---
title: "parameter_type"
---

{{< callout type="info">}}
  Header: `parameter_type.h`  
{{< /callout >}}

Allows the method of passing a parameter to be determined by the type.  
By default, if the type is fundamental or a pointer, then the parameter type is 'by value', otherwise 'by const reference'.

```cpp
template <typename T>
struct parameter_type;
```

## Defines 
```cpp
type
```

The template may be specialised for specific types.  

## Example

```cpp
class MyClass
{
};

template <>
struct parameter_type<MyClass>
{
  // Pass Myclass by value.
  typedef MyClass type;
};

template <typename T>
void Do_Stuff(typename etl::parameter_type<T>::type parameter)
{
}

// Pass by value.
int i = 1;
Do_Stuff(i);

// Pass by const reference.
etl::vector<int, 10> data;
Do_Stuff(data);

// Pass by value
MyClass myClass;
Do_Stuff(myClass);
```