yaml使用问题记录

YAML语法

https://learnxinyminutes.com/docs/yaml/
http://yaml.org/
http://yaml.org/spec/
http://yaml.org/refcard.html
http://www.yaml.org/spec/1.2/spec.html
https://zh.wikipedia.org/zh-cn/YAML
http://pyyaml.org/wiki/PyYAMLDocumentation
http://www.jianshu.com/p/5cf2f00b6656
http://www.ruanyifeng.com/blog/2016/07/yaml.html
http://www.yduba.com/biancheng-8553099226.html
http://blog.leanote.com/post/ozaki.lsc@gmail.com/YAML%E8%AF%AD%E6%B3%95
http://docs.saltstack.cn/topics/yaml/index.html
http://www.stay-stupid.com/?p=357

Python读取Yaml

class ConfigHandleClass:
    config = None

    @staticmethod
    def get_config_from_file(file_name):
        try:
            with open(file_name, 'r') as conf_fd:
                try:
                    ConfigHandleClass.config = yaml.load(conf_fd)
                except yaml.YAMLError as Err:
                    print("Error in configuration file: ", Err)

            return ConfigHandleClass.config
        except Exception as Err:
            print("Can not open configuration file: ", Err)

    @staticmethod
    def get_value_from_config(key, config=None):
        if config is None:
            config = ConfigHandleClass.config

        if isinstance(config, dict):
            temp_value = config.get(key)

            if temp_value is not None:
                return temp_value
            else:
                """
                for sub_key in config.keys():
                    sub_value = config.get(sub_key)
                    temp_value = ConfigHandleClass.get_value_from_config(key, sub_value)
                """
                for sub_value in config.values():
                    temp_value = ConfigHandleClass.get_value_from_config(key, sub_value)

                    if temp_value is not None:
                        return temp_value

yaml语法格式和使用示例(learnyaml.yaml)

https://learnxinyminutes.com/docs/yaml/


# Comments in YAML look like this.

################
# SCALAR TYPES #
################

# Our root object (which continues for the entire document) will be a map,
# which is equivalent to a dictionary, hash or object in other languages.
key: value
another_key: Another value goes here.
a_number_value: 100
scientific_notation: 1e+12
# The number 1 will be interpreted as a number, not a boolean. if you want
# it to be intepreted as a boolean, use true
boolean: true
null_value: null
key with spaces: value
# Notice that strings don't need to be quoted. However, they can be.
however: "A string, enclosed in quotes."
"Keys can be quoted too.": "Useful if you want to put a ':' in your key."

# Multiple-line strings can be written either as a 'literal block' (using |),
# or a 'folded block' (using '>').
literal_block: |
    This entire block of text will be the value of the 'literal_block' key,
    with line breaks being preserved.

    The literal continues until de-dented, and the leading indentation is
    stripped.

        Any lines that are 'more-indented' keep the rest of their indentation -
        these lines will be indented by 4 spaces.
folded_style: >
    This entire block of text will be the value of 'folded_style', but this
    time, all newlines will be replaced with a single space.

    Blank lines, like above, are converted to a newline character.

        'More-indented' lines keep their newlines, too -
        this text will appear over two lines.

####################
# COLLECTION TYPES #
####################

# Nesting is achieved by indentation.
a_nested_map:
    key: value
    another_key: Another Value
    another_nested_map:
        hello: hello

# Maps don't have to have string keys.
0.25: a float key

# Keys can also be complex, like multi-line objects
# We use ? followed by a space to indicate the start of a complex key.
? |
    This is a key
    that has multiple lines
: and this is its value

# YAML also allows mapping between sequences with the complex key syntax
# Some language parsers might complain
# An example
? - Manchester United
  - Real Madrid
: [ 2001-01-01, 2002-02-02 ]

# Sequences (equivalent to lists or arrays) look like this:
a_sequence:
    - Item 1
    - Item 2
    - 0.5 # sequences can contain disparate types.
    - Item 4
    - key: value
      another_key: another_value
    -
        - This is a sequence
        - inside another sequence

# Since YAML is a superset of JSON, you can also write JSON-style maps and
# sequences:
json_map: {"key": "value"}
json_seq: [3, 2, 1, "takeoff"]

#######################
# EXTRA YAML FEATURES #
#######################

# YAML also has a handy feature called 'anchors', which let you easily duplicate
# content across your document. Both of these keys will have the same value:
anchored_content: &anchor_name This string will appear as the value of two keys.
other_anchor: *anchor_name

# Anchors can be used to duplicate/inherit properties
base: &base
    name: Everyone has same name

foo: &foo
    <<: *base
    age: 10

bar: &bar
    <<: *base
    age: 20

# foo and bar would also have name: Everyone has same name

# YAML also has tags, which you can use to explicitly declare types.
explicit_string: !!str 0.5
# Some parsers implement language specific tags, like this one for Python's
# complex number type.
python_complex_number: !!python/complex 1+2j

# We can also use yaml complex keys with language specific tags
? !!python/tuple [5, 7]
: Fifty Seven
# Would be {(5, 7): 'Fifty Seven'} in python

####################
# EXTRA YAML TYPES #
####################

# Strings and numbers aren't the only scalars that YAML can understand.
# ISO-formatted date and datetime literals are also parsed.
datetime: 2001-12-15T02:59:43.1Z
datetime_with_spaces: 2001-12-14 21:59:43.10 -5
date: 2002-12-14

# The !!binary tag indicates that a string is actually a base64-encoded
# representation of a binary blob.
gif_file: !!binary |
    R0lGODlhDAAMAIQAAP//9/X17unp5WZmZgAAAOfn515eXvPz7Y6OjuDg4J+fn5
    OTk6enp56enmlpaWNjY6Ojo4SEhP/++f/++f/++f/++f/++f/++f/++f/++f/+
    +f/++f/++f/++f/++f/++SH+Dk1hZGUgd2l0aCBHSU1QACwAAAAADAAMAAAFLC
    AgjoEwnuNAFOhpEMTRiggcz4BNJHrv/zCFcLiwMWYNG84BwwEeECcgggoBADs=

# YAML also has a set type, which looks like this:
set:
    ? item1
    ? item2
    ? item3

# Like Python, sets are just maps with null values; the above is equivalent to:
set2:
    item1: null
    item2: null
    item3: null