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ebd::basic_fn

Overview

ebd::basic_fn is a basic function wrapper that users can customize. It is an alias of ebd::detail::function that allows direct specification of all configuration parameters, providing the most flexible way to instantiate a function wrapper.

Template Parameters

Parameter Description
Signature Function signature, e.g., Ret(Args...) or Ret(Args...) const.
BufferSize Size of the internal storage (in bytes). The value will be automatically aligned to a multiple of Alignment.
Alignment Alignment of the internal storage (in bytes).
IsCopyable If true, the stored callable object must be copy-constructible; otherwise, move-only is sufficient.
IsView If true, the wrapper acts as a non-owning view (no copy/move/destroy of the target).
IsThrowing If true, calling an empty wrapper throws std::bad_function_call (if exceptions are enabled); otherwise, std::terminate is called.
AssertObjectNoThrow If true, an owning wrapper additionally requires the callable object's copy and move constructors, when present, to be noexcept; a deleted move constructor is allowed, and a deleted copy constructor is allowed only when IsCopyable is false. A noexcept destructor is required regardless of this flag. View wrappers (IsView is true) ignore both requirements, because they never construct or destroy the target.

Member Functions

All member functions of ebd::detail::function are available for ebd::basic_fn. For detailed documentation, see ebd::detail::function.

Usage Examples

Custom Move-Only, Non-Throwing Wrapper

#include "embed/embed_function.hpp"

// Define a custom move-only, non-throwing function wrapper
template <
    typename Signature,
    std::size_t BufferSize = ebd::detail::default_values::owning::buffer_size,
    std::size_t Alignment = ebd::detail::default_values::owning::alignment
>
using unique_safe_fn = ebd::basic_fn<
    Signature,
    BufferSize,
    Alignment,
    false, // IsCopyable (move-only)
    false, // IsView (owning)
    false, // IsThrowing (call std::terminate() when empty)
    true   // AssertObjectNoThrow (require noexcept operations)
>;

// Usage
unique_safe_fn<void(int)> fn;

// Assign a move-only, noexcept lambda
std::unique_ptr<int> value = std::make_unique<int>(42);
fn = [value = std::move(value)](int x) noexcept { /* use value */ };
fn(100);

Notes

  • Prefer using the predefined aliases (ebd::fn, ebd::unique_fn, ebd::classic_fn, ebd::fn_ref) unless you need a combination not covered by them.
  • The buffer size is automatically aligned to a multiple of Alignment.
  • If the callable object is too large or requires a larger alignment than the specified BufferSize/Alignment, a static_assert will be triggered at compile time.

See Also