January 2023
Intermediate to advanced
458 pages
14h 16m
Chinese
Content preview from 可编程网络自动化
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124
｜
第
5
章
with
open("example.yml")
as
f:
result = yaml.load(f)
print
(result)
type(result)
{'Brocade': True, 'Cisco': 6500, 'Juniper': 'Also a plant',
'VMware': ['esxi', 'vcenter', 'nsx']}
<type 'dict'>
上例中的代码片段用到了
Python
包
pyyaml
自带的
yaml
模块。可以使用第
4
章
讨论过的
pip
轻松安装。
这个例子展示了将
YAML
文件载入
Python
字典有多么简单。首先，使用上下文管理器打
开文件进行读取（在
Python
中读取任意文本文件的常见方法）
。然后，使用
yaml
模块的
load()
方法将文件载入字典
result
。后续输出表明一切顺利。
5.2.3
YAML
的数据模型
本章在前面提到过数据模型定义了以特定格式（比如
YAML
、
XML
或
JSON
）存储的数据
的结构。让我们看一下上一节中的一个
Y
AML
示例，在
YAML
数据模型的上下文中展开
讨论。
假设
Y
AML
文档中保存了下列数据。
---
Juniper: vSRX
Cisco: Nexus
Brocade: VDX
VMware: NSX
直观地说，通过观察
YAML
中的这些数据，我们清楚地知道这是一个厂商及其网络产品的
列表。我们已经在脑海中创建了一个数据模型：该
Y
AML
文档中的每一个条目都包含了一
对字符串值，第一个字符串（键）是厂商名称
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I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.