Metadata-Version: 1.1
Name: cppimport
Version: 18.1.10
Summary: Import C++ files directly from Python!
Home-page: https://github.com/tbenthompson/cppimport
Author: T. Ben Thompson
Author-email: t.ben.thompson@gmail.com
License: MIT
Description-Content-Type: UNKNOWN
Description: If you've used cppimport version 0.0.\*, some new features for you! Compiler arguments, multiple source files, bug fixes! Read on.
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        Import C or C++ files directly from Python!
        ===========================================
        
        Let's try it out. First, if you're on Linux or OS X, install with the
        terminal command ``pip install cppimport``.
        
        Most cppimport users combine it with
        `pybind11 <https://github.com/pybind/pybind11>`__, but you can use a
        range of methods to create your Python extensions. Raw C extensions,
        Boost.Python, SWIG all work. Let's look at a simple C++ extension:
        
        .. code:: cpp
        
            /*cppimport
            <%
            setup_pybind11(cfg)
            %>
            */
            #include <pybind11/pybind11.h>
        
            namespace py = pybind11;
        
            int square(int x) {
                return x * x;
            }
        
            PYBIND11_PLUGIN(somecode) {
                pybind11::module m("somecode", "auto-compiled c++ extension");
                m.def("square", &square);
                return m.ptr();
            }
        
        Save this code as ``somecode.cpp``.
        
        Open a python interpreter and run these lines `[1] <#notes>`__:
        
        .. code:: python
        
            >>> import cppimport
            >>> somecode = cppimport.imp("somecode") #This will pause for a moment to compile the module
            >>> somecode.square(9)
            81
        
        I'm a big fan of the workflow that this enables, where you can edit both
        C++ files and Python and recompilation happens transparently.
        
        I want things to be even easier! (Python import hook)
        =====================================================
        
        Modify the first section of the .cpp file and add "cppimport" on the
        first line of the file. This MUST be on the first line. This is
        explained further down.
        
        .. code:: cpp
        
            /*cppimport
            <%
            setup_pybind11(cfg)
            %>
            */
        
        Then import the file using the import hook:
        
        .. code:: python
        
            >>> import cppimport.import_hook
            >>> import somecode #This will pause for a moment to compile the module
            >>> somecode.square(9)
            81
        
        What's actually going on?
        =========================
        
        **The technical description:** cppimport looks for a C or C++ source
        file that matches the requested module. If such a file exists, the file
        is first run through the Mako templating system. The compilation options
        produced by the Mako pass are then use to compile the file as a Python
        extension. The extension (shared library) that is produced is placed in
        the same folder as the C++ source file. Then, the extension is loaded.
        
        **Simpler language please:** Sometimes Python just isn't fast enough. Or
        you have existing code in a C++ library. So, you write a Python
        *extension module*, a library of compiled code. I recommend
        `pybind11 <https://github.com/pybind/pybind11>`__ for C++ to Python
        bindings or `cffi <https://cffi.readthedocs.io/en/latest/>`__ for C to
        Python bindings. I've done this a lot over the years. But, I discovered
        that my productivity goes through the floor when my development process
        goes from *Edit -> Test* in just Python to *Edit -> Compile -> Test* in
        Python plus C++. So, ``cppimport`` combines the process of compiling and
        importing an extension in Python so that you can type
        ``modulename = cppimport.imp("modulename")`` and not have to worry about
        multiple steps. Internally, ``cppimport`` looks for a file
        ``modulename.cpp``. If one is found, it's run through the Mako
        templating system to gather compiler options, then it's compiled and
        loaded as an extension module.
        
        Note that because of the Mako pre-processing, the comments around the
        configuration block may be omitted.
        
        Recompilation only happens when necessary:
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
        
        Compilation should only happen the first time the module is imported.
        The C++ source is compared with a checksum on each import to determine
        if the file has changed. Additional dependencies (header files!) can be
        tracked by adding to the Mako header:
        
        ::
        
            cfg['dependencies'] = ['file1.h', 'file2.h']
        
        I need to set the compiler or linker args!
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
        
        ::
        
            cfg['linker_args'] = ['...']
            cfg['compiler_args'] = ['...']
            cfg['libraries'] = ['...']
            cfg['include_dirs'] = ['...']
        
        For example, to use C++11, add:
        
        ::
        
            <%
            cfg['compiler_args'] = ['-std=c++11']
            %>
        
        I want multiple source files for one extension!
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
        
        ::
        
            cfg['sources'] = ['...']
        
        I need more output!
        ~~~~~~~~~~~~~~~~~~~
        
        Calling ``cppimport.set_quiet(False)`` will result in output that will
        be helpful in debugging compile errors.
        
        Sometimes I need to force a rebuild even when the checksum matches
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
        
        Call ``cppimport.force_rebuild()`` before running
        ``cppimport.imp(...)``.
        
        I want incremental compiles on extensions with multiple sources.
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
        
        (For the uninitiated, incremental compilation involves only recompiling
        those source files that have changed or include headers that have
        changed.)
        
        cppimport is built on top of the setuptools and distutils, the standard
        library for python packaging and distribution. Unfortunately, setuptools
        does not support incremental compilation. I recommend following the
        suggestions on `this SO
        answer <http://stackoverflow.com/questions/11013851/speeding-up-build-process-with-distutils>`__.
        That is:
        
        1. Use ccache to (massively) reduce the cost of rebuilds
        2. Enable parallel compilation. This can be done with
           ``cfg['parallel'] = True`` in the C++ file's configuration header.
        
        I need information about filepaths in my module configuration code!
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
        
        The module name is available as the ``fullname`` variable and the C++
        module file is available as ``filepath``. For example,
        
        ::
        
            <%
            module_dir = os.path.dirname(filepath)
            %>
        
        Why does the import hook need "cppimport" on the first line of the .cpp file?
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
        
        Modifying the Python import system is a global modification and thus
        affects all imports from any other package. As a result, to avoid
        accidentally breaking another package, the import hook uses an "opt in"
        system where C and C++ files can specify they are meant to be used with
        cppimport by having a comment including the phrase "cppimport" on the
        first line of the file.
        
        Windows?
        ~~~~~~~~
        
        I don't know if ``cppimport`` works on Windows. If you're on Windows,
        try it out and I'll happily accept a pull request for any issues that
        you fix. I have reports that ``cppimport`` works on Windows with Python
        3.6 and Visual C++ 2015 Build Tools.
        
        cppimport uses the MIT License
        ==============================
        
Platform: any
Classifier: Development Status :: 5 - Production/Stable
Classifier: Intended Audience :: Developers
Classifier: Operating System :: OS Independent
Classifier: Operating System :: POSIX
Classifier: Topic :: Software Development
Classifier: License :: OSI Approved :: MIT License
Classifier: Programming Language :: Python :: 2
Classifier: Programming Language :: Python :: 3
Classifier: Programming Language :: C++
