Template function accepting a template class
I have a few aggreagator classes that are supposed to aggregate over a list of variables, for instance:
template<class T>
class Min{
public:
T val=0;
void aggregate(T val_){
if(val_ < val){
val = val_;
}
};
Now, I want to have a merge function that merges two aggregators together. It would accept 2 aggregators ,like Min, and their type.
template<class Agg, class T>
Agg<T> merge(Agg<T> agg1, Agg<T> agg2);
And I want to have a template specialization for each aggregator, but abstraction for the inner aggregator type. But I couldn't find the syntax for it. For instance,
template <> // specialization for Agg
template <class T> // abstraction for Agg's type
Min<T> merge<Min<T>>(Min<T> agg1, Min<T> agg2){...}
generates an error
error: too many template-parameter-lists
Min<T> merge<Min<T>>(Min<T> agg1, Min<T> agg2){...}
^~~~~~~~~~~~~
What is the correct syntax, then?
c++ templates
asked Dec 30 '18 at 15:07
yoavm448yoavm448
32
add a comment |
I have a few aggreagator classes that are supposed to aggregate over a list of variables, for instance:
template<class T>
class Min{
public:
T val=0;
void aggregate(T val_){
if(val_ < val){
val = val_;
}
};
Now, I want to have a merge function that merges two aggregators together. It would accept 2 aggregators ,like Min, and their type.
template<class Agg, class T>
Agg<T> merge(Agg<T> agg1, Agg<T> agg2);
And I want to have a template specialization for each aggregator, but abstraction for the inner aggregator type. But I couldn't find the syntax for it. For instance,
template <> // specialization for Agg
template <class T> // abstraction for Agg's type
Min<T> merge<Min<T>>(Min<T> agg1, Min<T> agg2){...}
generates an error
error: too many template-parameter-lists
Min<T> merge<Min<T>>(Min<T> agg1, Min<T> agg2){...}
^~~~~~~~~~~~~
What is the correct syntax, then?
c++ templates
asked Dec 30 '18 at 15:07
yoavm448yoavm448
32
add a comment |
I have a few aggreagator classes that are supposed to aggregate over a list of variables, for instance:
template<class T>
class Min{
public:
T val=0;
void aggregate(T val_){
if(val_ < val){
val = val_;
}
};
Now, I want to have a merge function that merges two aggregators together. It would accept 2 aggregators ,like Min, and their type.
template<class Agg, class T>
Agg<T> merge(Agg<T> agg1, Agg<T> agg2);
And I want to have a template specialization for each aggregator, but abstraction for the inner aggregator type. But I couldn't find the syntax for it. For instance,
template <> // specialization for Agg
template <class T> // abstraction for Agg's type
Min<T> merge<Min<T>>(Min<T> agg1, Min<T> agg2){...}
generates an error
error: too many template-parameter-lists
Min<T> merge<Min<T>>(Min<T> agg1, Min<T> agg2){...}
^~~~~~~~~~~~~
What is the correct syntax, then?
c++ templates
asked Dec 30 '18 at 15:07
yoavm448yoavm448
32
I have a few aggreagator classes that are supposed to aggregate over a list of variables, for instance:
template<class T>
class Min{
public:
T val=0;
void aggregate(T val_){
if(val_ < val){
val = val_;
}
};
Now, I want to have a merge function that merges two aggregators together. It would accept 2 aggregators ,like Min, and their type.
template<class Agg, class T>
Agg<T> merge(Agg<T> agg1, Agg<T> agg2);
And I want to have a template specialization for each aggregator, but abstraction for the inner aggregator type. But I couldn't find the syntax for it. For instance,
template <> // specialization for Agg
template <class T> // abstraction for Agg's type
Min<T> merge<Min<T>>(Min<T> agg1, Min<T> agg2){...}
generates an error
error: too many template-parameter-lists
Min<T> merge<Min<T>>(Min<T> agg1, Min<T> agg2){...}
^~~~~~~~~~~~~
What is the correct syntax, then?
c++ templates
c++ templates
asked Dec 30 '18 at 15:07
yoavm448yoavm448
32
asked Dec 30 '18 at 15:07
yoavm448yoavm448
32
edited Dec 30 '18 at 15:12
yoavm448
asked Dec 30 '18 at 15:07
yoavm448yoavm448
32
asked Dec 30 '18 at 15:07
yoavm448yoavm448
32
asked Dec 30 '18 at 15:07
yoavm448yoavm448
32
32
add a comment |
add a comment |
1 Answer
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Note that you must use template template syntax here, unlike your original code.
template<template<class> class Agg, class T>
Agg<T> merge(Agg<T> agg1, Agg<T> agg2);
But that is not really needed, considering the rest of this answer.
As for the rest of the question, partial specialization is allowed for template classes, but not for template functions. For functions such as yours, you should use overloading.
template <class T> // abstraction for Agg's type
Min<T> merge(Min<T> agg1, Min<T> agg2) {...}
answered Dec 30 '18 at 15:28
Michael VekslerMichael Veksler
2,7471515
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1 Answer
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1 Answer
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active
oldest
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oldest
votes
Note that you must use template template syntax here, unlike your original code.
template<template<class> class Agg, class T>
Agg<T> merge(Agg<T> agg1, Agg<T> agg2);
But that is not really needed, considering the rest of this answer.
As for the rest of the question, partial specialization is allowed for template classes, but not for template functions. For functions such as yours, you should use overloading.
template <class T> // abstraction for Agg's type
Min<T> merge(Min<T> agg1, Min<T> agg2) {...}
answered Dec 30 '18 at 15:28
Michael VekslerMichael Veksler
2,7471515
add a comment |
Note that you must use template template syntax here, unlike your original code.
template<template<class> class Agg, class T>
Agg<T> merge(Agg<T> agg1, Agg<T> agg2);
But that is not really needed, considering the rest of this answer.
As for the rest of the question, partial specialization is allowed for template classes, but not for template functions. For functions such as yours, you should use overloading.
template <class T> // abstraction for Agg's type
Min<T> merge(Min<T> agg1, Min<T> agg2) {...}
answered Dec 30 '18 at 15:28
Michael VekslerMichael Veksler
2,7471515
add a comment |
Note that you must use template template syntax here, unlike your original code.
template<template<class> class Agg, class T>
Agg<T> merge(Agg<T> agg1, Agg<T> agg2);
But that is not really needed, considering the rest of this answer.
As for the rest of the question, partial specialization is allowed for template classes, but not for template functions. For functions such as yours, you should use overloading.
template <class T> // abstraction for Agg's type
Min<T> merge(Min<T> agg1, Min<T> agg2) {...}
answered Dec 30 '18 at 15:28
Michael VekslerMichael Veksler
2,7471515
Note that you must use template template syntax here, unlike your original code.
template<template<class> class Agg, class T>
Agg<T> merge(Agg<T> agg1, Agg<T> agg2);
But that is not really needed, considering the rest of this answer.
As for the rest of the question, partial specialization is allowed for template classes, but not for template functions. For functions such as yours, you should use overloading.
template <class T> // abstraction for Agg's type
Min<T> merge(Min<T> agg1, Min<T> agg2) {...}
answered Dec 30 '18 at 15:28
Michael VekslerMichael Veksler
2,7471515
answered Dec 30 '18 at 15:28
Michael VekslerMichael Veksler
2,7471515
answered Dec 30 '18 at 15:28
Michael VekslerMichael Veksler
2,7471515
answered Dec 30 '18 at 15:28
Michael VekslerMichael Veksler
2,7471515
2,7471515
add a comment |
add a comment |
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