#include <void_pointer.h>

#include <void_pointer.h>

void Example() {
    // Create some void* which know how to delete themselves
    void_ptr rover   = make_void<Dog>("Rover");
    void_ptr mittens = make_void<Cat>("Mittens");

    // Their types are erased, so feel free to store
    // them together in a container
    std::vector<void_ptr> pets;
    pets.emplace_back(std::move(rover));
    pets.emplace_back(std::move(mittens));

    // Cast them back to their original type
    Dog* rover_ptr   = pets[0]->as<Dog*>();
    Cat* mittens_ptr = pets[1]->as<Cat*>();
}

What?

A void* that knows how to delete itself.

Table of Contents

• #include <void_pointer.h>
  • What?
  • Table of Contents
  • Installation
    • xmake
      • xmake.lua
    • vcpkg
      • CMakeLists.txt
      • vcpkg.json
      • vcpkg-configuration.json
  • Why?
  • How?
  • Types
    • void_ptr
      • make_void()
      • make_void_ptr()
    • void_ptr_raw
      • make_raw_void()
      • make_raw_void_ptr()
  • Memory Management / Ownership
  • License

Installation

xmake

xmake.lua

add_repositories("MrowrLib https://github.com/MrowrLib/Packages.git")
add_requires("void_pointer")

target("Example")
    add_packages("void_pointer")

vcpkg

CMakeLists.txt

add_executable(Example main.cpp)

# Find void_pointer and link it to your target
find_package(void_pointer CONFIG REQUIRED)
target_link_libraries(Example PRIVATE void_pointer::void_pointer)

vcpkg.json

{
    "dependencies": ["mrowr-void-pointer"]
}

vcpkg-configuration.json

{
    "default-registry": {
        "kind": "git",
        "repository": "https://github.com/microsoft/vcpkg.git",
        "baseline": "95252eadd63118201b0d0df0b4360fa613f0de84"
    },
    "registries": [
        {
            "kind": "git",
            "repository": "https://github.com/MrowrLib/Packages.git",
            "baseline": "9721c54b76c90b0e644ed914886aa6d12ead452b",
            "packages": ["mrowr-void-pointer"]
        }
    ]
}

Update the default-registry baseline to the latest commit from https://github.com/microsoft/vcpkg
Update the MrowrLib/Packages baseline to the latest commit from https://github.com/MrowrLib/Packages

Why?

I needed a void* that knew how to delete itself.

True void* pointers are useful for storing pointers to unknown types.

But they come with the down side that you can't call delete on them.

This library provides a void* that knows how to delete itself.

You must know the type of the pointer when you create it, but after that you can use it as a void*.

Note: I need this for scenarios when I'm working with true void*.
If you have the option of using std::any, I recommend trying that instead!

How?

The latest version of <void_pointer.h> is is a thin wrapper around <managed_pointer.h>.

<managed_pointer.h>

https://github.com/MrowrLib/managed_pointer.h

The managed_pointer library offers a pointer which provides:

• Type-erasure
  • (e.g. to easily store any kind of pointers in the same container)
• Configuring the ownership of each pointer
  • (i.e. if the pointer should delete its internal pointer when it is destroyed)

Types

void_ptr

The void_ptr type is shorthand for:

std::unique_ptr<ManagedPointer::untyped_managed_ptr_impl>

The untyped_managed_ptr_impl type is the untyped base class for every managed_ptr.

It provides the type-erasure and ownership configuration features.

Note that it is a unique_ptr which means that:

• It cannot be copied, it must be moved
• It will be automatically deleted when it goes out of scope
  • This will delete its internal pointer (unless you configure it otherwise)

make_void()

Helper for creating void_ptr instances.

It constructs a new T.

void_ptr dog = make_void<Dog>("Rover");

make_void_ptr()

Helper for creating void_ptr instances from an existing pointer.

void_ptr dog = make_void_ptr(new Dog("Rover"));

void_ptr_raw

The void_ptr_raw type is shorthand for:

ManagedPointer::untyped_managed_ptr_impl*;

The untyped_managed_ptr_impl type is the untyped base class for every managed_ptr.

The void_ptr_raw type is the raw pointer version of void_ptr.

Note that it is a raw pointer which means that:

• It can be copied
• It will not be automatically deleted when it goes out of scope
• You must explicitly delete it when desired
  • This will delete its internal pointer (unless you configure it otherwise)

make_raw_void()

Helper for creating void_ptr_raw instances.

It constructs a new T.

void_ptr_raw dog = make_raw_void<Dog>("Rover");

make_raw_void_ptr()

Helper for creating void_ptr_raw instances from an existing pointer.

void_ptr_raw dog = make_raw_void_ptr(new Dog("Rover"));

Memory Management / Ownership

For the full memory management interface, see <managed_pointer.h>:

• https://github.com/MrowrLib/managed_pointer.h

By default, every void_ptr and void_ptr_raw will delete their internal pointer when they are destroyed.

This can be disabled:

void_ptr dog = make_void<Dog>("Rover");

// Disable automatic deletion
dog->disable_delete();

Here is an overview of the available functions:

void_ptr dog = make_void<Dog>("Rover");

// Disable automatic deletion
dog->disable_delete();

// Enable automatic deletion
dog->enable_delete();

// Explicitly configure automatic deletion
dog->set_deletes_pointer(true);

// Check if automatic deletion is enabled
bool deletes_pointer = dog->deletes_pointer();

License

Use however, no attribution required.

BSD Zero Clause License (SPDX: 0BSD)

Permission to use, copy, modify, and/or distribute this software for any purpose
with or without fee is hereby granted.

THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
THIS SOFTWARE.