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141 lines
2.3 KiB
Markdown
141 lines
2.3 KiB
Markdown
---
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title: "function_traits"
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---
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{{< callout type="info">}}
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Header: `function_traits.h`
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Since: `TBC`
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{{< /callout >}}
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Allows the traits of functions to be determined.
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```cpp
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template <typename TReturn, typename... TArgs>
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struct function_traits<TReturn(*)(TArgs...)>
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```
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## Member types
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`function_type`
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The signature of the function.
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`TReturn(TArgs...)`
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---
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`return_type`
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The return type.
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`TReturn`
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---
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`object_type`
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The object type, if a member function, otherwise `void`.
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---
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`argument_types`
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An `etl::type_list` of the arguments.
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`etl::type_list<TArgs...>`
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## Member constants
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`is_function`
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`true` if a free or static member function.
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`bool`
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---
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`is_member_function`
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`true` if a member function.
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`bool`
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---
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`is_const`
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`true` if a const member function.
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`bool`
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---
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`argument_count`
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The number of arguments.
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`size_t`
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---
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**Example**
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```cpp
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int free_int(int i, int j);
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class Object
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{
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public:
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int member_int(int i, int j);
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int member_int_const(int i, int j) const;
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static void member_static(int i, int j);
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};
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using traits1 = etl::function_traits<decltype(&free_int)>;
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```
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```cpp
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function_type int(int, int)
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return_type int
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object_type void
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argument_types etl::type_list<int, int>
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is_function true
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is_member_function false
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is_const false
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argument_count 2
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```
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---
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```cpp
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using traits2 = etl::function_traits<decltype(&Object::member_int)>;
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```
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```cpp
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function_type int(int, int)
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return_type int
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object_type Object
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argument_types etl::type_list<int, int>
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is_function false
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is_member_function true
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is_const false
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argument_count 2
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```
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---
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```cpp
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using traits3 = etl::function_traits<decltype(&Object::member_int_const)>;
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```
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```cpp
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function_type int(int, int) const
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return_type int
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object_type Object
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argument_types etl::type_list<int, int>
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is_function false
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is_member_function true
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is_const true
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argument_count 2
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```
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---
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```cpp
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using traits4 = etl::function_traits<decltype(&Object::member_static)>;
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```
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```cpp
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function_type void(int, int)
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return_type void
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object_type void
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argument_types etl::type_list<int, int>
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is_function true
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is_member_function false
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is_const false
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argument_count 2
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```
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