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							252 lines
						
					
					
						
							7.6 KiB
						
					
					
				"""
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Build a c-extension module on-the-fly in tests.
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See build_and_import_extensions for usage hints
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"""
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import os
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import pathlib
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import sys
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import sysconfig
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__all__ = ['build_and_import_extension', 'compile_extension_module']
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def build_and_import_extension(
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        modname, functions, *, prologue="", build_dir=None,
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        include_dirs=[], more_init=""):
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    """
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    Build and imports a c-extension module `modname` from a list of function
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    fragments `functions`.
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    Parameters
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    ----------
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    functions : list of fragments
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        Each fragment is a sequence of func_name, calling convention, snippet.
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    prologue : string
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        Code to precede the rest, usually extra ``#include`` or ``#define``
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        macros.
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    build_dir : pathlib.Path
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        Where to build the module, usually a temporary directory
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    include_dirs : list
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        Extra directories to find include files when compiling
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    more_init : string
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        Code to appear in the module PyMODINIT_FUNC
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    Returns
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    -------
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    out: module
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        The module will have been loaded and is ready for use
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    Examples
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    --------
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    >>> functions = [("test_bytes", "METH_O", \"\"\"
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        if ( !PyBytesCheck(args)) {
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            Py_RETURN_FALSE;
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        }
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        Py_RETURN_TRUE;
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    \"\"\")]
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    >>> mod = build_and_import_extension("testme", functions)
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    >>> assert not mod.test_bytes(u'abc')
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    >>> assert mod.test_bytes(b'abc')
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    """
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    from distutils.errors import CompileError
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    body = prologue + _make_methods(functions, modname)
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    init = """PyObject *mod = PyModule_Create(&moduledef);
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           """
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    if not build_dir:
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        build_dir = pathlib.Path('.')
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    if more_init:
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        init += """#define INITERROR return NULL
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                """
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        init += more_init
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    init += "\nreturn mod;"
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    source_string = _make_source(modname, init, body)
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    try:
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        mod_so = compile_extension_module(
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            modname, build_dir, include_dirs, source_string)
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    except CompileError as e:
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        # shorten the exception chain
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        raise RuntimeError(f"could not compile in {build_dir}:") from e
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    import importlib.util
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    spec = importlib.util.spec_from_file_location(modname, mod_so)
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    foo = importlib.util.module_from_spec(spec)
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    spec.loader.exec_module(foo)
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    return foo
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def compile_extension_module(
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        name, builddir, include_dirs,
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        source_string, libraries=[], library_dirs=[]):
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    """
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    Build an extension module and return the filename of the resulting
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    native code file.
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    Parameters
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    ----------
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    name : string
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        name of the module, possibly including dots if it is a module inside a
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        package.
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    builddir : pathlib.Path
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        Where to build the module, usually a temporary directory
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    include_dirs : list
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        Extra directories to find include files when compiling
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    libraries : list
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        Libraries to link into the extension module
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    library_dirs: list
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        Where to find the libraries, ``-L`` passed to the linker
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    """
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    modname = name.split('.')[-1]
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    dirname = builddir / name
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    dirname.mkdir(exist_ok=True)
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    cfile = _convert_str_to_file(source_string, dirname)
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    include_dirs = include_dirs + [sysconfig.get_config_var('INCLUDEPY')]
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    return _c_compile(
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        cfile, outputfilename=dirname / modname,
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        include_dirs=include_dirs, libraries=[], library_dirs=[],
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        )
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def _convert_str_to_file(source, dirname):
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    """Helper function to create a file ``source.c`` in `dirname` that contains
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    the string in `source`. Returns the file name
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    """
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    filename = dirname / 'source.c'
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    with filename.open('w') as f:
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        f.write(str(source))
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    return filename
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def _make_methods(functions, modname):
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    """ Turns the name, signature, code in functions into complete functions
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    and lists them in a methods_table. Then turns the methods_table into a
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    ``PyMethodDef`` structure and returns the resulting code fragment ready
