前面的冒号：YAML语法

I'm currently using Sidekiq in a project and I have the following YAML config file:

我目前正在项目中使用Sidekiq，我有以下YAML配置文件：

:concurrency: 5
:pidfile: /tmp/pids/sidekiq.pid
:logfile: log/sidekiq.log
staging:
  :concurrency: 10
production:
  :concurrency: 20
queues:
  - default

I haven't seen having a colon in front of a key before but omitting that colon produces interesting results. In the case of the :pidfile: for example, with the colon in front it creates/overrides the destination file where is without it, it uses the one already there and does not write to it.

我之前没有看到在一把钥匙前面有一个冒号，但省略了冒号会产生有趣的结果。对于：pidfile：例如，前面有冒号，它创建/覆盖没有它的目标文件，它使用已存在的目标文件而不写入它。

Is this documented somewhere or is this simply how Sidekiq expects certain keys?

这是在某处记录的，还是Sidekiq对某些键的期望？

2 个解决方案

#1

YAML keys starting with a colon generate symbolized keys in Ruby, whereas keys without a colon will generate stringified keys:

以冒号开头的YAML键在Ruby中生成符号化键，而没有冒号的键将生成字符串化键：

require 'yaml'

string =<<-END_OF_YAML
:concurrency: 5
:pidfile: /tmp/pids/sidekiq.pid
:logfile: log/sidekiq.log
staging:
  :concurrency: 10
production:
  :concurrency: 20
queues:
  - default
END_OF_YAML

YAML.load(string)
# {
#     :concurrency => 5,
#     :pidfile     => "/tmp/pids/sidekiq.pid",
#     :logfile     => "log/sidekiq.log",
#     "staging"    => {
#         :concurrency => 10
#     },
#     "production" => {
#         :concurrency => 20
#     },
#     "queues"     => [
#         [0] "default"
#     ]
# }

Note: If a gem depends on symbolized keys then the stringified keys will not override its defaults.

注意：如果gem依赖于符号化键，则字符串化键不会覆盖其默认值。

#2

It is actually not sidekiq specific. The colon in front of a key just makes this key a symbol instead of a string:

它实际上不是sidekiq特定的。键前面的冒号只是使该键成为符号而不是字符串：

# example.yml
a:
  value: 1
:b:
  value: 2


yaml = YAML.load_file('example.yml')

yaml["a"] => { "value" => 1 }
yaml[:b] => { "value" => 1 }

So if your code accesses the config with key symbols, you should either add a colon in front of the key in the yaml file, or use some conversion of keys like #with_indifferent_access for the result hash (after parsing the yaml file)

因此，如果您的代码使用键符号访问配置，您应该在yaml文件中的键前添加冒号，或者使用#with_indifferent_access之类的一些键转换为结果哈希（在解析yaml文件之后）

#1