Why can't this initializer-list match to a template argument?
#include <iostream>
class Foo
{
public:
template <typename Container>
Foo (const Container & args)
{
for (auto arg : args)
std::cout << "ARG(" << arg << ")n";
}
};
int main ()
{
Foo foo ({"foo", "bar", "baz"});
}
The error (using g++ -std=c++17) is
error: no matching function for call to ‘Foo::Foo(<brace-enclosed initializer list>)’
This works
Foo foo (std::vector<const char*> ({"foo", "bar", "baz"}));
Why can't the initializer-list match the template constructor?
c++ templates c++17 initializer-list template-deduction
edited Nov 7 '18 at 11:02
max66
36.8k74166
asked Nov 7 '18 at 10:29
spraffspraff
17.9k1486165
add a comment |
#include <iostream>
class Foo
{
public:
template <typename Container>
Foo (const Container & args)
{
for (auto arg : args)
std::cout << "ARG(" << arg << ")n";
}
};
int main ()
{
Foo foo ({"foo", "bar", "baz"});
}
The error (using g++ -std=c++17) is
error: no matching function for call to ‘Foo::Foo(<brace-enclosed initializer list>)’
This works
Foo foo (std::vector<const char*> ({"foo", "bar", "baz"}));
Why can't the initializer-list match the template constructor?
c++ templates c++17 initializer-list template-deduction
edited Nov 7 '18 at 11:02
max66
36.8k74166
asked Nov 7 '18 at 10:29
spraffspraff
17.9k1486165
add a comment |
#include <iostream>
class Foo
{
public:
template <typename Container>
Foo (const Container & args)
{
for (auto arg : args)
std::cout << "ARG(" << arg << ")n";
}
};
int main ()
{
Foo foo ({"foo", "bar", "baz"});
}
The error (using g++ -std=c++17) is
error: no matching function for call to ‘Foo::Foo(<brace-enclosed initializer list>)’
This works
Foo foo (std::vector<const char*> ({"foo", "bar", "baz"}));
Why can't the initializer-list match the template constructor?
c++ templates c++17 initializer-list template-deduction
edited Nov 7 '18 at 11:02
max66
36.8k74166
asked Nov 7 '18 at 10:29
spraffspraff
17.9k1486165
#include <iostream>
class Foo
{
public:
template <typename Container>
Foo (const Container & args)
{
for (auto arg : args)
std::cout << "ARG(" << arg << ")n";
}
};
int main ()
{
Foo foo ({"foo", "bar", "baz"});
}
The error (using g++ -std=c++17) is
error: no matching function for call to ‘Foo::Foo(<brace-enclosed initializer list>)’
This works
Foo foo (std::vector<const char*> ({"foo", "bar", "baz"}));
Why can't the initializer-list match the template constructor?
c++ templates c++17 initializer-list template-deduction
c++ templates c++17 initializer-list template-deduction
edited Nov 7 '18 at 11:02
max66
36.8k74166
asked Nov 7 '18 at 10:29
spraffspraff
17.9k1486165
edited Nov 7 '18 at 11:02
max66
36.8k74166
asked Nov 7 '18 at 10:29
spraffspraff
17.9k1486165
edited Nov 7 '18 at 11:02
max66
36.8k74166
edited Nov 7 '18 at 11:02
max66
36.8k74166
edited Nov 7 '18 at 11:02
max66
36.8k74166
36.8k74166
asked Nov 7 '18 at 10:29
spraffspraff
17.9k1486165
asked Nov 7 '18 at 10:29
spraffspraff
17.9k1486165
asked Nov 7 '18 at 10:29
spraffspraff
17.9k1486165
17.9k1486165
add a comment |
add a comment |
2 Answers
2
active
oldest
votes
{"foo", "bar", "baz"} has no type, so it cannot be deduced for
template <typename Container>
Foo (const Container&);
You can only use it for deduction for
template <typename T>
Foo (const std::initializer_list<T>&);
edited Nov 23 '18 at 20:00
Peter Mortensen
13.7k1986111
answered Nov 7 '18 at 10:32
Jarod42Jarod42
117k12103185
add a comment |
As explained by Jarod42, {"foo", "bar", "baz"} has no type, so it cannot be deduced for template <typename Container> Foo (const Container&).
