6.2 KiB
| title | weight |
|---|---|
| inplace_function | 1 |
{{< callout type="info">}}
Header: inplace_function.h
Since: 20.45.0
Similar to: std::function
{{< /callout >}}
A small, in-place function wrapper that stores callable objects inside a fixed-size buffer (no dynamic allocation). It supports free functions, member functions, functors, and lambdas, with both runtime and compile-time bindings.
template <typename TSignature,
size_t Object_Size = ETL_DEFAULT_INPLACE_FUNCTION_SIZE,
size_t Object_Alignment = ETL_DEFAULT_INPLACE_FUNCTION_ALIGNMENT>
class inplace_function;
The defaults are defined as follows:-
#if !defined(ETL_DEFAULT_INPLACE_FUNCTION_SIZE)
#define ETL_DEFAULT_INPLACE_FUNCTION_SIZE 32
#endif
#if !defined(ETL_DEFAULT_INPLACE_FUNCTION_ALIGNMENT)
#define ETL_DEFAULT_INPLACE_FUNCTION_ALIGNMENT alignof(void*)
#endif
Set your own definitions if you require different defaults.
Template Parameters
TSignature
Description
The function signature. e.g. int(char, float)
Object_Size
Description
Size of the internal storage buffer.
Defaults to ETL_DEFAULT_INPLACE_FUNCTION_SIZE.
Object_Alignment
Description
Alignment of the internal storage buffer.
Defaults to ETL_DEFAULT_INPLACE_FUNCTION_ALIGNMENT.
Exceptions
etl::inplace_function_exception
Description
Base exception.
etl::inplace_function_uninitialized
Description
Thrown (via ETL_ASSERT) when invoked without a target.
Member Types
function_type
Description
return_type
Description
argument_types
Description
Constructors
Description
Default constructor.
Description
Copy/move constructors.
Description
Construction from a free function pointer.
Description
Construction from an object + member function pointer (const or non-const).
Description
Construction from a lambda/functor (const or non-const).
Assignment
Description
Copy/move assignment.
Description
Assignment from nullptr clears the target.
Description
Assignment from function pointer.
Description
Assignment from lambda/functor.
Invocation
operator()
Description
Invokes the bound callable and asserts if uninitialised.
Parameters
Returns
call_if(...)
Description
Calls the delegate function, if valid.
Indicates success in the return type.
Parameters
TArgs...
Returns
For void return bool indicating whether it executed.
For non-void returns etl::optional<TReturn>.
call_or(...)
Description
Invokes the target or a fallback callable.
Parameters
Returns
Observers
bool is_valid() const
Returns
true if there is a valid callable.
explicit operator bool() const
Description
Parameters
Returns
The result of is_valid()
Modifiers
void clear()
Description
Clears any stored callable.
Parameters
None
Returns
void
void swap(inplace_function& other)
Description
Swaps with another inplace_function.
Parameters
None
Returns
'void`
Storage Introspection
static constexpr size_t size()
Description
Interogates the internal storage size.
Parameters
None
Returns
The size of the internal storage.
static constexpr size_t alignment()
Description
Interogates the internal storage alignment.
Parameters
None
Returns
The alignment of the internal storage.
Compile-Time Binding (No Payload)
Free function
template <TReturn(*Function)(TArgs...)>
void set()
Description
Sets the callable to Function.
template <TReturn(*Function)(TArgs...)>
inplace_function<TReturn(TArgs...),
Object_Size,
Object_Alignment> create()
Description
Creates an etl::inplace_function using Function.
Member function + instance (external linkage)
template <typename TObject, TReturn(TObject::*Method)(TArgs...), TObject& Instance>
set<TObject, &TMethod, Instance>()
Description
Sets the callable to the member function Method for the object Instance.
create<TObject, &TMethod, Instance>()
Description
Parameters
Returns
Callable object + instance (operator())
set<T, Instance>()
Description
Parameters
Returns
create<T, Instance>()
Description
Parameters
Returns
Helper Aliases
etl::inplace_function_for<TSignature, TStorage>
Description
Parameters
Returns
etl::inplace_function_for_any<TSignature, T0, ...>
Description
Parameters
Returns
Helper Factories
make_inplace_function(function_ptr)
Description
Parameters
Returns
make_inplace_function(obj, &Type::Method)
Description
Parameters
Returns
make_inplace_function(lambda_or_functor)
Description
make_inplace_function<TSignature>(function_like)
Description
Parameters
Returns
C++17-only overloads also exist for compile-time binding.
Example
#include "etl/inplace_function.h"
int add(int a, int b) { return a + b; }
struct Accumulator
{
int base = 0;
int add_to(int v) { return base + v; }
};
void example()
{
etl::inplace_function<int(int, int)> f(add);
int sum = f(1, 2);
Accumulator acc{ 10 };
etl::inplace_function<int(int)> g(&Accumulator::add_to, acc);
int result = g(5);
}
Notes
If the callable object is larger than Object_Size or requires stricter alignment than Object_Alignment, compilation fails with a static_assert.
operator() asserts when called without a target; use call_if or call_or to avoid this.
Prefer inplace_function_for, inplace_function_for_any or make_inplace_function to deduce storage sizes safely.