traceback.py 文件源码

def _extract_tb_or_stack_iter(curr, limit, extractor):
    if limit is None:
        limit = getattr(sys, 'tracebacklimit', None)

    n = 0
    while curr is not None and (limit is None or n < limit):
        f, lineno, next_item = extractor(curr)
        co = f.f_code
        filename = co.co_filename
        name = co.co_name

        linecache.checkcache(filename)
        line = linecache.getline(filename, lineno, f.f_globals)

        if line:
            line = line.strip()
        else:
            line = None

        yield (filename, lineno, name, line)
        curr = next_item
        n += 1