PMM - The Package Manager Manager

PMM is a module for CMake that manages... package managers.

Wha- Why?

People hate installing new software. Especially when they already have a perfectly working tool present. PMM uses the CMake scripting language to manage external packaging tools. PMM will automatically download, install, and control package managers from within your CMake project.

(As you are reading this, only Conan and VCPKG are supported.)

But This is Just Another Tool I have to Manage!

Never fear! PMM is the lowest-maintenance software you will ever use.

How Do I Use PMM?

Using PMM is simple:

1. Download the pmm.cmake file (available at the top level of this respository), and place it at the top level of your repository (alongside your CMakeLists.txt).
2. In your CMakeLists.txt, add a line include(pmm.cmake).
3. Call the pmm() CMake function.

That's it! The pmm.cmake file is just 23 significant lines. Take a look inside if you doubt.

Wait... It's Downloading a Bunch of Stuff!

Precisely! pmm.cmake is just a bootstrapper for the real PMM code, which can be found in the pmm/ directory in the repository. The content is served over HTTPS from the gh-pages branch of the PMM repository, so it is all publicly visible.

I Don't Want to Automatically Download and Run Code from the Internet

Great! I sympathize, but remember: If you run apt, yum, pip, or even conan, you are automatically downloading and running code from the internet. It's all about whose code you trust.

Even still, you can host the PMM code yourself: Download the pmm/ directory as you want it, and modify the pmm.cmake script to download from your alternate location (eg, a corporate engineering intranet server).

Will PMM Updates Silently Break my Build?

Nope. pmm.cmake will never automatically change the version of PMM that it uses, and the files served will never be modified in-place: New versions will be added, but old versions will remain unmodified.

PMM will notify you if a new version is available, but it won't be annoying about it, and you can always disable this nagging by setting PMM_IGNORE_NEW_VERSION before including pmm.cmake.

How do I Change the PMM Version?

There are two ways:

1. Set PMM_VERSION before including the pmm.cmake script.
2. Modify the PMM_VERSION_INIT value at the top of pmm.cmake.

Prefer (1) for conditional/temporary version changes, and (2) for permanent version changes.

How do I Change the Download Location for PMM?

For permanent changes, set PMM_URL and/or PMM_URL_BASE in pmm.cmake. For temporary changes, set PMM_URL before including pmm.cmake

The pmm() Function

The only interface to PMM (after including pmm.cmake) is the pmm() CMake function. Using it is very simple. At the time or writing, pmm() only supports Conan and vcpkg, but other packaging solutions may be supported in the future.

The VERBOSE and DEBUG options enable verbose and debug logging, respectively. You may set PMM_{DEBUG,VERBOSE} before include(pmm.cmake) to enable these options globally and see information about the PMM bootstrapping process.

The pmm() signature:

pmm(
    # Enable verbose logging
    [VERBOSE]
    # Enable debug logging (implies VERBOSE)
    [DEBUG]
    # Use Conan
    [CONAN
        # Set additional --setting flags
        [SETTINGS ...]
        # Set additional --option flags
        [OPTIONS ...]
        # Set the --build option. (Default is `missing`)
        [BUILD <policy>]
        # Ensure remotes are present before installing
        [REMOTES [<name>[::no_verify] <url> [...]]]
        # Enable the Bincrafters repository
        [BINCRAFTERS]
        # Enable the conan-community repository
        [COMMUNITY]
    ]
    # Use vcpkg
    [VCPKG
        # Specify the revision of vcpkg that you want to use (required)
        REVISION <rev>
        # Ensure the given packages are installed using vcpkg
        [REQUIRES [req [...]]]
        # Copy custom ports to the vcpkg ports directory
        [PORTS [dirpath [...]]]
    ]
    # Use CMakeCM
    [CMakeCM
        # Either use the latest release, or specify a specific base URL to
        # download from
        {ROLLING | FROM <base-url>}
    ]
    # Use dds
    [DDS
        # Specify a toolchain. Given as the --toolchain argument to `build-deps`.
        # If not specified, one will be generated automatically based on the
        # current CMake settings.
        [TOOLCHAIN <toolchain>]
        # Give a path to a catalog json5 file to import before doing dependency
        # resolution. If not provided, the user-local catalog will be used.
        [CATALOG <catalog-json-path>]
        # List of dependency files. Given as --deps to `build-deps`.
        [DEP_FILES [filepath [...]]]
        # List of direct dependency strings.
        [DEPENDS [dep [...]]]
        # Call 'import_packages()' on the caller's behalf. With 'AUTO', all
        # packages named with 'DEPENDS' will be imported automatically.
        # Packages from DEP_FILES will need to be named explicitly.
        [IMPORT < AUTO | [pkg-name [...]] >]
    ]
)

CONAN PMM mode

In CONAN mode, PMM will find, obtain, and use Conan to manage project packages.