Another possible solution is
template <typename T, std::size_t N>
Foo (T const (& arr)[N])
{
for (auto arg : arr)
std::cout << "ARG(" << arg << ")n";
}
so {"foo", "bar", "baz"} is deduced as an initialization list for a C-style array with the correct size (3).
edited Nov 23 '18 at 20:00
Peter Mortensen
13.7k1986111
answered Nov 7 '18 at 11:01
max66max66
36.8k74166
add a comment |
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
{"foo", "bar", "baz"} has no type, so it cannot be deduced for
template <typename Container>
Foo (const Container&);
You can only use it for deduction for
template <typename T>
Foo (const std::initializer_list<T>&);
edited Nov 23 '18 at 20:00
Peter Mortensen
13.7k1986111
answered Nov 7 '18 at 10:32
Jarod42Jarod42
117k12103185
add a comment |
{"foo", "bar", "baz"} has no type, so it cannot be deduced for
template <typename Container>
Foo (const Container&);
You can only use it for deduction for
template <typename T>
Foo (const std::initializer_list<T>&);
edited Nov 23 '18 at 20:00
Peter Mortensen
13.7k1986111
answered Nov 7 '18 at 10:32
Jarod42Jarod42
117k12103185
add a comment |
{"foo", "bar", "baz"} has no type, so it cannot be deduced for
template <typename Container>
Foo (const Container&);
You can only use it for deduction for
template <typename T>
Foo (const std::initializer_list<T>&);
edited Nov 23 '18 at 20:00
Peter Mortensen
13.7k1986111
answered Nov 7 '18 at 10:32
Jarod42Jarod42
117k12103185
{"foo", "bar", "baz"} has no type, so it cannot be deduced for
template <typename Container>
Foo (const Container&);
You can only use it for deduction for
template <typename T>
Foo (const std::initializer_list<T>&);
edited Nov 23 '18 at 20:00
Peter Mortensen
13.7k1986111
answered Nov 7 '18 at 10:32
Jarod42Jarod42
117k12103185
edited Nov 23 '18 at 20:00
Peter Mortensen
13.7k1986111
edited Nov 23 '18 at 20:00
Peter Mortensen
13.7k1986111
edited Nov 23 '18 at 20:00
Peter Mortensen
13.7k1986111
13.7k1986111
answered Nov 7 '18 at 10:32
Jarod42Jarod42
117k12103185
answered Nov 7 '18 at 10:32
Jarod42Jarod42
117k12103185
answered Nov 7 '18 at 10:32
Jarod42Jarod42
117k12103185
117k12103185
add a comment |
add a comment |
As explained by Jarod42, {"foo", "bar", "baz"} has no type, so it cannot be deduced for template <typename Container> Foo (const Container&).
Another possible solution is
template <typename T, std::size_t N>
Foo (T const (& arr)[N])
{
for (auto arg : arr)
std::cout << "ARG(" << arg << ")n";
}
so {"foo", "bar", "baz"} is deduced as an initialization list for a C-style array with the correct size (3).
edited Nov 23 '18 at 20:00
Peter Mortensen
13.7k1986111
answered Nov 7 '18 at 11:01
max66max66
36.8k74166
add a comment |
As explained by Jarod42, {"foo", "bar", "baz"} has no type, so it cannot be deduced for template <typename Container> Foo (const Container&).
Another possible solution is
template <typename T, std::size_t N>
Foo (T const (& arr)[N])
{
for (auto arg : arr)
std::cout << "ARG(" << arg << ")n";
}
so {"foo", "bar", "baz"} is deduced as an initialization list for a C-style array with the correct size (3).
edited Nov 23 '18 at 20:00
Peter Mortensen
13.7k1986111
answered Nov 7 '18 at 11:01
max66max66
36.8k74166
add a comment |
As explained by Jarod42, {"foo", "bar", "baz"} has no type, so it cannot be deduced for template <typename Container> Foo (const Container&).
Another possible solution is
template <typename T, std::size_t N>
Foo (T const (& arr)[N])
{
for (auto arg : arr)
std::cout << "ARG(" << arg << ")n";
}
so {"foo", "bar", "baz"} is deduced as an initialization list for a C-style array with the correct size (3).
edited Nov 23 '18 at 20:00
Peter Mortensen
13.7k1986111
answered Nov 7 '18 at 11:01
max66max66
36.8k74166
As explained by Jarod42, {"foo", "bar", "baz"} has no type, so it cannot be deduced for template <typename Container> Foo (const Container&).
Another possible solution is
template <typename T, std::size_t N>
Foo (T const (& arr)[N])
{
for (auto arg : arr)
std::cout << "ARG(" << arg << ")n";
}
so {"foo", "bar", "baz"} is deduced as an initialization list for a C-style array with the correct size (3).
edited Nov 23 '18 at 20:00
Peter Mortensen
13.7k1986111
answered Nov 7 '18 at 11:01
max66max66
36.8k74166
edited Nov 23 '18 at 20:00
Peter Mortensen
13.7k1986111
edited Nov 23 '18 at 20:00
Peter Mortensen
13.7k1986111
edited Nov 23 '18 at 20:00
Peter Mortensen
13.7k1986111
13.7k1986111
answered Nov 7 '18 at 11:01
max66max66
36.8k74166
answered Nov 7 '18 at 11:01
max66max66
36.8k74166
answered Nov 7 '18 at 11:01
max66max66
36.8k74166
36.8k74166
add a comment |
add a comment |
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