Lambda作为参数传递给方法，错误的参数数量错误

Trying to sum values of items in a collection of sets by passing a lambda. I'm thinking this is just some syntax error:

尝试通过传递lambda来对集合集合中的项的值求和。我在想这只是一些语法错误:

# inputs
setCosts = {["A"] => 3, ["B"] => 4, ["A", "B"] => 5 }
collectionOfSets= [[["A"], ["B"]], [["A"], ["A", "B"]]]
# method and lambda
getSetCost = ->(x) { setCosts[x] }
def SumEachBy(collec, &lamb)    # stack trace starts here
    sum = 0
    collec.each { |x| sum += lamb(x) }
    return sum
end
# process output
collecValues = Hash[collectionOfSets.map { |set| [set, SumEachBy(set, getSetCost)] }]

I'm getting:

ArgumentError: wrong number of arguments (2 for 1)

I'm expecting collecValues to be:

我期待collecValues是:

{[["A"], ["B"]] => 7, [["A"], ["A", "B"]] => 8}

Where is my error?

我的错误在哪里?

By the way, if there's a better way to do this in Ruby, please let me know that too.

顺便说一句,如果有更好的方法在Ruby中这样做,请告诉我。

2 个解决方案

#1

Adding & before the last parameter means it would be bound to a block used along with method invocation, and you want to pass lambda as a param.

在最后一个参数之前添加&表示它将绑定到与方法调用一起使用的块,并且您希望将lambda作为参数传递。

Just remove it (def SumEachBy(collec, lamb)) and enjoy your lambda :)

只需删除它(def SumEachBy(collec,lamb))并享受你的lambda :)

#2

-1

I Dont know about the hole code but u can update the sum part by using inject:

我不知道孔代码,但你可以使用inject更新sum部分:

def SumEachBy(collec, lamb) 
  collection.inject(0) { |sum, value| sum += value }
end

I could understand your code at all, what do u want to achieve here?

我完全可以理解你的代码,你想在这里实现什么?

I edit the answer following Anton suggestion. =)

我根据安东的建议编辑答案。 =)

#1