python - 试试……除了……除了……: how to avoid repeating code

Question

• 我想避免在多个地方写入 error Count += 1。
• 我正在寻找比
更好的方法

    success = False    try:        ...    else:        success = True    finally:        if success:            storage.store.commit()        else:            storage.store.rollback()

• I'm trying to avoid store.rollback() in every except clause.

Any idea on how to do this?

count = 0
successCount = 0
errorCount = 0
for row in rows:
    success = False
    count += 1
    newOrder = storage.RepeatedOrder()
    storage.store.add(newOrder)
    try:
        try:
            newOrder.customer = customers[row.customer_id]
        except KeyError:
            raise CustomerNotFoundError, (row.customer_id,)
        newOrder.nextDate = dates[row.weekday]
        _fillOrder(newOrder, row.id)
    except CustomerNotFoundError as e:
        errorCount += 1
        print u"Error: Customer not found. order_id: {0}, customer_id: {1}".format(row.id, e.id)
    except ProductNotFoundError as e:
        errorCount += 1
        print u"Error: Product not found. order_id: {0}, product_id: {1}".format(row.id, e.id)
    else:
        success = True
        successCount += 1
    finally:
        if success:
            storage.store.commit()
        else:
            storage.store.rollback()
print u"{0} of {1} repeated orders imported. {2} error(s).".format(successCount, count, errorCount)

Answer 1

这看起来像是 Python 的新 with 语句的可能应用。无论代码块产生什么结果，它都允许安全地展开操作和释放资源。

阅读 PEP 343