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    for compilation
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    """
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    methods_table = []
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    codes = []
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    for funcname, flags, code in functions:
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        cfuncname = "%s_%s" % (modname, funcname)
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        if 'METH_KEYWORDS' in flags:
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            signature = '(PyObject *self, PyObject *args, PyObject *kwargs)'
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        else:
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            signature = '(PyObject *self, PyObject *args)'
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        methods_table.append(
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            "{\"%s\", (PyCFunction)%s, %s}," % (funcname, cfuncname, flags))
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        func_code = """
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        static PyObject* {cfuncname}{signature}
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        {{
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        {code}
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        }}
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        """.format(cfuncname=cfuncname, signature=signature, code=code)
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        codes.append(func_code)
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    body = "\n".join(codes) + """
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    static PyMethodDef methods[] = {
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    %(methods)s
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    { NULL }
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    };
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    static struct PyModuleDef moduledef = {
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        PyModuleDef_HEAD_INIT,
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        "%(modname)s",  /* m_name */
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        NULL,           /* m_doc */
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        -1,             /* m_size */
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        methods,        /* m_methods */
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    };
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    """ % dict(methods='\n'.join(methods_table), modname=modname)
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    return body
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def _make_source(name, init, body):
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    """ Combines the code fragments into source code ready to be compiled
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    """
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    code = """
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    #include <Python.h>
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    %(body)s
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    PyMODINIT_FUNC
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    PyInit_%(name)s(void) {
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    %(init)s
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    }
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    """ % dict(
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        name=name, init=init, body=body,
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    )
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    return code
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def _c_compile(cfile, outputfilename, include_dirs=[], libraries=[],
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               library_dirs=[]):
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    if sys.platform == 'win32':
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        compile_extra = ["/we4013"]
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        link_extra = ["/LIBPATH:" + os.path.join(sys.base_prefix, 'libs')]
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    elif sys.platform.startswith('linux'):
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        compile_extra = [
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            "-O0", "-g", "-Werror=implicit-function-declaration", "-fPIC"]
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        link_extra = None
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    else:
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        compile_extra = link_extra = None
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        pass
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    if sys.platform == 'win32':
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        link_extra = link_extra + ['/DEBUG']  # generate .pdb file
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    if sys.platform == 'darwin':
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        # support Fink & Darwinports
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        for s in ('/sw/', '/opt/local/'):
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            if (s + 'include' not in include_dirs
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                    and os.path.exists(s + 'include')):
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                include_dirs.append(s + 'include')
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            if s + 'lib' not in library_dirs and os.path.exists(s + 'lib'):
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                library_dirs.append(s + 'lib')
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    outputfilename = outputfilename.with_suffix(get_so_suffix())
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    saved_environ = os.environ.copy()
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    try:
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        build(
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            cfile, outputfilename,
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            compile_extra, link_extra,
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            include_dirs, libraries, library_dirs)
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    finally:
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        # workaround for a distutils bugs where some env vars can
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        # become longer and longer every time it is used
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        for key, value in saved_environ.items():
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            if os.environ.get(key) != value:
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                os.environ[key] = value
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    return outputfilename
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def build(cfile, outputfilename, compile_extra, link_extra,
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          include_dirs, libraries, library_dirs):
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    "cd into the directory where the cfile is, use distutils to build"
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    from numpy.distutils.ccompiler import new_compiler
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    compiler = new_compiler(force=1, verbose=2)
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    compiler.customize('')
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    objects = []
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    old = os.getcwd()
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    os.chdir(cfile.parent)
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    try:
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        res = compiler.compile(
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            [str(cfile.name)],
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            include_dirs=include_dirs,
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            extra_preargs=compile_extra
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            )
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        objects += [str(cfile.parent / r) for r in res]
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    finally:
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        os.chdir(old)
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    compiler.link_shared_object(
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        objects, str(outputfilename),
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        libraries=libraries,
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        extra_preargs=link_extra,
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        library_dirs=library_dirs)
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def get_so_suffix():
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    ret = sysconfig.get_config_var('EXT_SUFFIX')
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    assert ret
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    return ret
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