def _link(self, source, link_name, relative):
        '''
        Links link_name to source.

        Returns true if successfully linked files.
        '''
        success = False
        destination = os.path.expanduser(link_name)
        absolute_source = os.path.join(self._context.base_directory(), source)
        if relative:
            source = self._relative_path(absolute_source, destination)
        else:
            source = absolute_source
        if (not self._exists(link_name) and self._is_link(link_name) and
                self._link_destination(link_name) != source):
            self._log.warning('Invalid link %s -> %s' %
                (link_name, self._link_destination(link_name)))
        # we need to use absolute_source below because our cwd is the dotfiles
        # directory, and if source is relative, it will be relative to the
        # destination directory
        elif not self._exists(link_name) and self._exists(absolute_source):
            try:
                os.symlink(source, destination)
            except __HOLE__:
                self._log.warning('Linking failed %s -> %s' % (link_name, source))
            else:
                self._log.lowinfo('Creating link %s -> %s' % (link_name, source))
                success = True
        elif self._exists(link_name) and not self._is_link(link_name):
            self._log.warning(
                '%s already exists but is a regular file or directory' %
                link_name)
        elif self._is_link(link_name) and self._link_destination(link_name) != source:
            self._log.warning('Incorrect link %s -> %s' %
                (link_name, self._link_destination(link_name)))
        # again, we use absolute_source to check for existence
        elif not self._exists(absolute_source):
            if self._is_link(link_name):
                self._log.warning('Nonexistent target %s -> %s' %
                    (link_name, source))
            else:
                self._log.warning('Nonexistent target for %s : %s' %
                    (link_name, source))
        else:
            self._log.lowinfo('Link exists %s -> %s' % (link_name, source))
            success = True
        return success
dataset/ETHPy150Open anishathalye/dotbot/plugins/link.py/Link._link