, 2005 2:32 pm Post subject: Re: STL typedefs and incomplete types |
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John Grabner wrote:
| Quote: | Given the following is it expected to compile.
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No. The standard prohibits instantiating standard templates with
incomplete types.
http://devnet.developerpipeline.com/documents/s=9849/cujcexp2002austern/
I need to use the iterator definition in the actual definition of
incomplete.
| Quote: |
#include <map
class incomplete;
typedef std::map
typedef myMap::iterator myMapIter;
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You might like to redesign it. Provided information is not enough to
advise anything particular.
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kanze
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| Posted: Tue Sep 27, 2005 2:33 pm Post subject: Re: STL typedefs and incomplete types |
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John Grabner wrote:
| Quote: | Given the following is it expected to compile. I need to use the
iterator definition in the actual definition of incomplete.
#include <map
class incomplete;
typedef std::map
typedef myMap::iterator myMapIter;
|
No. The second typedef (if not the first) will provoke the
instantiation of the template, and the standard is clear:
instantiation of a template componant over an incomplete type is
undefined behavior.
--
James Kanze GABI Software mailto:james.kanze (AT) free (DOT) fr
Conseils en informatique orientée objet/
Beratung in objektorientierter Datenverarbeitung
9 place Sémard, 78210 St.-Cyr-l'École, France, +33 (0)1 30 23 00 34
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John Grabner
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| Posted: Wed Sep 28, 2005 10:13 am Post subject: Re: STL typedefs and incomplete types |
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| Quote: | #include <map
class incomplete;
typedef std::map
typedef myMap::iterator myMapIter;
You might like to redesign it. Provided information is not enough to
advise anything particular.
|
Ok second try.
#include <map>
#include <vector>
#include <string>
class Incomplete;
typedef std::vector<incomplete> Incompletes;
typedef std::map<std::string, Incomplete> IncompleteDict;
class Incomplete
{
public:
explicit Incomplete(const Incompletes &incompletes);
explicit Incomplete(const IncompleteDict &dict);
};
Is this standards conforming?
John.
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kanze
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| Posted: Thu Sep 29, 2005 8:15 pm Post subject: Re: STL typedefs and incomplete types |
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John Grabner wrote:
| Quote: | #include <map
class incomplete;
typedef std::map
typedef myMap::iterator myMapIter;
You might like to redesign it. Provided information is not
enough to advise anything particular.
Ok second try.
#include <map
#include
#include
class Incomplete;
typedef std::vector
typedef std::map<std::string, Incomplete> IncompleteDict;
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My current understanding is that the typedef's are legal. It is
undefined behavior to instantiate a template component of the
library with an incomplete type, but my understanding is that a
typedef does not trigger implicit instantiation.
I would really like it if someone who knows templates better
than I do would confirm this.
| Quote: | class Incomplete
{
public:
explicit Incomplete(const Incompletes &incompletes);
explicit Incomplete(const IncompleteDict &dict);
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Again, as long as only references to the standard classes are
used, there should be no problem. (In this case, there is an
explicit statement in the standard that declaring a reference or
a pointer to a template class does not trigger instantiation, so
I am pretty sure.)
| Quote: | };
Is this standards conforming?
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I think so. Note, however, that any code in the class
definition which uses the template class would not be; e.g. a
class member:
Incompletes children ;
--
James Kanze GABI Software
Conseils en informatique orientée objet/
Beratung in objektorientierter Datenverarbeitung
9 place Sémard, 78210 St.-Cyr-l'École, France, +33 (0)1 30 23 00 34
[ See http://www.gotw.ca/resources/clcm.htm for info about ]
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