锚点 & 和别名 * , 可以用来引用
defaults: &defaults
adapter: postgres
host: localhost
development:
database: myapp_development,
<<: *defaults
test:
database: myapp_test,
<<: *defaults
相当于
defaults:
adapter: postgres
host: localhost
development:
database: myapp_development,
adapter: postgres
host: localhost
test:
database: myapp_test,
adapter: postgres
host: localhost
&用来建立锚点（defaults），<<表示合并到当前数据，*用来引用锚点。
下面另外一个例子
- &showell Steve - Clark - Brian - Oren - *showell转为JavaScript
[ 'Steve', 'Clark', 'Brian', 'Oren', 'Steve' ]