How to use the pbr.packaging function in pbr

"""Obtain a version from pkg_resources or setup-time logic if missing.

        This will try to get the version of the package from the pkg_resources
        record associated with the package, and if there is no such record
        falls back to the logic sdist would use.
        """
        try:
            requirement = pkg_resources.Requirement.parse(self.package)
            provider = pkg_resources.get_provider(requirement)
            return provider.version
        except pkg_resources.DistributionNotFound:
            # The most likely cause for this is running tests in a tree
            # produced from a tarball where the package itself has not been
            # installed into anything. Revert to setup-time logic.
            from pbr import packaging
            return packaging.get_version(self.package)

record associated with the package, and if there is no such record
        falls back to the logic sdist would use.
        """
        # Lazy import because pkg_resources is costly to import so defer until
        # we absolutely need it.
        import pkg_resources
        try:
            requirement = pkg_resources.Requirement.parse(self.package)
            provider = pkg_resources.get_provider(requirement)
            result_string = provider.version
        except pkg_resources.DistributionNotFound:
            # The most likely cause for this is running tests in a tree
            # produced from a tarball where the package itself has not been
            # installed into anything. Revert to setup-time logic.
            from pbr import packaging
            result_string = packaging.get_version(self.package)
        return SemanticVersion.from_pip_string(result_string)

record associated with the package, and if there is no such record
        falls back to the logic sdist would use.
        """
        # Lazy import because pkg_resources is costly to import so defer until
        # we absolutely need it.
        import pkg_resources
        try:
            requirement = pkg_resources.Requirement.parse(self.package)
            provider = pkg_resources.get_provider(requirement)
            result_string = provider.version
        except pkg_resources.DistributionNotFound:
            # The most likely cause for this is running tests in a tree
            # produced from a tarball where the package itself has not been
            # installed into anything. Revert to setup-time logic.
            from pbr import packaging
            result_string = packaging.get_version(self.package)
        return SemanticVersion.from_pip_string(result_string)

self.add_command('pbr.packaging.LocalEggInfo')
        self.add_command('pbr.packaging.LocalSDist')
        self.add_command('pbr.packaging.LocalInstallScripts')
        self.add_command('pbr.packaging.LocalDevelop')
        self.add_command('pbr.packaging.LocalRPMVersion')
        self.add_command('pbr.packaging.LocalDebVersion')
        if os.name != 'nt':
            easy_install.get_script_args = packaging.override_get_script_args

        if packaging.have_sphinx():
            self.add_command('pbr.builddoc.LocalBuildDoc')

        if os.path.exists('.testr.conf') and packaging.have_testr():
            # There is a .testr.conf file. We want to use it.
            self.add_command('pbr.packaging.TestrTest')
        elif self.config.get('nosetests', False) and packaging.have_nose():
            # We seem to still have nose configured
            self.add_command('pbr.packaging.NoseTest')

        use_egg = options.get_boolean_option(
            self.pbr_config, 'use-egg', 'PBR_USE_EGG')
        # We always want non-egg install unless explicitly requested
        if 'manpages' in self.pbr_config or not use_egg:
            self.add_command('pbr.packaging.LocalInstall')
        else:
            self.add_command('pbr.packaging.InstallWithGit')

def hook(self):
        self.add_command('pbr.packaging.LocalEggInfo')
        self.add_command('pbr.packaging.LocalSDist')
        self.add_command('pbr.packaging.LocalInstallScripts')
        self.add_command('pbr.packaging.LocalDevelop')
        self.add_command('pbr.packaging.LocalRPMVersion')
        self.add_command('pbr.packaging.LocalDebVersion')
        if os.name != 'nt':
            easy_install.get_script_args = packaging.override_get_script_args

        if packaging.have_sphinx():
            self.add_command('pbr.builddoc.LocalBuildDoc')

        if os.path.exists('.testr.conf') and packaging.have_testr():
            # There is a .testr.conf file. We want to use it.
            self.add_command('pbr.packaging.TestrTest')
        elif self.config.get('nosetests', False) and packaging.have_nose():
            # We seem to still have nose configured
            self.add_command('pbr.packaging.NoseTest')

        use_egg = options.get_boolean_option(
            self.pbr_config, 'use-egg', 'PBR_USE_EGG')
        # We always want non-egg install unless explicitly requested
        if 'manpages' in self.pbr_config or not use_egg:
            self.add_command('pbr.packaging.LocalInstall')

def hook(self):
        self.config['include_package_data'] = 'True'
        packaging.append_text_list(
            self.config, 'dependency_links',
            packaging.parse_dependency_links())
        packaging.append_text_list(
            self.config, 'tests_require',
            packaging.parse_requirements(
                packaging.TEST_REQUIREMENTS_FILES,
                strip_markers=True))

#
    # fred =
    #     foo:marker
    #     bar
    # -> {'fred': ['bar'], 'fred:marker':['foo']}

    if 'extras' in config:
        requirement_pattern = (
            r'(?P[^:]*):?(?P[^#]*?)(?:\s*#.*)?$')
        extras = config['extras']
        # Add contents of test-requirements, if any, into an extra named
        # 'test' if one does not already exist.
        if 'test' not in extras:
            from pbr import packaging
            extras['test'] = "\n".join(packaging.parse_requirements(
                packaging.TEST_REQUIREMENTS_FILES)).replace(';', ':')

        for extra in extras:
            extra_requirements = []
            requirements = split_multiline(extras[extra])
            for requirement in requirements:
                m = re.match(requirement_pattern, requirement)
                extras_value = m.group('package').strip()
                env_marker = m.group('env_marker')
                extra_requirements.append((extras_value, env_marker))
            all_requirements[extra] = extra_requirements

    # Transform the full list of requirements into:
    # - install_requires, for those that have no extra and no
    #   env_marker
    # - named extras, for those with an extra name (which may include
    #   an env_marker)