带冒号的 Groovy 扩展运算符映射语法

Question

我想知道为什么这种语法对于传播列表和 map 不一致。例如在这段代码中

def list =[1,2,3]
def map =[a:1,b:2]
println "${[*list]}"
println "${[*:map]}"

列表以单个 * 展开，并以 * 进行映射:

它与传播运算符内部的工作方式有关吗？因为没有看到 *map 构造的任何其他用法(比如用 [:] 定义一个空映射，以便将它与列表区分开来)。

Answer 1

展开运算符 (*) 用于从集合中提取条目并将它们作为单独的条目提供。

1. Spread list elements:

When used inside a list literal, the spread operator acts as if the spread element contents were inlined into the list:

def items = [4,5]               
def list = [1,2,3,*items,6]             
assert list == [1,2,3,4,5,6] 

来源:http://docs.groovy-lang.org/latest/html/documentation/#_spread_list_elements

2. Spread map elements:

The spread map operator works in a similar manner as the spread list operator, but for maps. It allows you to inline the contents of a map into another map literal, like in the following example:

def m1 = [c:3, d:4]         
def map = [a:1, b:2, *:m1] 
assert map == [a:1, b:2, c:3, d:4]​

来源:http://docs.groovy-lang.org/latest/html/documentation/#_spread_map_elements