Python sqlalchemy 模块，ext() 实例源码

def accumulate_size_by_extension(files):
    d = {}
    for (ext, size) in files:
        acc = d.get(ext, AccumulatedSize(ext, 0, 0))
        d[ext] = AccumulatedSize(acc.extension, acc.size + size, acc.files + 1)
    yield from d.values()

def main(directory):
    total_files, extensions = 0, set()
    for accumulated in accumulate_size_by_extension(get_files_info(directory)):
        total_files += accumulated.files
        extensions |= {accumulated}

    for (ext, size, files) in sorted(extensions, key=lambda acc: acc.files, reverse=True):
        yield render_row(ext, size, get_his(files, total_files))