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Scott Frazer
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 Posted: Thu Sep 22, 2005 8:53 am Post subject: Template templates |
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I want to create template functions to clear out containers of pointers
to objects. I started out with this for std::list
template<typename T>
class DeleteObjectPtr {
public:
void operator()(T* objPtr) const { delete objPtr; }
};
template<typename T>
void destroyListOfPtrs(std::list<T*>& l) {
std::for_each(l.begin(), l.end(), DeleteObjectPtr<T>());
l.clear();
}
which works fine. Now I want it to work for other containers such as
std::deque and so on, but I don't want to write a template function for
each one. So how do I replace the "std::list" part of the template
function? I think I need to use template template parameters, but all
the syntax combinations I've tried won't compile.
Thanks,
Scott
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TonyO
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| Posted: Thu Sep 22, 2005 11:33 am Post subject: Re: Template templates |
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| Quote: | template<typename T
void destroyListOfPtrs(std::list
std::for_each(l.begin(), l.end(), DeleteObjectPtr<T>());
l.clear();
}
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template<typename ContainerT>
void destroyListOfPtrs(ContainerT& container) {
std::for_each(container.begin(), container.end(),
DeleteObjectPtr<typename ContainerT::value_type>());
container.clear();
}
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kwikius
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| Posted: Thu Sep 22, 2005 2:21 pm Post subject: Re: Template templates |
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Scott Frazer wrote:
| Quote: | I want to create template functions to clear out containers of pointers
to objects. I started out with this for std::list
template<typename T
class DeleteObjectPtr {
public:
void operator()(T* objPtr) const { delete objPtr; }
};
template
void destroyListOfPtrs(std::list
std::for_each(l.begin(), l.end(), DeleteObjectPtr<T>());
l.clear();
}
which works fine. Now I want it to work for other containers such as
std::deque and so on, but I don't want to write a template function for
each one. So how do I replace the "std::list" part of the template
function? I think I need to use template template parameters, but all
the syntax combinations I've tried won't compile.
|
This is one way (There are several others too of course).
template<
template
typename T,
typename A // allocator
| Quote: |
void destroyListOfPtrs(Container<T*,A> & c) { |
std::for_each(c.begin(), c.end(),DeleteObjectPtr<T>());
c.clear();
}
regards
Andy Little
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TonyO
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| Posted: Thu Sep 22, 2005 7:06 pm Post subject: Re: Template templates |
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TonyO wrote:
| Quote: | template<typename ContainerT
void destroyListOfPtrs(ContainerT& container) {
std::for_each(container.begin(), container.end(),
DeleteObjectPtr
container.clear();
}
|
Oops - you'll also need to modify DeleteObjectPtr<> to be templated on
the pointer type itself (not the object type):
template<typename PointerT>
class DeleteObjectPtr {
public:
void operator()(PointerT objPtr) const { delete objPtr; }
};
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kwikius
Guest
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| Posted: Sat Sep 24, 2005 2:07 am Post subject: Re: Template templates |
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Scott Frazer wrote:
| Quote: | I want to create template functions to clear out containers of pointers
to objects. I started out with this for std::list
template<typename T
class DeleteObjectPtr {
public:
void operator()(T* objPtr) const { delete objPtr; }
};
template
void destroyListOfPtrs(std::list
std::for_each(l.begin(), l.end(), DeleteObjectPtr<T>());
l.clear();
}
which works fine. Now I want it to work for other containers such as
std::deque and so on, but I don't want to write a template function for
each one. So how do I replace the "std::list" part of the template
function? I think I need to use template template parameters, but all
the syntax combinations I've tried won't compile.
|
You should look at :
http://www.boost.org/libs/smart_ptr/shared_ptr.htm
as an alternative approach to the problem above
regards
Andy Little
[ See http://www.gotw.ca/resources/clcm.htm for info about ]
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