PMM will always use the cmake Conan generator, and will define imported targets for consumption (Equivalent of conan_basic_setup(TARGETS)). It will also set CMAKE_PREFIX_PATH and CMAKE_MODULE_PATH for you to use find_package() and include() against the installed dependencies.

NOTE: No other CMake variables from regular Conan usage are defined.

CONAN mode requires a conanfile.txt or conanfile.py in your project source directory. It will run conan install against this file to obtain dependencies for your project.

The nitty-gritty of how PMM finds/obtains Conan:

1. Check for the CONAN_EXECUTABLE variable. If found, it is used.
2. Try to find a conan executable. Searches:
   1. Any pyenv versions in the user home directory
   2. ~/.local/bin for user-mode install binaries
   3. C:/Python{36,27,}/Scripts for Conan installations
   4. Anything else on PATH
3. If still no Conan, attempts to obtain one automatically, trying first Python 3, then Python 2:
   1. Check for a venv or virtualenv executable Python module.
   2. Create a user-local virtualenv.
   3. Installs Conan within the created virtualenv and uses Conan from there.

PMM Will Not do Everything for You

While PMM will ensure that Conan has been executed for you as part of your configure stage, it is up to you to provide a Conanfile that Conan can consume to get your dependency information.

You will still need to read the Conan documentation to understand the basics of how to declare and consume your dependencies.

VCPKG PMM mode

In VCPKG mode, PMM will download the vcpkg repository at the given REVISION, build the vcpkg tool, and manage the package installation in a use-local data directory.

REVISION should be a git tree-ish (A revision number (preferred), branch, or tag) that you could git checkout from the vcpkg repository. PMM will download the specified commit from GitHub and build the vcpkg command line tool from source. You will need std::filesystem or std::experimental::filesystem support from your compiler and standard library.

If you want to copy custom ports to the vcpkg ports folder, you can define PORTS with a list of folders to copy over.

REQUIRES is a list of packages that you would like to install using the vcpkg command line tool.

When using PMM, you do not need to use the vcpkg.cmake CMake toolchain file: PMM will take care of this aspect for you.

After calling pmm(VCPKG), all you need to do is find_package() the packages that you want to use.

CMakeCM PMM mode

If CMakeCM is provided, PMM will download and make available the CMake Community Modules for you project.

Once the pmm() function is run, you may include or find_package any of the modules provided by CMakeCM.

You must also specify either ROLLING or FROM <base-url> to use CMakeCM with PMM:

• If you specify ROLLING, PMM will download the latest version of the CMakeCM module index every time you configure (with a few minutes of cooldown).
• If you specify FROM, the module index will only be obtained from the given base URL. Note: This URL is not the URL of a CMakeCM.cmake file: It is a url that prefixes the CMakeCM.cmake module URL.

DDS PMM mode

With DDS, PMM will automatically download and use dds to install dependencies. This will result in the generation of an INDEX.lmi file within the build directory that can be imported using the libman CMake module's import_packages function (currently available via CMakeCM).

Calling pmm(DDS) multiple times is allowed: Each call will append to the set of installed dependencies rather than override it.

The current compile flags, definitions, and include directories will be used to generate a toolchain file automatically if one is not provided.

The value of CMAKE_CXX_COMPILER_LAUNCHER will be given as the compiler launcher in the generated toolchain file. This can be override with PMM_DDS_COMPILER_LAUNCHER, including setting an empty string "" to disable it completely.

NOTE: dds support is still very experimental, and dds itself is very new at the time of this writing. Refer to the dds documentation for information about using dds.

Helper Commands

The pmm.cmake script can be run with -P to access a set of utility subcommands and options. See cmake -P pmm.cmake /Help for options. Additionally, after PMM has run for the first time, it will generate a sh and bat script that can be used to access the same set of options without needing cmake -P pmm.cmake:

Get help with the /Help option:

> pmm-cli.sh /Help

As an example, you can rebuild a Conan package with this command:

> pmm-cli.sh /Conan /Rebuild <package name> /BuildType <Release or Debug>