def load(self, requirements_file=None):
        """Load or reload requirements from a requirements.txt file.

        :param requirements_file: if not given, the filename used from
            initialization will be read again.
        """
        if requirements_file is None:
            requirements_file = self.filename
            if requirements_file is None:
                raise ValueError("no filename provided")
        elif isinstance(requirements_file, text_type):
            requirements_file = Path(requirements_file)
        self.clear()
        with requirements_file.open() as f:
            self.loads(f.read())

        if isinstance(requirements_file, (text_type, Path)):
            self.filename = requirements_file
def install_links(self):
        """Add symlinks into bin/, lib/ (eg, for other applications)"""
        # Make build log visible - it contains OpenFOAM-specific information
        with working_dir(self.projectdir):
            os.symlink(
                join_path(os.path.relpath(self.install_log_path)),
                join_path('log.' + str(self.foam_arch)))

        if not self.config['link']:
            return

        # ln -s platforms/linux64GccXXX/lib lib
        with working_dir(self.projectdir):
            if os.path.isdir(self.archlib):
                os.symlink(self.archlib, 'lib')

        # (cd bin && ln -s ../platforms/linux64GccXXX/bin/* .)
        with working_dir(join_path(self.projectdir, 'bin')):
            for f in [
                f for f in glob.glob(join_path('..', self.archbin, "*"))
                if os.path.isfile(f)
            ]:
                os.symlink(f, os.path.basename(f))