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scl@ict.ac.cn
Guest
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 Posted: Sat Mar 19, 2005 1:02 am Post subject: wrong link to destructor |
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there are two class with same name in an ugly program:
a.so
class REGION {
....
~REGION(){...}
}
b.so
class REGION {
....
~REGION(){}
}
where a.so's ~REGION is linked to b.so's ~REGION.
if i move the defination of ~REGION in a.so to a .cxx file, the ~REGION
in b.so will be linked to the ~REGION in a.so
what's wrong?
how to fixed?
(rename is NOT a practical idea!)
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Ron Natalie
Guest
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| Posted: Sat Mar 19, 2005 10:46 am Post subject: Re: wrong link to destructor |
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[email]scl (AT) ict (DOT) ac.cn[/email] wrote:
Violation of the One Definition Rule.
| Quote: | how to fixed?
(rename is NOT a practical idea!)
|
rename is the only portable answer. Either change one or the other
or put it in a namespace to disambiguate it.
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codigo
Guest
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| Posted: Sun Mar 20, 2005 11:56 pm Post subject: Re: wrong link to destructor |
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"scl (AT) ict (DOT) ac.cn" <sangchunlei (AT) gmail (DOT) com> wrote
| Quote: | there are two class with same name in an ugly program:
|
That breaks a fundamental rule. Say you declare:
Region region;
Which implementation should be called?
| Quote: |
a.so
class REGION {
...
~REGION(){...}
}
b.so
class REGION {
...
~REGION(){}
}
where a.so's ~REGION is linked to b.so's ~REGION.
|
That's impossible.
| Quote: |
if i move the defination of ~REGION in a.so to a .cxx file, the ~REGION
in b.so will be linked to the ~REGION in a.so
what's wrong?
how to fixed?
(rename is NOT a practical idea!)
|
Yes it is, use namespaces to seperate the decarations / implementations.
namespace A
{
class Region
{
....
};
};
namespace B
{
class Region
{
....
};
};
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kanze@gabi-soft.fr
Guest
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| Posted: Mon Mar 21, 2005 9:51 pm Post subject: Re: wrong link to destructor |
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[email]scl (AT) ict (DOT) ac.cn[/email] wrote:
| Quote: | there are two class with same name in an ugly program:
a.so
class REGION {
...
~REGION(){...}
}
b.so
class REGION {
...
~REGION(){}
}
where a.so's ~REGION is linked to b.so's ~REGION.
if i move the defination of ~REGION in a.so to a .cxx file,
the ~REGION in b.so will be linked to the ~REGION in a.so
what's wrong?
how to fixed?
(rename is NOT a practical idea!)
|
This isn't actually a C++ problem (since C++ doesn't have shared
objects), and is very dependant on the implementation. Since
you speak of .so files, I will suppose Posix, where the answer
is to pass the RTLD_LOCAL flag to dlopen when you load the
objects.
--
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
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Ben Hutchings
Guest
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| Posted: Tue Mar 22, 2005 9:07 am Post subject: Re: wrong link to destructor |
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[email]scl (AT) ict (DOT) ac.cn[/email] wrote:
| Quote: | there are two class with same name in an ugly program:
a.so
class REGION {
...
~REGION(){...}
}
b.so
class REGION {
...
~REGION(){}
}
where a.so's ~REGION is linked to b.so's ~REGION.
if i move the defination of ~REGION in a.so to a .cxx file, the ~REGION
in b.so will be linked to the ~REGION in a.so
what's wrong?
|
In a standard C++ program, there must only be one definition of a
named entity with external linkage. Unix dynamic linking normally
emulates static linking, so that this rule applies throughout all
shared objects. If the rule is violated, anything can happen.
| Quote: | how to fixed?
(rename is NOT a practical idea!)
|
You need to limit which symbols are exported. This is outside the
scope of standard C++. You may find section 2.2 of
<http://people.redhat.com/drepper/dsohowto.pdf> helpful.
--
Ben Hutchings
Having problems with C++ templates? Your questions may be answered by
<http://womble.decadentplace.org.uk/c++/template-faq.html>.
[ See http://www.gotw.ca/resources/clcm.htm for info about ]
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