etl/docs/utilities/function_traits.md

title
function_traits

{{< callout type="info">}} Header: function_traits.h
Since: TBC
{{< /callout >}}

Allows the traits of functions to be determined.

template <typename TReturn, typename... TArgs>
struct function_traits<TReturn(*)(TArgs...)>

Member types

function_type
The signature of the function.
TReturn(TArgs...)

---

return_type
The return type.
TReturn

---

object_type
The object type, if a member function, otherwise void.

---

argument_types
An etl::type_list of the arguments.
etl::type_list<TArgs...>

Member constants

is_function
true if a free or static member function.
bool

---

is_member_function
true if a member function.
bool

---

is_const
true if a const member function.
bool

---

argument_count
The number of arguments.
size_t

---

Example

int free_int(int i, int j);

class Object
{
public:
  int member_int(int i, int j);
  int member_int_const(int i, int j) const;
  static void member_static(int i, int j);
};

using traits1 = etl::function_traits<decltype(&free_int)>;

function_type      int(int, int)
return_type        int
object_type        void
argument_types     etl::type_list<int, int>
is_function        true
is_member_function false
is_const           false
argument_count     2

---

using traits2 = etl::function_traits<decltype(&Object::member_int)>;

function_type      int(int, int)
return_type        int
object_type        Object
argument_types     etl::type_list<int, int>
is_function        false
is_member_function true
is_const           false
argument_count     2

---

using traits3 = etl::function_traits<decltype(&Object::member_int_const)>;

function_type      int(int, int) const
return_type        int
object_type        Object
argument_types     etl::type_list<int, int>
is_function        false
is_member_function true
is_const           true
argument_count     2

---

using traits4 = etl::function_traits<decltype(&Object::member_static)>;

function_type      void(int, int)
return_type        void
object_type        void
argument_types     etl::type_list<int, int>
is_function        true
is_member_function false
is_const           false
argument_count     2