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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.
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, the wrapper requires that the callable object's construction, destruction, copy, and move operations are noexcept.

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_buffer_size::value>
using unique_safe_fn = ebd::basic_fn<
    Signature,
    BufferSize,
    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);

Custom View Wrapper with Larger Buffer

// Define a custom view wrapper with a larger buffer
template <typename Signature>
using large_fn_view = ebd::basic_fn<
    Signature,
    64,    // Larger buffer size
    true,  // IsCopyable (views are copyable)
    true,  // IsView (non-owning)
    false, // IsThrowing (call std::terminate() when empty)
    false  // AssertObjectNoThrow (no requirement)
>;

// Usage
void foo(int x) { /* do something */ }
large_fn_view<void(int)> view = &foo;
view(42);

Notes

  • Prefer using the predefined aliases (ebd::fn, ebd::unique_fn, ebd::safe_fn, ebd::fn_view) unless you need a combination not covered by them.
  • The buffer size is automatically aligned to the nearest word size.
  • If the callable object is too large for the specified buffer size, a static_assert will be triggered at compile time.

See Also